一株具有植物促生作用的重金属铅吸附菌的筛选与鉴定

【背景】随着工业化的发展，重金属污染逐渐成为主要的环境污染之一。微生物修复去除重金属污染成为近些年来新兴的修复方法，筛选开发具有良好修复功能的微生物菌株具有重要的现实意义。【目的】筛选具有促进植物生长作用的重金属修复菌株，为生物修复和植物促生等综合开发利用提供微生物资源。【方法】利用选择性培养基从淤泥中筛选重金属铅的抗性菌株，根据形态学观察、生理生化鉴定和16S rRNA基因序列分析对菌株进行分离鉴定，通过单因素分析不同培养条件对菌株生长的影响；采用原子吸收光谱法、比色法及平板对峙法等对菌株的重金属铅吸附率、无机磷溶解能力、吲哚乙酸(indole-3-acetic acid，IAA)分泌及拮抗镰刀菌效果等进行分析。【结果】从污染严重的塘泥中筛选到一株对重金属铅有较好吸附率的菌株，在150 mg/L Pb²⁺浓度下，对Pb²⁺的吸附率达90%以上；初步鉴定该菌株为蜡样芽孢杆菌，命名为SEM-15；菌株还具有较好的溶解无机磷、分泌IAA及拮抗镰刀菌的能力；菌株生长适应性强，可以在pH 10.0的强碱性环境下生长，该菌株具有很好的重金属铅污染修复及促生防病的应用潜力。【结论】菌株SEM-15是一株具有植物促生作用的重金属铅吸附菌株，在重金属污染土壤联合植物修复的应用中可能具有较好的开发价值。

Screening and identification of a heavy metal lead-adsorbing strain with plant growth-promoting activity

Background] With the industrialization, heavy metals have been under the major environmental pollutant category. Microbial remediation has become a popular method for heavy metal removal in recent years. Thus, screening and developing related efficient microbial strains is of important practical significance. Objective] To screen the strain with heavy metal-absorbing function and plant growth-promoting (PGP) activity, so as to provide microbial resources for both bioremediation and plant growth promotion. Methods] The selective medium was used to screen the lead-tolerant strain from sludge. The strain was identified based on morphological observation, physiological and biochemical determination, and 16S rRNA gene sequence analysis. Through single-factor experiment, the effects of different culture conditions on the growth of the strain were analyzed. Atomic absorption spectrometry, colorimetry, and plate confrontation assay were employed to analyze the lead-absorbing efficiency, inorganic phosphorus-solubilizing ability, secretion of indole-3-acetic acid (IAA), and the ability of antagonizing Fusarium. Results] A strain with high lead-adsorbing efficiency (over 90% for 150 mg/L Pb²⁺), which was identified as Bacillus cereus and named SEM-15, was screened out. It can solubilize inorganic phosphorus, secrete IAA, and antagonize Fusarium. Moreover, it had strong adaptability, as it survived at pH 10.0. Therefore, the strain has great potential in removing lead, promoting plant growth, and preventing diseases. Conclusion] SEM-15, with lead-adsorbing function and PGP activity, is of great value in remediation of heavy metal-contaminated soil and plant growth.