Isolation and partial characterization of Bacillus subtilis mutants impaired in DNA entry

Abstract

Transformation-deficient mutants of Bacillus subtilis have been identified either by screening for a nuclease-deficient phenotype on methyl green-DNA agar or for nontransformability on transforming DNA-containing agar. After purification of the mutations causing a reduction in the entry of DNA, a set of isogenic entrydeficient strains was obtained. In addition to being entry deficient to various extents, the strains usually were less capable of association with DNA than the entry-proficient parent. Likewise, the specific transforming activity in the purified mutant strains continued to be less than that in the wild type. With the possible exception of one strain, no evidence was obtained that the mutant strains were impaired in recombination. Since the breakdown of transforming DNA to acidsoluble products correlated fairly well with the residual capacity of the strains to take up DNA, nucleolytic activity is likely to be involved in the entry of DNA in B. subtilis.

The regulation of genetic competence in Bacillus subtilis

“…The use of chemicai mutagens, as well as transposon and plasmid insertion mutagenesis, has allowed the isolation of a variety of mutants deficient in competence (Albano et ai, 1987;Fani etai, 1984;Hahn efa/., 1987;Matromei e( ai, 1988;Mulder and Venema, 1982;Nakano and Zuber, 1989;Weinrauch efa/., 1990). These mutants cannot bind, process and transport transforming DNA.…”

Replacement of the lysine residue in the consensus ATP‐binding sequence of the AddA subunit of AddAB drastically affects chromosomal recombination in transformation and transduction of Bacillus subtilis

“…a. The transformation frequencies are defined as the percentages of the number of trp + transformants per total number of viable cells, corrected for DNA uptake as described by Mulder and Venema (1982). The transformation frequencies of strain 8GK02 were taken as 100%.…”

Evidence for natural transformation of Bacillus subtilis in foodstuffs

“…The organisms were grown in minimal salts medium [10] with supplements, and stock cultures were prepared as described by Bron and Venema [9] and van Sinderen and Venema [11]. Minimal agar was prepared according to Mulder and Venema [12].…”