Colonization of Bacillus cereus NJSZ-13,a species with nematicidal activity in Masson pine(Pinus massoniana Lamb.)

Bacillus cereus NJSZ-13,an endophytic bacterium with nematicidal activity,was isolated from stems of healthy Pinus elliottii Engelm.Colonization of P.massoniana Lamb.by endophytic B.cereus was studied using scanning electron microscopy and confocal laser scanning microscopy.After the plasmid p GFP78 containing the green fluorescent protein(GFP)gene was transformed into the NJSZ-13 strain,the NJSZ-13:gfp showed the same nematicidal activity and growth curve as the wild-type strain,and the plasmid p GFP78 was stably maintained in strain NJSZ-13 for at least 96 h of bacterial cultivation on medium without antibiotics.After inoculation into Masson pine roots,colonization of the NJSZ-13:gfp strain in plant roots and stems was visualized using confocal laser scanning and the strain was enumerated in inoculated roots and stems.These results suggest that NJSZ-13:gfp is an efficient colonizer of Masson pine and can transfer vertically from roots to stems.

松墨天牛成虫室内外种群肠道细菌的多样性及功能分析

【目的】为明确松墨天牛Monochamus alternatus成虫中、后肠细菌群落结构,探索肠道细菌的潜在功能。【方法】分别提取室外和室内饲养的松墨天牛成虫各15头(室内和室外各15个中肠、15个后肠)的肠道DNA,利用二代测序技术对松墨天牛成虫肠道细菌的16S rDNA V3–V4区序列进行测序,统计操作分类单元(OTUs)数量,分析物种组成、Alpha多样性和Beta多样性;采用PICRUSt软件预测肠道细菌的功能。【结果】共获得544180条高质量序列,在97%相似度下将其聚类为615个OTUs,总共注释到22个门、48个纲、112个目、172个科、285个属和408个种。室内种群的OTUs数量多于室外种群,室内外种群的OTUs种类存在差异性。同一种群的中、后肠之间差异不明显。变形菌门Proteobacteria为室内外松墨天牛肠道细菌的最优势门;肠杆菌属Enterobacter为室外种群肠道细菌和室内种群后肠细菌的最优势属,沙雷氏菌属Serratia为室内种群中肠的最优势属。Alpha多样性结果表明松墨天牛成虫室内种群肠道菌群的丰度显著高于室外种群;Beta多样性结果显示室外种群肠道菌群均一性和稳定性比室内种群好。室外和室内种群的中肠与后肠之间在菌群丰度和多样性上均无显著差异。功能预测结果表明,室内外松墨天牛成虫肠道菌群中代谢通路的丰度最高,其中以糖类代谢和氨基酸代谢为主,还有降解外源化学物质、萜类和聚酮类化合物及其他次生代谢物质的能力。不同种群、不同肠段之间的功能丰度均无显著差异。【结论】明确了取食不同食料的松墨天牛成虫中、后肠的细菌群落结构及差异,了解了肠道细菌的潜在作用,为进一步探究松墨天牛肠道共生菌的功能提供了理论基础。