Submitted to: American Society of Microbiologists Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/23/1996
Publication Date: N/A
Technical Abstract: Previous DNA relatedness studies showed that strains identified as Bacillus mycoides segregated into two genetically distinct yet phenotypically similar groups, one being B. mycoides sensu stricto and the other, an unclassified taxon. In the present study, the taxonomic position of this second group was assessed by measuring DNA relatedness spectrophotometrically and observing phenotypic characteristics of an increased number of B. mycoides strains. Also determined was the second group's 16S RNA gene sequence. The 40 B. mycoides strains studied segregated into two genetically distinct groups with DNA interrelatedness of about 30%. DNA relatedness to the type strains of presently recognized species with G+C contents of approximately 35 mol% (B. alcalophilus, B. cereus-group, B. circulans, B. lentus and B. megaterium) ranged from 22 to 31%. Although shown to be genetically distinct, the two B. mycoides groups had 16S RNA sequence similarity of 98% and were shown to be closely related phylogenetically to B. cereus. Unique 21-base segments at position 174 (E. coli numbering) in the 16S RNA gene were used as probes to differentiate the second B. mycoides group from the recognized species. Definite phenotypic differences clearly separated the unclassified group from the recognized species. The data have established that the second B. mycoides group merits recognition as a new species for which the name Bacillus pseudomycoides is proposed.