Screening and growth promoting characteristics of efficient organophosphate-degradation bacteria

Abstract:

[Objective] Our aim is to screen efficient organophosphate-degradation bacteria from environment and study their growth promoting mechanism. [Methods] We screened organophosphate-degradation bacteria from environment using selective medium, and studied the promoting growth characteristics by biochemical assays, then screened organophosphate-degradation and plant-growth-promoting bacteria by pot experiment. [Results] In total 35 strains of organophosphate-degradation bacteria were isolated from bulk soil of grass by Mengjinna organophosphate-degradation medium. The promoting growth characteristics of these bacteria were checked by biochemical methods. Five representative strains were selected for cucumber seedlings pot experiment. Strain G3-6 had the strongest ability to solubilize organic phosphorus, the ratio of hydrolysis circle diameter (HD) and colony diameter (CD) was 3.28. Strain G3-6 had the highest ability to promote cucumber growth than other strains. Compared with the control, G3-6 increased fresh weight, dry weight and height of cucumber seedlings by 71.53%, 69.78% and 33.55%, respectively. Compared with the positive control Bacillus subtilis F-H-1, G3-6 increased fresh weight, dry weight and height of cucumber seedlings by 2.52%, 21.14% and 8.27%, respectively. The results of correlation analysis showed that the ability of organophosphate-degradation might play a more important role in promoting cucumber growth than other functions. Strain G3-6 was identified as Pseudomonas sp. by 16S rRNA analysis. [Conclusion] Pseudomonas sp. G3-6 has strong ability of depredating organic phosphate, and can strongly promote cucumber growth. This strain would be a potential growth promoting bacterium.