Entomology Research Laboratory, Department of Plant and Soil Science, University of Vermont, 661 Spear Street, Burlington, VT 05405-0105, USA.
J Ind Microbiol Biotechnol. 2010 Apr;37(4):419-23. doi: 10.1007/s10295-010-0692-y. Epub 2010 Feb 16.
Low thermotolerance of entomopathogenic fungi is a major impediment to long-term storage and effective application of these biopesticides under seasonal high temperatures. The effects of high temperatures on the viability of an entomopathogenic fungus, Isaria fumosorosea SFP-198 (KCTC 0499BP), produced on different substrates amended with various additives were explored. Ground corn was found to be superior in producing the most thermotolerant conidia compared to yellow soybean, red kidney bean, and rice in a polyethylene bag production system. Using ground corn mixed with corn oil as a substrate resulted in only 7% reduction in germination compared to ground corn alone (67% reduction) after exposure of conidia to 50 degrees C for 2 h. Corn oil as an additive for ground corn was followed by inorganic salts (KCl and NaCl), carbohydrates (sucrose and dextrin), a sugar alcohol (sorbitol), and plant oils (soybean oil and cotton seed oil) in ability to improve conidial thermotolerance. Unsaturated fatty acids, such as linoleic acid and oleic acid, the main components of corn oil, served as effective additives for conidial thermotolerance in a dosage-dependent manner, possibly explaining the improvement by corn oil. This finding suggests that the corn-corn oil mixture can be used to produce highly thermotolerant SFP-198 conidia and provides the relation of unsaturated fatty acids as substrates with conidial thermotolerance.
在高温季节，昆虫病原真菌的耐热性低是长期储存和有效应用这些生物农药的主要障碍。本研究探讨了高温对不同基质上产生的昆虫病原真菌（玫烟色棒束孢 SFP-198，KCTC 0499BP）活力的影响。结果表明，与黄大豆、红芸豆和大米相比，在聚乙烯袋生产系统中，用玉米粉生产的分生孢子最耐热。与单独使用玉米粉（67%）相比，用玉米粉和玉米油混合作为基质，暴露于 50°C 2 小时后，仅减少 7%的萌发率。在提高分生孢子耐热性方面，玉米粉中的添加剂依次为无机盐（KCl 和 NaCl）、碳水化合物（蔗糖和糊精）、糖醇（山梨醇）和植物油（大豆油和棉籽油）。玉米油中的主要成分，即不饱和脂肪酸（如亚油酸和油酸），以剂量依赖的方式作为分生孢子耐热性的有效添加剂，这可能解释了玉米油的作用。这一发现表明，玉米-玉米油混合物可用于生产高度耐热的 SFP-198 分生孢子，并提供了作为基质的不饱和脂肪酸与分生孢子耐热性的关系。
