The Bacillus firmus-Bacillus lentus complex and pH 7.0 variants of some alkalophilic strains

Summary: Variants capable of growth at pH 7·0 were obtained from 174 alkalophilic strains (optimum pH 9·7) of the genus Bacillus by successive transfer on media with decreasing pH values. Nearly half of the pH 7·0 variants were like strains of the B. firmus–B. lentus complex. The remaining pH 7·0 variants grew at 50 °C and were assigned to two groups closely related to B. lentus.