Extreme thermophilic polypeptide exhibited strong antagonism to magnaporthe grisea and its N-terminal amino acid residues sequencing

Chinese. 本试验用加热法从多粘类芽孢杆菌（Paenibacillus polymyxa）LM-3菌株的发酵液中纯化得到2个极端嗜热多肽。平板拮抗实验表明,5μL纯化多肽对稻瘟病菌（Magnaporthe grisea）抑菌率达89.6%。SDS-PAGE电泳显示纯化多肽分子量介于6000～7000D之间。多肽复性后,其中之一对稻瘟病菌表现出强的拮抗活性,命名为ETPMG（extreme thermophilic polypeptide against M.grisea）;另一个则无此活性,命名为ETPL3（extreme thermophilic polypeptide from LM-3）。ETPMG经氨基酸测序,获得了其N-末端5个氨基酸序列（H2N-ANDPR）。以ETPMG为主效成分配得5种微生物源生防乳剂,对水稻苗瘟进行了田间防效试验。试验结果表明,这5种乳剂的防效都优于LM-3拮抗液直接喷雾,其中处理AB4的防效最佳,达80.73%,其拮抗成分、吐温80、乳化剂OP、溶剂的质量比为50：6.5：1.75：41.75。ETPMG为首次报道的兼具极端嗜热性和稻瘟病菌拮抗活性的小分子多肽。

English. Two extreme thermophilic polypeptides were isolated from fermentation liquor of LM-3 bacterium of Paenibacillus polymyxa.The inhibition capacity of 5μL purified polypeptides against Magnaporthe grisea reached to 89.6%.These two polypeptides had a molecular weight of 6 000～7 000 D by SDS-PAGE assay and were recovered from electro-lanes for detection of inhibition activity to M.grisea respectively.One polypeptide with strong inhibition activity was named ETPMG（extreme Thermophilic Polypeptide against M. grisea）.and the other without such activity was named ETPL3（extreme Thermophilic Polypeptide from LM-3）.N-terminal amino acid residues of ETPMG were then sequenced and the determined sequence was H2N-ANDPR.To evaluate its performance against M. grisea in paddy field at seedling stage,5 oil-in-water（O/W） microbial emulsions were confected.ETPMG was used as the active agent of the five emulsions.According to field evaluation,AB4 performed well with a control effect of 80.73% and the weight fraction of its components was 50∶6.5∶1.75∶41.75（ETPMG∶tween80∶emulsifier OP∶methanol）.ETPMG was the first reported polypeptide which combined the extreme thermophilic characteristic and strong antagonistic activity against M.grisea.