Tag: bacteria

A surprisingly wide range of bacteria live inside microwaves

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Microwaves heat up food, but don’t necessarily kill bacteria

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Microwave ovens in homes, offices and laboratories are home to a surprising diversity of bacteria.

Although microwaves are widely used to heat up food and sterilise samples, the radiation they emit is non-ionising, which means that it doesn’t damage biological molecules. They heat things up by making water molecules vibrate, but this only kills bacteria if they reach a high enough temperature.

Nevertheless, repeated bouts of heating and drying mean that microwaves were thought to be a difficult environment for microorganisms to survive in.

Alba Iglesias at the University of Valencia, Spain, and her colleagues took samples from 30 microwave ovens: 10 from single-household, domestic kitchens; 10 from shared kitchens such as corporate centres, scientific institutes and cafeterias; and 10 from molecular biology and microbiology laboratories.

In total, the researchers found 747 different genera of bacteria within 25 bacterial phyla. Diversity was lowest in single-household microwaves, and highest in laboratory appliances.

Many of the bacteria found in shared, domestic microwaves and the single-household microwaves overlapped, and were similar to the bacteria often found on human hands and in other parts of the kitchen. However, those in labs, where food was not cooked, were more distinct and were similar to the microbiome found in other extreme, dry, hot and irradiated environments, such as on solar panels.

The researchers noted that some bacteria found in domestic microwaves, such as Klebsiella, Enterococcus and Aeromonas, may pose a risk to human health. However, they say the microbial population found in microwaves does not present a unique or increased risk compared with other common kitchen surfaces. The researchers didn’t respond to an interview request.

Belinda Ferrari at the University of New South Wales, Australia, says she is not surprised at all that the researchers found bacteria living in microwaves. “They can survive in almost any extreme-exposure environment and they can adapt to everything,” she says.

Ferrari recommends regularly cleaning microwaves with disinfectant products. “Some workplace microwaves are disgusting and no one cleans them,” she says.

She would like to see more information in the study about when the microwaves were last cleaned. “If I was doing this experiment, I would also like to study the biome before and after cleaning,” she says.

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August 8, 2024
How to Avoid Getting Sick This Summer

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This article is republished from The Conversation under a Creative Commons license.

As flowers bloom and temperatures climb, many are eager to get back outside. But while the sun may be shining, there is a dark side that can make the great outdoors not so great.

Gangs of germs are lurking in the woods, in the soil, in the water, and in your food, ready to rain on your summer parade.

I’m a professor of microbiology at the Indiana University School of Medicine, where I study and teach about infectious disease. Here are some things to keep in mind to help you and your loved ones stay free of illness while enjoying summer activities.

Germs in the Backyard

There’s nothing like the smell of a good barbecue and fresh goodies from your own garden. To make sure people leave your party with only good memories, be aware of germs commonly linked to food poisoning, which can result in diarrhea, cramps, nausea, vomiting, and fever.

Meats, including fish and poultry, often house harmful bacteria such as Salmonella, E. coli, or Listeria. Raw meat can contaminate anything it touches, so be sure to wash your hands and disinfect surfaces and utensils. To avoid cross contamination, do not keep uncooked meat near prepared foods. Meat products must be cooked to proper temperatures to ensure harmful germs are destroyed before consuming.

Washing cooking utensils that touch raw meat can reduce cross contamination.

Photograph: Catherine Falls Commercial/Moment via Getty Images

In addition to bacteria, a parasite called Toxoplasma gondii can cause acute food poisoning. Toxoplasma parasites are shed as microscopic oocysts in the feces of infected cats. Oocysts persist in the environment for a year or more, and other animals, including people, can inadvertently ingest them.

Upon infection, Toxoplasma forms tissue cysts in the flesh of food animals—another reason to cook your meats thoroughly. Pregnant people need to take special care in avoiding Toxoplasma, since the parasite can cross the placenta and cause miscarriage or birth defects.

To avoid getting toxoplasmosis from oocysts, people should wear gloves while gardening, wash fruits and vegetables, and make sure the sandbox is free of cat poop and covered when not in use.

Germs in the Water

Recreational water facilities such as pools, water parks, and fountains are a great way to beat the summer heat. The smell of chlorine is a good sign that the water is being treated to kill many types of germs.

Unfortunately, some germs can remain infectious in chlorine for several minutes or days, which is plenty of time to spread from one person to another. These include viruses such as norovirus, bacteria such as E. coli, and parasites such as Cryptosporidium and Giardia.

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June 15, 2024
Red squirrels were hosts for leprosy in medieval England

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Red squirrels can carry bacteria that cause leprosy

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The DNA of leprosy-causing bacteria has been found in the remains of people and a red squirrel unearthed at medieval sites in the UK. This makes red squirrels the earliest known non-human hosts of the infection and suggests it may have spread between the rodents and people at the time.

In 2016, scientists found that red squirrels (Sciurus vulgaris) around the UK carry strains of Mycobacterium leprae, the bacterium that causes the chronic disease leprosy. Some of the strains were similar to ones that infected people in England more than 700 years ago.

