乳白香青内生解磷菌的筛选鉴定及解磷特性研究

选择东祁连山高寒草地优势植物乳白香青为试验材料,分离和筛选内生解磷细菌,并对筛选的解磷细菌进行了鉴定,在此基础上,研究了其对玉米的促生作用。结果表明,从乳白香青植株中分离到4株内生解磷菌,解磷量(P₂O₅)为65.24～315.36 mg/L,其中菌株RA8的解磷能力最高;经形态特征、生理生化特性和16S rDNA 序列系统发育学分析,初步鉴定RA8为副球菌属细菌;RA8代谢产酸,但解磷能力与培养液的pH值之间无相关性,产生的非酸类代谢物质是其解磷的主要机制;RA8可以与土壤中的土著微生物互惠协作,增强RA8的解磷能力;经RA8处理的玉米在第70天和第100天生物量显著高于对照(P<0.05),第100天株高极显著高于对照(P<0.01),即RA8对玉米的生长有明显的促进作用。

Screening,identification and solubilizing properties of the endophytic phosphate-solubilizingbacteria isolated from Anaphalis lactea

To screen and identify endophytic phosphate-solubilizing bacteria, endophytic bacteria were isolated from Anaphalis lacteal, the dominant grass of the alpine grasslands in the Eastern Qilian Mountains. They were screened using Pikovaskaia’s culture medium (PKO), and identified by physiological and biochemical tests and 16S rDNA analysis. How the endophytic phosphate-solubilizing bacteria affect the growth of corn was also studied. Four endophytic phosphate-solubilizing bacterial strains were isolated on media with phosphate (P₂O₅) contents between 65.24 and 315.36 mg/L. Isolate RA8 had the highest phosphate-solubilizing capacity and was identified as Paracoccus sp. on the basis of morphological, physiological, and biochemical characteristics, and on phylogenetic analysis of the 16S rDNA gene sequence. RA8 can produce acid, but the phosphate (P₂O₅) content had no correlation with the pH value of the culture media. It was the non-acid metabolic substances of RA8 that played a role in the mechanism of dissolving phosphate. RA8 can cooperate with indigenous microorganisms in the soil, and as a result, RA8 has a strong phosphate-solubilizing capacity in the soil. The plant biomass of the corn treated with RA8 was significantly (P<0.05) higher than that of the control at the 70th day and 100th day, and the plant height of the corn treated with RA8 was significantly (P<0.01) higher than that of the control at the 100th day showing that RA8 can significantly promote the growth of corn.