渐狭蜡蚧菌Lecanicillium attenuatum产几丁质酶的活性及对南方根结线虫卵孵化的抑制作用

Inhibition of chitinase-producing fungus Lecanicillium attenuatum on egg-hatching of root-knot nematode Meloidogyne incognita

为探究卵寄生真菌产生的几丁质酶对南方根结线虫卵孵化的抑制作用,采用分离自黑龙江大豆孢囊线虫孢囊上的菌株CGMCC5328,利用NAG和p NP法测定其几丁质降解酶系和外切酶的活性,分析几丁质酶粗酶液对南方根结线虫卵的孵化抑制效果。结果表明,菌株CGMCC5328经形态学和ITS序列分析鉴定为渐狭蜡蚧菌Lecanicillium attenuatum;在几丁质酶诱导培养基中培养第4天时其分泌的几丁质降解酶系达酶活高峰,为16.90 U/m L;第6天外切酶达酶活高峰,为0.59 U/m L,之后酶活趋于稳定持续至第14天;几丁质酶分子量分别为79.6、65.6、54.1、42.1和32.9 k Da;其中培养第7天的几丁质酶粗酶原液对南方根结线虫卵孵化的抑制率为83.17%;第6天菌株CGMCC5328对卵的寄生率为85.10%。表明高效产几丁质酶的卵寄生真菌渐狭蜡蚧菌菌株CGMCC5328对南方根结线虫卵孵化具有明显的抑制效果。

In order to explore the inhibitory effect of the chitinase produced by egg-parasitic fungi on Meloidogyne incognita, a nematode egg-parasitic fungus CGMCC5328 was isolated from cysts of Heterodera glycines infecting soybean in Heilongjiang Province. Based on morphological characters and ITS sequence analysis,the strain was identified as Lecanicillium attenuatum. The chitinolytic systems and exochitinase produced by the fungus were measured by means of NAG and p NP,respectively. The molecular weights of chitinase were measured by activity staining of chitinases. The eggs of M. incognita were treated by different concentrations of crude chitinase from L. attenuatum CGMCC5328 to determine the suppression of egg-hatching. The results indicated that the activity of chitinolytic systems reached the highest level of 16. 90 U / m L on the fourth day. The exochitinase activity reached the highest level of0. 59 U / m L on the sixth day and then plateaued until 14 days. The molecular weights of chitinase were estimated as 79. 6,65. 6,54. 1,42. 1,and 32. 9 k Da,respectively. The maximum inhibitory rate of egg-hatching reached 83. 17% on the seventh day by original crude enzyme after treatment and the rate of parasitism was 85. 10% on the sixth day after egg inoculation. The egg-parasitic fungus L. attenuatum CGMCC5328 with high level production of chitinase provided significant suppression of egg-hatching of M. incognita.