ACC脱氨酶活性菌株ACC 30的分离、鉴定及其促生作用

ACC 30 strain with ACC deaminase activity: its isolation, identification and growth-promoting effect

【目的】筛选具有1-氨基环丙烷-1-羧酸(简称ACC)脱氨酶活性的菌株,并探索该类菌的促生作用,有助于研发微生物肥料,实现农业增产。【方法】以ACC为唯一氮源,从土壤中富集和分离ACC脱氨酶产生菌;测定ACC脱氨酶的比活力,对酶活性最强的菌株根据形态和培养特征、生理生化特征及16S rDNA序列进行分类鉴定;分别采用菌液培养接种法与菌液浸种接种法初步研究该菌株对紫花苜蓿幼苗生长的促生作用。【结果】筛选得到6株ACC脱氨酶阳性细菌,其中菌株ACC 30酶活性最高,为0.217 U/mg,根据培养特征观察和生理生化指标测定结果,结合16S rDNA序列比对分析,确定ACC 30为产气肠杆菌(Enterobacter aerogenes)。促生试验表明,ACC 30可促进紫花苜蓿幼苗根伸长,菌液培养接种法与菌液浸种接种法两种处理方法下ACC 30分别使幼苗根相对伸长135%、136%,促生作用均明显且基本一致。但是,两种方法处理下ACC 30均抑制幼苗下胚轴伸长。【结论】筛选获得ACC脱氨酶活性菌株ACC 30,其酶活性较高且促生作用明显,有望进一步研发成为微生物肥料。

[Objective] Screening strains with 1-aminocyclopropane-1-carboxylate （ACC） deaminase and exploring the growth promoting effect were conducive to further develop microbial fertilizers and increase agricultural yield. [Methods] ACC deaminase positive bacteria were enriched and isolated with ACC as the sole nitrogen source. These strains’ ACC deaminase activities were also evaluated. The strain with the highest enzyme activity was identified according to morphological, physiological-biochemical characteristics and 16S rDNA sequences analysis. The target strain’s ability to promote the growth of alfalfa seedlings was preliminarily studied. [Results] Six ACC deaminase positive strains were obtained. Among them the strain ACC 30 was prominent with high ACC deaminase activity 0.217 U/mg. Based on the cultural morphological features as well as physiological-biochemical parameters in combination with 16S rDNA sequences analysis, the strain ACC 30 was identified as Enterobacter aerogenes. The growth-promoting trial indicated that both seeds incubating with bacterium suspension （SIBS） and seeds dipping with bacterium suspension （SDBS） elongated the roots of alfalfa seedlings by 135%, 136% respectively compared with the control group. The growth-promoting effects under two treatments were equally significant and consistent. Inter-estingly, they all showed that ACC 30 strain prohibited hypocotyl elongation. [Conclusion] The isolated strain ACC 30 with high ACC deaminase activity was expected to be developed into an excellent microbial fertilizer.