Use of Fecal Slurry Cultures to Study In Vitro Effects of Bacteriocins on the Gut Bacterial Populations of Infants
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Bacteriocins are antimicrobial peptides produced by bacteria to compete with other bacteria for nutrients and ecological niches. The antimicrobial effect of these peptides on the bacterial populations in the gut is likely dynamic as the survival of the microbes in this environment depends on both competition and cooperation. In this study, we evaluated four different bacteriocins from lactic acid bacteria (LAB): nisin, enterocin A (EntA), enterocin K1 (EntK1), and garvicin ML (GarML), which have different inhibition spectra and physicochemical properties. The bacteriocins were tested in vitro using fecal slurry batch cultures from infants. The abundances of some bacterial populations in the cultures were determined using quantitative PCR (qPCR) and the metabolic activity of the gut microbiota was assessed by measuring the production of short-chain fatty acids (SCFA) using gas chromatography. The effects of the bacteriocins correlated well with their antimicrobial spectra and the administered concentrations. Nisin and GarML, with broad antimicrobial spectra, shifted the abundance of several intestinal bacterial groups, while EntA and EntK1, with relative narrower inhibition spectra, showed no or little effect. Moreover, the results from the SCFA analysis were consistent with changes obtained in the bacterial composition. In particular, a reduction in acetate concentration was observed in the samples with low abundance of Bifidobacterium, which is a well-known acetate producer. The variability imposed on the intestinal bacterial populations by the different bacteriocins tested suggests that this type of antimicrobials have great potential to modulate the gut microbiota for medical purposes.
KeywordsGut bacteria Bacteriocins Nisin Enterocin A Enterocin K1 Garvicin ML
We thank Lars-Gustav Snipen for his advices on statistics.
OCOU was supported by a strategic scholarship program to food science research, from Norwegian University of Life Sciences (NMBU) (project 1205051025), and she has currently a postdoctoral position funded by Research Council of Norway. NS was the recipient of a “Clarín” postdoctoral contract (Marie Curie European CoFund Program) cofounded by the “Plan Regional de Investigación” of Principado de Asturias and she is currently the recipient of a postdoctoral contract awarded by the Fundación para la Investigación Biosanitaria de Asturias (FINBA). Travels and stays in Spain and Norway for this study were supported by EEA Coordinated Mobility of Researchers NILS Science and Sustainability Project 017-CM-01-2013.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
The study was approved by the Regional Ethical Committee of Asturias Public Health Service (SESPA).
Informed consent was obtained from the parents of all individual participant infants included in the study.
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