LAUSR

BACKGROUND Protein glutaminase (PG) is a novel protein modification biotechnology that is increasingly being used in the food industry. However, the current level of fermentation of PG-producing strains still does not meet the requirements of industrial production. In order to obtain the mutant strains with high PG production, the atmospheric and room temperature plasma (ARTP) combined with LiCl chemical mutagen were used in mutagenesis of a PG producing Chryseobacterium proteolyticum 1003. RESULTS A mutant strain (WG15) was successfully obtained based on malonic acid resistance screening after compound mutagenesis of the starting strain C. proteolyticum 1003 using ARTP with LiCl, and it was proved to be genetically stable in PG synthesis after 15 generations. The protein glutaminase production of WG15 was 2.91 U mL-1 after optimization of fermentation conditions, 48.69% higher than the original strain C. proteolyticum 1003. The PG obtained from fermentation showed good activities in deamidation of soy protein isolate. The solubility and foaming properties of the PG-treated soy protein isolate was significantly increased by 36.50% and 10.03%, respectively, when PG was added at the amount of 100 U mL-1 . In addition, the emulsifying activity and emulsion stability of the treated soy protein isolate were improved by 12.44% and 10.34% respectively at the PG addition of 10 U mL-1 . And the secondary structure of the soy protein isolate changed after PG treatment, with an increased proportion of glutamate. CONCLUSION All the results acquired indicated that the PG produced by this mutant strain could improve the functional properties of soybean protein isolate and the C. proteolyticum mutant WG15 had great potential in food industry. This article is protected by copyright. All rights reserved.