嗜麦芽窄食单胞菌CA1定殖及促生长特性相关基因挖掘

Mining of genes associated with colonization and growth pro⁃moting properties of Stenotrophomonas maltophilia CA1

【目的】挖掘嗜麦芽窄食单胞菌CA1定殖和促生长特性相关基因,为探究其促生长作用机制提供理论参考。【方法】利用Nanopore测序技术平台对CA1菌株进行全基因组测序,将其基因组序列与GO、NR、KEGG、COG等数据库进行比对,获得基因功能注释信息,挖掘分析其功能特异性基因;使用基质培法收集甘蔗根系分泌物,并分析根系分泌物对菌株CA1的趋化性、生物膜形成和定殖相关基因表达的影响。【结果】嗜麦芽窄食单胞菌CA1基因组大小为4371327 bp,携带6个质粒,GC含量64.58%,其中4696个基因被注释预测,包括4525个蛋白编码基因、87个tRNA、13个rRNA和1个tmRNA。GO、COG、KEGG和NR数据库分别成功注释2795、2078、2494和2584个基因。该菌基因组含有细菌趋化性(cheA、cheV、cheY)、生物膜形成(flhA、flk、flgG)、细菌黏附(pgaA、mrkD)、嗜铁(fes、fepA、fecA)、合成氨(gltP、gltB、gltD)和磷酸盐代谢(phoR、phoB、pstA)等促进植物生长和定殖相关的基因。趋化性试验结果显示,与对照组相比,根系分泌物处理下的菌落数显著增加(P<0.05,下同),且cheA、cheV和cheY基因的相对表达量显著升高,CA1生物膜形成显著增加。【结论】甘蔗根系分泌物有助于菌株CA1的趋化性及生物膜形成,提高与趋化性相关基因的表达量。菌株CA1基因组含有多个与促生长和定殖特性相关的基因,是其促生长特性的分子基础,细菌的趋化性和生物膜的形成是其定殖的关键步骤,根系分泌物有利于菌株的定殖。

【Objective】The genes related to Stenotrophomonas maltophilia CA1 colonization and growth promoting characteristics were excavated to lay a foundation for exploring its growth promoting mechanism.【Method】Nanopole se-quencing technology platform was used for whole genome of CA1 sequencing.Compared the genome sequence with GO,NR,KEGG,COG and other databases to obtain gene function annotation information,the function specific genes were analyzed.Meanwhile,sugarcane root exudates were collected by substrate culture,and the effects of the root exudates on the expression of genes related to colonization,chemotaxis and biofilm formation of CA1 were analyzed.【Result】The ge-nome size of S.maltophilia CA1 was 4371327 bp,carrying 6 plasmids with a GC content of 64.58%,of which 4696 genes were predicted by annotation,including 4525 protein coding genes,87 tRNA,13 rRNA,and 1 tmRNA.The GO,COG,KEGG,and NR databases successfully annotated 2795,2078,2494 and 2584 genes respectively.The genome of the strain presented some functional genes that were associated with plant growth promoting and colonization,such as bacterial chemotaxis(cheA,cheV,cheY),biofilm formation(flhA,flk,flgG),bacterial adhesion(pgaA,mrkD),siderophores(fes,fepA,fecA),ammonia synthesis(gltP,gltB,gltD)and phosphate metabolism(phoR,phoB,pstA).The results of chemotaxis test showed that compared with the control group,the number of colonies under root exudates treatment was significantly increased(P<0.05,the same below),and the relative expression levels of cheA,cheV and cheY genes were increased,and the formation of CA1 biofilm was also significantly increased.【Conclusion】The root exu-dates of sugarcane contributed to the chemotaxis and biofilm formation of strain CA1,and increased the expression of chemotaxis related genes.CA1 contains multiple genes related to growth promotion and colonization,which is the mo-lecular basis of its growth promotion characteristics.The bacterial chemotaxis and biofilm formation are the key steps for its colonization and root exudates were conducive to the strain colonization.