Optimization of growth medium for a PGPR strain (SZ7-1) from mangrove rhizosphere

Abstract:

A plant growth-promoting rhizobacteria (PGPR) strain, SZ7-1, was obtained from mangrove rhizosphere and tested previously for potential applications. To develop an economical and practical fermentation medium for the growth of SZ7-1, response surface method was used in this study. Plackett– Burman factorial design was used to examine the significance of 11 different media on the growth of SZ7-1. Experimental result demonstrated that media consisting of corn syrup, yeast extract and K₂HPO₄ significantly improved the growth process. The effect of different combinations of the three nutrients on the growth of SZ7-1 were further explored in a Box-Behnken design. The optimal concentration of each nutrient for maximum growth were corn syrup 28 g/L, yeast extract14 g/L and K₂HPO₄ 2.2 g/L. The optimized medium enhanced the growth of SZ7-1 by 12.4, 2.4 and 5.5 times more than the original medium, LB and cow meat extract protein peptone medium, respectively. This research indicates that it is possible to increase bacterial yield and reduce its costs using optimized growth medium.