Abstract:

Bacillus mucilaginosus is a kind of heterotrophic aerobic bacteria, which can decompose phosphorus and potassium in soil and silicate minerals, and is widely used in microbial fertilizers. The bacteria is cultured by liquid fermentation and followed by peat adsorption, but the effective number of viable microorganisms and spore rate were lower. Therefore, it is important to identify how to increase the number of viable cells and spore rate with optimized fermentation pattern and condition of Bacillus mucilaginosus. In this study, a strain named YA\|07 was isolated from apple orchard soil in Luochuan County of Shannxi Province, which was identified as Bacillus Mucilaginosus through the morphological, physiological and biochemical experiments and the sequence of 16s rDNA. By single factor, and orthogonal experiments, a kind of solid\|state fermentation condition, which could produce high density of effective living bacterium and high rate of spore was established. The Results showed that the medium that can make YA\|07 produce a large number of effective number of living bacterium, and high spore rate can be divided into 500 mL bottles of peat 50 g, starch 3%, peptone 3%, without inorganic salts and trace elements. At 30℃ pH 7.0, 10% inoculation amount, and 144 h cultivation time, the effective number of living bacterium of YA\|07 can reach 1.58×109 cfu/g, and the spore rate can reach 91.3%. In this study, the effective number of viable cells and rate of Bacillus mucilaginosus spores were increased by solid fermentation, which not only improved the quality of microbial fertilizer, but also reduced the environmental pollution, so it is of important significance for promoting the development of green agriculture in China.

Key words: Bacillus mucilaginosus, solid fermentation, classification and identification, orthogonal experiment, single factor experiment

摘要：

胶质芽胞杆菌（Bacillus mucilaginosus）是一类能分解土壤中磷、钾和硅酸盐矿物的化能异养型好氧细菌，广泛应用于微生物肥料中。该菌在微生物肥料生产过程中主要是经液体发酵后由草炭吸附而成，这种工艺生产的微生物肥料有效活菌数和芽胞率均较低。因此，如何通过改善胶质芽胞杆菌的发酵方式和发酵条件以提高其有效活菌数和芽胞率显得尤为重要。对陕西省洛川县苹果园土壤中分离到的一株YA\|07菌株通过形态学、生理生化实验和16s rDNA序列比对鉴定为胶质芽胞杆菌（Bacillus mucilaginosus）。通过单因素实验和正交试验，建立了一种使该菌产生高密度有效活菌数和高芽胞率的固体发酵条件。结果表明：YA\|07能够产生大量有效活菌数和高芽胞率的培养基组分为500 mL培养瓶装草炭50 g，淀粉添加量3%，蛋白胨添加量3%，不添加无机盐和微量元素。在培养温度30℃，pH 7.0左右，接种量10%，培养时间144 h条件下，YA\|07的有效活菌数可以达到1.58×109 cfu/g，芽胞率可以达到91.3%。利用固体发酵技术提高了胶质芽胞杆菌的有效活菌数和芽胞率，在改善微生物肥料产品质量的同时减少了环境的污染，对促进我国绿色农业的发展具有重要意义。

关键词: 胶质芽胞杆菌；固体发酵；分类鉴定；正交试验；单因素实验