“So, we had an inkling that maybe medieval red squirrels have had it too,” says Sarah Inskip at the University of Leicester in the UK.

To investigate further, Inskip and her colleagues examined the remains of 25 people uncovered at the site of a medieval hospital for people with leprosy in Winchester and 12 red squirrels found at a nearby site that was home to at least one fur shop between the 11^th and 13^th centuries.

Most of the human bones exhibited the characteristic lesions associated with leprosy, while the squirrel bones showed signs of inflammation, another possible sign of the disease.

By analysing the DNA in the bones, the team found genetic sequences from M. leprae in three people and one red squirrel.

“There really was leprosy circulating among medieval squirrels,” says Inskip, making the species the earliest reported non-human carrier of leprosy.

The DNA showed that the strain of M. leprae found in the medieval red squirrel was more closely related to those in the three medieval people than to those in modern red squirrels. This indicates that the infection probably spread back and forth between squirrels and people in England in the Middle Ages.

“There were a lot of opportunities for transmission in medieval Winchester,” says Verena Schünemann at the University of Basel, Switzerland, who also worked on the study. In addition to the hospital and well-known fur trade in the city, historical reports from the period suggest that people in the area often kept squirrels as pets, she says.

The findings also suggest that the leprosy strains found in modern squirrels may not necessarily have descended from the strain found in this specimen. “It may be that there has been more than one transmission event between humans and squirrels over history,” says Inskip.

Although some small populations of red squirrels have leprosy today, it is important to stress that the transmission risk to people is basically zero, says Schünemann.

“Leprosy has definitely been around for a long time and M. leprae likely has a far more robust ecological history than our previous modern-day observations might have suggested,” says Richard Truman, formerly at the US Public Health Service. “It is important that we understand this better.”

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May 3, 2024
How Synthetic Bacteria Could Revolutionize Chemical Production

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The chemical industry, which heavily relies on fossil resources to produce plastics, dyes, and artificial flavors, consumes over one million tons of these resources daily, contributing to approximately 5% of global emissions. Researchers, led by Professor Julia Vorholt, are working on reducing this dependency by developing synthetic bacteria that can convert ‘green methanol’—created from CO2 and water using renewable energy—into useful chemicals, potentially minimizing the industry’s carbon footprint. Credit: Sean Kilian

The chemical industry primarily depends on fossil resources like crude oil to manufacture a range of chemicals, including plastics, dyes, and synthetic flavors.

“Globally, it consumes 500 million tons per year, or more than one million tons per day,” says Julia Vorholt, Professor at the Institute of Microbiology at ETH Zurich. “Since these chemical conversions are energy-intensive, the true CO₂ footprint of the chemical industry is even six to ten times larger, amounting to about five percent of total emissions globally.” She and her team are looking for ways to reduce the chemical industry’s dependence on fossil fuels.

Green methanol

Bacteria that feed on methanol, known as methylotrophs, are at the center of these efforts. Containing just a single carbon atom, methanol is one of the simplest organic molecules and can be synthesized from the greenhouse gas carbon dioxide and water. If the energy for this synthesis reaction comes from renewable sources, the methanol is termed “green”.

“There are natural methylotrophs, but using them industrially remains difficult despite considerable research effort,” says Michael Reiter, a postdoctoral researcher in Vorholt’s research group, which instead works with the biotechnologically well-understood model bacterium Escherichia coli. Vorholt’s team has been pursuing the idea of equipping the model bacterium, which grows on sugar, with the ability to metabolize methanol for several years.

Complete restructuring of metabolism

“This is a major challenge because it requires a complete restructuring of the cell’s metabolism,” says Vorholt. Initially, the researchers simulated this change using computer models. Based on these simulations, they chose two genes to remove and three new genes to introduce. “As a result, the bacteria could take up methanol, albeit only in small quantities,” says Reiter.

They continued to grow the bacteria under special conditions in the laboratory for more than a year until the microbes could produce all cell components from methanol. Over the course of around 1,000 more generations, these synthetic methylotrophs became increasingly efficient, eventually doubling every four hours when fed only with methanol. “The improved growth rate makes the bacteria economically interesting,” says Vorholt.

Optimization through loss of function

As Vorholt’s team describes in their recently published paper, several randomly occurring mutations are responsible for the increased efficiency of methanol utilization. Most of these mutations resulted in the loss of function of various genes. This is surprising at first glance, but upon closer inspection, it becomes apparent that the cells can save energy thanks to the loss of function of the genes. For example, some mutations cause the reverse reactions of important biochemical reactions to fail. “This abolishes superfluous chemical conversions and optimizes the metabolic flux in the cells,” the researchers write.

To explore the potential of synthetic methylotrophs for the biotechnological production of industrially relevant bulk chemicals, Vorholt and her team have equipped the bacteria with additional genes for four different biosynthetic pathways. In their study, they now show that the bacteria indeed produced the desired compounds in all cases.

