Open AccessSelected faecal bacteria and nutrients essential for antagonism of Salmonella typhimurium in anaerobic continuous flow cultures
Author(s) -
Tsutomu Ushijima,
A. Seto
Publication year - 1991
Publication title -
journal of medical microbiology/journal of medical microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.91
H-Index - 117
eISSN - 1473-5644
pISSN - 0022-2615
DOI - 10.1099/00222615-35-2-111
Subject(s) - microbiology and biotechnology , bacteria , biology , antagonism , bacteroides , population , anaerobic bacteria , enterobacter aerogenes , obligate anaerobe , enterococcus faecalis , enterobacter , fusobacterium , escherichia coli , food science , biochemistry , genetics , receptor , gene , staphylococcus aureus , demography , sociology
As few as five of the species of bacteria commonly found in human faeces--Escherichia coli, Enterobacter aerogenes, Enterococcus faecalis, Bacteroides ovatus and Fusobacterium varium--when grown together in anaerobic continuous flow cultures exerted antagonistic effects on Salmonella typhimurium as great as those given by mixed bacteria from extracts of human faeces. In a single culture, the population of S. typhimurium was c. 10(8) cfu/ml but in mixed cultures with the five antagonistic bacteria or mixed faecal bacteria it was reduced to c. 10(3) cfu/ml. Antagonism appeared to be the result of competition for the growth limiting amino acids, arginine, serine, threonine and aspartic acid. Optimal manifestation of antagonism required the presence of carbon sources fermentable only by antagonistic bacteria, such as lactose 0.1%, w/v, sucrose 0.1% (w/v) and starch 0.2-0.3% w/v. These carbohydrates promoted the growth of the antagonistic bacteria, particularly E. coli and B. ovatus. However, an increase in concentration by several fold of any one of four growth-limiting amino acids in the medium diminished the antagonistic effects and the population of S. typhimurium rose 10(2)-10(3)-fold.