害虫防治用玫烟色拟青霉分生孢子粉的干燥工艺优化*

用液—固两相法生产的玫烟色拟青霉Paecilomyces fumosoroseus Pfr116菌株的分生孢子粉,在高真空冷冻干燥、高真空室温抽干、35℃下烘干和低真空低热干燥条件下进行不同程序的干燥处理,以筛选适合该菌孢子粉生产的干燥工艺条件。结果表明,低真空(0.1 MPa)低热(30℃)抽干20~24 h的干燥方法最适合用于该菌孢子粉的干燥,既能保证含水量在9.0%以下,又能保证87%以上的活孢率和1130亿~1310亿/g的含孢量,而且操作简便,成本较低,可作为高纯度孢子粉生产的首选干燥工艺。高真空(15.86 Pa)条件下无论冻干还是室温抽干,虽然孢子粉的含水量(2.2%~8.7%)和含孢量(1270亿~1360亿/g)指标符合生产要求,但活孢率仅62%,说明该菌孢子不适合在高真空条件下干燥。在35℃下烘干24 h所获孢子粉含水量、24 h萌发率和含孢量分别为9.6%、82.8%和1200亿/g,该方法也可在生产中应用,但其活孢率显著低于(P<0.05)低真空低热抽干24 h的孢子粉。

OPTIONAL DRYING PROCEDURES FOR MASS PRODUCTION OF PAECILOMYCES FUMOSOROSEUS CONIDIA FOR INSECT CONTROL

Several drying methods and procedures, including high-vacuum freeze drying (HVFD), high-vacuum (15.86 Pa) drying at ambient temperature (HVDAT), heating drying at 35C (HD), and low-vacuum (0.1 MPa) low-heat (30C) drying for 16~34 h (LVLHD), were tested for exploring an appropriate method for drying aerial conidia of the entomopathogenic fungus Paecilomyces fumosoroseus Pfr116 produced in diphasic fermentation. The 20~24-hour LVLHD procedures were found being most suitable for drying of the fungal conidia, leading to a powdery product with a water content of <9.0%, a viability of >87%, and a density of 1.131011~1.311011 conidia per gram. These indices all met requirements for industry standards, suggesting that the LVLHD procedures be applied to mass production of the fungal conidia. Under the high vacuum conditions, both freeze and ambient temperature drying procedures resulted in powdery products with satisfactory water contents of 2.2%~8.7% and 1.271011~1.361011 conidia per gram but a significantly lower viability of about 62%. Thus, the fungus was considered to be less tolerable to the high-vacuum drying procedures. The regular HD procedure yielded an acceptable product containing 9.6% water, 82.8% viability, and 1.201011 conidia per gram. However, its viability was significantly lower than those of the 24-h LVLHD procedures (P<0.05).