瓦莱氏芽孢杆菌YH-18发酵液的喷雾干燥工艺

【目的】瓦莱氏芽孢杆菌(Bacillus valeriana) YH-18菌株是1株对多种林木具有抗病促生效果的优良菌株。菌粉是生物菌剂应用在生产上的一种类型,以高集粉率和活菌量作为主要目标,确定YH-18菌粉制备的最佳喷雾干燥的工艺条件,为抗病促生瓦莱氏芽孢杆菌YH-18的规模化应用提供技术支撑。【方法】利用喷雾干燥法对YH-18菌株的发酵液进行喷雾干燥,采用单因素试验和正交试验设计,研究了瓦莱氏芽孢杆菌YH-18菌粉制备的喷雾干燥工艺条件。【结果】瓦莱氏芽孢杆菌YH-18发酵液喷雾干燥的最佳工艺条件为:进风口温度95 ℃,最佳保护剂为15%脱脂奶粉,雾化压力0. 25 MPa,进样速度10 mL/min,真空度-0. 03 Pa。在该条件下喷雾干燥得到的YH-18固体菌剂产物,活菌量可以达到3. 28×10 ⁹ cfu/g。YH-18固体菌剂对林木溃疡病病原菌拟茎点霉(Phomopsis sp.)保持有明显拮抗作用。【结论】固体菌剂相对于液体菌剂具有更易储藏、便于运输、货架期长等优点。喷雾干燥法具有控制性强、稳定性高的特点,是实现液体菌剂到固体菌剂的有效途径。YH-18发酵液喷雾干燥工艺条件的确定为未来规模化固体菌剂应用提供了技术支持。

Spray drying processes of Bacillus valeriana YH-18

【Objective】Bacillus valeriana YH-18 is a bacterial strain that exhibits an excellent antifungal ability in different kinds of trees. This strain is used as a biological agent in the form of bacterial powder. In this study, the spray drying of YH-18 strain was investigated as a method for producing the bacterial powder.【Method】The conditions of spray drying of YH-18 strain were studied using single-factor and orthogonal tests that were designed to attain a high powder collection rate and number of living bacteria as the outcomes.【Result】The best conditions for the spray drying of B. valeriana YH-18 fermentation liquid are as follows: air inlet temperature, 95 ℃; addition of 15 % skim milk powder; atomization pressure, 0.25 MPa; feeding speed, 10 mL/min; and vacuum degree, -0.03 Pa. Under these conditions, the yield of YH-18-based solid product obtained after the spray drying of B. valeriana YH-18 fermentation liquid reached up to 3.28 × 10 ⁹ cfu/g. The obtained solid fungicide provided potent protection against the disease caused by Phomopsis sp., a pathogen of wood canker disease.【Conclusion】Solid fungicides possess several advantages over liquid fungicides, such as ease of storage and transportation and long shelf life. The spray drying method can be applied in a highly controlled manner and has been shown to impart increased stability to the end product. It is an effective way of converting liquid fungicides to solid fungicides. Therefore, the determination of spray drying conditions of B. valeriana YH-18 fermentation liquid will provide further technical support in the application and production of large-scale solid fungicides in future.