海洋细菌NH-8防治草莓灰霉病机理及其抗菌物质分析
The mechanism of biological control of strawberry gray mould using the marine bacterial NH-8 strain and analysis of the antifungal substances from the strain

为探讨从海藻分离获得的枯草芽胞杆菌Bacillus subtilis菌株NH-8对草莓灰霉病的防治机理,采用酸沉淀法分析其抗菌活性成分,并从促生、抑菌和诱导草莓防御酶活性方面进行了研究。结果表明:接种菌株NH-8后,草莓体内苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性均有不同程度提高,最大分别为35.4、3.63、51.5、43.8U;同时接种菌株NH-8和灰霉病菌比单一接种菌株NH-8或灰霉病菌对草莓体内防御酶活性的影响更大,PAL、POD、SOD、CAT活性最大分别为37.5、3.91、55.5、47.6U。NH-8菌株发酵液对草莓生长具有明显的促进作用,苗株高、鲜重和干重分别比对照显著增加57.58%、131.43%和45.45%;发酵液的粗提物对灰霉病菌具有抑菌活性,可引起菌丝不规则生长,菌丝顶端或中间膨大成泡囊状,引起原生质泄露;NH-8菌株及其分泌物质对草莓具有抗性诱导作用,分泌的抗菌活性产物为伊枯草素(iturin)。
In order to understand the mechanism of biological control of strawberry gray mould by treatment with the Bacillus subtilis strain NH-8 isolated from marine algae, the extract from NH-8 fermentation liquid was prepared by using acid precipitation, detected with the plate experiment of antagonism. The promoted growth, inhibitory activities, and induced activity of antioxidant system were studied. The results showed that activities of phenylalaninammo nialyase (PAL), peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) were increased after inoculated with strain NH-8, and the highest antioxidization activities were 35.4, 3.63, 51.5, and 43.8 U, respectively. Strain NH-8 and Botrytis cinereawereinoculated at the same time, which had stronger influences on enzymes activity than single-inoculated B. cinerea or strain NH-8. The highest antioxidization activities were 37.5 U of PAL, 3.91 U of POD, 55.5 U of SOD, 47.6 U of CAT. An obvious promotion on strawberry growth was observed after inoculation with suspension of strain NH-8, and the plant height, fresh weight, dry weight were significantly increased by 57.58%, 131.43% and 45.45%, respectively. Serious mycelium malformation of B. cinerea was observed after treated with strain NH-8 fermentation liquid, including short growth, cytoplasm condensation, cell wall break and protoplasm leak. The strain NH-8 and the secreted substances induced resistance to strawberry. The active substance from NH-8 strain belonged to iturin.