Shoichiro Suzuki

Transfer of Peptococcus indolicus, Peptococcus asaccharolyticus, Peptococcus prevotii, and Peptococcus magnus to the genus Peptostreptococcus and proposal of Peptostreptococcus tetradius sp. nov.

The guanine-plus-cytosine (G+C) contents of the deoxyribonucleic acids (DNAs) of Peptococcus asaccharolyticus ATCC 14963T (T = type strain), Peptococcus indolicus ATCC 29427T, Peptococcus prevotii ATCC 9321T, and Peptococcus magnus ATCC 15794T ranged from 29 to 34 mol%, whereas the G+C content of the DNA of Peptococcus niger ATCC 27731T, the type species of the genus Peptococcus, is 51 mol%. The G+C content of the DNA of Peptostreptococcus anaerobius ATCC 27337T, the type species of the genus Peptostreptococcus, was 33 mol%. Thus, the DNA base compositions of Peptococcus asaccharolyticus, Peptococcus indolicus, Peptococcus prevotii, and Peptococcus magnus resemble the DNA base composition of the type species of the genus Peptostreptococcus rather than the DNA base composition of the type species of the genus Peptococcus. It is not desirable for the genus Peptococcus to include any species whose G+C content is far from the G+C content of the type species of the genus. The levels of DNA-DNA homology between Peptostreptococcus anaerobius ATCC 27337T and the four species of Peptococcus with low G+C DNA contents ranged from 23 to 36%. The cellular fatty acid profiles of Peptococcus asaccharolyticus, Peptococcus indolicus, Peptococcus prevotii, and Peptococcus magnus also resembled the cellular fatty acid profile of the type species of Peptostreptococcus. Other biochemical characteristics of these species revealed their close resemblance to Peptostreptococcus anaerobius. For these reasons we propose transfer of the four Peptococcus species that have low G+C contents to the genus Peptostreptococcus as Peptostreptococcus asaccharolyticus (Distaso 1912) comb. nov., Peptostreptococcus indolicus (Christiansen 1934) comb. nov., Peptostreptococcus prevotii (Foubert and Douglas 1948) comb. nov., and Peptostreptococcus mangus (Prevot 1933) Smith 1957 comb. rev. A group of organisms previously referred to as “Gaffkya anaerobia” (Choukevitch) Prevot is an identifiable Peptostreptococcus species based on phenotypic and genotypic characteristics. The name of Peptostreptococcus tetradius sp. nov. is proposed for this group of organisms. Strain GIFU 7672 (= ATCC 35098) is designated the type strain. Clinical strains of P. asaccharolyticus that were identified by conventional methods were divided into two homology groups and one unclassified group (A-1). DNA-DNA homology between the type strain of P. prevotii and clinical strains which had been received as P. prevotii ranged from O to 73%.

The Susceptibility of Clostridia from the Antarctic Soil to Antibiotics

From the Antarctic soil, a total of 193 strains of clostridia were isolated and identified. Of them were assigned to 11 species; i.e., C.perfringens, C.bifermentans and C.sordellii were isolated frequently.

Antibacterial Susceptibility Testing of Anaerobes

There are a lot of ploblems associated with susceptibility testing of anaerobes which are not encountered in the testing of aerobes and facultative anaerobes. Anaerobiosis itself,medium composition and carbon dioxide concentration in the atmosphere may all influence the test results. In this study,we examined influence of these variants and established a standardized agar dilution test.