Rapid solubilization of insoluble phosphate by a novel environmental stress-tolerant Burkholderia vietnamiensis M6 isolated from ginseng rhizospheric soil

Abstract

We isolated and characterized novel insoluble phosphate (P)-solubilizing bacteria tolerant to environmental factors like high salt, low and high pHs, and low temperature. A bacterium M6 was isolated from a ginseng rhizospheric soil and confirmed to belong to Burkholderia vietnamiensis by BIOLOG system and 16S rRNA gene analysis. The optimal cultural conditions for the solubilization of P were 2.5% (w/v) glucose, 0.015% (w/v) urea, and 0.4% (w/v) MgCl(2).6H(2)O along with initial pH 7.0 at 35 degrees C. High-performance liquid chromatography analysis showed that B. vietnamiensis M6 produced gluconic and 2-ketogluconic acids. During the culture, the pH was reduced with increase in gluconic acid concentration and was inversely correlated with P solubilization. Insoluble P solubilization in the optimal medium was about 902 mg l(-1), which was approximately 1.6-fold higher than the yield in NBRIP medium (580 mg l(-1)). B. vietnamiensis M6 showed resistance against different environmental stresses like 10-45 degrees C, 1-5% (w/v) salt, and 2-11 pH range. The maximal concentration of soluble P produced by B. vietnamiensis M6 from Ca(3)(PO(4))(2), CaHPO(4), and hydroxyapatite was 1,039, 2,132, and 1,754 mg l(-1), respectively. However, the strain M6 produced soluble P with 20 mg l(-1) from FePO(4) after 2 days and 100 mg l(-1) from AlPO(4) after 6 days, respectively. Our results indicate that B. vietnamiensis M6 could be a potential candidate for the development of biofertilizer applicable to environmentally stressed soil.

Isolation and characterization of phosphate solubilizing bacteria (Klebsiella oxytoca) with enhanced tolerant to environmental stress

“…Therefore, K. oxytoca could be considered as thermo, acid, alkali and salt tolerant phosphate solubilizing bacterium with a high potential to be used in a wide range of soils. Among the other strains, only Burkholderia vietnamiensis M6 has so far been reported to perform well over wide range of soils (Park et al, 2010). Therefore, K. oxytoca is highly impressed to be applied in maintaining phosphorus level in extreme environment conditions, where the other microbes showed reduced phosphate solubilizing capacity.…”

“…Though, there are some information regarding the stress tolerant PSMs such as Rhodotorula sp., PS4 is highly tolerant to temperature, pH and salt variations (Mundra et al, 2011); Kushneria sp. YCWA18 is tolerant to salt conditions (Zhu et al, 2011); Bacillus megatherium is tolerant to salt conditions (Xiang et al, 2011); Burkholderia vietnamiensis M6 is tolerant to temperature, pH and salt conditions (Park et al, 2010), and Pantoea agglomerans R-42 is tolerant to temperature, pH and salt conditions (Sharan et al, 2008;Son et al, 2006); most of the previously isolated PSMs are reported to perform poorly under stress conditions making them less appropriate for such environments. In this context, PSMs with the genetic potential for increasing tolerance to high temperature, pH and high salt concentration are still considered to be important for the establishment, multiplication and production of environmentally friendly bio-inoculants.…”

Evaluation of Phosphate Solubilizing Potential of Three Burkholderia Species Isolated from Green House Soils

“…Our results showed a significant negative correlation for soluble phosphorus and pH with all carbon sources. Corresponding to this result, it has been reported that glucose is the best carbon source for phosphate solubilization in Burkholderia vietnamiensis M6 (Park et al, 2010) and Burkholderia cepacia DA23 (Song et al, 2008).…”

“…4, phosphate solubilization was enhanced with increasing amounts of glucose up to 2% in PSB-1 and PSB-2 and up to 3% in PSB-3, but beyond this limit, there was reduction in the level of phosphate solubilization. It has been reported that insoluble phosphate solubilization by was enhanced with increasing amounts of glucose up to 2.5% in Burkholderia vietnamiensis M6 (Park et al, 2010) and up to 3% in Burkholderia cepacia DA23 (Song et al, 2008).…”

“…Therefore, most soils are deficient in soluble forms of phosphorus. This leads to an excess application to crop plants and continuous application of phosphate fertilizers cause economical and environmental problem due to soil and water pollution (Park et al, 2010).…”