番茄潜叶蛾幼虫肠道可培养细菌结构组成及对大分子化合物的降解作用研究

Study on the composition of culturable gut bacteria in the larvae of Yunnan population of Tuta absoluta and the degradation for macromolecular compounds

番茄潜叶蛾Tuta absoluta是一种世界毁灭性番茄害虫。为明确其幼虫肠道可培养细菌的多样性及功能,本研究采用LB和NA两种培养基分别对番茄潜叶蛾幼虫肠道细菌组成进行了分离培养,根据细菌菌落形态和16S rDNA序列分析对细菌进行种属鉴定,采用比浊法测定了优势种的生长曲线,并采用透明圈法测定了肠道各可培养细菌对大分子化合物淀粉和纤维素的降解能力。结果表明,从番茄潜叶蛾3龄幼虫肠道中共分离到27株细菌,分属于3门10科17属24种,优势门、科、属、种分别是变形菌门Proteobacteria、欧文氏菌科Erwiniaceae、欧文氏菌属Erwinia、Erwinia iniecta,其相对多度分别达到90.68%、89.41%、89.41%和89.41%。优势种Erwinia iniecta在25℃,180 r/min的条件下培养无迟缓期,0~14 h为对数生长期,14~28 h为稳定期,28 h以后为衰亡期。Glutamicibacter属的L7和L9、考克氏菌属Kocuria的L14和短状杆菌属Brachybacterium的L20能同时降解淀粉和纤维素,考克氏菌属Kocuria的L15和L17只能降解淀粉,欧文氏菌属Erwinia的L、动性球菌属Planococcus的L11、微杆菌属Microbacterium的L18和Prolinoborus属的L22只能降解纤维素,其他菌株无淀粉和纤维素降解能力。综上所述,番茄潜叶蛾幼虫含有24种肠道可培养细菌,种类较为丰富,且部分细菌对淀粉和纤维素大分子化合物具有较强的降解作用,该结果将为番茄潜叶蛾肠道细菌多样性及其功能的深入研究提供依据,同时还为功能细菌的开发利用提供菌株。

Tuta absoluta is a world-destructive tomato pest.In order to clarify the composition of culturable gut bacteria in the larvae,Luria-Bertani and Nutrient Agar media were used to isolate and culture the gut bacteria of T.absoluta larvae in this study,and culturable bacteria were identified according to colony morphology and 16S rDNA sequence analysis.Turbidimetric method was used to determine the growth curve of dominant species,and transparent circle method was used to determine the degradation ability of starch and cellulose by culturable gut bacteria.The results showed that there were 27 strains were isolated from the gut of the 3^(th) instar larvae of T.absoluta,which belonging to 24 species,17 genuses,10 families and 3 phyla,among which dominant phylum,family,genus and species were Proteobacteria,Erwiniaceae,Erwinia and Erwinia iniecta with relative abundances of 90.68%,89.41%,89.41%and 89.41%,respectively.The dominant species,E.iniecta,had no lag period at 25℃and 180 r/min,it s logarithmic growth period was 0~14 h,the stable period was 14~28 h,and the decline period was after 28 h.Starch and cellulose could be degraded by L7 and L9 of Glutamicibacter,L14 of Kocuria and L20 of Brachybacterium,while L15 and L17 of Kocuria could only degrade starch.L of Erwinia,L11 of Planococcus,L18 of Microbacterium and L22 of Prolinoborus could only degrade cellulose,while other strains had no ability of starch and cellulose degradation.These results indicated that 24 kinds of gut culturable bacteria which were contained by T.absoluta larvae and it s abundant in species,starch and cellulose could be degraded by several bacteria.Collectively,the results will provide evidence for the further study of gut bacterial diversity and function of T.absoluta,and also culturable strains for the development and utilization of functional bacteria can be provided.