Culture media for increased antimicrobial activity of mixed bacterial antagonists
2011
Sunanthnat Nurapak(Kasetsart University, Bangkok (Thailand). Faculty of Agriculture. Department of Plant Pathology) E-mail:[email protected] | Sutruedee Prathuangwong(Kasetsart University, Bangkok (Thailand). Faculty of Agriculture. Department of Plant Pathology)
Four bacterial antagonists including Bacillus amyloliquefaciens KPS46, Paenibacillus pabuli SW01/4, Pseudomonas fluorescens SP007s and Serratia marcescens Spt360 which each strains have been reported to suppress multiple diseases on varies economic crops. One approach to enhance biocontrol efficacy is to combined different strains into mixtures. This is needed to determine their compatibility, large amount of optimal biomass and secondary metabolite production, by utilizing and inexpensive ingredients such as molasse or vinasse (alcohol and crude extract of molasse). Among ten-combinations of two- strains mixtures, the highest population density of strain KPS46 and SP007s mixture in a new medium developed, VS liquid medium (liquid medium of vinasse+soybean meal = 5:10 g/L) was observed with 3*10**(15) cfu/ml (from 1*10**(8) cfu/ml original culture) at 24 h after incubation compared to MS medium (molasse + soybean meal) or molasse and vinasse alone media, and nutrient glucose broth. The agar plate, and seed treatment bioassay, secondary metabolite obtained from strains KPS46 and SP007s mixture grew in VS medium (after 24 h incubation) also significantly higher inhibited Xanthomonas axonopodis pv. glycines (Xag), the causal agent of soybean bacterial pustule and reduced Xag-infested seeds with 2.2 cm indiameter of inhibition zone, and 96 percent respectively (P=0.05). This work demonstrates the first report for new liquid-based VS medium and increased effectiveness of mixed biocontrol agents.
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