Deoxyribonucleic Acid Base Compositions among Thermophilic Actinomycetes: the Occurrence of two Strains with Low GC Content

Abstract

SUMMARYDeoxyribonucleic acid (DNA) was extracted from two strains of Thermomonospora, two strains of Thermoactinopolyspora and one thermophilic strain of Streptosporangium. Base compositions were determined from ' melting-temperatures ' (Tm) and, in two cases, from buoyant density. DNAs from both Thermoactinopolyspora strains and one Thermomonospora strain were of similar base composition to those previously reported for mesophilic actinomycetes. The other Thermomonospora strain and the Streptosporangium strain, both of which had higher temperature requirements and tolerance for growth, possessed DNA of lower GC content. These findings are discussed in relation to phylogeny, thermophily and the universality of the genetic code.

Amino Acid Composition of the Cell-Proteins from Mesophilic, Thermofacultative and Thermophilic Actinomycetes

“…The protein amino acid composition of actinomycetes thus indicates another differential characteristic which emphasizes, within this group, the distinction between true thermophilic forms on one hand and mesophilic or thermofacultative forms on the other. We also believe that the apparent evolutionary paradox exhibited by the thermophilic actinomycetes, namely their phenotypic similarity, yet widely different G C content of DNA when compared with other forms, which has already been considered by Craveri et al (1965), Rosypal & Rosypalova (1966, Gause (1968), De Ley (1g70), Prauser (1970), Silvestri (1970) and Lechevalier, Lechevalier & Gerber (1971), has been reinforced.…”

Reassociation of Deoxyribonucleic Acids fromActinoplanesand Other Actinomycetes

“…Yamaguchi reported the following GC values: A. philippinensis, 72%; A. utahensis, 73 %; Ampullariella digitata, 72%; M. flavea, 70%; Spirillospora albida, 73%; Streptomyces albus, 72%; and Streptosporangium roseum, 71%. Craveri et al (10) and Manachini et al (18) determined the DNA base composition of various mesophilic and thermophilic actinomycetes. The species that they considered were different from ours; however, comparing genera, they obtained per cent GC values that were a few per cent higher than ours.…”