知识与财富的链接
采用血琼脂平板法, 从菜园土壤中分离到8株代谢表面活性剂的菌株, 比较各菌株的排油性、抑菌性, 根据合成脂肽类物质表面活性素(Surfactin)和伊枯草菌素A (Iturin A)必需的sfp、ituD和lpa-14基因设计引物, 结合PCR的方法筛选到一株具广谱抗菌性且含有sfp、ituD和lpa-14 3个关键基因的细菌XZ-173。经过生理生化试验测定和16S rDNA序列系统发育学分析, 将其鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。通过红外光谱(FT-IR)分析该菌株代谢产物, 初步鉴定为脂肽类物质, 并对照高效液相色谱(HPLC)与标准品比对结果, 确定含有Surfactin和Iturin A组分。该菌株产生的脂肽粗品能使纯水的表面张力降低至26.6 mN/m, 临界胶束浓度(CMC)为500 mg/L, 具有很好的乳化性能, 对立枯丝核菌和青枯菌表现出很好的拮抗活性。因此, 产脂肽细菌XZ-173是一株应用前景广阔的功能菌。
After preliminarily isolated from soil of vegetable gardens by using blood-agar method, eight strains were further examined by oil-spreading test and inhibitory test. Primers were designed according to genes (sfp, ituD, lpa-14) related to surfactin and iturinA synthesis, and one bacterial strain XZ-173 with a broad spectrum of phytopathogens was screened out by PCR of the sfp, ituD, lpa-14 gene. Based on the physiological and biochemical properties and 16S rDNA sequence analysis, it was identified as Bacillus amyloliquefaciens. The FT-IR and HPLC results indicated that the biosurfactnat produced by strain XZ-173 was lipopeptides that contained surfactin and iturin A. The prepared crude lipopeptides reduced the surface tension of water to 26.6 mN/m with a critical micelle concentration (CMC) of 500 mg/L and showed stable emulsification capability and strong inhibition against Rhizoctonia solani and Ralstonia solanacearum. Lipopeptide-producing stain XZ-173 had potential to be used in biological control of soil-borne plant diseases.
