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Studies on mixed populations of human intestinal bacteria grown in single-stage and multistage continuous culture systems.

Authors
Type
Published Article
Journal
Applied and environmental microbiology
Publication Date
Volume
55
Issue
3
Pages
672–678
Identifiers
PMID: 2930171
Source
Medline
License
Unknown

Abstract

Mixed intestinal bacteria were grown for 336 h in two identical single-stage chemostats at low growth rates in a carbohydrate-limited medium. Complex bacterial populations were maintained and anaerobes always outnumbered aerobes. The predominant organisms belonged to the genera Bacteroides, Bifidobacterium, Lactobacillus, Clostridium, Eubacterium, Propionbacterium, Peptococcus, and Peptostreptococcus. Bacteroides species predominated in both fermentors, particularly B. ovatus and B. thetaiotaomicron. A high degree of reproducibility of bacteriological and fermentation product data was obtained in these experiments. When gut contents were inoculated into a five-stage continuous culture system (retention time of 79 or 38 h) containing soya bran, the medium flow rate had little quantitative effect on the formation of acidic fermentation products; however, more oxidized fermentation acids were produced at the higher retention time. Diverse bacterial populations were maintained in every vessel at each flow rate. Bacteroides fragilis group organisms, especially B. ovatus, were numerically the most important. The viability of bacteria decreased through the system, especially at a retention time of 79 h, when the bacteria were growing under severely nutrient-limited conditions.

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