Isolation and characterization of halotolerant phosphate solubilizing bacteria naturally colonizing the peanut rhizosphere in salt-affected soil

Abstract

In search of efficient salt-tolerant phosphate solubilizing bacteria (PSB), we conducted a survey of PSB that naturally colonize the rhizosphere of peanuts in Xinjiang, China, a typical inland saline area. A total of 23 PSB were isolated, which included 12 Bacillus strains, three Acinetobacter strains, two Pseudomonas strains, two Brevibacillus, and one strain of Gordonia terrae, Chryseobacterium lathyri, Ensifer sesbaniae, and Paenibacillus illinoisensis. All PSB have high potential for dissolving calcium phosphate [Ca3(PO4)2] within the range of 65–496 mg·L−1, but relatively weak ability to dissolve AlPO4 in amounts ranging from 0.4 to 11.4 mg·L−1, FePO4 ranging from 0.1 to 5.5 mg·L−1, and lecithin ranging from 2.1 to 10.3 mg·L−1. The maximum tolerance for pH is 10, and the maximum tolerance for Na2CO3 is 50 mm. Six isolates that can grow under the condition of 1.5 M NaCl (YMX5, YMX11, TPMX5, TPMX16, TPMX18, and TPMX19) were selected to determine their ability to dissolve Ca3(PO4)2 and tolerate pH changes. This study characterized salt-tolerant PSB isolates that can be used as bioinoculants to protect plants against salt stress. In addition, we describe the phosphate-solubilizing ability of Gordonia terrae at high NaCl concentrations.