Versatile production platform

For the researchers, this is clear evidence that their engineered bacteria can deliver on what was originally promised: the microbes are a kind of highly versatile production platform into which biosynthesis modules can be inserted according to the “plug-and-play” principle, prompting the bacteria to convert methanol into desired biochemical substances.

However, the researchers still need to significantly increase the yield and productivity to enable economically viable use of the bacteria. Vorholt and her team recently received an innovation fund “to further expand plans towards applications and to select products to focus on first,” says Vorholt.

When Reiter talks about how the cultivation of bacteria in bioreactors can be optimized, he is filled with enthusiasm. “Given the challenges of climate change, it is clear that alternatives to fossil resources are needed,” he says. “We are developing a technology that does not emit additional CO₂ into the atmosphere,” says Reiter. And since the synthetic methylotrophs, besides green methanol, do not require any additional carbon sources for their growth and products, they allow “renewable chemicals to be produced that do not burden the environment.”

Reference: “A synthetic methylotrophic Escherichia coli as a chassis for bioproduction from methanol” by Michael A. Reiter, Timothy Bradley, Lars A. Büchel, Philipp Keller, Emese Hegedis, Thomas Gassler and Julia A. Vorholt, 23 April 2024, Nature Catalysis.
DOI: 10.1038/s41929-024-01137-0

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April 28, 2024
Diet’s impact on gut bacteria offers new clues in Parkinson’s disease management
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A recent Npj Parkinson’s Disease study investigates the association between diet and gut microbiome composition in an effort to identify the functional pathways that affect patients with Parkinson’s disease (PD).

Study: Diet and the gut microbiome in patients with Parkinson’s disease. Image Credit: Chinnapong / Shutterstock.com

Diet and PD risk

PD is one of the most common neurodegenerative diseases associated with aging. Some common symptoms associated with PD include progressive motor impairment, as well as non-motor symptoms, such as gastrointestinal (GI) dysfunction, depression, constipation, and cognitive impairment. Specific non-motor symptoms may manifest decades before clinical diagnosis during its prodromal stages.

Previous studies have shown that diet plays a critical role in PD incidence and progression. For example, those who adhere to a high-quality diet measured by the alternate Mediterranean Diet Score (aMED) and Alternative Healthy Eating Index (AHEI) are at a lower risk of PD, whereas lower Healthy Eating Index (HEI) —2015 scores have been associated with chronic constipation and hyposmia in PD patients.

Previously, a correlation between cognitive impairment and low fiber intake was established. Additionally, many patients diagnosed with PD at a relatively younger age have reported greater sugar consumption habits.

Poor diet and aging modify the composition of the gut microbiome, in which the concentration of beneficial bacteria decreases and harmful bacteria increases. The gut microbiome’s inadequate synthesis of essential nutrients and elevated levels of toxins could result in neurodegeneration and neuroinflammation.

PD patients typically exhibit lower levels of putative short-chain fatty acid (SCFA)- producing bacteria, such as Coprococcus and Butyricicicoccus, as well as higher levels of Akkermansia, pro-inflammatory bacteria. Importantly, SCFAs have anti-inflammatory properties that influence the enteric nervous system, modulate inflammation in the central nervous system, and support normal microglia development.

To date, few studies have examined the role of diet in the development and progression of PD. Therefore, additional research is needed to explore this relationship and ultimately use these findings to develop suitable interventions to alleviate GI symptoms in PD.

About the study

The current study investigated the association between diet and gut microbial diversity, composition, abundance, and its predicted metagenome in PD patients. To this end, a cross-sectional analysis was performed using a subgroup of PD patients from the Parkinson’s Environment and Gene (PEG) study that recruited 832 PD patients between 2001-2007 (PEG1) and 2011-2017 (PEG2).

Patients diagnosed with PD in the last three to five years, were residents of California for at least five years, and did not have other neurological conditions or a terminal illness were recruited. Fecal samples were collected from patients who were re-contacted between 2017-2020 (PEG-Gut).

A total of 85 participants fulfilled all eligibility criteria and were considered in the current analysis. The study cohort completed the Diet History Questionnaire II (DHQ II) for dietary assessments. Diet quality was measured using the HEI-2015, with total scores ranging between zero and 100 points.

Study findings

Most of the study participants were men of European ancestry, non-smokers, overweight, and well-educated. Interestingly, most PD patients developed constipation in the lowest HEI score tertile.

Consistent with previous reports, the current study confirmed the benefits of a high-quality diet in maintaining a healthy gut in PD patients. A healthy diet leads to reduced putative pro-inflammatory bacteria, which are abundantly found in PD patients as compared to healthy individuals.

Adherence to a high-quality diet with a high HEI score increased the abundance of SCFA-producing bacteria, such as Coprococcus1, Ruminococcaceae, Butyricicoccus, NK4A214 group, Hydrogenoanaerobacterium, Romboutsia, Negativibacillus, and Ruminococcaceae UCG-003 in PD patients. These bacteria synthesize butyrate that reduces inflammation, thereby providing energy for intestinal epithelial cells and strengthening the intestinal epithelium.

