Gut microbiome homeostasis in vivo is due to complex microbial interactions which can be perturbed by acute stress-induced changes in the gastrointestinal environment, potentially leading to dysbiosis. Diet in particular, can greatly influence the dynamics of gut microbiome composition and metabolism. Here, the influence of a sudden change in diet, namely 21 days sole sustenance on the Meals Ready to Eat (MRE) U.S. military combat ration, on population dynamics within the gut microbiome was examined using resistant starch (RS) as a model fermentable fiber substrate. Fecal samples collected from 10 individuals before and after consuming their habitual diet or only MREs for 21d underwent 24hr in vitro fermentation in nutrient-rich media supplemented with RS under ascending colon domain-specific conditions. Quantitative Polymerase Chain Reaction (qPCR) analysis of 9 selected organisms revealed differential community responses to RS. Specifically, relative to habitual diet-exposed samples, Lactobacillus spp. growth was attenuated in MRE-exposed samples (p-interaction ≤ 0.001), whereas growth of Ruminococcus bromii was enhanced (p-interaction ≤ 0.05). These findings suggest that an acute stressor such as a sudden change in diet may impact inter-species competition for nutritional substrates and alter gut microbiota community dynamics. Additional research is needed to elucidate underlying mechanisms of the microbial community dynamics and how those perturbations influence nutrient competition and metabolic functions. 16S rRNA sequencing analysis is planned for a deeper understanding of the effects of diet consumption on the whole gut microbial community.

Acute stressor alters inter-species competition for resistant starch in the gut microbiota

256th National Meeting (2018)

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