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摘要
Potato starch wastewater contains high concentration of starch, protein and other organic matter. Using potato starch wastewater to cultivate plant growth-promoting bacteria is a method to realize its resource utilization. The growth conditions of Paenibacillus polymyxa EBL06 strain cultured in potato starch wastewater were optimized using a comibined single-factor and central composite design (CCD) approach, in which three key factors, i.e., wastewater volume fraction (concentration), culture temperature and initial pH, were focused. In this context, the optimum conditions for the culture of P. polymyxa obtained from the experiment were as follows: COD concentration 13.7 g·L?1, initial pH 7.17, culture temperature 31.4 ℃. Under this condition, the number of living bacteria was 6.2×109 cfu·mL?1, which was consistent with the CCD predictions, and satisfying the national standard of agricultural microbial agents (GB 20287-2006). To verify the application effect of the microbial agent, the experiment of vegetable planting was then carried out. The results showed that the P. polymyxa biofertilizer could significantly increase the yield and quality of pakchoi; its fresh weight, dry weight, plant height and vitamin C content increased by 68.6%, 13.7%, 5.6% and 41.3%, respectively; compared with the fertilization of chemical fertilizer only, the mixed fertilization of P. polymyxa biofertilizer and urea fertilizer could improve the nitrogen utilization efficiency, and resulted in an increment in the content of vitamin in pakchoi plant by nearly 25.3%, and meanwhile, contributed to an decrease in the content of nitrate decreased by 15.3%. Overall, this study provides a meaningful reference for the resource utilization of potato starch wastewater, as well as the application and popularization of P. polymyxa.
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