煤矿区耐镉细菌的筛选鉴定和重金属耐性研究

Isolation of a cadmium-resistant bacterium from coal mining and heavy metal tolerance

采用梯度浓度法从煤矸石山中筛选分离出一株Cd耐性细菌ZGKD2,并研究了其重金属耐性和吸附能力。菌落形态、生理生化和16SrDNA序列分析表明,ZGKD2为铜绿假单胞菌(Pseudomonas aeruginosa),耐Cd2+浓度为1000mg/L,最适生长条件是37℃、pH=8.0和1%的NaCl溶液。重金属吸附实验表明,在100～800mg/L的Cd2+液体培养基中接种ZGKD2活菌体20h后,Cd2+的吸附效率为82.4%～76.7%。多种重金属耐性分析表明,重金属Cd2+、Mn2+、Cu2+、Zn2+和Ni2+对ZGKD2生长的最小抑制浓度依次为:1000、220、256、227.5和146.7mg/L。正交实验表明,在复合重金属污染条件下,不同重金属对ZGKD2生长的抑制作用大小依次为Ni2+>Cu2+>Zn2+>Mn2+>Cd2+,其中浓度为130mg/L的Zn2+、112.4mg/L的Cd2+、110mg/L的Mn2+、12.8mg/L的Cu2+和29.3mg/L的Ni2+的复合污染对ZGKD2生长的抑制作用最小,表明ZGKD2能耐多种重金属。

A cadmium-resistant bacterium strain designated as ZGKD2,was isolated by gradient concentration from gangue pile of coal area,and its metal tolerance and biosorption capacity were evaluated.ZGKD2 is identified as Pseudomonas aeruginosa on the basis of its colony morphology,physiological and biochemical characteristics,as well as 16S rDNA sequence homology analysis.ZGKD2 can tolerate to 1000 mg/L Cd2 ＋,the optimum temperature,pH and NaCl for growth are 37℃,pH = 8.0 and 1% NaCl,respectively.Heavy-metal adsorption experiment shows that the adsorption rate of Cd ranges from 82.4% to 76.7% for 20 h incubation with ZGKD2 living cells in the presence of 100～800 mg/L Cd2 ＋ liquid culture.Multiple heavy-metal tolerance analysis shows that its minimal inhibitory concentration（MIC） for Cd2 ＋,Mn2 ＋,Cu2 ＋,Zn2 ＋ and Ni2 ＋ are 1 000,220,256,227.5 and 146.7 mg/L,respectively.The orthogonal experiment indicates the order of metal toxicity to ZGKD2 is Ni2 ＋ Cu2 ＋ Zn2 ＋ Mn2 ＋ Cd2 ＋,under various heavy-metal compound.The combination of 130 mg/L Zn2 ＋,112.4 mg/L Cd2 ＋,110 mg/L Mn2 ＋,12.8 mg/L Cu2 ＋ and 29.3 mg/L Ni2 ＋ have the least effect on ZGKD2 growth,it indicates that ZGKD2 strain is tolerant to various metal compound.