Isolation and identification of milk oligosaccharide-degrading bacteria from the intestinal contents of suckling rats.
BIOSCIENCE OF MICROBIOTA FOOD AND HEALTH 2020;
40:27-32. [PMID:
33520566 PMCID:
PMC7817515 DOI:
10.12938/bmfh.2020-024]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/17/2020] [Indexed: 12/19/2022]
Abstract
We report the isolation of bacteria capable of degrading milk oligosaccharides from
suckling infant rats. The bacteria were successfully isolated via a selective enrichment
method, in which the serially diluted intestinal contents of infant rats were individually
incubated in an enrichment medium containing 3′-sialyllactose (3′-SL), followed by the
isolation of candidate strains from streaked agar plates and selection of 3′-SL-degrading
strains using thin-layer chromatography. Subsequent genomic and phenotypic analyses
identified all strains as Enterococcus gallinarum. The strains were
capable of degrading both 3′-SL and 6′-SL, which was not observed with the type strain of
E. gallinarum used as a reference. Furthermore, a time-course study
combining high-performance anion-exchange chromatography with pulsed amperometric
detection revealed that the representative strain AH4 degraded 3′-SL completely to yield
an equimolar amount of lactose and an approximately one-fourth equimolar amount of sialic
acid after 24 hr of anaerobic incubation. These findings point to a possibility that the
enterococci degrade rat milk oligosaccharides to “cross-feed” their degradants to other
members of concomitant bacteria in the gut of the infant rat.
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