产ACC脱氨酶细菌的筛选及对低温胁迫下垂穗披碱草生长的影响

Screening of ACC deaminase producing bacteria and their effects on the growth of Elymus nutans under low-temperature stress

摘要:

为筛选具有 1‐氨基环丙烷‐1‐羧酸(ACC)脱氨酶活性的植物促生菌，验证其对低温胁迫牧草生长的影响，为多功能生物菌肥研制提供菌种资源与数据基础，以实验室前期从祁连山高寒草地优势牧草根际或根内分离的 821 株固氮、溶磷菌为材料，采用 DF 和 ADF 培养基筛选产 ACC 脱氨酶菌株， 并定量分析酶活性，结合 16S rRNA 基因测序和系统发育分析确定菌株的分类地位。选取 ACC 脱氨酶活性最高的菌株接种垂穗披碱草幼苗，验证其幼苗对低温胁迫的响应。结果共筛选到 11 株 ACC 脱氨酶活性较高的菌株，分属于 5 个不同细菌属。用 ACC 脱氨酶活性最高的 4 株菌接种垂穗披碱草，在低温胁迫下不仅能有效提高植株株高、茎粗、地上干重和地下干重，而且能减缓叶绿素含量的下降，提高超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)等抗氧化酶活性 ，减少丙二醛 (MDA)的积累。本研究筛选到的产 ACC 脱氨酶菌株能有效促进垂穗披碱草在低温下生长，增强其抗逆性，对进一步开发适用于高寒草地的生物菌肥有重要意义。

Abstract:

To screen plant growth‐promoting bacteria (PGPB) with ACC deaminase activity and verify their ef‐ fects on forage growth under low temperature conditions，a total of 821 PGPB strains were used to identify the ACC (1‐aminocyclopropane‐1‐carboxylic acid) deaminase activity in DF and ADF medium. These PGPB strains were all isolated from the dominant forage species in alpine grassland of the Qilian Mountains. 16S rRNA gene sequences coupled with phylogenetic analysis were used to determine the taxonomic status of ACC deaminase producing bacte‐ ria. Moreover，the growth-promoting effects of 4 strains with high enzyme activity on the growth of Elymus nutans seedlings were verified by a seedling sand culture experiment under low-temperature stress. A total of 11 strains with high ACC deaminase activity were identified and divided into 5 genera. The inoculation of ACC deaminase strains could increase the stem height，stem diameter，stem dry weight and root dry weight. It also affected the root de‐ velopment，inhibited the decrease of chlorophyll content. Moreover，the activity of superoxide dismutase (SOD)，per‐ oxidase (POD)，and catalase (CAT) in the seedlings were enhanced. These ACC deaminase producing bacteria can effectively promote the growth of E. nutans at low temperature and enhance the stress resistance. These bacteria have potential for the further development of biological fertilizer suitable for alpine grassland.