Bacillus mojavensis and Bacillus subtilis require DNA or deoxyribonucleosides for anaerobic growth.

Abstract

Bacillus mojavensis strain JF-2 grows to an A600 of 0.8 to 1.0 in aerobic medium E but growth in this medium under strict anaerobic conditions is difficult to establish and replicate. Anaerobic growth of JF-2 was not improved by the addition of vitamins, amino acids, ribonucleic acids, polyglutamate, polyglutamine, polytryptophan, rumen fluid, fatty acids or Tween 80 to medium E. The addition of enzymatic digests of protein to medium E improved anaerobic growth of JF-2. DNA from various sources replaced the requirement for enzymatic digests of protein for anaerobic growth of Bacillus mojavensis JF-2 and two other B. mojavensis strains. The addition of a mixture of four deoxyribonucleosides to medium E replaced the requirement for DNA. The addition of a mixture of five nucleic acid bases, four ribonucleotides or four ribonucleosides to medium E did not replace the requirement for four deoxyribonucleosides. The addition of four deoxyribonucleosides to aerobic medium rescued B. mojavensis JF-2 from hydroxyurea-induced, aerobic growth inhibition. DNA was not used as a sole carbon and energy source.

Five Bacillus subtilis strains also required DNA or deoxyribonucleosides for anaerobic growth. Bacillus subtilis 168 required deoxyribonucleosides at a concentration approximately 10 times the theoretical requirement. Bacillus subtilis JH642 required about one quarter of the deoxyribonucleosides required by Bacillus subtilis 168. Amino acids were also required by Bacillus subtilis 168 for anaerobic growth. The addition of pyruvate to the medium did not replace the requirement for deoxyribonucleosides or amino acids. The addition of glutamine or nitrate did not replace the requirement for amino acids. Microaerophilic growth of Bacillus subtilis 168 and Bacillus subtilis JH642 was inhibited by 0.1 g/l hydroxyurea and growth inhibition by hydroxyurea was overcome with the addition of deoxyribonucleosides. Microaerophilic growth of B. sonorensis and B. licheniformis was not inhibited by 0.1 g/l hydroxyurea. A BLAST (NCBI) search failed to identify a Class II or a Class III ribonucleotide reductase in the Bacillus subtilis subsp. subtilis strain 168 genome and no nrdD or nrdJ has been annotated for B. subtilis . All other Bacillus genomes available on the NCBI website had at least a putative nrdD gene (at least 32% identical and 49% similar) and most were annotated as anaerobic ribonucleotide-triphosphate reductases.