- Volume 21, Issue 4, 1971

Genetic relatedness among 179 strains representing 13 named species and several unnamed taxa of the genus Bifidobacterium from three main habitats, i.e., (i) feces of man, (ii) feces of various other animals, and (iii) the bovine rumen, was assessed by means of deoxyribonucleic acid (DNA)—DNA hybridization by using a filter-paper technique in competition experiments. Assignment of these strains to the genus Bifidobacterium was based on the production of lactic and acetic acids as chief products from glucose, lack of gas production, fructose-6-phosphate phosphoketolase activity, and on morphology. About 180 DNA competitors were tested with 23 reference systems. Several genetically distinct groups were recognized. Little or no DNA homology was demonstrated between some of the groups, suggesting large evolutionary divergence in this genus. B. infantis, B. liberorum, and B. lactentis form one of these groups; the ecological significance of this relatedness was discussed. The DNA of the following pairs are homologous: (i) B. breve and B. parvulorum, (ii) B. thermophilum and B. ruminale, and (iii) B. pseudolongum and B. globosum. Within a number of strains assigned to B. adolescentis, many of which were isolated from waste waters, a large genetic heterogeneity was demonstrated: in addition to B. adolescentis, at least three unrelated groups were recognized and are provisionally referred to as “dentium,” “catenulatum,” and “angulatum.” Since these groups are not related genetically to any species of the genus and are phenotypically distinct, they may represent new species. The validity of the species B. bifidum, B. longum, and B. suis was confirmed at the genetic level.

Using a theoretical method, the highest possible per cent deoxyribonucleic acid homology between 26 isolates of Rhizobium japonicum was determined. The homologies between the isolates and a reference strain ranged from 69.5% to 95%. Least significant difference analysis resulted in three statistically different but overlapping clusters. It was concluded on the basis of homology data that the species is a valid one, although one which shows considerable diversity.

ATCC 25559 (Prévot strain 1899B; VPI 0255) is designated as the neotype strain of Eubacterium lentum (Eggerth) Prévot 1938; a description of this strain is given. This strain conforms to the original description of this organism by Eggerth based on 23 strains from human feces. An emended description of E. lentum is given on the basis of a study of 53 strains, including 38 recent isolates, mostly from human infections, and 3 strains labeled E. lentum from the Prévot collection.

A type strain for Catenabacterium contortum Prévot has heretofore not been established. Prévot's strain 113 VI [ATCC (American Type Culture Collection) 25540; VPI (Virginia Polytechnic Institute) 0119], one of the two strains upon which the original description of this organism was based, possesses characteristics which closely agree not only with those given in the original description of C. contortum by Prévot, but also with those in the description of this organism as emended by the present authors. This strain is here designated as the type strain. The characteristics of C. contortum indicate that this organism properly belongs in the genus Eubacterium Prévot, to which genus it is transferred as Eubacterium contortum (Prévot) comb. nov.

The characteristics of ATCC 25986 conform very closely to those given in the original description of Bacteroides aerofaciens Eggerth 1935 as well as to those which form the current concept of this organism. The authors propose ATCC 25986 as the neotype strain of Eubacterium aerofaciens (Eggerth) Prévot 1938 and provide an updated description of this species.

Peptococcus Kluyver and van Niel, Peptostreptococcus Kluyver and van Niel, and Ruminococcus Sijpestein have recently been placed in the family Peptococcaceae Rogosa. Because Sarcina Goodsir also comprises gram-positive, anaerobic cocci whose general metabolism and other characteristics are consistent with the characteristics of Peptococcaceae, it is herein proposed that the genus Sarcina Goodsir be transferred from Micrococcaceae Pribram to Peptococcaceae Rogosa.

Micrococcus sp. ATCC 407 (Micrococcus freudenreichii ATCC 407), a metabolically active organism, uses maltose, maltotriose, and maltotetraose but not glucose or other carbohydrates as carbon sources. Organic acids (e.g., succinate, lactate, acetate) and amino acids (e.g., dicarboxylic, alanine, histidine, and lysine) are used more readily than maltose and maltodextrins. The organism uses ammonia as a nitrogen source provided that the medium contains thiamine, biotin, methionine, and a suitable carbon source (e.g., succinate). In a medium containing biotin, thiamine, and methionine, glutamine or glutamic acid served as single sources of carbon and nitrogen for growth. Some characteristics of M. freudenreichii ATCC 407 are presented for consideration by the Subcommittee on Taxonomy of Staphylococci and Micrococci of the International Committee on Systematic Bacteriology before any decisions are reached concerning the status of Micrococcus freudenreichii. However, on the basis of the available evidence, it is suggested that ATCC 407 should not be designated as the neotype strain of the species and that the name Micrococcus freudenreichii should be placed on the list of nomina rejicienda as a nomen dubium.

Boháček et al. have proposed that the flagellated, gram-positive cocci be included in the genus Planococcus Migula, particularly on the basis of their per cent guanine plus cytosine content. A serological examination of these organisms (10 strains) by the author revealed no antigenic relationship to staphylococci or micrococci, thus substantiating the conclusion of Boháček et al. that they do not belong to the genus Micrococcus. Antigenically, the group of strains was rather heterogeneous.

A new species of Streptomyces which produces two new cephalosporin antibiotics is named and described. Sporophores are produced on an extensive aerial mycelium and consist of networks of short, sympodially branched hyphae. One to four spores are borne usually on short, club-shaped side branches. Sporophores eventually segment to form chains of spores. The spores are oblong to slightly cylindrical, smooth-walled, and gray to grayish green en masse. The species name proposed, Streptomyces clavuligerus, refers to the production of club-like side branches.

It is proposed that the family Chlamydiaceae, which contains only one recognized genus, Chlamydia, be placed in a new order, Chlamydiales, coordinate with Rickettsiales Buchanan and Buchanan 1938. The principal argument for this change is that chlamydiae multiply by a developmental cycle that is unique among all other forms of bacteria.