Those who reported greater consumption of added sugar exhibited decreased levels of Romboutsia Butyricicoccus and Coprococcus 1. Increased levels of amyloid-producing bacteria, Klebsiella, were also observed.

PD patients often exhibit increased levels of pro-inflammatory cytokines in the serum and colon, which reflects systemic inflammation that could ultimately activate microglia. The activation of microglia is inherently associated with the progression of PD.

Mechanistically, a healthy diet decreases taurine degradation, lipopolysaccharide biosynthesis, as well as the number of circulating lipopolysaccharides and systemic inflammation in PD. A healthy diet in PD patients also increases the Ruminococcaceae family genera in the gut, which supports taurine metabolism and reduces taurine degradation.

Conclusions

The current study indicated that a healthy diet could be extremely beneficial for PD patients, as it could reduce both motor and non-motor symptoms, as well as delay disease progression. Furthermore, a healthy diet increases the levels of putative anti-inflammatory butyrate-producing bacteria and decreases putative pro-inflammatory bacteria in PD patients.

Thus, the study findings emphasize the importance of adhering to a high-quality diet from the initial diagnosis of PD, as it could help maintain a healthy microbiome and delay disease progression. Nevertheless, it should be noted that the ability to maintain a healthy diet can become increasingly difficult as the disease progresses.
Journal reference:

Kwon, D., Zhang, K., Paul, K. C., et al. (2024) Diet and the gut microbiome in patients with Parkinson’s disease. Npj Parkinson’s Disease 10(1); 1-9. doi:10.1038/s41531-024-00681-7
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April 26, 2024
Meta-analysis reveals drivers of antibiotic resistance in infants

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A meta-analysis of genetic studies analyzing the microbiota (bacteria in the gut) of 1,275 infants from 10 countries finds that cesarean delivery and antibiotic use are driving the increase of antibiotic resistance genes load among infants, according to new research being presented at this year’s ESCMID Global Congress (formerly ECCMID) in Barcelona, Spain (27-30 April).

The study, by researchers from UiT The Artic University of Norway, highlights the urgent need for more research on targeted interventions to reduce antibiotic resistance in infants. They speculate that probiotics, for example, could reduce the abundance of antibiotic-resistance genes and merit further investigation.

Antimicrobial resistance (AMR) is a global health emergency. Drug-resistant infections kill more than 1.27 million people a year worldwide. If no action is taken, antimicrobial resistance could overtake cancer as the leading cause of death worldwide by 2050, and is projected to kill 10 million people globally.

Infants are highly susceptible to infections due to their immature immune system. At the same time, their gut microbiota is full of diverse bacteria, many of which harbor resistance against a broad range of antibiotics, even in the absence of antibiotic exposure. The gut resistome-;the collection of antibiotic-resistant genes (ARGs) harbored in the genomes of infant gut microbes-;develops when microbes flood the gut immediately after birth, and is an important piece of the AMR puzzle.

The gut mobilome-;the collection of diverse mobile genetic elements (MGEs) within the gut, plays a key role in the spread of ARGs. Bacteria swap genetic material, like ARGs, through horizontal gene transfer. With so many bacteria in close proximity, the gut provides ideal conditions for this exchange of ARGs.

While many intestinal bacteria harbouring ARGs do not pose a health threat, some ARGs are acquired by microbes with pathogenic potential. When these genes are transmitted to a pathogen, this has dire consequences for both the individual patient and society.

Understanding the factors influencing the development of the infant gut resistome and mobilome is therefore crucial for developing strategies to mitigate AMR prevalence.

Several previous clinical studies have provided important but fragmented insights into the gut resistome, but their small sample sizes and inherent biases (e.g., selection bias and confounding) limit the generalisability of the findings.

To overcome these limitations, researchers conducted a meta-analysis of infant cohorts based on metagenomics data from 14 studies spanning 10 countries and three continents.

They investigated the extent to which antibiotic use, birth mode, prematurity, feeding practices, and geography influenced the abundance and diversity of ARGs and MGEs in 3,981 gut metagenome faecal samples from 1,275 infants. To track the infants’ microbiomes, infants’ stools were sampled longitudinally up to 14 months of age.

Researchers used published shotgun metagenomes (untargeted genetic sequencing of all bacteria living in the gut) to examine the associations between the diversity and load of ARGs and MGEs and antibiotic use, birth mode, prematurity, feeding practices, and geography, as well as to identify which bacterial species are major hosts of ARGs within infants’ gut.

Overall, the analyses found that use of antibiotics, Caesarean delivery, and prematurity was significantly associated with reduced beneficial gut microbe diversity compared to full-term, vaginally-born infants not exposed to antibiotics.

On the other hand, vaginal birth was linked to lower abundance but more diverse ARGs compared to C-section delivery.

Vaginally born infants are exposed to more vaginal and gut bacteria compared to C-section born babies, who are primarily exposed to skin bacteria. Since bacteria correlate with the collection of antibiotic-resistant genes in the gut, higher antibiotic-resistant gene diversity in vaginally born infants is expected. However, the presence of higher levels of certain commensal bacteria-;which supply their host with essential nutrients and help defend the host against opportunistic pathogens-;in vaginally born infants may suppress pathogenic bacteria (which are likely to carry a higher abundance of antibiotic-resistant genes), thereby reducing the overall abundance.”

