Identification of aryl-phospho-β-D-glucosidases in Bacillus subtilis

Four aryl-phospho-beta-D-glucosidases were identified in Bacillus subtilis by using 4-methylumbelliferyl-phospho-beta-D-glucopyranoside as a substrate. Two of these enzymes are the products of the bglA and bglH genes, previously suggested to encode aryl-phospho-beta-D-glucosidases, while the other enzymes are encoded by the yckE and ydhP genes. Together, these four genes account for >99.9% of the glucosidase activity in B. subtilis on aryl-phospho-beta-D-glucosides. yckE was expressed at a low and constant level during growth, sporulation, and spore germination, and was not induced by aryl-beta-D-glucosides. ydhP was also not induced by aryl-beta-D-glucosides. However, while ydhP was expressed at only a very low level in exponential-phase cells and germinating spores, this gene was expressed at a higher levels upon entry into the stationary phase of growth. Strains lacking yckE or ydhP exhibited no defects in growth, sporulation, or spore germination or in growth on aryl-beta-D-glucosides. However, a strain lacking bglA, bglH and yckE grew poorly if at all on aryl-beta-D-glucosides as the sole carbon source.