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

Abstract:

[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.

Key words:Strain with ACC deaminase activity, Enterobacter aerogenes, Growth-promoting effect, Alfalfa