Medium optimization for production of antifungal active substances from antagonistic Brevibacillus laterosporus and its antifungal activity analysis

Abstract

The antagonist bacterium Brevibacillus laterosporus ZQ2 with broad-spectrum antifungal activity was isolated from an apple rhizosphere at Mount Tai in China. The fermentation medium for the production of antifungal substances from ZQ2 was statistically optimized. In one-factor-at-a-time experiments, five components, including carbon sources, nitrogen sources, and inorganic salt, were selected. Two factors were determined as critical based on the Plackett-Burman design. Steepest ascent experiments were then used to determine the design space containing the optimum point, followed by application of the response surface methodology. A quadratic model fitting the actual production was established using a central composite design. The obtained optimum medium for the antifungal substances production consisted of the following (in g/L): glucose, 15.6; soybean meal, 8.2; starch, 20; ammonium sulfate, 2; and monopotassium phosphate, 1. Furthermore, the inhibition rate of the substances against Rhizoctonia solani increased by more than 132% compared with the control. B. laterosporus ZQ2 strongly inhibited the growth of many apple phytopathogens in vitro. The inhibition rates against different fungi ranged from 55.26 to 79.02%. As well, the strain significantly reduced the disease damage caused by R. solani in the in vivo tests. Maximum disease protection (46.89%) was recorded when the bacterium applied 3 days before pathogen inoculation.

Characterization and Antimicrobial Studies of Iturin-Like and Bogorol-Like Lipopeptides From Brevibacillus spp. Strains GI9 and SKDU10

“…Strains of Brevibacillus are well known for antimicrobial peptides with activity against bacteria and plant pathogenic fungi (Orlova et al, 1998;Singh et al, 2015;Baindara et al, 2016;Yang and Yousef, 2018). The strong inhibition and selective spectrum exhibited by some of these antimicrobial substances have attracted the researchers to exploit them for applications like antibiotic, biocontrol agents and food additives or preservatives (Cleveland et al, 2001;Song et al, 2012Song et al, , 2013. Therefore, in this study, we have identified two lipopeptides by mass spectrometry and investigated their antimicrobial activity against various bacteria, yeast, and filamentous fungi for their plausible applications.…”