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PubMed1984

Microbial removal of wastewater organic compounds as a function of input concentration in soil columns.

The fate of six organic compounds during rapid infiltration of primary wastewater through soil columns was studied. Feed solutions were prepared which contained all six compounds in individual concentrations ranging from 1 to 1,000 micrograms/liter and were applied to separate soil columns on a flooding-drying schedule. Feed solutions and column effluents were analyzed for the compounds by XAD resin (Rohm and Haas Co.) extraction and gas chromatography-mass spectrometry during each of three successive inundation cycles. Breakthrough profiles of o-phenylphenol were relatively consistent during the test, with fractional breakthrough (mass output/mass input) being independent of input concentration. Consistent profiles were also observed for 2-(methylthio)benzothiazole, although fractional breakthroughs were higher at lower input concentrations, indicating that removal processes were operating less efficiently at these levels. The behavior of p-dichlorobenzene was similar to that of 2-(methylthio)benzothiazole after the first inundation cycle, with the exception that increased fractional breakthroughs were observed at the highest input concentration as well. Microbial adaptation was evident for benzophenone, 2-methylnaphthalene, and p-(1,1,3,3-tetramethylbutyl)phenol, as indicated by increased removal efficiencies during successive inundation cycles, especially at the higher input concentrations. Column effluent concentrations of the latter two compounds were independent of input concentrations during the final stage of the test. Microbial activity and adaptation were confirmed for several of the compounds by using isotopes and measuring the extent of mineralization in batch tests with soil from one of the columns.(ABSTRACT TRUNCATED AT 250 WORDS)

Benzophenones↗
PubMed1979

Microbial introduction of a 16 alpha-hydroxyl function into the steroid nucleus.

The introduction of a 16 alpha-hydroxyl function into the steroid nucleus was studied in resting cells of Streptomyces roseochromogenes NRRL B-1233. The oxidation product of dehydroepiandrosterone (DHEA) was identified as 16 alpha-hydroxy DHEA by using thin-layer and gas-liquid chromatography. A linear relation between cell concentration and 16 alpha-OH-DHEA formation was observed. 16 alpha-Hydroxylase showed good activity at pH 8.0 for 16 alpha-OH-DHEA formation. The enzyme showed good activity at 3.1 x 10(-4) M DHEA. The oxidation products of pregnenolone, 4-androstene-3,17-dione, estrone, and 5-androstene-3 beta,17 beta-diol as well as of other substrates were identified as the 16 alpha-hydroxy steroid, respectively. The rates of microbial 16 alpha-hydroxylation were as follows: 76.9% for DHEA, 50.4% for pregnenolone, 43.9% for 4-androstene-3,17-dione, 34.3% for estrone, and 19.6% for 5-androstene-3 beta,17 beta-diol. The organism tested catalyzes 16 alpha-hydroxylation of a wide variety of steroids.

Androstenediol↗
PubMed2026

Sex-Dependent Microbial and Host Profiles Following Fecal Microbiota and Bifidobacterium longum Treatment in Stress-Induced Gut Dysbiosis.

BACKGROUND/AIMS: Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder influenced by stress, microbial dysbiosis, and immune activation. Microbiota-directed therapies, including fecal microbiota transplantation and probiotics, show promise, but their sex-specific effects remain unclear. We compared the therapeutic effects of lyophilized fecal microbiota (LFM) with Bifidobacterium longum BBH016 in male and female Wistar rats subjected to repeated water avoidance stress. METHODS: Fecal pellet output (FPO), colonic mast cell infiltration, and fecal short-chain fatty acids were measured. Gut microbial composition and function were analyzed by 16S rRNA sequencing and Kyoto Encyclopedia of Genes and Genomes pathway prediction. RESULTS: Both interventions significantly reduced FPO and mast cell infiltration in males but had less pronounced effects in females. Microbiota analyses revealed sex-dependent responses, with distinct microbial trajectories in each treatment group. Using linear discriminant analysis effect size, we identified seven key taxa with treatment- or sex-specific enrichment. Alistipes onderdonkii and Bacteroides uniformis consistently increased in both LFM- and B. longum-treated groups, regardless of sex. Bacteroides finegoldii and Barnesiella intestinihominis were specifically enriched in the LFM group. In males, Blautia faecis and Fusicatenibacter saccharivorans were enriched following the interventions, whereas Parabacteroides goldsteinii appeared exclusively in stressed males. Functional predictions revealed the enrichment of estrogen signaling and bile acid pathways in males and the attenuation of proinflammatory pathways in females following LFM. Correlations between microbial taxa and host outcomes were predominantly observed in male rats. CONCLUSIONS: These findings highlight sex-specific microbial and host responses to microbiota-targeted therapies in a stress-induced IBS model, emphasizing sex as a biological variable in designing personalized microbiome-based treatments.

