乌鲁木齐市道路林带土壤抗重金属细菌的筛选及重金属去除能力

Screening of heavy metal-resistant bacteria from the soil of road forest belt in Urumqi of China and testing of the heavy metal-removing ability

摘要:

【背景】道路重金属污染问题日益严峻，寻找高效的微生物资源用于环境修复已迫在眉睫。【目的】从乌鲁木齐市道路林带土壤中筛选抗重金属菌株，并对其重金属去除能力进行探究。【方法】使用含5种重金属离子(铅、镉、锌、铜、镍)的4种培养基进行抗性菌株筛选，通过形态学特征和16S rRNA基因序列进行鉴定，采用电感耦合等离子体发射光谱仪(inductively coupled plasma optical emission spectrometer, ICP-OES)检测分离株对重金属离子的去除情况。【结果】4种分离培养基中，TSA是抗重金属菌株筛选的最适培养基，共筛选出16株抗重金属菌，其中4株抗Pb菌、4株抗Cd菌、4株抗Zn菌、3株抗Cu菌和1株抗Ni菌，其抗性分别高达3 000、800、600、300和400 mg/L，16株菌中以芽孢杆菌属(Bacillus)数量最多。在初始浓度为700 mg/L Pb²⁺下，菌株Pb6的去除率高达92.48%，菌株Pb11、Pb3和Pb9的去除率分别为27.70%、40.37%和58.88%；在200 mg/L Cd²⁺下，菌株Cd4的去除率最高，为63.84%，其余抗Cd菌株去除率在30%-40%；在200 mg/L Zn²⁺下，菌株Zn1和Zn4的去除率较高，分别为65.34%和60.87%，而菌株Zn5和Zn6的去除率为15.78%和12.60%；在300 mg/L Cu²⁺下，3株抗Cu菌的去除率均较低，未超过3%；在200 mg/L Ni²⁺下，菌株Ni2的去除率为4.31%。对菌株Pb6、Cd4、Zn1紫外照射30 s并连续传代培养后得到3株去除率较稳定菌株，去除率分别为91.11%、65.10%和66.48%。【结论】获得3株对重金属有较高耐受性和去除率的优势菌株，分别为Bacillus sp. Pb6、Pseudomonas sp. Cd4和Bacillus sp. Zn1，这将为重金属污染土壤或水体修复和治理提供优良菌种资源。

Abstract:

[Background] Heavy metal pollution of roads becomes more and more serious, and it is urgent to find efficient microbial resources for environmental remediation. [Objective] To screen heavy metal-resistant strains from the soil of road forest belt in Urumqi of China and test the heavy metal-removing ability. [Methods] Four media containing five heavy metal ions (Pb, Cd, Zn, Cu, and Ni) were used to screen the resistance strains which were then identified based on morphological characteristics and 16S rRNA gene. The removal of heavy metal ions by the strains was tested by inductively coupled plasma optical emission spectrometer (ICP-OES). [Results] Among the four media, TSA was the optimal one for the screening of strains. A total of 16 resistance strains were screened out: 4 Pb-resistant strains (tolerant concentration: 3 000 mg/L), 4 Cd-resistant strains (tolerant concentration: 800 mg/L), 4 Zn-resistant strains (tolerant concentration: 600 mg/L), 3 Cu-resistant strains (tolerant concentration: 300 mg/L), and 1 Ni-resistant strain (tolerant concentration: 400 mg/L). Among the 16 strains, the majority were Bacillus. The removal rate of 700 mg/L Pb²⁺ by strain Pb6 stood at 92.48%, and the removal rates by strains Pb11, 3 and 9 hit 27.70%, 40.37%, and 58.88%, separately. The removal rate of 200 mg/L Cd²⁺ by strain Cd4 was the highest (63.84%), and the removal rates by other Cd-resistant strains were about 30%-40%. The removal rates of 200 mg/L Zn²⁺ by strains Zn1 and Zn4 were 65.34% and 60.87%, respectively, while those by strains Zn5 and Zn6 registered 15.78% and 12.60%, separately. The removal rates of 300 mg/L Cu²⁺ by the three Cu-resistant strains were low (<3%). The removal rate of 200 mg/L Ni²⁺ by strain Ni2 was 4.31%. The strains (except for Cu1 and Cu3) mainly removed the heavy metals by adsorption, supplemented by absorption. After UV irradiation of strains Pb6, Cd4, and Zn1 for 30 s and continuous subculture, the removal rates of the corresponding heavy metals by three stable strains were 91.11%, 65.10%, and 66.48%, respectively. [Conclusion] Three strains with high tolerance to and removal rate of heavy metals were screened out: Bacillus sp. Pb6, Pseudomonas sp. Cd4, Bacillus sp. Zn1, which can be used as candidate strains for the remediation and treatment of soil or water polluted by heavy metals.