Biology subjects

Koval, J. C.

Publications and source records attributed to Koval, J. C..

3 recordsLinked to original sources

bioRxiv2022

Inhibition of Microbial Methane Oxidation by 2-Chloro-6-Methylpyridine

Several pyridine derivatives including the pesticide nitrapyrin [2-chloro-6-(trichloromethyl) pyridine] are strong inhibitors of methane monooxygenase, a key enzyme of aerobic methane (CH4) oxidation. In this study we examined the effects of 2-chloro-6-methylpyridine (2C6MP) concentration on aerobic CH4 oxidation and the development of populations of putative methanotrophs in sediment from Old Woman Creek, a freshwater estuary in Huron Co., Ohio. Experimental systems were prepared in serum bottles containing minimal medium with a headspace containing 20% O2 and 10% CH4. The microcosms were spiked with 2C6MP to achieve concentrations of 0, 0.1, 1, or 10 mM and inoculated with sediment. When headspace CH4 concentrations decreased from 10% to < 2%, subsamples were taken for DNA extraction and sequencing of 16S rRNA gene amplicons. There was minimal effect of 2C6MP on CH4 oxidation at concentrations of 0.1, and 1 mM, but complete inhibition for > 20 months was observed at 10 mM. ANOSIM of weighted UniFrac distances between groups of triplicate samples supported a primary distinction of the inoculum relative to the enrichments (R=0.999) and a secondary distinction between bottles containing 2C6MP versus those without (R=0.464 [0.1 mM]; R=0.894 [1 mM]). The inoculum was dominated by members of the Proteobacteria (49.9{+/-}1.5%), and to a lesser extent by Bacteroidetes (8.8{+/-}0.2%), Acidobacteria (8.9{+/-}0.4%), and Verrucomicrobia (4.4{+/-}0.3%). In enrichments with or without 2C6MP, Proteobacteria expanded to comprise 65-70% of the total. In the absence of inhibitor, members of the Methylococcaceae and Methylophilaceae increased in relative abundance from < 0.1% of the inoculum to 8.5{+/-}1.0% and 13.4{+/-}2.3%, of the total community respectively. At both 0.1 and 1 mM concentrations of the inhibitor, the Methylococcaceae were much less abundant, representing 3.3{+/-}0.5% and 2.8{+/-}3.3% respectively. No inhibition of the Methylophilaceae was seen at the lower concentration of 2C6MP, but at the higher concentration this taxon was only 7.8{+/-}1.1% of the total. In contrast, members of the Crenotrichaceae, another group of methane oxidizers, increased in relative abundance with greater amounts of inhibitor, representing 8.6{+/-}3.6% of the total at 0.1 mM and 12.0{+/-}4.5% at 1 mM, compared to only 4.1{+/-}0.4% when no inhibitor was present. These results clearly show changes in the populations of putative aerobic methanotrophs relative to the amount of 2C6MP present.

microbiology↗

bioRxiv2020

Metagenomic alterations in gut microbiota precede and predict onset of colitis in the IL10 gene-deficient murine model

Background & AimsInflammatory bowel diseases (IBD) are chronic inflammatory disorders where predictive biomarkers for the disease development and clinical course are sorely needed for development of prevention and early intervention strategies that can be implemented to improve clinical outcomes. Since gut microbiome alterations can reflect and/or contribute to impending host health changes, we examined whether gut microbiota metagenomic profiles would provide more robust measures for predicting disease outcomes in colitis-prone hosts. MethodsUsing the IL-10 gene-deficient (IL-10 KO) murine model where early life dysbiosis from antibiotic (cefoperozone, CPZ) treated dams vertically-transferred to pups increases risk for colitis later in life, we investigated temporal metagenomic profiles in the gut microbiota of post-weaning offspring and determined their relationship to eventual clinical outcomes. ResultsCompared to controls, offspring acquiring maternal CPZ-induced dysbiosis exhibited a restructuring of intestinal microbial membership both in bacteriome and mycobiome that were associated with alterations in specific functional subsystems. Furthermore, among IL-10 KO offspring from CPZ-treated dams, several functional subsystems, particularly nitrogen metabolism, diverged between mice that developed spontaneous colitis (CPZ-colitis) versus those that did not (CPZ-no-colitis) at a time point prior to eventual clinical outcome. ConclusionsOur findings provide support that functional metagenomic profiling of gut microbes has potential and promise meriting further study for development of tools to assess risk and manage human IBD. SynopsisCurrently, predictive markers for the development and course of inflammatory bowel diseases (IBD) are not available. This study supports the notion that gut microbiome metagenomic profiles could be developed into a useful tool to assess risk and manage human IBD.

microbiology↗

bioRxiv2017

Community dynamics in parallelized, aerobic, single carbon-source enrichments

Here we seek to test the extent to which laboratory enrichments mimic natural community processes and the degree to which the initial structure of a community determines its response to a press disturbance via the addition of environmentally-relevant carbon compounds. By utilizing aerobic substrate arrays to examine the effect of carbon amendment on microbial communities taken from six distinct environments (soil from a temperate prairie and forest, tropical forest soil, subalpine forest soil, and surface water and soil from a palustrine emergent wetland), we examined how carbon amendment and inoculum source shape the composition of the community in each enrichment. Dilute subsamples from each environment were used to inoculate 96-well microtiter plates containing triplicate wells amended with one of 31 carbon sources from 6 different classes of organic compound (phenols, polymers, carbohydrates, carboxylic acids, amines, amino acids). After incubating each well aerobically in the dark for 72 hours, we analyzed the composition of the microbial communities on the substrate arrays as well as the initial inocula by sequencing 16S rRNA gene amplicons using the Illumina MiSeq platform. Comparisons of alpha and beta diversity in these systems showed that, while the composition of the communities that grow to inhabit the wells in each substrate array diverges sharply from that of the original community in the inoculum, these enrichment communities are still is strongly affected by the inoculum source. We found most enrichments were dominated by one or several OTUs most closely related to aerobes or facultative anaerobes from the Proteobacteria (e.g. Pseudomonas, Burkholderia, and Ralstonia) or Bacteroidetes (e.g. Chryseobacterium). Comparisons within each substrate array based on the class of carbon source further show that the communities inhabiting wells amended with a carbohydrate differ significantly from those enriched with a phenolic compound. Niche selection therefore seems to play a strong role in shaping the communities in the substrate arrays, although some stochasticity is seen whereby several replicate wells within a single substrate array display strongly divergent community compositions. Overall, the use of highly parallel substrate arrays offers a promising path forward to study the response of microbial communities to a changing environment.

microbiology↗