Effects of Short-Chain Fatty Acids Propionate, Acetate, Butyrate on the Growth of Clostridium difficile in Co-culture with an Escherichia coli atoE Mutant
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There are three major short-chain fatty acids (SCFAs) that play a role in gastrointestinal health: propionate, butyrate, and acetate. SCFAs have probiotic effects that lead to a healthy gastrointestinal environment such as providing energy, maintaining the epithelial lining, and roles in gene regulation and immunity. There is evidence that SCFAs function as important cell signals that affect the metabolism and overall physiology of the gastrointestinal tract. While SCFAs have been shown to reduce the amount of inflammation in association with GIT diseases, they also have been known to affect metabolic signaling processes and immunity. Determining which species of SCFAs are present could help us better understand their roles in the gut microbiome, metabolism, and cellular signaling propagation. High fiber diets and dietary supplementation of commensal strains such as Lactobacillus and Bifidobacterium have been shown to increase the amounts of SCFAs in the gastrointestinal tract. Clostridium difficile (C. diff) is a gram-positive, spore-forming, bacillus-shaped anaerobe. C. diff, normally a minor component of the gastrointestinal flora, is resistant to most broad-spectrum antibiotics. Dystopia of the normal flora, caused by antibiotic treatment for unrelated infections, causes an overgrowth of C. diff. In recent years there has been an increased number cases of C. diff infection (CDI) and antibiotic-associated diarrhea (AAD). The antibiotic-induced disruption in the natural gastrointestinal flora diminishes our own microbiome-mediated colonization resistance, allowing C. diff to proliferate, sporulate and produce toxins. This study aimed to examine if SCFAs play a role in the initial onset and growth of C. diff in a broth culture. Upon examining each of the three major SCFAs singly and in combination (1 uM/SCFA concentration), no major effect on the growth of C. diff was observed. Using spent media from BW25113 (WT) and BW25113 (atoE, SCFA mutant), C. diff showed a trend toward less growth and delayed onset of exponential growth as the concentration of spent media went up. Using mM concentrations in a 3:1:1 ratio of acetate, propionate, and butyrate respectively will mimic the human gastrointestinal tract more efficiently, and may have more of an effect on the growth of C. diff. It is suggested to try 30mM for acetate, and 10mM for propionate and butyrate.