Sodium alginate improves phytase stability and enhances soil phosphorous utilization

Abstract

A plant growth-promoting endophytic strain Bacillus sp. WR11 produces high-level phytase. Phytase degrades phytate, which is the major form of organic phosphate in soils that cannot be readily utilized by plants. To strengthen the strain or its phytase for cost-efficient biodegradation of phytate, we compared the impacts of different chemical additives on phytase production and preservation. Phytate degradation ability in soils and growth promotion effect in wheat were evaluated. To ensure safe application, potential pathogenicity of the strain was also predicted. Phytase activity assay suggests that sodium alginate (SA) significantly improves phytase production to as higher as 2.21-fold, but has little influence on the growth of WR11 during liquid fermentation. During liquid storage of cell-free supernatant (CFS) at room temperature, SA maintains 68% phytase activity indicating significantly improved stability within four weeks. Determination of water-soluble P and phytate-P indicates Bacillus sp. WR11 and CFS effectively degrade 20.17–38.55% phytate in soils. Quantification of biomass, phosphorus and iron contents shows positive effect of WR11 and its CFS on wheat growth. Particularly, the degradation ability (63.2%) and growth promoting effect of CFS is much stronger in the presence of 0.8% SA. Genomic prediction demonstrates strain WR11 has a large number of genes in the databases of Pathogen-Host Interactions, Virulence Factors of pathogenic bacteria, Antibiotic Resistance Genes, and the Comprehensive Antibiotic Research Database, respectively. In conclusion, SA significantly improves phytase production and phytate degradation. Phytase accompanied with SA may be an alternative strategy for phytate degradation and plant growth promotion, when microorganisms have safety issues.