Open AccessInvestigations on a hyper‐proteolytic mutant of B eauveria bassiana : broad substrate specificity and high biotechnological potential of a serine protease
Author(s) -
Borgi Ines,
Gargouri Ali
Publication year - 2014
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/1574-6968.12339
Subject(s) - beauveria bassiana , protease , serine protease , mutant , substrate specificity , proteases , biology , microbiology and biotechnology , chemistry , biochemistry , enzyme , botany , biological pest control , gene
A new strain of B eauveria bassiana was identified on the basis of the 18S rRNA gene sequence homology. This strain, called P2, is a spontaneously arisen mutant that was isolated after successive sub‐culturing the wild‐type B . bassiana P1 strain. P2 showed hyper‐production of extracellular protease(s) as much as ninefold more than P1. An extracellular protease ( SBP ) having a molecular weight of 32 kDa was purified from the P2 strain. SBP was completely inhibited by the phenyl methyl sulphonyl fluoride, which suggests that it belongs to the serine protease family. Based on the homology analysis of its N‐terminal and the gene sequences, the enzyme was identified as subtilisin. The enzyme displays maximum activity at 60 °C and pH 8, and was stable at pH 6–12. The enzyme hydrolyses natural proteins such as keratin and is activated in presence of β‐mercaptoethanol and T ween detergents. SBP was compatible with some laundry detergent formulations and showed high efficacy in the removal of blood stains from cotton fabric. Moreover, it was observed to degrade the melanised feathers and to hydrolyse the gelatine from X‐ray films. All these results highlight the suitability of SBP protease as a very efficient microbial bio‐resource.