Phosphorus is an essential nutrient element for plant growth and development. However, the available phosphorus in soil is extremely limited due to the presence of large amounts of organic phosphorus that is difficult to be degraded, with phytate (inositol hexaphosphate) accounting for a significant proportion. Phytases can efficiently hydrolyze phytate and release available phosphorus. [Objective] By taking advantage of the efficient hydrolysis ability of phytase, the phytase gene was gene modified in the indigenous bacteria of black soil to increase the available phosphorus content in the soil. [Methods] We employed the anchored protein pGSA for surface display of the bacterial phytaseAppA, thereby enhancing the stability and enzymatic activity of the protein as well as improving the substrate contact efficiency. Furthermore, leveraging the CRISPR-targeted gene editing technology, we precisely integrated the surface-displayed phytase fusion protein into the 16S rRNA gene of Ralstonia pickettii G3 genome, isolated from black soil to overcome the dependence of protein expression on vectors. [Results] The 16S rRNA gene site could be used as a target for gene modification without significant effect on the proliferation of the bacteria. The phytase-modified engineered bacteria showed a more than 8-fold increase in the hydrolytic ability of phytate and functioned in a wide pH range. After this indigenous engineered bacterial strain was applied to black soil, the soil phytase activity significantly increased, and the available phosphorus content rose by nearly 30%. [Conclusion] Modifying phytase by gene editing can promote the hydrolysis of phytate, increase the content of available phosphorus, and improve the phosphorus availability in the soil.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |