生物转化玉米浆生产生物菌肥的共生发酵特性

玉米深加工是全球第二大宗农产品加工行业，玉米淀粉制备过程中产生大量的副产物，如玉米浆（Maize Steep Liquor, MSL）。玉米浆色深味重、毒素含量高、处理困难，已经成为众多玉米深加工企业发展的桎梏。该研究主要利用玉米浆中丰富的速效氮源和微生物的促生长因子进行微生物菌肥的开发。通过对前期筛选到的3株植物根际促生菌（PGPMs）的共生发酵研究，评估了3种菌在玉米浆中高密度发酵的可行性，并对发酵特性进行了研究。试验结果表明，三种菌通过共生发酵，并在模拟流加工业废料结晶糖母液作为补料时，发酵体系中的总生物量从6.6×109提升到了2.17×1010 CFU/mL，并在52 h氨基酸态氮含量达到最大。同时，采用葡萄糖模拟结晶葡萄糖母液流加补料显著提高了共生体系的总糖以及溶磷的利用率，可溶性磷利用率提高了近50%；此外，添加葡萄糖还能保持发酵体系的pH值稳定，奠定了生产稳定性。该研究为玉米浆的再利用提供了一种解决方法，对低成本生物肥料的开发与生产提供了一种新的思路。

Symbiotic fermentation characteristics of biotransformed maize pulp for biofertilizer production

Maize deep processing has been the second-largest agricultural processing industry in the world. The products (such as starch sugar, maize oil, and crude fiber) have been very important food and chemical raw materials. Among them, maize starch is currently the main resource for the production of glucose syrup and various sugar derivatives. However, the preparation process of maize starch can produce a large number of by-products, such as Maize Steep Liquor (MSL). Alternatively, the maize pulp has been confined during processing, due to the dark color, heavy taste, high toxin content, and difficult handling. Particularly, maize pulp presents great potential in the field of bio-exploitation, due to a large number of nutrient contents with more than 40% nitrogen and more than 25% carbohydrates. Therefore, a cheap nitrogen source can be served for the fermentation production of bioproducts. This study aims to develop microbial fertilizers using the abundant source of fast-acting nitrogen in the maize pulp and the growth-promoting factors of microorganisms. The slow release and degradation of toxins by soil were avoided to reduce the direct toxicity of biotoxins to humans and livestock. A systematic evaluation was made on the high-density fermentation of three strains of plant inter-rhizosphere growth-promoting bacteria (PGPMs) in the maize pulp. The fermentation characteristics were investigated via the symbiotic fermentation of three strains of PGPMs that screened in the previous stage. The experimental results showed that the three species significantly increased the biomass in the fermentation system after the symbiotic fermentation. The flow addition of starch industrial waste (crystalline glucose mother liquor) was taken as a supplement during the simulation. The total biomass was elevated from 6.6×109 to 2.17×1010 CFU/mL in the fermentation system. The maximum viable bacterial count and amino acid nitrogen were obtained at the end of 45 h fermentation. Meanwhile, the glucose was added in the mimic crystalline glucose mother liquor flow in the symbiotic system. Then, there was a significant increase in the utilization of total sugars and soluble phosphorus. Specifically, the soluble phosphorus utilization increased by nearly 50%. The addition of glucose also maintained the stable pH value in the fermentation system, particularly for the stable production of bacterial fertilizer. This finding can provide a better solution and practical basis for the reuse of maize pulp in the production of low-cost biofertilizers using a variety of bacteria. The high value-added reuse of crystalline glucose mother liquor can be produced using the waste of maize starch.