Genes encoding xylan and β-glucan hydrolysing enzymes in Bacillus subtilis: characterization, mapping and construction of strains deficient in lichenase, cellulase and xylanase

The gene encoding extracellular xylanase (~rynA) was amplified as a 770 bp DNA fragment from Bacillus subtilis 168 chromosomal DNA by PCR. The genes encoding endo-jl-184-glucanase (eglS) and endo-~I,3-1,4-glucanase (bg/S) were isolated from a genomic library of B. subtilis 168. The sequences of xynA and eglS were identical to those of the xylanase and cellulase genes from B. subti/is PAP1 15. Integrative plasmids containing DNA fragments with deletions in the coding region oC the genes were constructed and used to replace the chromosomal egis, bg/S and xynA genes of B. subtilis 168. Strains without any detectable activity against xylan (Xyn-), carboxymethylcellulose (Egl-) or mixed linked /?-183-1,4-glucan (Egl- Bgl-) were obtained. The genes were mapped at 170" (eg/S), 175" (xynA) and 340" (bglS) on the B. subti/is chromosome.