SUMMARY: From s244, 45 deletion mutants have been isolated which belong to six groups. In four groups the identity of the auxotrophic markers deleted has been established: -2, -I, -3 and -I. Furthermore, a and a marker were found in the two other groups of deletion mutants. From S1026, derived from strain ATCC9945A, 36 single site mutants were obtained and classified into eight groups, to , by transformation and phage SP 15-mediated transduction. The deletion comprises the mutations and In total, 13 mutations have been found and there may be up to 13 genes. Of the single-site mutations, only is linked with a known reference marker, -I. All mutants are unable to form nitrate reductase under conditions of oxygen shortage. This nitrate reductase is mainly associated with the cytoplasmic membrane. Most mutations have pleiotropic effects: (i) retarded growth under anaerobic conditions; (ii) an increased sensitivity to penicillin and related antibiotics; (iii) completely altered membrane protein patterns on acrylamide-SDS gels.

In the wild-types, II membrane protein bands are observed. There are only small, quantitative differences between membrane protein patterns of cells cultivated aerobically or anaerobically. Membrane protein patterns of the mutants are most different from those of the wild-types after anaerobic cultivation. Differences include appearance of a new protein band, disappearances, decreases, doublings and often large increases of other protein bands. Aerobically, the mutants have membrane protein patterns less different from those of the wild-types. Differences include appearance of a new protein band, decrease and disappearance of protein bands. An explanation for all these changes may be a wholesale disorganization of protoplasmic membrane biosynthesis.


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