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Construction of the mutant strain in Aspergillus oryzae 3.042 for abundant proteinase production by the N + ion implantation mutagenesis
Author(s) -
Zhao Guozhong,
Hou Lihua,
Lu Meifang,
Wei Yonghua,
Zeng Bin,
Wang Chunling,
Cao Xiaohong
Publication year - 2012
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2011.02870.x
Subject(s) - aspergillus oryzae , protease , serine protease , fermentation , mutant , biochemistry , carboxypeptidase , casein , mutagenesis , strain (injury) , agar plate , enzyme , biology , chemistry , food science , microbiology and biotechnology , bacteria , gene , genetics , anatomy
Summary Because of secreting large amounts of enzymes, Aspergillus oryzae was widely used in the fermentation of soy sauce in many Asian countries. Here, N + ion implantation mutagenesis was applied to improve the ability of A. oryzae to secrete acid protease. Several mutants were screened using three kinds of plates (Casein medium, Czapek’s medium and carboxymethyl cellulose medium agar plates). Compared with the other mutants, the mutant A100‐8 could secrete the most protease. Acid protease activity of A100‐8 was enhanced about 44.1% at 36 h by koji fermentation test. In addition, A100‐8 was stable by periodically subculturing and maintaining on the agar slant. The mRNA expression levels of two kinds of acid protease (serine carboxypeptidase and aspartyl protease) were measured by RT‐PCR at different periods. Serine carboxypeptidase and some kinds of aspartyl protease of A100‐8 were significantly ( P < 0.01) expressed higher than the control at all times.