Distribution of the fecal microflora in several specimens from different locations of the human stool was analyzed with the steel wool method and the plate-in-bottle method. Total bacterial counts and the number of bacteroidaceae at the upper portion of the stool were significantly higher than those at the lower portion by both culture methods. Lecithinase-negative clostridia were recovered in significantly higher numbers at the middle or upper portion compared with the lower portion by the plate-in-bottle method. The number of lactobacilli was significantly higher at the upper portion than at the other portions. There was no significant difference in the numbers of other bacterial groups observed. The percentage of bifidobacteria in the total bacterial populations enumerated by the steel wool method varied among the three portions of the stool, while those counted by the plate-in-bottle method were consistent. These results indicate that the composition of the fecal microflora was differently analyzed at the parts of the stool possibly because of oxygen diffused from the anus. A culture method for highly oxygen sensitive anaerobes could minimize this difference.

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The inhibitory effects of human-derived Bifidobacterium longum BB536 on harmful intestinal bacteria were examined by co-cultivation of BB536 with each one of the following eight bacterial strains: Escherichia coli, Klebsiella pneumoniae, Clostridium clostridiiforme, C. perfringens, Bacteroides distasonis, B. fragilis, B. thetaiotaomicron and B. vulgatus. In comparison with the results of mono-cultivation, BB536 inhibited both the growth of these putrefactive bacteria and their production of ammonia, and decreased the pH of the culture medium by producing lactic and acetic acids. Enzy-matic assays showed that in BB536 the sorts of the enzymes involved in ammonia production (urease and amino acid deaminases) were rather few and their activities were weaker than observed in the harmful bacteria, whereas the activities of enzymes involved in ammonia assimilation (glutamine synthetase, glutamate synthase and glutamate dehydrogenase) were much higher in BB536 than in the putrefactive bacteria.

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A comparative study was conducted on the antibacterial activities of linoleic acid hydroperoxide (LAHPO) and linoleic acid (LA) against the intestinal bacteria including 35 strains, and the representative species were examined for lipid degradation activity. Enterobacterial species (Escherichia coli, Proteus mirabilis, Citrobacter sp. and Enterobacter sp.), Lactobacillus species (acidophilus, casei and plantarum), and Enterococcus faecalis generally showed the same levels in susceptibility to LA and LAHPO. Bacteroides species (distasonis, vulgatus and thetaiotaomicron) and Clostridium ramosum were highly resistant against LA but not LAHPO. Staphylococcus species (aureus and epidermidis), Lactobacillus species (salivarius and fermentum) and the Grampositive anaerobic bacteria including Clostridium perfringens, Bifidobacterium species (bifidum, infantis, adolescentis, breve, longum, animalis, pseudolongum and thermophilus), Peptostreptococcus productus, and Eubacterium sp. were more susceptible to LAHPO than were the enterobacterial species and E. faecalis although they were more resistant against LAHPO than LA. Eubacterium aerofaciens was more susceptible to LAHPO, but strikingly susceptible to both lipids compared to the other bacterial strains. Thin layer chroma-tography showed that C. perfringens degrade LAHPO and C. ramosum degrade LA, which was consistent with the resistance of the corresponding species to the fatty acids. A similar trend in the resistance to and degradation of the fatty acids was found with B. adolescentis and B. infantis. Much higher degradation abilities were observed in the live bacterial cells than the heat-killed cells of B. adolescentis, C. perfringens, and E. coli, suggesting that they can enzymatically degrade LAHPO in vitro.

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