Lifestyle Influences on the Microbiome
David Perlmutter in The Microbiome and the Brain, 2019
For example, by trapping hydrogen in CH3, Archea help Ruminococcus double ATP production.22 The Ruminoccus/Methanobrevibacter syntrophic cluster also includes Candida and Prevotella. Candida species cooperate with host amylase to degrade starches to simpler carbohydrates that are fermented by Prevotella and Ruminococcus. Biofilms containing Candida albicans support increased colonization with Prevotella species.23 Fermentation byproducts are then consumed by Methanobrevibacter, yielding carbon dioxide and/or methane. Prevotella degradation of starch produces small poly- and monosaccharides,24 which provide Candida with additional substrate for fermentation. Prevotella can catabolize small polysaccharides to succinate, which is then consumed by Ruminococcus, yielding substrate for Methanobrevibacter.25,26 Archeal methanogens play a key role in maintaining the robustness of this network in its response to dietary carbohydrate.
Inorganic Chemical Pollutants
William J. Rea, Kalpana D. Patel in Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
The authors’ identified homologs of hgcA and hgcB in genomes of 52 bacteria and methanogenic archaea. Although most have not been tested for their ability to methylate mercury in pure culture, field studies have implicated methanogens in mercury methylation.556 The distribution of methylation ability is sporadic, with methylating and nonmethylating strains occurring in the same species.557 These observations raise the questions how methylation evolved and what its purpose might be. Methylation may be a detoxification mechanism,558,559 possibly an ancient pathway used to deal with toxic inorganic mercury. Further experiments and analyses of the genomes in which hgcA and hgcB are found will help establish the evolutionary path of mercury methylation.560
An Overview of Parasite Diversity
Eric S. Loker, Bruce V. Hofkin in Parasitology, 2023
As presently known, the adoption of parasitism has not been a conspicuous feature in the Archaea. One species of Archaea, Nanoarchaeum equitans, has been discovered that parasitizes another member of the Archaea (Figure 2.5). Both host and parasite live in scalding hot, sulfur-rich water. We have come to think of Archaea as being extremophiles, inhabiting hot, salty or acidic environments, but it is becoming clear that Archaea are ubiquitous in nature and often occur in complex microbial consortia, including as part of the microbiome of humans (they are especially diverse in the nose), other animals and plants. Because it is difficult to grow Archaea in pure culture, progress has been somewhat slow in unraveling key aspects of their biology. We have archaea like Methanobrevibacter living in our mouths, populations of which seem to be enriched in patients suffering from periodontal disease. A member of this genus, M. brevis, has been recovered from brain abscesses. Most human-associated archaea are found in the gut and many like Methanobrevibacter smithii play a role in the production of methane. The archaeal methanogens of ruminants and termites add significant amounts of methane, a greenhouse gas, to the atmosphere! Human gut methanogens may indirectly favor the growth of pathogenic bacteria or cause constipation, but thus far, archaea have been described as being essentially salutogenic, that is playing a role in promoting human health and well-being. For the two remaining domains, the Bacteria and Eukarya, as we discuss in the sections that follow, adoption of parasitism has figured prominently.
Breathing new life into clinical testing and diagnostics: perspectives on volatile biomarkers from breath
Published in Critical Reviews in Clinical Laboratory Sciences, 2022
Jordan J. Haworth, Charlotte K. Pitcher, Giuseppe Ferrandino, Anthony R. Hobson, Kirk L. Pappan, Jonathan L. D. Lawson
More importantly, genetic tests do not detect secondary lactase deficiency or assess symptoms. As a provocation test, tracking patient symptoms concurrently with hydrogen breath tests provides a measure of true intolerance (i.e. symptomatic response to lactose ingestion). However, a rise in hydrogen may also be consequent to SIBO, which means that it is important to establish whether a patient has SIBO before testing for malabsorption. When lactose is administered to a patient with SIBO, the substrate could be fermented by microbes in the small intestine leading to a false positive result for lactose malabsorption [13,43]. Alternatively, a false-negative result for lactose malabsorption can be obtained in people with a non-hydrogen producing-microbiota capable of metabolizing lactose. Methanogens, such as Methanobrevibacter smithii, can convert hydrogen into methane. The extent of breath methane production is also associated with the severity of constipation as a symptom [44]. HMBT is, therefore, favorable to traditional hydrogen breath testing to identify a cohort of patients with excessive methane production.
Addition of Trichocladium canadense to an anaerobic membrane bioreactor: evaluation of the microbial composition and reactor performance
Published in Biofouling, 2021
Hadi Fakhri, Duygu Nur Arabacı, İlayda Dilara Ünlü, Cigdem Yangin-Gomec, Suleyman Ovez, Sevcan Aydin
Figure 4 illustrates the microbial community in sludge samples. Within the domain Archaea, the C1 and C2 reactors were found to be inhabited exclusively by members of the Euryarchaeota, while in the TC reactor Euryarchaeota made up 95%. In terms of relative abundance, the orders Methanobacteriaceae and Methanomicrobia were the dominant archaeal communities. The dominant methanogens were hydrogenotrophic Methanobacterium, Methanolinea and Methanothermobacter; and acetoclastic Methanosaeta and Methanoculleus. While C1 reactor had low diversity with hydrogenotrophic Methanobacterium making up the total of the population, this diversity increased in the presence of antibiotics in the C2 reactor. The Methanobacterium population, which is known to produce CH4 through interspecific hydrogen transfer (IHT), completely disappeared and was replaced by Methanothermobacter, which made up 74% of Archaea in the C2 reactor. Hence, bioaugmentation with T. canadense allowed a significant increase in genera diversity, where Methanosaeta, repeatedly shown to be positively correlated with biogas production (Lin et al. 2012; van Wolferen et al. 2018; Ji et al. 2020), was predominant with 67% relative abundance, with Methanolinea following second with 13%, a substantial increase compared with the C2 reactor.
Assessment of small intestinal bacterial overgrowth in chronic pancreatitis patients using jejunal aspirate culture and glucose hydrogen breath test
Published in Scandinavian Journal of Gastroenterology, 2021
Rajesh Sanjeevi, Kapil Dev Jamwal, Sudipta Dhar Chowdhury, Balamurugan Ramadass, R. Gayathri, Amit Kumar Dutta, Anjilivelil Joseph Joseph, Balakrishnan S. Ramakrishna, Ashok Chacko
The major limitation of our study was not having a control group with normal individuals. Another limitation was that methane concentration in breath was not measured. A small number of people (5–15%) have methane-producing organisms (methanogens) in the gastrointestinal tract. Measuring methane would have helped in the estimation of this group of individuals. In this study, the estimation of PEI was done by using the 72 h fecal fat estimation test. Though the test is considered to be a gold-standard test it is a cumbersome one and is considered to be difficult for both patients and laboratory personnel alike. The Wellcome Trust Research Laboratory at Christian Medical College (Vellore, India) has been performing the 72 h fecal fat estimation for more than 50 years [34]. Fecal elastase-1 (FE-1) estimation is a simple test which can be performed on a spot stool sample. In an earlier study, our group had compared FE-1 with 72 h fecal fat estimation, and found that FE-1 is a sensitive test but it does not have a good agreement with 72 h fecal fat estimation [17]. Therefore, considering the experience our laboratory has and the poor agreement between FE1 and 72 h fecal fat we decided to use the 72 h fecal fat estimation for assessment of PEI.