粉红螺旋聚孢霉NF-06固体发酵条件优化及对南方根结线虫的防治效果

Optimization of Solid State Fermentation Conditions of Clonostachys rosea NF-06 and Its Control Efficiency on Meloidogyne incognita

南方根结线虫是一种严重危害我国蔬菜安全生产的土传病害,生产上亟需一种有效的防控方法。本研究从根结线虫卵囊中分离到一株生防真菌NF-06,通过形态学和分子生物学方法将其鉴定为粉红螺旋聚孢霉Clonostachys rosea。通过离体活性测定的方法测定NF-06发酵滤液对根结线虫2龄幼虫的致死作用,发现24、48和72 h后2龄幼虫的相对死亡率分别达63.6%,75.5%和87.0%。以产孢量为指标,优化菌株NF-06固体发酵条件,确定最佳基础培养基为麦麸和麦秸秆混合物,其比例为4:1(wt/wt),在基础培养基中添加10%玉米粉、2%蚕豆粉和0.05%KH2PO4可获得最大产孢量;最优培养条件为初始pH值7.0,初始含水量40%,接种量5%,产孢量达8.9×1010 CFU/g。室内盆栽防治效果测定显示,菌株NF-06固体发酵物能够有效降低土壤中的线虫数量和番茄根结指数,其中5 g/株穴施处理的线虫减退率和防治效果分别达67.9%和69.6%。本研究为生物杀线虫剂的开发和利用提供理论依据。

Root-knot nematode Meloidogyne incognita is an important soil-borne disease that threatens the safety of vegetables. Effective control measures are in urgent need. In this study, a biocontrol fungal strain NF-06 was isolated from the egg masses of M. incognita, identified as Clonostachys rosea by morphological and rDNA-ITS sequence analysis. An initial assay of NF-06 culture filtrates on second-stage juveniles was conducted, which showed relative mortalities of 63.6%, 75.5% and 87.0% at 24 h, 48 h and 72 h post treatment, respectively. The solid state fermentation conditions of the strain NF-06 were optimized using the conidium number as an index. The results showed that the optimal basal medium was the mixture of wheat bran and wheat straw, with a mass ratio of 4:1(wt/wt). When corn flour(10%), broad bean(2%) and KH2 PO4(0.05%) were supplemented into the basal medium, the maximum conidial production was achieved. The viable conidial number reacheed 8.9×1010 CFU/g at the optimal culture conditions of initial pH 7.0, initial water content 40%, and inoculum dose 5%. The NF-06 solid culture significantly reduced the population densities of juveniles in soil and root-knot index in tomato in a greenhouse test. When hole applied at 5 g per plant, the NF-06 solid culture afforded reduction rates of juveniles and control efficiency of 67.9% and 69.6%, respectively. This study provides a basis for the research and development of bio-nematicide.