Bergey's Manual of Systematic Bacteriology was published from 1984 to 1989 and contains a methodic listing of a large amount of taxonomic data. It is one of the most comprehensive and authoritative works in the field of bacterial taxonomy. However, rapid advances in molecular biology and determination of a large amount of sequencing data of genes coding for the 16S rDNA have resulted in numerous taxonomic rearrangements and changes in nomenclature. Recently, the second edition of Bergey's Manual of Systematic Bacteriology was published, and this paper summarizes the present state of the taxonomy of anaerobic Gram positive bacteria.

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Recent taxonomic study of bacteria has progressed using techniques such as analysis of GC mol%, 16S rRNA, and DNA-DNA hybridization. Since Bergey's Manual of Systematic Bacteriology Vol. 2 was published in 1986, numerous new bacterial species and taxonomic rearrangements of lactic acid bacteria such as Lactobacillus, Enterococcus and Lactococcus, and Bifidobacterium have been reported. This paper summarizes the present status of the taxonomy of these bacteria isolated from human and animals, and used for probiotics.

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Instead of making classifications based on physiological and biochemical traits, comparative analysis of the 16S rRNA sequences has been used to explore the phylogenetic relationships of bacteria. The establishment of this new taxonomy has also brought new insight to the field of microbiology ecology. 16S rRNA molecules are used as the marker because: they are universally present in all organisms; they contain sufficient information for reliable phylogenetic analyses (more than 1,000 nucleotides); they are easy to handle with a high degree of precision to characterize; and the fact that the sequences of almost all species are found in public databases. To discuss the relationship between a host and its flora, it is essential to know the composition and phylogeny of the intestinal bacteria. In this review, I would like to focus on the phylogeny of predominant bacteria in human intestinal flora such as the Clostridium coccoides group, the Clostridium leptum subgroup, Bacteroides, Bifidobacterium, and the Atopobium cluster, to identify which species are assigned to these bacterial groups.

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Chitosan is a food ingredient recognized as safe, which is produced by deacetylation of chitin which is found in the shells of crabs and shrimps. Chitosan is a potential biomaterial for colon-specific drug delivery, because it is not digested in the stomach or intestine, but is degraded and digested in the colon by indigenous bacteria such as Bacteroides. We demonstrated that a chitosan hard capsule disintegrated in the ascending and transverse colon in humans in our previous work. In the present experiment, newly developed chitosan-coated tablets containing barium sulfate were ingested by healthy male volunteers, and the fates of the tablets were monitored using chronological abdominal radiography. The tablets were shown to disintegrate in the transverse colon.

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