Improving Agar Degradation Activity of Vibrio natriegens WPAGA4 via Atmospheric and Room Temperature Plasma (ARTP)

Abstract

Agar oligosaccharides from the degradation of agar harbor great potential in the food and pharmaceutical industries. An agar-degrading bacterium, Vibrio natriegens WPAGA4, was isolated from the deep sea in our previous work. However, the agar-degrading activity of WPAGA4 remains to be improved for more production benefits of this strain. The aim of this study was to enhance the agar-degrading activity of WPAGA4 by using atmospheric and room temperature plasma (ARTP) mutagenesis. Three mutant strains, including T1, T2, and T3, with good genetic stability were obtained, and the agar-degrading activities of these strains increased by 136%, 141%, and 135%, respectively. The optimal temperature and pH for agar degradation were slightly changed in the mutant strains. No sequence mutation was detected in all the agarase genes of WPAGA4, including agaW3418, agaW3419, agaW3420, and agaW3472. However, ARPT mutagenesis increased the relative expression levels of agaW3418, agaW3419, and agaW3420 in the mutant strains, which could be the reason for the improvement of degradation activities in the mutant strains. Furthermore, T3 had the lowest consumption rate of agar oligosaccharide, which was 21% less than the wild-type strain. Therefore, T3 possessed a preferable production value due to its higher degrading activity and lower consumption of agar oligosaccharides. The current work enhanced the agar-degrading activity of WPAGA4 and offered strains with greater potential for agar oligosaccharide production, thereby laying the foundation for industrial applications.