Animals↗
PubMed2005

Lactoferrin: an important host defence against microbial and viral attack.

The first function attributed to lactoferrin (Lf), an iron binding protein belonging to the non-immune natural defences, was antimicrobial activity that depended on its capacity to sequester iron. Iron-independent microbicidal activities, requiring direct interaction between this cationic protein and microbial surface components, were later demonstrated. Many other anti-microbial and anti-viral functions have since been ascribed to Lf. In mucosal secretions, iron and Lf modulate the motility and aggregation of pathogenic bacteria. Lf inhibits bacterial adhesion on abiotic surfaces through ionic binding to biomaterials, or specific binding to bacterial structures or both. Lf inhibition of bacterial adhesion to host cells requires Lf binding to bacteria and/or host cells. Lf hinders microbial internalization by binding to both glycosaminoglycans and bacterial proteins which can be degraded by Lf-mediated proteolysis. Moreover, Lf internalisation and localisation to the host cell nuclei could modulate bacterial entry into cells through gene regulation. Finally, the capability of Lf to exert antiviral activity, through its binding to host cells and/or viral particles, strengthens the idea that it is an important brick in the mucosal wall, effective against both microbial and viral attacks.

Animals↗
PubMed1998

Overview of gut flora and probiotics.

Scientific developments in recent years have opened new frontiers and enable a better understanding of the gastrointestinal tract (GIT) as a complex and delicately balanced ecosystem. This paper focuses on more recent information related to the microbial population of the GIT and its functional role in human physiology and health. Special attention is also given to modern approaches for improving or stabilising the intestinal system and its functioning by the deliberate application of viable microbial cultures, so-called 'probiotics', selected for special functional properties.

Bacterial Physiological Phenomena↗
PubMed1999

The composition and function of M cell apical membranes: implications for microbial pathogenesis.

M cells, an epithelial cell phenotype that occurs only over organized mucosal lymphoid follicles, deliver samples of foreign material by transepithelial transport from the lumen to organized lymphoid tissues within the mucosa of the small and large intestines. The apical membranes of M cells in the intestine are designed to facilitate adherence and uptake of antigens and microorganisms, a prerequisite for immunological sampling. The molecular features of M cell apical surfaces that promote adherence and transport are crucial for understanding the strategies that pathogens use to exploit this pathway.

Animals↗
PubMed2026

Lipid metabolism is a key central, systemic and gut microbial feature of the decline in rat hippocampal function during middle age.

Middle age is emerging as a turning point in brain ageing, prognostic of future cognitive health and amenable to intervention. Metabolic and proteomic differences during this period are not yet fully understood and may potentially influence functions of the hippocampus, a brain area that regulates memory and anxiety. While the gut microbiota is implicated in brain ageing, the relationship between the gut microbiota, the metabolic state, and hippocampal proteome in middle age has not been investigated. We hypothesise that peripheral metabolic or protein features are associated with hippocampal vulnerability in middle age. Therefore, young adult and middle-aged rats were assessed for behavioural, proteomic, metabolic, and gut microbiota differences. Proteomic profiling of the hippocampus revealed differential expression of proteins indicative of altered synaptic signalling. Concurrently, adult hippocampal neurogenesis was decreased in middle age. Hippocampal microglia exhibited a lipid rich, inflammatory phenotype in middle age which correlated with poorer memory performance. CSF and serum proteomic and metabolomic analyses identified dysregulated lipid-related pathways potentially contributing to hippocampal vulnerability in middle age. Furthermore, 16S rRNA sequencing revealed reduced abundance of bacteria involved in lipid metabolism regulation. However, faecal microbiota transfer from young to middle aged rats was not sufficient to robustly improve hippocampus-dependent spatial memory. Together, these findings highlight dysfunctional lipid metabolism as a key feature of middle age that may contribute to decline in hippocampal function. Given that the scope for intervention is limited during older age, targeting biomarkers involved in metabolic and lipid homeostasis may be pivotal for the development of pharmacological or lifestyle-based interventions during middle age which could ultimately delay future cognitive ageing.

