Phosphate solubilizing bacteria from subtropical soil and their tricalcium phosphate solubilizing abilities
The ability of a few soil microorganisms to convert insoluble forms of phosphorus to an accessible form is an important trait in plant growth-promoting bacteria for increasing plant yields. The use of phosphate solubilizing bacteria as inoculants increases the P uptake by plants. In this study, isolation, screening and characterization of 36 strains of phosphate solubilizing bacteria (PSB) from Central Taiwan were carried out. Mineral phosphate solubilizing (MPS) activities of all isolates were tested on tricalcium phosphate medium by analyzing the soluble-P content after 72 h of incubation at 30 °C. Identification and phylogenetic analysis of 36 isolates were carried out by 16S rDNA sequencing. Ten isolates belonged to genus Bacillus, nine to genus Rhodococcus, seven to genus Arthrobacter, six to genus Serratia and one each to genera Chryseobacterium, Delftia, Gordonia and Phyllobacterium. In addition, four strains namely, Arthrobacter ureafaciens, Phyllobacterium myrsinacearum, Rhodococcus erythropolis and Delftia sp. 
Phosphate solubilizing bacteria and their role in plant growth promotion
The use of phosphate solubilizing bacteria as inoculants simultaneously increases P uptake by the plant and crop yield. Strains from the genera Pseudomonas, Bacillus and Rhizobium are among the most powerful phosphate solubilizers. The principal mechanism for mineral phosphate solubilization is the production of organic acids, and acid phosphatases play a major role in the mineralization of organic phosphorous in soil. Several phosphatase-encoding genes have been cloned and characterized and a few genes involved in mineral phosphate solubilization have been isolated. 
An Efficient Method for Qualitative Screening of Phosphate-Solubilizing Bacteria
An efficient protocol was developed for qualitative screening of phosphate-solubilizing bacteria, based upon visual observation. Our results indicate that, by using our formulation containing bromophenol blue, it is possible to quickly screen on a qualitative basis the phosphate-solubilizing bacteria. Qualitative analysis of the phosphate solubilized by various groups correlated well with grouping based upon quantitative analysis of bacteria isolated from soil, effect of carbon, nitrogen, salts, and phosphate solubilization-defective transposon mutants. However, unlike quantitative analysis methods that involve time-consuming biochemical procedures, the time for screening phosphate-solubilizing bacteria is significantly reduced by using our simple protocol. Therefore, it is envisaged that usage of this formulation based upon qualitative analysis will be salutary for the quick screening of phosphate-solubilizing bacteria. Our results indicate that the formulation can also be used as a quality control test for expeditiously screening the commercial bioinoculant preparations, based on phosphate solubilizers. 
Isolation and Characterization of Phosphate Solubilizing Bacteria from the Rhizosphere of Faba Bean (Vicia faba L.) in Meknes Region, Morocco
Aims: The objective of this research was to isolate phosphate solubilizing bacteria (PSB) from faba bean rhizosphere in Meknes region and evaluate in vitro their potential for P solubilization as well as their response to the effect of temperature, NaCl, pH and antibiotics.
Study Design: Rhizosphere soil and root nodules from faba bean crop in different sites from Meknes region were collected for the study.
Place and Duration of Study: Department of Biology (Soil & Environment Microbiology Unit) Faculty of Sciences, Moulay Ismail University, Meknes, Morocco; between February and August 2014.
Methodology: Four strains, which retained their P-solubilizing ability after repeated subculturing, from a total of seventy eight isolates were purified, characterized and identified by 16S rRNA gene sequencing.
Results: The isolates were closely related to Pseudomonas cedrina (PT19), Rahnella aquatilis HX2 (P24), Rhizobium nepotum (BSP30) and Rhizobium tibeticum (Rh8). P solubilization index of these isolates ranged from 1, 57-2, 88 in tricalcium phosphate amended National Botanical Research Institute’s Phosphate (NBRIP) agar medium. Amount of phosphate solubilized ranged from 62.45 to 119.95 mg P L-1 and drop in pH of the medium ranged from 7 to 3.5. Besides, these strains exhibited resistance to several antibiotics.
Conclusion: The ability of the PSB to solubilize insoluble P and their adaptation to environmental conditions add value to these strains, which could lead to improved inoculants to increase the available phosphorus in the soil for faba bean plant growth and to promote sustainable agriculture. 
Phosphate-Solubilizing Bacteria in the Rhizosphere of Some Cultivated Legumes from Meknes Region, Morocco
Aims: Through the National Botanical Research Institute’s phosphate growth medium (NBRIP) and 16S rDNA sequence analysis were used to isolate and identify the bacterial groups that actively solubilized phosphates in vitro from rhizosphere soil for three cultvited leguminous in agricultural soils from Meknes region.
Study Design: Rhizosphere soil samples for three cultivated legumes in different sites from Meknes region were collected for the study.
Place and Duration of Study: Department of biology (Soil & Environment Microbiology Unit) Faculty of Sciences, Moulay Ismail University, Meknes, Morocco; between January and July 2014.
Methodology: Out of several hundred colonies that grew on NBRIP medium eight best isolates were selected based on the solubilization of insoluble phosphates in solid medium with solubilizing index (SI) and Phosphate concentration solubilized in liquid medium; The bacterial isolates were identified based on their phenotypic and 16S rDNA genes sequencing. 
 Chen, Y.P., Rekha, P.D., Arun, A.B., Shen, F.T., Lai, W.A. and Young, C.C., 2006. Phosphate solubilizing bacteria from subtropical soil and their tricalcium phosphate solubilizing abilities. Applied soil ecology, 34(1), pp.33-41.
 Rodrı́guez, H. and Fraga, R., 1999. Phosphate solubilizing bacteria and their role in plant growth promotion. Biotechnology advances, 17(4-5), pp.319-339.
 Mehta, S. and Nautiyal, C.S., 2001. An efficient method for qualitative screening of phosphate-solubilizing bacteria. Current microbiology, 43(1), pp.51-56.
 Rfaki, A., Nassiri, L. and Ibijbijen, J. (2015) “Isolation and Characterization of Phosphate Solubilizing Bacteria from the Rhizosphere of Faba Bean (Vicia faba L.) in Meknes Region, Morocco”, Microbiology Research Journal International, 6(5), pp. 247-254. doi: 10.9734/BMRJ/2015/14379.
 Rfaki, A., Nassiri, L. and Ibijbijen, J. (2014) “Phosphate-Solubilizing Bacteria in the Rhizosphere of Some Cultivated Legumes from Meknes Region, Morocco”, Biotechnology Journal International, 4(9), pp. 946-956. doi: 10.9734/BBJ/2014/12387.