Screening and detecting of denitrifying phosphorus-removing Pseudomonas sp.

Abstract:

[Objective] We selected a strain with high capability of denitrifying and phosphorus removal. Besides we established an assay of sandwich hybridization with S1 nuclease protection to analyze the microbial community of this strain in fermentation process. [Methods] We used anaerobic culture in a phosphorus deficient medium, aerobic culture in a phosphorus-rich medium and nitrate-reducing experiment for bacterial isolation. Physiological and biochemical tests and 16S rRNA gene probing technique were used to identify the selected strain. A set of DNA probe was synthesized and used in quantification. [Results] The selected strain was identified as Pseudomonas sp. and named as LY10. The phosphorus removal rate of LY10 was 90.31% under aerobic condition in 24 hours, the denitrifying and phosphorus removal rate were 84.71% and 89.37%, respectively, under anoxic condition in 48 hours. Bacterial detection with the reported technique showed LY10 could be well identified from other strains such as Commonas with the probe Probe-P. sp. which was complementary to the conservative region of 16S rRNA of Pseudomonas genus. The cell density range was from 103 to 106 cells per milliliter and the equation was y=?0.967 87+0.372 99x (R2=0.996 7, n=5). [Conclusion] The selected strain showed strong activity on removing compounds with N and P, thus it can have potential application in industrial bio-denitrifying and phosphorus removal.

Key words:Denitrifying phosphorus-removing bacteria, Pseudomonas, Quantitative detection, S1 nuclease protection assay, 16S rRNA