Animals↗
PubMed2005

Changes in enzymes activity, substrate utilization pattern and diversity of soil microbial communities under cadmium pollution.

Heavy metal pollution has received increasing attention in recent years mainly because of the public awareness of environmental issues. In this study we have evaluated the effect of cadmium (Cd) on enzymes activity, substrate utilization pattern and diversity of microbial communities in soil spiked with 0, 20, 40, 60, 80, and 100 mg/kg Cd, during 60 d of incubation at 25 degrees C. Enzyme activities determined at 0, 15, 30, 45, and 60 d after heavy metal application (DAA) showed marked declines for various Cd treatments, and up to 60 DAA, 100 mg/kg Cd resulted in 50.1%, 47.4%, and 39.8% decreases in soil urease, acid phosphatase and dehydrogenase activities, respectively to control. At 60 DAA, substrate utilization pattern of soil microbial communities determined by inoculating Biolog ECO plates indicated that Cd addition had markedly inhibited the functional activity of soil microbial communities and multivariate analysis of sole carbon source utilization showed significantly different utilization patterns for 80 and 100 mg/kg Cd treatments. The structural diversity of soil microbial communities assessed by PCR-DGGE method at 60 DAA, illustrated that DGGE patterns in soil simplified with increasing Cd concentration, and clustering of DGGE profiles for various Cd treatments revealed that they had more than 50% difference with that of control.

Acid Phosphatase↗
PubMed1983

[In vitro estimation using radioactive phosphorus of the phosphorus requirements of rumen microorganisms].

Microbial requirements for P were assumed to be a function of the amount of microbial protein synthesis (microbial growth) and of the quantity of organic matter (OM) fermented in the rumen. The relationships among P incorporation into microbial matter and protein synthesis, ammonia utilization, volatile fatty acid (VFA) production and organic matter fermented (OMF) were studied in short-term incubations (3 h) using 32P-labelled phosphate. The amount of P incorporated was calculated from extracellular phosphate pool specific activity and the radioactivity incorporated into the microbial sediment during incubation (table 1). The inocula came from sheep fed a protein-free purified diet. In order to vary the intensity of fermentation, carbohydrates with a wide range of degrees of enzymatic susceptibility were used as substrates and the medium was either provided or was deficient in S and trace elements (table 4). Nitrogen was supplied as ammonium salts. Linear regression analyses showed that P incorporation was positively correlated with the criteria of protein synthesis and OM fermentation (figs. 1, 2, 3, 4). However, there was significant phosphorus incorporation when the value for nitrogen incorporation was zero (equation A: (Pi (mg) = 0.162 NH3-N + 0.376; r = 0.9). This was assumed to result either from energetic uncoupling (fermentation without concomitant bacterial growth) or from the lysis of cold microbial cells only. Equation A would reflect total P incorporation and equation A' Pi (mg) = 0.162 NH3-N (mg), net P incorporation. It was assumed that in vitro microbial requirements for P were in the range of 30-70 mg of P/liter of medium for 3-hour incubation, depending on the intensity of fermentation. From a mean value of microbial N yield of 30 g/kg of DOMR (organic matter apparently digested in the rumen), it was calculated that the total and net P requirements in vivo were 6 and 4.9 g/kg of DOMR, respectively, corresponding to 3.9 and 3.2 g/kg of DOM (digestible organic matter). From equation D, relating Pi to OMF, the P requirements were about 4.4 g/kg of DOM. It is suggested that microbial requirements for P varied from 3 to 5 g of P/kg of DOM, depending on the efficiency of microbial synthesis and the extent of carbohydrate fermentation. These results, considered as indicative, should be checked in in vivo experiments.

Animals↗
PubMed2026

Host immunogenetic variation and gut microbiome functionality in a wild vertebrate population.

