Identification for Streptomyces padanus Strain PMS-702 as A Biopesticide Agent

Abstract

A Streptomyces PMS-702 strain was isolated from farmland soil collected from Taiwan. Antimicrobial activities of PMS-702 strain against phytopathogenic fungi and bacteria showed differential inhibitory effects on the growth of fungal pathogens, but no effect for Sclerotium rolfsii and nine plant pathogenic bacteria. According to the results of morphological, physiological and biochemistry characteristics, and 16S rRNA gene sequence, the PMS-702 strain was identified as Streptomyces padanus. Biomass of S. padanus PMS-702 strain varied among different nutrient media for growing. Soybean Meal-Glucose Broth (SMG) medium was the best for enhancing the growth of S. padanus strain PMS-702 and its crude culture filtrate diluted to 10 fold completely suppressed spore germination of Fusarium oxysporum f. sp. cubense, which was used as an indicator for assessing antimicrobial activities. In bioassay experiment, the culture filtrates of S. padanus from SMG cultures fermented at 30 degrees Centigrade for 4 days could control effectively a broad range of plant diseases including lettuce brown spot, mango anthracnose, Chinese cabbage anthracnose, peach fruit rot, and orange green mold. These results suggested that S. padanus strain PMS-702 is potential to be used as a biological control agent to suppress fungal crop diseases. 放線菌PMS-702 菌株係由台灣農田中分離所獲得，其對於各種供試植物病原真菌具有不同程度的拮抗能力，對於 白絹病菌 (Sclerotium rolfsii) 與9 株植物病原細菌則均不具有拮抗的效果。分析PMS-702 菌株之形態、生理、生化特 徵及16S rRNA 基因序列後，確定PMS-702 菌株為稠李鏈黴菌 (Streptomyces padanus)。PMS-702 菌株在不同營養配方培養具有差異化，以黃豆粉葡萄糖培養基 (SMG) 培養PMS-702 具有最佳的生質量，其10 倍稀釋培養粗濾液具有抑制香蕉黃葉病菌 (Fusarium oxysporum f. sp. cubense) 孢子發芽的效果。PMS-702 菌株在SMG 培養基於30oC 培養4 天後，利用生物檢定分析法測試其對於數種植物病害的影響，結果發現PMS-702 菌株培養濾液對於萵苣褐斑病、芒果炭疽病、白菜炭疽病、甜桃果實疫病及椪柑果實綠黴病均具有防治功效，這些結果顯示稠李鏈黴菌PMS-702 具有研發成為生物製劑，用於防治作物真菌性病害的潛力。