关键词: 多功能菌株, 筛选, 鉴定, 解磷特征, 响应面优化

Abstract:

In order to explore multifunctional microorganism resources to achieve the effective utilization of agricultural waste, some efficient phosphate-solubilizing bacteria were isolated from the compost of mushroom chaff and chicken manure, and their phosphate-solubilizing abilities were subsequently optimized. Efficient phosphorus-solubilizing bacteria were screened from the compost by inorganic phosphorus selective medium. The selected strain was identified through the combination of morphological observation, physiological and biochemical test and molecular biology identification. Single factor and response surface experiments were used to optimize the inorganic phosphorus-solubilizing conditions of this strain. In addition, the compost potential of this strain was evaluated by determining the ability of releasing organophosphorus and potassium, and indole acetic acid production. An efficient phosphate-solubilizing strain Pb1 was isolated and identified as belonging to Bacillus smithii strain. The highest phosphorus-solubilizing capacity of strain B. smithii Pb1 was achieved when the culture condition was kept as: glucose 15.0 g /L, ammonium sulfate 3 g/L, tricalcium phosphate 7.0 g/L, inorganic salt 0.48 g/L, temperature 55.0℃, rotating speed 225 r/min, initial pH 7.0, loaded liquid 60.0 mL/250 mL, and inoculum volume 3.0%（V/V）. Further response surface optimization showed that under the conditions of tricalcium phosphate 6.4 g/L, rotating speed 207 r/min and loaded liquid 65.0 mL/250 mL, the solubilized phosphorus content in the fermentation broth of strain Pb1 cultured for 3 dreached 534.68 mg/L, which was 1.58 times higher than that before optimization. Moreover, B. smithii Pb1 was found to be capable of detoxifying organophosphates, detoxifying potassium and producing indole-3-acetic acid with the content of 238.99 mg/L, 81.06 mg/L and 23.26 mg/L, respectively. B. smithii Pb1 demonstrated the ability of releasing inorganic phosphorus, organophosphates and potassium, and producing indoleacetic acid at high temperature（55℃）, laying the foundation for the development of B. smithii Pb1 as an aerobic composting bacterial agent.

Key words: multifunctional strain, screening, identification, characteristics of phosphorus solubilizing, response surface optimization