Search bioRxiv⌕ Search

Biology subjects

Ewin, D.

Publications and source records attributed to Ewin, D..

3 recordsLinked to original sources

MiGut: a scalable in vitro platform for simulating the human gut microbiome - development, validation, and simulation of antibiotic induced dysbiosis

In vitro models of the human colon have been used extensively in developing understanding of the human gut microbiome and how internal and external factors affect the residing bacterial populations. Such models can be highly predictive of in vivo effects of antibiotics, and indeed more so than animal models. The complexity required by current in vitro models to closely mimic the physiology of the colon poses practical limits on their scalability. MiGut allows considerable expansion of model runs, increasing the capacity to test reproducibility or parameters under investigation. The MiGut platform has been assessed against a well-studied triple-stage chemostat model in a demanding nine-week study, with exposure to multiple antibiotics inducing a state of dysbiosis in the microbiome. A good correlation is found, both between individual MiGut models and against the triple-stage chemostat. Together with high-throughput molecular techniques for sample analysis, it is now conceivable that tens of in vitro models could be run simultaneously, allowing complex microbiome-xenobiotic interactions to be explored in far greater detail. MiGut is a unique platform whereby multiple colonic models can be run simultaneously with minimal added resource and complexity to support our understanding of the cause-effect relationships that govern the gut microbiome. This model system expands the capacity to generate clinically relevant data that can optimize interventions which target the gut microbiome directly or indirectly.

microbiology↗

Insights into the regulatory mechanisms of Clostridioides difficile biofilm formation

Mucosal biofilms play an important role in intestinal health; however, the mucosal bacterial community has been implicated in persistent infections. Clostridioides difficile is an important nosocomial pathogen, with an unacceptable high rate of recurrence following antibiotic treatment. As C. difficile is a known biofilm producer, a property which may contribute to this suboptimal therapeutic response, we have investigated the transcriptional changes and regulatory pathways during the transition from planktonic to biofilm mode of growth. Widespread metabolic reprogramming during biofilm formation was detected, characterised by an increased usage of glycine metabolic pathways to yield key metabolites, which are used for energy production and synthesis of short chain fatty acids. We detected the expression of 107 small non-coding RNAs that appear to, in some part, regulate these pathways; however, 25 of these small RNAs were specifically expressed during biofilm formation, indicating they may play a role in regulating biofilm-specific genes. Similar to Bacillus subtilis, biofilm formation is a multi-regulatory process and SinR negatively regulates biofilm formation independently of other known mechanisms. This comprehensive analysis furthers our understanding of biofilm formation in C. difficile, identifies potential targets for anti-virulence factors, and provides evidence of the link between metabolism and virulence traits.

microbiology↗

Profiling the effects of rifaximin on the healthy human colonic microbiota using a chemostat model

Rifaximin is a low solubility antibiotic with activity against a wide range of bacterial pathogens. It accumulates in the intestine and is suitable for prolonged use. Three chemostat models (A, B and C) were used to investigate the effects of three rifaximin formulations (, {beta} and {kappa}, respectively) on the gut microbiome. Bacterial populations were monitored by bacterial culture and 16S rRNA gene amplicon (16S) sequencing. Limited disruption of bacterial populations was observed for rifaximin , {beta} and {kappa}. All formulations caused declines in total spores ([~]2 log10 cfu ml-1), Enterococcus spp. ([~]2 log10 cfu ml-1 in models A and C, and [~]1 log10 cfu ml-1 in model B), and Bacteroides spp. populations ([~]3 log10 cfu ml-1 in models A and C, and [~]4 log10 cfu ml-1 in model B). Bacterial populations fully recovered during antibiotic dosing in model C, and before the end of the experiment in models A and B. According to the taxonomic analysis, prior to rifaximin exposure, Bifidobacteriaceae, Ruminococcaceae, Acidaminococcaceae, Lachnospiraceae and Rikenellaceae families represented >92% of the total relative abundance, in all models. Within these families, 15 bacterial genera represented >99% of the overall relative abundance. Overall, the 16S sequencing and culture data showed similar variations in the bacterial populations studied. Among the three formulations, rifaximin {kappa} appeared to have the least disruptive effect on the colonic microbiota, with culture populations showing recovery in a shorter period and the taxonomic analysis revealing the least global variation in relative abundance of prevalent groups.

microbiology↗