链霉菌Snea253菌株的变异分析及对根结线虫活性影响

Variance Analysis of Streptomyces Venezuelae Snea253 Mutants against Meloidogyne Incognita

为明确委内瑞拉链霉菌(Streptomyces venezuelae)自发突变对南方根结线虫活性的影响。本研究利用继代培养法选育Snea253突变株,对形态分化及相关基因进行分析,并测其代谢产物的生物活性。获得6株菌落形态差异大的自发突变菌株,其中不产色素的3株突变菌株Snea253-G、Snea253-B和Snea253-F杀线虫活性分别为61.0%、45.5%和35.0%;产色素的3株突变株Snea253-A、Snea253-H和Snea253-J杀线虫活性分别为48.7%、37.2%和37.9%。ssgA、bldC、bldD、whiB、whiE和whiI基因克隆测序结果显示各突变株基因序列没有差异,可能此6个基因没有直接参与控制Snea253菌株的自发突变。链霉菌自发突变不但使其形态发生变异,而且也影响了其代谢产物的生物活性,研究为从形态上筛选优良菌株提供了相关理论依据。

The main objective is to evaluate the spontaneous mutants of Streptomyces venezuela Snea253 against Meloidogyne incognita by its metabolites. Six mutates of separate colony morphology were obtained through spontaneous mutation by successively sub-culturing original Streptomyces Snea253 strain, and the morphological differentiation and related genes were analyzed in the paper. Then, the bioactivity of metabolites against Meloidogyne incognita was measured by immersion method in small dish. Six mutants had significant differences in morphology compared with the original strain. Their nematicidal activity were decreased significantly using metabolites treated the secondary juveniles J2 of M. incognita.. Among three non-brown pigment producing mutants, the corrected mortality of Snea253 - G, Snea253 - B and Snea253 - F respectively was 60.0% , 45.5% and 35.0% to M. incognita J2. Among three pigment producing mutants, Snea253 - A, Snea253 - H and Snea253 - J produced lower nematicidal activity （respectively 48.7% , 37.2% and 37.9% ） than that of the mutant Snea253 - G（60.0% ）. It should be noted that there were no difference among the sequences of morphological differentiation related genes （ ssgA, bldC, bldD, whiB, whiE, whil） through sequencing analysis. The six genes may not be directly involved in controlling the spontaneous mutation of Snea253 in here. This research comfirmed that spontaneous mutation of Streptomyces Snea253 strains not only showed in the morphological variation, but also decreased the nematicidal activity. It provides a possibility for screening of biocontrol microbial by morphology.