Ahmed Bargheet, lead author from UiT The Artic University of Norway

As expected, the analyses found that antibiotic use was linked to higher ARG and MGE abundance. However, antibiotic use had no significant impact on the ARGs’ diversity.

Surprisingly, exclusively breastfed infants showed no significant effects on ARG diversity or abundance.

Importantly, the researchers detected 199 clinically relevant ARGs (that confer resistance to clinically relevant antibiotics), whose diversity increased with age during the first two years of life. “The diversity of the ARGs increased over time, mirroring the diversity of the bacteria. However, the abundance of ARGs decreased over time, possibly due to a reduction in the abundance of pathogenic bacteria such as Escherichia coli“, says Bargheet.

Interestingly, two African cohorts (from Zimbabwe and South Africa) had a statistically significant and higher ARG and MGE abundance compared to the European cohorts. “It’s possible that Zimbabwe and South Africa used more antibiotics in their infant cohorts than the Europeans”, says Bargheet. “In Zimbabwe, the regulation and control of antibiotics is not as strict as in some regions of Europe, leading to a situation where antibiotics can often be purchased over the counter without a prescription, potentially exacerbating antimicrobial resistance.”

The authors further confirmed E. Coli as the main host of ARGs in the guts of infants, and concerningly, nearly half of the ARGs co-localized with plasmids, allowing efficient transfer between bacteria. Furthermore, E. coli strain diversity was found to be reduced during breastfeeding, but increased with age. Interestingly, antibiotic use had no significant impact on the E. coli strain diversity.

“Our meta-analysis of the available evidence clearly shows that C-section delivery, antibiotic use, and prematurity play an underappreciated role in antibiotic resistance in infants by altering early life resistome and mobilome, leading to an increased gut carriage of antibiotic resistance genes and mobile genetic elements”, says Bargheet.

“This has important implications for the antibiotic resistance crisis. By gaining insight into these factors, we aim to develop targeted interventions like probiotics, that could significantly reduce the number of deaths caused by antimicrobial resistance. This research not only addresses a pressing global health challenge but also sets the stage for breakthroughs in medical treatment and infection control. As we move forward, our focus remains on turning these findings into actionable strategies that can save lives and curb the spread of resistant infections.”

Despite the important findings, the authors note several limitations, including that the impact of hospitalization and other clinical variables could not be examined in this analysis due to a lack of data.

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April 25, 2024
Undernourished household contacts three times more likely to develop TB

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Mycobacterium tuberculosis, the bacteria that causes tuberculosis (TB), is distinct from most germs in its capacity to silently infect individuals for months and even years before waking up and causing active disease that can lead to severe illness and death. The immune system plays an important role in controlling the germ and keeping it dormant.

Decades of epidemiological data have linked undernutrition to TB. While undernourished individuals have blunted immune systems, a phenomenon which has been dubbed nutritionally acquired immune deficiency (N-AIDS), it is not clear why undernourished individuals are at increased risk of TB disease.

In a new study that followed household contacts (family members/people who share the same dwelling) of persons with TB, researchers have found that undernourished household contacts were three times more likely to progress to TB disease. The study did not find that undernourished contacts were at increased risk of testing positive for TB infection as compared to well-nourished individuals.

Are they more likely to become infected with the TB germ? Or are their immune systems unable to contain the germ resulting in severe disease? This fundamental question is important to answer as it can guide how we can best protect undernourished individuals who form a key and vulnerable population in the fight against TB.”

Pranay Sinha, MD, corresponding author, assistant professor of medicine at Boston University Chobanian & Avedisian School of Medicine

The researchers, which included investigators from both U.S. and Indian institutions (which are part of the Regional Prospective Observational Research for Tuberculosis (RePORT) India consortium), identified nearly 900 household contacts of persons who were newly diagnosed with TB, screening them to make sure they did not have TB disease at enrollment. They then followed these contacts to see if they developed TB disease for up to four years. Those who had a negative TB infection test at enrollment were retested to see if it had turned positive. The researchers then compared the rate of TB disease and TB infection between undernourished household contacts and well-nourished household contacts.

According to the researchers, these findings have clinical implications. “We now have greater insight into the mechanism by which undernutrition leads to greater TB risk. It is not by increasing infection, instead, it is by failing to contain the infection when it happens. Fortunately, undernutrition is a modifiable risk factor. Our findings should prompt TB programs to promptly provide adequate rations for the entire household to prevent TB disease among household contacts in addition to TB preventive therapy,” adds Sinha.

These findings appear online in the journal Clinical Infectious Diseases.

Source:

Boston University School of Medicine

Journal reference:

Sinha, P., et al. (2024) Undernourished Household Contacts Are at Increased Risk of Tuberculosis (TB) Disease, but not TB Infection— a Multicenter Prospective Cohort Analysis. Clinical Infectious Diseases. doi.org/10.1093/cid/ciae149.

