Regulation of extracellular laccase production of Agaricus bisporus by nitrogen sources in the medium

Abstract The substrate specificity of cystathionine γ-synthase (EC 4.2.99.9) in various bacteria was examined. O-Succinyl- l -homoserine was used preferably as a substrate by facultative anaerobic Gram-negative bacteria belonging to such genera as Escherichia, Klebsiella, Enterobacter, Citrobacter, Erwinia, Serratia, Proteus and Salmonella . Among Gram-negative aerobic bacteria, bacteria belonging to the genera Pseudomonas, Xanthomonas and Alcaligenes also used O -succinyl- l -homoserine in preference to O -acetyl- l -homoserine. On the other hand, bacteria belonging to the genera Agrobacterium and Flavobacterium used O -acetyl- l -homoserine preferably. As to Gram-positive aerobic bacteria, bacteria of the genus Bacillus used O -acetyl- l -homoserine exclusively. Bacteria belonging to the genera Micrococcus, Corynebacterium, Brevibacterium and Arthrobacter used both O -acetyl- and O -succinyl- l -homoserine to similar extents.