杉木人工林土壤溶磷细菌筛选及培养条件优化

目的]从红壤区杉木人工林土壤中,筛选出具有高效溶磷能力的菌株及优化其培养条件。方法]通过Pikovskava(PVK)无机磷培养基分离、筛选溶磷细菌,通过生理生化试验16SrDNA基因序列分析对溶磷能力强的菌株进行鉴定;采用单因素试验,比较菌株在不同培养时间、培养初始pH、培养温度、接种量、碳源、氮源、磷源条件下的溶磷能力;采用正交试验进行菌株培养条件优化。结果]筛选出13株具有溶磷能力的细菌,其中P5的溶磷能力最强,在PVK培养基中溶解磷含量为196.61 mg·L^-1。根据其生理生化特性和16SrDNA基因序列分析,该细菌鉴定为Burkholderia ubonensis。单因素试验表明菌株较耐高温,耐低pH,正交试验结果显示P5溶磷效果最佳培养基组合和培养条件为2.0%(w/v)蔗糖,0.2%(w/v)氯化铵,初始p H为5.5,培养温度为30℃。在最佳条件下培养基有效磷含量为268.69 mg·L^-1,约为PVK培养基的1.4倍。结论]菌株P5耐高温、低pH,溶磷能力较强,在微生物肥料的开发利用及在环境胁迫土壤中具有应用潜力。

Screening Phosphorus-Solubilizing Bacteria from Chinese Fir Plantation Soil and Optimizing Its Culture Conditions

Objective] To isolate and screen phosphorus-solubilizing bacteria from the soil of Chinese fir(Cunninghamia lanceolata) plantation in red soil region and optimize its culture conditions. Method] The phosphorus-solubilizing bacteria were isolated and screened by Pikovskava(PVK) medium. The strains with strong phosphorus-solubilizing capacity were identified by physiological and biochemical tests and 16 SrDNA gene sequence alignment.Single factor test was used to compare the phosphorus-solubilizing capacity of the strains under different culture time,initial pH, culture temperature, inoculum size, carbon source, nitrogen source and phosphorus source. Orthogonal test was used to optimize the culture conditions of the strains. Result] Thirteen strains were screened out, among which the phosphorus-solubilizing capacity of strain P5 was the highest. The content of available phosphorus of strain P5 in PVK was 196.61 mg·L^-1. Strain P5 were identified as Burkholderia ubonensis by physiological and biochemical tests and sequence analysis of 16 SrDNA gene. Single factor test showed that strain P5 was resistant to high temperature and low pH. The result of the orthogonal experiment indicated that the optimal culture condition of strain P5 are as follows: 2.0%(w/v) sucrose, 0.2%(w/v) ammonium chloride, pH 5.5, 30 ℃, under which the maximum phosphorussolubilizing capacity could be up to 268.69 mg·L^-1 and the content of available phosphorus was about 40% higher.Conclusion] The result indicates that strain P5, a highly efficient phosphorus-solubilizing bacteria, could be a potential candidate for the development of microbial fertilizer applied to environmentally stressed soil due to their phosphorus-solubilizing capacity and tolerance to high temperature and low pH.