Strain improvement of Aspergillus sojae for increased l-leucine aminopeptidase and protease production

• Published in: Food science and biotechnology Vol. 28; no. 1; pp. 121 - 128
• Main Authors: Lim, Jaeho, Choi, Yong-Ho, Hurh, Byung-Serk, Lee, Inhyung
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01.02.2019; Springer Nature B.V; 한국식품과학회
• Subjects: Aminopeptidase; Aspergillus sojae; Chemistry; Chemistry and Materials Science; Ethyl methanesulfonate; Fermentation; Food Science; Gene expression; Leucine; leucyl aminopeptidase; Mutagenesis; Mutants; Nutrition; Protease; Proteinase; proteinases; Random mutagenesis; Sauces; screening; Solid state fermentation; Soybeans; Substrates; 식품과학; Soybean fermentation; leucine aminopeptidase (LAP); Protease; Random mutagenesis; l-leucine aminopeptidase (LAP); Aspergillus sojae
• ISSN: 1226-7708; 2092-6456; 2092-6456
• DOI: 10.1007/s10068-018-0427-9

Conventional random mutagenesis was implemented to improve l -leucine aminopeptidase (LAP) and protease production in Aspergillus sojae . Through successive mutagenesis by ethyl methanesulfonate (EMS), UV, and 1-methyl-2-nitro-1-nitrosoguanidine (NTG), EMS25, EU36, and EUN13 mutants from each mutagenesis process were screened using a newly developed quick and easy screening method. The mutant EUN13 exhibited a 9.6-fold increase in LAP [50.61 ± 4.36 U/g-initial dried substrate (IDS)] and a 3.8-fold increase in protease production (13.36 ± 0.31 U/g-IDS) on solid-state fermentation. This mutant showed more frequent branching and higher lap1 mRNA expression as compared to the parent strain SMF 131, which at least in part contributed to the increased LAP and protease production. The mutant EUN13 can be used as a starter organism for diverse industrial soybean fermentation processes for the production of conventional products such as meju , doenjang , and ganjang as well as for the production of new fermented soybean-based sauces.