致病疫霉诱导放线菌Sy11菌株的抑菌作用

Antagonistic effect of Streptomyces microflavus Sy11 strain induced by Phytophthora infestans

在筛选致病疫霉拮抗菌过程中,发现放线菌Sy11菌株对致病疫霉的抑制作用是由于致病疫霉对Sy11的诱导作用.为了进一步明确致病疫霉对Sy11的诱导方式和条件,采用平板对峙共培养法探讨了致病疫霉诱导Sy11的适宜培养基、培养温度、培养时间以及诱导后Sy11菌株抑菌作用的持续时间等.结果显示,只有活体致病疫霉才能诱导Sy11的抑菌作用,死亡的致病疫霉菌体没有诱导作用;用黑麦培养基20℃黑暗对峙培养7d,从Sy11菌落向外12mm处的无菌体琼脂块的抑菌作用最强,抑菌率达到79.38%,与Sy11菌株完整菌落的抑菌率86.47%相近;而且发现致病疫霉诱导1次后,Sy11的抑菌能力即可连续传递13代,且抑菌率保持在65%以上.这些结果表明,Sy11是在受到活体致病疫霉诱导之后才对致病疫霉有抑制作用,且抑菌作用具有遗传性.

Actinomycetes Streptomyces microflavus Sy11 strain had strong suppression to mycelial growth and sporangia germination of Phytophthora infestans.And it was found that suppression was induced by P.infestans during antagonists screening in early experiments.In order to further reveal the induction effect and conditions of P.infestans to strain Sy11,dual culture method was used for investigating the suitable culture medium,temperature,time,and continual inhibition of Sy11 strain after induction.The results showed that only the alive P.infestans could induce the inhibition effect of Sy11,dead P.infestans could not;The strongest restrain of Sy11 was found on Rye medium,20℃for culture 7 d in dark,with free cell agar block which was 12 mm from Sy11 colony edge,the inhibition rate reached 79.38%and was close to that of whole colony of Sy11 strain(86.47%).In addition,prohibition capability of Sy11 could be continuously transmited for 13 generations after only once induction,and inhibition rate could remain above 65%.These findings suggest only alive P.infestans can induce the inhibition effect of Sy11,and the capability of Sy11 has inheritance.