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April 23, 2024
Korean fermented food Doenjang shows promise in alleviating menopausal symptoms
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In a recent study published in the journal Nutrients, researchers compare the efficacy between traditional and commercial Doenjang in alleviating menopausal syndrome.

Study: Evaluation of menopausal syndrome relief and anti-obesity efficacy of the Korean fermented food doenjang: a randomized, double-blind clinical trial. Image Credit: mino choi / Shutterstock.com

Treating menopause

Menopause leads to hormonal changes that may cause psychological and physical symptoms like hot flashes, sleep disturbances, insomnia, sweating, atrophy of the genitourinary system, and anxiety. Menopausal symptoms are often treated with hormone replacement therapy (HRT), primarily progesterone and estrogen.

Soy consumption, especially in Asian countries, is associated with lower rates of menopausal symptoms, thereby offering a natural substitute for HRT when it may be contraindicated or otherwise undesirable due to possible side effects such as breast cancer or cardiovascular disease.

Doenjang, a form of soybean paste consumed in Korea, is rich in antioxidants and fermented with beneficial microorganisms like Bacillus subtilis, Aspergillus oryzae, Rhizopus, and Mucor. Previously, Doenjang has been identified as a potential solution for alleviating menopausal symptoms; however, careful evaluation is needed to identify formulations that may be most effective for this purpose.

About the study

In the current study, researchers conducted an eight-week randomized and double-blind clinical trial involving postmenopausal women with menopausal syndrome.

The Kupperman index is a widely accepted diagnostic tool for menopausal syndrome that measures a wide range of vasomotor, urinary tract, psychoneurological, motor, digestive, and systemic symptoms. Scores below 20 indicate mild symptoms, while those between 20 and 40 signify moderate severity. Scores exceeding 40 indicate severe symptoms and scores of 60 or more denote a particularly severe manifestation of the syndrome.

Participants received Doenjang supplementation in three forms, including high-content beneficial microorganism traditional Doenjang (HDC), low-content beneficial microorganism traditional Doenjang (LDC), and commercially available Doenjang (CD).

Medication compliance, vital signs, and side effects were evaluated after four weeks of supplementation. Researchers collected measures of menopausal syndrome relief, including the Kupperman index, at the beginning and end of the trial, along with bioelectrical impedance analysis (BIA) results, weight, lipid profiles, serum blood markers, and inflammatory markers.

Safety assessments included blood chemistry, hematological tests, and monitoring for side effects. Obesity indicators and inflammation markers were also assessed, as were changes in the gut microbiome analyzed through stool tests.

Doenjang pills were prepared through a traditional fermentation process and freeze-dried for clinical trials. Statistical analysis included chi-square tests, analysis of variance (ANOVA), and paired t-tests to compare baseline and post-intervention data.

Study findings

A total of 56 individuals were included in the study and received HDC, LDC, or CD, none of whom reported any adverse events. Anthropometric parameters, including age, weight, and body mass index (BMI), did not differ significantly among the study participants.

Safety assessments indicated no adverse effects on liver or kidney function, with some improvements in blood urea nitrogen (BUN), uric acid, and total protein levels in the HDC group. Doenjang was not associated with anti-obesity effects; however, its use reduced LDL cholesterol levels.

Kupperman index scores significantly decreased in all groups following the administration of Doenjang, with improvements observed in various symptoms. Microbiome analysis showed decreased Firmicutes and increased Bacteroidetes across all groups, with beneficial bacteria increasing and harmful bacteria decreasing, particularly in the CD group.

Short-chain fatty acid analysis indicated varied effects across groups. Overall, while Doenjang showed promise in alleviating menopausal symptoms and modifying gut microbiota, its effects on obesity and inflammation were limited.

Conclusions

Traditional Doenjang fermented with beneficial microorganisms was found to be superior in its ability to mitigate menopausal symptoms as compared to commercial Doenjang. Nevertheless, a significant reduction in Kupperman index scores was observed across all groups, with the most notable improvement observed in LDC recipients.

LDL cholesterol levels decreased in both traditional Doenjang groups, thus indicating its potential cardiovascular benefits. Although Doenjang was not associated with anti-obesity or anti-inflammatory effects, its treatment positively influenced gut microbiota by increasing beneficial bacteria and reducing the levels of harmful bacteria.

Taken together, these findings demonstrate that traditional Doenjang has the potential to effectively alleviate menopausal symptoms, particularly when considering cardiovascular health, with implications for improving intestinal health through its impact on gut microbiota.

Some limitations of the current study include the inability to control participants’ lifestyle factors, the short study duration, and the small sample size. Thus, future studies with larger samples and longer durations to elucidate the therapeutic potential of Doenjang.
Journal reference:

Han, A.L., Ryu, M.S., Yang, H., et al. (2024). Evaluation of menopausal syndrome relief and anti-obesity efficacy of the Korean fermented food doenjang: a randomized, double-blind clinical trial. Nutrients. doi:10.3390/nu16081194
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April 22, 2024
The role of yogurt in diabetes and obesity prevention
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A recent study published in Frontiers in Nutrition discusses the role of yogurt as a nutritious food in preventing and managing diabetes and obesity.

