致病疫霉拮抗细菌筛选及J-28菌株鉴定

Screening of antagonistic bacteria against Phytophthora infestans and identification of J-28 strain

为明确从马铃薯根际土壤中分离获得的细菌对致病疫霉的抑制作用,采用平板划线分离法分离马铃薯根际细菌,以对峙培养法和打孔法分别测试细菌菌株、菌液及无菌体发酵液对致病疫霉菌丝生长的抑制作用,并对其中最具优势的菌株通过培养特征、形态、生理生化特性及16S rDNA序列进行鉴定。结果显示,在分离的60株细菌中,有16株细菌对致病疫霉有明显拮抗作用,有6株抑菌率达60%以上。其中,J-5和J-26的抑菌率最高(90.24%和91.54%),其次为J-28,抑菌率87.80%;菌液以J-5和J-33的抑菌率最高(95.34%和92.93%);J-28菌液抑菌率为81.36%:无菌体发酵液以J-28和J-26的抑菌率最高(82.92%和75.60%)。综合评价以J-28菌株的抑菌作用最为稳定。经鉴定J-28菌株为一株巨大芽孢杆菌(Bacillus megaterium)。该菌株在马铃薯晚疫病防治中有较大潜力。

In order to understand inhibition effect of potato rhizosphere bacteria on Phytophthora infestans,crossed plate separation method was used for isolation bacteria strains from potato rhizosphere,and dual culture and punch method were applied for detection suppression efficiencies of bacterial living strains,bacterial fluid and fermentation liquid on mycelial growth of P.infesUms,respectively.In addition,one of the most advantageous strains was identified by culture characterization,biochemical properties and 16 S rRNA gene sequencing.The results showed that 16 strains showed antagonism against P.infesUms in isolated 60 strains.And inhibition rates of the 6 in these 16 strains were higher than 60%.Among them,J-25 and J-26 strains had the highest inhibition rates with 90.24%and 91.54%in living strains,and J-5 and J-33 strains with95.34%and 92.93%in bacterial fluid,and J-28 and J-26 strains with 82.92%and 75.60%in fermentation liquid,respectively.Overall evaluation,J-28 strain was high stable and potential and was identified as Bacillus megaterium.