- Volume 136, Issue 1, 1990

5S rRNA sequences were determined for the green sulphur bacteria Chlorobium limicola, Chlorobium phaeobacteroides and Prosthecochloris aestuarii, for Thermomicrobium roseum, which is a relative of the green non-sulphur bacteria, and for Cytophaga aquatilis, Cytophaga heparina, Cytophaga johnsonae, Flavobacterium breve, Flexibacter sp. and Saprospira grandis, organisms allotted to the phylum ‘Bacteroides-Cytophaga-Flavobacterium’ and relatives as determined by 16S rRNA analyses. By using a clustering algorithm a dendrogram was constructed from these sequences and from all other known eubacterial 5S RNA sequences. The dendrogram showed differences, as well as similarities, with respect to results obtained by 16S RNA analyses. The 5S RNA sequences of green sulphur bacteria were closely related to one another, and to a cluster containing 5S RNA sequences from Bacteroides and its relatives, including Cytophaga aquatilis. 5S RNA sequences of all other representatives of the ‘Bacteroides-Cytophaga-Flavobacterium’ phylum as distinguished by 16S RNA analysis failed to group with Bacteroides and related clusters. On the basis of 5S RNA sequences, Thermomicrobium roseum clustered with Chloroflexus aurantiacus, as was expected from 16S RNA analysis.

Sixty-eight Actinoplanes isolates from freshwater sediments were compared through 89 unit characters with marker strains of the genera Actinoplanes, Ampullariella, Dactylosporangium, Micromonospora, Planobispora, Spirillospora and Streptosporangium. The data were examined using the simple matching, Jaccard and pattern coefficients and clustering was achieved using the unweighted pair group method with arithmetic averages algorithm. The numerical classification was only marginally affected by the statistics used or by test error, estimated at 5 %. Most of the environmental isolates were recovered in five major clusters that were equated with taxospecies. Seven major, nine minor and 29 single-member clusters defined by the S SM coefficient at the 83 % similarity (S-) level, were assigned to two aggregate groups circumscribed at the 68 % S-level. The first cluster group was composed of strains belonging to the genera Actinoplanes (including Ampullariella), Dactylosporangium and Micromonospora and the second included representatives of the genera Planobispora, Planomonospora, Spirillospora and Streptosporangium. Selected Actinoplanes strains subjected to chemical analyses contained complex mixtures of straight- and branched-chain fatty acids, tetrahydrogenated menaquinones with nine isoprene units as the predominant isoprenologue, and major amounts of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol; the representative environmental isolates were also shown to contain meso- and hydroxydiaminopimelic acid; the principal wall sugars were arabinose, galactose, glucose, mannose and xylose. The chemical and numerical taxonomic data support the integrity of established species of Actinoplanes, with the exception of Actinoplanes caeruleus, and show that the five major clusters encompassing environmental isolates merit the rank of species. It is proposed that the five novel taxa be assigned to the genus Actinoplanes as Actinoplanes consettensis sp. nov., Actinoplanes derwentensis sp. nov., Actinoplanes durhamensis sp. nov., Actinoplanes humidus sp. nov., and Actinoplanes palleronii sp. nov. Similarly, the genera Actinoplanes, Dactylosporangium, Micromonospora and Pilimelia have many properties in common and it is proposed that they be classified in the family Micromonosporaceae Krassil′nikov 1938 ; an emended description of this taxon is given. The family Streptosporangiaceae fam. nov. is proposed to accommodate organisms assigned to the genera Microbispora, Microtetraspora, Planobispora, Planomonospora and Streptosporangium.

The intra- and intergeneric relationships of the genus Actinomyces were determined by comparing long 16S rRNA sequences, generated by reverse transcriptase. All species formed a phylogenetically coherent cluster in which Actinomyces bovis, A. viscosus, A. naeslundii, A. odontolyticus and A. israelii constituted genetically well defined species. A. israelii DSM 43322 (serotype 2) was not closely related to three other strains of this species (serotype 1) and, as judged from phylogenetic distances, could be accommodated within A. naeslundii, or represent a new species. In contrast to previous findings, members of the genus Actinomyces appear to be related to Bifidobacterium bifidum. Sequence information was used to develop an oligonucleotide probe for the A. israelii serotype 1 strains, which did not react with the serotype 2 strain or with rRNA from strains of eight Actinomyces species.