Study: Yogurt, in the context of a healthy diet, for the prevention and management of diabetes and obesity: a perspective from Argentina. Image Credit: Aquarius Studio / Shutterstock.com

Risk factors for diabetes

Diabetes is a non-communicable chronic disease characterized by persistently high blood glucose levels. In some cases, diabetes can develop due to unhealthy lifestyles, including inadequate diet and lack of physical activity; therefore, obesity is considered a major risk factor for diabetes onset. The prevalence of both obesity and diabetes is exponentially increasing worldwide.

Health benefits of yogurt

Yogurt is a low-calorie fermented dairy product that provides a balanced proportion of proteins, essential nutrients, as well as a range of viable beneficial bacteria. In fact, consuming 100 grams of yogurt each day as part of a healthy diet of 2,000 kcal is responsible for 5% of overall diet quality.

Several nutritional studies have demonstrated that the consumption of yogurt is associated with a reduced risk of obesity, diabetes, osteoporosis, and cardiovascular disease. Yogurt has also been shown to improve gastrointestinal health and proper functioning of the immune system.

Dietary patterns in Argentina

In Argentina, the most recent national survey report indicates that about 52% and 13% of the population has obesity and diabetes, respectively. A decline of about 44% in moderate-to-high intensity physical activity has also been observed in the population as compared to previous surveys. Furthermore, the survey finds that only 6% of the Argentinian population consume recommended amounts of fruits and vegetables, while 22% of the population use tobacco products.

Recent diet-quality surveys in Argentina indicate that the dietary pattern of only 11% of households has a high nutritional density. The food gap, which is defined as the difference between apparent intake and healthy recommendations, is about 60% in high nutrient density vegetable foods and 48% in dairy products.

Thus, improving the nutritional quality of the Argentinian diet can be achieved by reducing food gaps, as well as starchy food and meat intake.

Yogurt intake in Argentina

The current annual consumption of yogurt in Argentina is about four kilograms/person/year, which is a significant reduction from 2012 estimates of 10 kg/person/year. Overall, the consumption of both full-fat and skim yogurt has declined by 44% in the past 10 years in Argentina.

Yogurt is not indicated as a source of viable beneficial bacteria in the dietary guidelines for Argentina. However, in north American and European countries, yogurt is recognized as a nutritious dairy product with significant health benefits.

According to an economic model for yogurt use in diabetes risk reduction in the United Kingdom, the consumption of 100 grams of yogurt each day by adults can lead to 388,000 fewer people developing diabetes in the next 25 years. In the United States, similar levels of yogurt consumption by adults can potentially reduce healthcare costs by billions of dollars.

Yogurt for diabetes management

In 2019, the prevalence of diabetes in Argentina was estimated to be 13%. The anti-diabetic activity of low-fat yogurt could be attributed to its low glycemic load and presence of various nutrients, including proteins, calcium, magnesium, and vitamin D.

Furthermore, certain saturated fatty acids present in yogurt, such as pentadecanoic and heptadecanoic acids, are associated with diabetes risk reduction. In this context, previous studies have predicted that daily yogurt consumption of 50 grams can lead to a 7% reduced risk of diabetes.

Plain or natural yogurt has a lower glycemic index than sweetened yogurt, which could be due to a higher protein to carbohydrate ratio in plain yogurt. The fermentation process involved in yogurt production can reduce carbohydrate bioavailability by converting then into organic acids and polysaccharides.

The viable beneficial bacteria present in yogurt have been shown to improve blood lipid profiles, reduce cholesterol levels, and increase antioxidant status in diabetic patients. Moreover, organic acids present in yogurt, such as lactic acid, can reduce postprandial blood glucose levels and insulinemia.

Yogurt for obesity management

The prevalence of obesity among children and adolescents in Argentina has been estimated to be over 40%. Among adults, the prevalence of obesity is six for every 10 individuals.

Gut microbiota dysbiosis, which is characterized by an imbalance in the composition and diversity of the microbiome, is a major contributor to obesity. Obesity-related alterations in gut microbiota can lead to increased fat deposition, impaired energy balance, increased inflammation, and metabolic dysfunction.

Yogurt can reduce the risk of obesity by replacing less healthy foods with its diverse nutritional components and viable beneficial bacteria. Yogurt can also impact appetite regulation, energy balance, and different anthropometric parameters, including body mass index (BMI).

Epidemiological studies have shown that yogurt consumption is associated with reduced BMI, overall obesity, and abdominal obesity. Yogurt consumption has also been associated with reduced total body and abdominal fat deposition, as well as lower weight gain.

