Abstract
The possibility of producing amino acids under conditions of denitrification, i.e., with nitrate respiration as an energy-supplying system, was investigated using denitrifying bacteria. We found that Bacillus licheniformis A35 accumulated γ-polyglutamic acid (PGA) to a concentration of 8 mg per ml in a medium containing glucose and ammonium chloride or glutamic acid under denitrifying conditions. The bacterium also produced PGA aerobically. Thus, we found the de novo synthesis of PGA with B. licheniformis A35. The optimum conditions for PGA production were determined.
The purified PGA was found to be composed solely of glutamic acid; both D- and L -glutamic acid, in a molar ratio of 4:1. The molecular weight of PGA was about 3 × 105.
Other bacilli tested produced some free amino acids but not under nitrate-respiration conditions, although some of them did produce PGA aerobically from L-glutamic acid.
