Food Science and Biotechnology

, Volume 28, Issue 1, pp 121–128 | Cite as

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

  • Jaeho Lim
  • Yong-Ho Choi
  • Byung-Serk Hurh
  • Inhyung LeeEmail author


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.


l-leucine aminopeptidase (LAP) Protease Aspergillus sojae Random mutagenesis Soybean fermentation 



This study was supported by the World-Class 300 project, and by the Partnership programs of Strengthening technological competency for Small and Medium Enterprise (S2483241) funded by the Ministry of SMEs and Startups (MSS, Korea).


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Copyright information

© The Korean Society of Food Science and Technology and Springer Science+Business Media B.V., part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Bio and Fermentation Convergence Technology, BK21 PLUS ProjectKookmin UniversitySeoulKorea
  2. 2.Sempio Fermentation Research CenterSempio Foods CompanyOsongKorea

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