BACKGROUND: The gut microbiome (GM) -important for host health and survival- is partially shaped by host immunogenetics. However, to date, no study has investigated the influence of host Major Histocompatibility Complex (MHC) genes on gut microbiome functionality in a wild population. Here we use a natural population of the Seychelles warbler (Acrocephalus sechellensis) to assess the effects of MHC genes on GM taxonomy and functionality using shotgun metagenomics. RESULTS: Our results show that taxonomic GM composition was associated with MHC-II diversity and the presence of one specific MHC-I allele (Ase-ua 7). Specifically, MHC-II diversity was associated with decreased Lactococcus lactis and increased Staphylococcus lloydii abundance, while Ase-ua 7 was linked to reduced Enterococcus casselifavus and Gordonia sp OPL2 but increased Escherichia coli and Vulcaniibacterium thermophilum. These taxonomic changes may reflect differences in MHC-mediated microbial recognition. In contrast, functional GM composition was significantly associated with increasing individual MHC-I diversity but not MHC-II diversity. In particular, increasing MHC-I diversity was associated with an increased prevalence of microbial defence genes but a reduced prevalence of microbial metabolism genes. Analysis also revealed that functional GM networks were more fragmented in high compared to low MHC-I diversity hosts. CONCLUSION: These results suggest that MHC variation (particularly at MHC-I) plays an important role in shaping both the taxonomy and function of the GM in wild vertebrates. In the Seychelles warbler, this results in trade-offs whereby there is an increase in microbial defence and a reduction in GM metabolic potential in individuals with higher MHC-I diversity. Thus, this work sheds light on the possible costs and benefits of maintaining a healthy microbiome, which is essential for understanding how the GM and immune system co-evolve. Video Abstract.

Animals↗
PubMed2025

Nutritional modulation of host physiology, behavior, and gut microbiome in the captive rodent Octodon degus.

Diet is a key determinant of health by affecting nutrient metabolism, energy balance, body weight regulation, and mental health. The gut-brain axis is a critical pathway through which dietary factors influence cognitive function and behavior via microbial metabolites. While this relationship has been extensively studied in traditional laboratory models, diet-microbiome-cognition interactions remain largely unexplored in Octodon degus, an emerging model for aging, neurodegeneration, and cognitive research. Here, we compared two widely used rodent diets-LabDiet and Champion-to evaluate their effects on digestive efficiency, behavior, and gut microbiome composition. We also examined the relationships between these variables using piecewise structural equation modeling (pSEM). Our results indicated that LabDiet-fed degus exhibited enhanced nutrient absorption, higher fecal acetic acid levels, and a higher abundance of Actinobacteria (particularly Bifidobacterium), likely driven by its vitamin C supplementation. These animals also showed improved working memory and social motivation, but they displayed increased anxiety-like behavior. In contrast, Champion-fed degus, which consumed a more fiber-diverse, plant-based diet, showed lower anxiety traits and significantly greater gut microbial richness, with higher abundance of Bacteroidota and Tenericutes. Innate behaviors, such as burrowing and nesting, remained unaffected by the diet. SEM analysis revealed that diet explained most of the variance in microbial activity and identified a positive association between acetic acid levels and cognitive performance. This emphasizes a strong relationship among diet, microbiome, and brain function. Overall, our results suggest that dietary composition is a key factor influencing experimental outcomes in degus, with important implications for physiology, cognition, and microbial ecology. Standardizing dietary inputs is essential to ensure reproducibility in behavioral and biomedical studies using this model. Additionally, our results reinforce the microbiome's role as a mediator of diet-driven brain function via SCFAs, underscoring degus as a powerful system for investigating diet-microbiome-neurobehavioral interactions relevant to aging and mental health.

Animals↗
PubMed2003

Structure and seasonal dynamics of hyporheic zone microbial communities in free-stone rivers of the western United States.

The hyporheic zone of a river is characterized by being nonphotic, exhibiting chemical/redox gradients, and having a heterotrophic food web based on the consumption of organic carbon entrained from surface waters. Hyporheic microbial communities constitute the base of food webs in these environments and are important for maintaining a functioning lotic ecosystem. While microbial communities of rivers dominated by fine-grained sediments are relatively well studied, little is known about the structure and seasonal dynamics of microbial communities inhabiting the predominantly gravel and cobble hyporheic zones of rivers of the western United States. Here, we present the first molecular analysis of hyporheic microbial communities of three different stream types (based on mean base discharge, substratum type, and drainage area), in Montana. Utilizing 16S rDNA phylogeny, DGGE pattern analysis, and qPCR, we have analyzed the prokaryotic communities living on the 1.7 to 2.36 mm grain-size fraction of hyporheic sediments from three separate riffles in each stream. DGGE analysis showed clear seasonal community patterns, indicated similar community composition between different riffles within a stream (95.6-96.6% similarity), and allowed differentiation between communities in different streams. Each river supported a unique complement of species; however, several phylogenetic groups were conserved between all three streams including Pseudomonads and members of the genera Aquabacterium, Rhodoferax, Hyphomicrobium, and Pirellula. Each group showed pronounced seasonal trends in abundance, with peaks during the Fall. The Hyphomicrobium group was numerically dominant throughout the year in all three streams. This work provides a framework for investigating the effects of various environmental factors and anthropogenic effects on microbial communities inhabiting the hyporheic zone.

