热带土壤中解淀粉芽孢杆菌HNU1的鉴定及发酵条件优化

重金属毒性强、不可降解，在环境中可持续存在，土壤中的重金属可通过食物链累积，对生物体的健康构成严重威胁。土壤微生物修复重金属污染方法具有经济成本低、周期短、效率高、无二次污染等优点，也存在外源微生物在土壤环境中不易存活和繁殖的缺点。通过形态观察、生理生化试验以及16S rDNA同源性序列分析对前期研究中分离保存的一株铜富集细菌HNU1菌株进行鉴定，鉴定该菌为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。并通过单因素试验和正交试验找出该菌株的最适发酵条件，该菌的最适培养基组成为蔗糖2 g·L-1，酵母粉4 g·L-1，胰蛋白胨6 g·L-1，MgSO4 5 g·L-1。培养条件为初始pH为8.0，温度37 ℃，接种量0.1%，摇床转速180 r·min-1，50 mL三角瓶中装液量20 mL。鉴定的解淀粉芽孢杆菌HNU1菌株对Cu具有良好的富集作用，可进一步开发为微生物肥料用于重金属污染农田土壤的修复，对土壤修复和改良具有重大意义。

Identification and Optimization of Fermentation Conditions of the Bacillus amyloliquefaciens HNU1 in Tropical Soil

Heavy metals are highly toxic, nondegradable, sustainable in the environment and can accumulate in the soil through food chain which result in a serious threat to the health of organisms. Although the microbial remediation has advantages of low economic cost, high efficiency and no secondary pollution, there are several disadvantages including exogenous microorganisms not easy to survive and reproduce in soil. Therefore, this study identified the strain of HNU1, an enriched copper ion bacterium, which was isolated and preserved in previous study. The strain HNU1 was identified as Bacillus amyloliquefaciens through morphological observation, physiological and biochemical test and the analysis of 16S rDNA. Based on single factor experiment and orthogonal experimental, the optimum fermentation conditions were designed: the optimal medium contained 2 g·L-1 sucrose, 4 g·L-1 yeast extract, 6 g·L-1 tryptone, and 5 g·L-1 MgSO4. The optimum condition was pH 8.0, temperature 37 °C, inoculation quantity of 0.1%, rotation speed of 180 r·min-1, liquid volume of 25 mL and a 50 mL shake flask. In this study, the strain HNU1 was identified as Bacillus amyloliquefaciens with good properties of copper ions adsorption. Therefore, the strain HNU1 could be further developed into microbial fertilizer for the remediation of copper contaminated soil, which was of great significance for the remediation of heavy metal contaminated soil.