Conclusions

Existing scientific evidence indicates that yogurt consumption could be beneficial for the prevention and management of both diabetes and obesity. The rising prevalence of these chronic diseases throughout the world emphasizes the importance of encouraging people to incorporate yogurt as part of their healthy diet to improve public health and reduce healthcare costs.
Journal reference:

Britos, S., Gonzalez, A. F., Marco, F. F., et al. (2024). Yogurt, in the context of a healthy diet, for the prevention and management of diabetes and obesity: a perspective from Argentina. Frontiers in Nutrition. doi:10.3389/fnut.2024.1373551.
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April 18, 2024
Study reveals human gut plasmid with biomarker potential

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A component of the human intestinal flora that has been little studied to date is the focus of a new study. Plasmids are small extrachromosomal genetic elements that frequently occur in bacterial cells and can influence microbial lifestyles – yet their diversity in natural habitats is poorly understood. An international team led by Prof. Dr. A. Murat Eren from the Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB) reports in the science journal Cell, a mysterious plasmid, is one of the most numerous genetic elements in the human gut that could potentially serve as a powerful biomarker for identifying health hazards such as fecal contamination of water or human disorders such as Inflammatory Bowel Disease. According to the team’s analyses, this plasmid is present in the intestines of more than 90 percent of individuals in industrialized countries.

Plasmids are extrachromosomal DNA sequences which are common to cells from all domains of life. Eren describes them as “typically small genetic entities that carry additional genes”. They can be exchanged between different bacterial cells and even between different types of bacteria. The replication of plasmids is dependent on their host cells: but they make up for it by providing their hosts with in some cases extremely important fitness determinants. For instance, some plasmids contain genes that encode antibiotic resistance, which help their bacterial hosts to survive antibiotics, contributing one of the most pressing public health concerns around the globe.

There are also other plasmids which, according to the research to date, do not contain genes encoding obvious beneficial functions for their host. “These so-called ‘cryptic plasmids’ are often referred to as genetic parasites. They remain a mystery in microbial ecology because from an evolutionary perspective they should not exist at all,” explains Eren, a computer scientist and Professor of Ecosystem Data Science at the University of Oldenburg.

Identifying plasmids has been a difficult undertaking so far. For some time now, scientists have been able to extract genetic material directly from environmental samples and, for example, analyze the microbial community in the human gut in its entirety, without having to cultivate individual bacterial organisms. However, the ability to confidently distinguish what is a plasmid among this conglomeration of genetic material, referred to as the metagenome, poses a considerable challenge.

To solve this problem, Eren and his colleagues developed a new machine learning approach. As the team reported in an article recently published in the science journal Nature Microbiology, using this approach they identified over 68,000 plasmids in human intestinal flora, and also discovered that a certain cryptic plasmid called pBI143 was particularly abundant in their dataset.

One of the most numerous genetic entities in the human gut

In the study published in Cell, the team of researchers took a closer look at this plasmid, which consists of only two genes that rather surprisingly only serves for its own replication and mobilization across bacterial cells with no other clear benefit. To better understand the ecology of pBI143, the team analyzed 60,000 human and 40,000 environmental metagenomes generated from various habitats.

“We found that pBI143 has a list of very interesting features,” Eren explains. The team discovered that more than 90 percent of people in industrialized countries carry the plasmid and that on average it is one of the most numerous genetic entities in the human gut. “On average it was more than ten times as numerous as a viral genome which was previously thought to be the most abundant genetic extrachromosomal element in the human gut,” says the researcher.

Further analyses revealed that the plasmid occurred almost exclusively in the human gut but was virtually absent in datasets from other environments such as the oceans, soils, plants and the digestive organs of animals and their feces. The only other samples in which the researchers were able to detect the characteristic gene sequence for these plasmids was in samples from environments that are influenced by humans, such as waste water, hospital surfaces and laboratory rats.

Due to its sheer numbers, prevalence across humans, and its conservancy across human populations, the team of researchers hypothesized that pBI143 could, for instance, be used as a biomarker in testing for fecal contamination.

In fact, we were able to show that this plasmid is a more sensitive marker for detecting fecal contamination in drinking water compared to state-of-the-art biomarkers based on specific gene sequences of human intestinal bacteria.”

Dr. A. Murat Eren, Professor of Ecosystem Data Science at the University of Oldenburg

Non-invasive method to quantify progress of IBD

The team also identified another potential application of this prevalent genetic entity in the context of human disorders such as Inflammatory Bowel Disease (IBD), a medical condition that affects 3 million people in Europe alone. They were able to demonstrate that the relative copy number of this cryptic plasmid increased almost four times in the intestines of people suffering from IBD compared as in the intestines of healthy individuals, suggesting that the changes of the copy number of the plasmid can serve as a non-invasive method to quantify the disease progress or severity.

At the HIFMB, Eren’s team is developing new tools at the intersection of computer science and microbiology to identify and characterize naturally occurring plasmids and other mobile genetic elements in bacteria that live in the ocean. They strive to gain a better understanding of the ecology and evolution of microbes, and strategies that enable to them to respond to their everchanging environments for new biotechnological applications that can ameliorate crises we face.

Source:

Journal reference:

Fogarty, E. C., et al. (2024). A cryptic plasmid is among the most numerous genetic elements in the human gut. Cell. doi.org/10.1016/j.cell.2024.01.039.

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April 16, 2024