Xanthomonas campestris, a novel stress tolerant, phosphate-solubilizing bacterial strain from saline–alkali soils

Abstract

A total of 198 bacterial strains were isolated from various niches of saline-alkali soils, out of which 85 strains were able to solubilize phosphate on plates at 30°C. The strain RMLU-26, identified as Xanthomonas campestris, was the most efficient with its ability to solubilize P, subjected to N-methyl-N 0 -nitro-N-nitrosoguanidine (NTG) for development of mutants. The P solubilizing ability of X. campestris is reported for the first time. The wild type and mutant strains of X. campestris revealed a differential response to various stress factors (high pH, temperature, and salt concentration). The mutant strain revealed maximum P solubilization (67.1%) at 30°C and pH 8.0 while the wild type strain showed maximum solubilization (41.9%) at 35°C and pH 7.0. Percent P 2 O 5 solubilization by both strains revealed a steep decline in tricalcium phosphate solubilization with an increase in NaCl concentration from 0.5 to 10% along with a concomitant drop in pH of the medium from 8.0 to 4.5 in wild type and 4.0 in mutant strain. However, a 1.5-to 2-fold increase in 'P' solubilization was observed in the mutant strain when compared to the wild type strain in the presence of NaCl. The overall improved tolerance of the strains to alkalinity and salinity could be due to accumulation and/or secretion of specific solute (xanthan).

In vitro DISSOLUTION OF ACIDULATED ROCK PHOSPHATE BY PHOSPHATE SOLUBILIZING MICROORGANISMS

“…The dissolution of RP by microorganisms through acidification has been well documented. This acidification is caused by the extrusion of protons associated with the assimilation of ammonium or the production of organic acids (Kang et al, 2008;Sharan et al, 2008;Ben Farhat et al, 2009;Oliveira et al, 2009;Habte and Osorio 2012;Selvakujmar et al, 2013). Evidence of these mechanisms in the present study is seen in the decrease in pH from an initial value of 5.09 to 3.58 with the use of A. niger.…”

Efficient phosphorus solubilization by mutant strain of Xanthomonas campestris using different carbon, nitrogen and phosphorus sources

“…These strains were further tested at varying salt concentrations (NaCl 2.5 and 5.0%) at pH 7, 8 and 9 and temperature 30°C in a plate assay followed by quantitative estimation of 'P' solubilization in Erlenmeyer flasks containing Pikovskaya (PVK) medium (Pikovskaya 1948) having Ca 3 PO 4 at a concentration of 5 g l -1 as an insoluble P sources (Sharan et al 2008). …”

Phenology, Growth and Biomass Yield Response of Maize (Zea mays L.) to Integrated Use of Animal Manures and Phosphorus Application With and Without Phosphate Solubilizing Bacteria

“…About 30 to 40% crop yield is reduced due to the unavailability of P [18], and lower P use efficiency [19]. Phosphate solubilizing bacteria (PSB) has the ability of solubilizing the fixed soil P by releasing of organic acid, which convert the insoluble P to soluble form by increasing the P availability to plants [20,21]. Organic manures [22][23][24][25] and P application [19] under semiarid condition is very important for increasing P availability and yield [26,27] as well as profitability [14,28].…”