牛蒡根际土壤中解钾菌筛选、鉴定及解钾条件优化

该研究通过选择性培养基初筛，可溶性钾含量和产吲哚乙酸（IAA）能力测定复筛，从牛蒡根际土壤中筛选解钾能力较强的菌株，通过形态观察、生理生化试验及分子生物学技术对其进行鉴定，并通过单因素试验和响应面试验对其解钾条件进行优化，最后，通过牛蒡盆栽试验验证其促生能力。结果表明，从牛蒡根际土壤中筛选到一株降解钾能力及IAA生产能力较高的菌株PB-9，并被鉴定为巨大芽孢杆菌（Bacillus megateriums）。其最优解钾条件为发酵温度31 ℃、初始pH值6.8、接种量6.6%、发酵时间53 h。在此最优条件下，可溶性钾含量为38.46 mg/L，增长率为136.24%。与空白对照（CK）组相比，菌株PB-9能使牛蒡的株高、叶片数和地上部分鲜质量分别提高25.78%、28.48%、26.54%，对牛蒡的生长具有显著的促进作用（P＜0.05）。

Screening and identification of potassium-dissolving bacterium in burdock rhizosphere soil and optimization of potassium-dissolving conditions

Through the screening of selective medium, the determination of the content of soluble potassium and indole-acetic acid (IAA) production capacity, the strains with strong ability of dissolving potassium were screened from burdock rhizosphere soil, identified by morphological observation, physiological and biochemical tests and molecular biological technology, and the dissolving potassium conditions were optimized through single factor test and response surface methodology. Finally, through burdock basin, the growth promoting ability was verified by planting experiments. The results showed that a strain PB-9 with high capacity of potassium degradation and IAA production was screened from burdock rhizosphere soil, and it was identified as Bacillus megateriums. The optimal conditions of potassium solution were fermentation temperature 31 ℃, initial pH 6.8, inoculum 6.6%, and fermentation time 53 h. Under the optimal conditions, the content of soluble potassium was 38.46 mg/L, with an increasing rate of 136.24%. Compared with control group, the plant height, leaf number and fresh mass of burdock increased by 25.78%, 28.48% and 26.54%, respectively, by strain PB-9, which had a significant effect on the growth of burdock (P＜0.05).