Screening and biodiversity of endophytic and rhizosphere bacteria containing ACC deaminase from halophyte Limonium sinense (Girard) Kuntze

Abstract:

[Objective] We isolated and screened endophytic and rhizosphere bacteria with 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase from halophyte Limonium sinense (Girard) Kuntze collected from Jiangsu coastal area and investigated their diversity and plant growth promoting potential. [Methods] Strains were obtained from inner tissues and rhizosphere soils using pure culture cultivation method and identified by 16S rRNA gene sequencing and phylogenetic analysis. Their potential plant growth promoting index of nitrogen fixation, phosphate solubilization, indoleacetic acid (IAA) production and NaCl tolerance ability were evaluated. [Results] Eighteen strains with ACC deaminase were obtained and 13 of them exhibited more than 20 nmol α-KA/(mg Pr·h) ACC deaminase activity. Nine isolates produced IAA, 11 had nitrogen fixation ability and 7 of them had phosphate solubilization ability. Most of the isolates could grow under 0%-13% NaCl. The results of 16S rRNA sequencing showed that these strains belonged to seven genera, with Arthrobacter as the most predominant genus. Among them, strain KLBMP 5180 was found to be a potential novel species of the genus Arthrobacter. [Conclusion] The halophyte plants Limonium sinense (Girard) Kuntze located in the area of coastal shoal contain a variety of symbiotic bacteria with ACC deaminase as well as the source of novel species. Some of them had good research prospect in the future.