DNA, Bacterial↗
PubMedDate not supplied

[The classification and the monitoring of the state of mouth riverine and lacustrine ecosystems in lake Baikal based on the composition of local microbiocenoses and their activity].

The paper presents the results of the long-term investigation of microbial communities in the technogenically vulnerable mouth riverine and lacustrine ecosystems of Lake Baikal. The structural and functional parameters of the microbial communities were analyzed from the standpoint of developing destructive processes. The analysis showed that the total number of microorganisms (TNM), the number of saprophytic bacteria (NSB), and bacterial production (BP) were greater in the river-mouth water than in the near-mouth lake water. In the offshore direction, TNM and NSB decreased by a factor of 1.5 to 2, and BP decreased by a factor of 4 to 7. Based on TNM, NSB, and BP data, we classified the Lake Baikal rivers with respect to the degree of the impact of human activities on them. The degrading capability of the riverine microbial communities was found to be such that they degrade daily from tenths of a percent to 3.5% of the total amount of organic compounds polluted the river waters.

Bacteria↗
PubMed2005

Cutting edge: all-trans retinoic acid down-regulates TLR2 expression and function.

A major consequence of microbial infection is the tissue injury that results from the host inflammatory response. In acne, inflammation is due in part to the ability of Propionibacterium acnes to activate TLR2. Because all-trans retinoic acid (ATRA) decreases inflammation in acne, we investigated whether it regulates TLR2 expression and function. Treatment of primary human monocytes with ATRA led to the down-regulation of TLR2 as well as its coreceptor CD14, but not TLR1 or TLR4. The ability of a TLR2/1 ligand to trigger monocyte cytokine release was inhibited by pre- and cotreatment with ATRA; however, TLR4 activation was affected by cotreatment only. ATRA also down-regulated monocyte cytokine induction by P. acnes. These data indicate that ATRA exerts an anti-inflammatory effect on monocytes via two pathways, one specifically affecting TLR2/1 and CD14 expression and one independent of TLR expression. Agents that target TLR expression and function represent a novel strategy to treat inflammation in humans.

Acne Vulgaris↗
PubMed2006

Relationships between microbial community structure and soil processes under elevated atmospheric carbon dioxide.

There is little current understanding of the relationship between soil microbial community composition and soil processes rates, nor of the effect climate change and elevated CO(2) will have on microbial communities and their functioning. Using the eastern cottonwood (Populus deltoides) plantation at the Biosphere 2 Laboratory, we studied the relationships between microbial community structure and process rates, and the effects of elevated atmospheric CO(2) on microbial biomass, activity, and community structure. Soils were sampled from three treatments (400, 800, and 1200 ppm CO(2)), a variety of microbial biomass and activity parameters were measured, and the bacterial community was described by 16S rRNA libraries. Glucose substrate-induced respiration (SIR) was significantly higher in the 1200 ppm CO(2) treatment. There were also a variety of complex, nonlinear responses to elevated CO(2). There was no consistent effect of elevated CO(2) on bacterial diversity; however, there was extensive variation in microbial community structure within the plantation. The southern ends of the 800 and 1200 ppm CO(2) bays were dominated by beta-Proteobacteria, and had higher fungal biomass, whereas the other areas contained more alpha-Proteobacteria and Acidobacteria. A number of soil process rates, including salicylate, glutamate, and glycine substrate-induced respiration and proteolysis, were significantly related to the relative abundance of the three most frequent bacterial taxa, and to fungal biomass. Overall, variation in microbial activity was better explained by microbial community composition than by CO(2) treatment. However, the altered diversity and activity in the southern bays of the two high CO(2) treatments could indicate an interaction between CO(2) and light.

Biodiversity↗