基因envZ、iscS、asnC调控根瘤菌胞外多糖产量和环境适应性
Exopolysaccharide Yield and Environmental Adaptation of Rhizobia Regulated by Gene envZ,iscS and asnC
杨冰洁 1袁晓霞 1高梦哲 1申奥龙 1李华 1冀照君1
作者信息
- 1. 内蒙古民族大学生命科学与食品学院,通辽 028000
- 折叠
摘要
[目的]Rhizobium yanglingense CCBAU 01603 可与豆科锦鸡儿属植物形成高效固氮根瘤,前期研究在含碱培养基中连续进化 500 代得到进化菌株,发现与其他进化菌株相比,Alk_40 中基因envZ、iscS、asnC发生特异SNPs变化导致胞外多糖产量大幅降低,进而探究关键基因调控根瘤菌胞外多糖产量和环境适应性.[方法]采用同源重组法构建根瘤菌envZ、iscS、asnC单基因缺失突变株,测定突变株的胞外多糖产量和不同环境条件下的生长情况.[结果]根瘤菌envZ、iscS、asnC基因缺失突变株在YMA培养基中胞外多糖产量显著下降,酸性环境适应性降低,65℃热处理的耐受能力减弱,且胞外多糖产量与根瘤菌耐酸性和耐热性具有一定相关性;根瘤菌envZ和asnC基因缺失突变株对NaCl十分敏感,在含NaCl培养基中的生长繁殖严重受限,在弱碱性环境中适应能力显著降低.[结论]根瘤菌胞外多糖产量受基因iscS、envZ、asnC的调控.
Abstract
[Objective]Rhizobium yanglingense CCBAU 01603 form efficient nitrogen-fixing nodules with Caragana legumes.Alk_40,one of the offspring of CCBAU 01603,was obtained through experimental evolution in alkaline medium for 500 generations.It was discovered that a significant decrease in exopolysaccharide(EPS)yields of Alk_40 with specific SNPs changes in the gene envZ,iscS,and asnC.EPS yields and environmental adaptability of rhizobia regulated by these key genes were investigated.[Method]Three mutants of rhizobia were created by deleting gene envZ,iscS,and asnC,respectively.EPS yields and growth under different environmental conditions of mutants were assessed.[Result]In comparison to CCBAU 01603,the envZ,iscS,and asnC mutants presented significantly lower EPS yields in YMA medium,demonstrated diminished fitness in acidic environments,and had a weakened tolerance to high temperatures of 65℃.This observation suggests a correlation between the EPS yield of rhizobia and their resistances to acidic or heat stress.In addition,the mutants lacking the envZ and asnC genes showed the sensitivity to NaCl,resulting in severely limited growth and reproduction in NaCl-containing media.Furthermore,their adaption in alkalescent environments significantly reduced as well.[Conclusion]It is discovered that EPS yields of rhizobia can be regulated by gene envZ,iscS,and asnC.
关键词
根瘤菌/envZ/iscS/asnC/胞外多糖/环境适应性Key words
Rhizobium/envZ/iscS/asnC/exopolysaccharide/environmental adaptation引用本文复制引用
出版年
2024
国家科技期刊平台
NSTL
万方数据