Sani Rajesh K, Peyton Brent M, Jandhyala Malathi
Department of Chemical Engineering, Center for Multiphase Environmental Research, Washington State University, Dana Hall, Room 118, Pullman, Washington 99164-2710, USA.
Environ Toxicol Chem. 2003 Feb;22(2):252-60.
The toxicity of Pb(II) to sulfate-reducing bacteria (SRB) was studied using Desulfovibrio desulfuricans G20 in a medium specifically designed to assess metal toxicity. The effects of Pb(II) toxicity were observed in terms of longer lag times, lower specific growth rates, and in some cases no measurable growth. With an increase in medium pH from 6 to 8, Pb(II) toxicity decreased. At all pH values, in the presence of Pb(II) concentrations ranging from 3 to 15 microM, specific growth rates decreased and lag times increased. The minimum inhibiting concentration (MIC) of Pb(II) causing a complete inhibition in growth at pH 6 was 10 microM, as compared to 15 microM at pH 7.2 and 8. These MIC values are 40 times lower than previously reported for SRB. Results also show that with increases in initial cell protein concentration (inoculum size), soluble Pb(II) removal rates increased and the degree to which Pb(II) caused increased lag times was reduced. In the presence of Pb(II), in all cases in which D. desulfuricans grew (even after a 312-h lag time), the final cell protein concentration was equivalent to that of the Pb-free control. Live/dead staining, based on membrane integrity, indicated that while Pb(II) inhibited growth, Pb(II) did not cause a loss of D. desulfuricans membrane integrity.
使用脱硫弧菌G20在专门设计用于评估金属毒性的培养基中研究了Pb(II)对硫酸盐还原菌(SRB)的毒性。从更长的延迟期、更低的比生长速率以及在某些情况下无法测量的生长情况等方面观察到了Pb(II)毒性的影响。随着培养基pH值从6增加到8，Pb(II)毒性降低。在所有pH值下，当Pb(II)浓度在3至15 microM范围内时，比生长速率降低，延迟期增加。在pH 6时导致生长完全抑制的Pb(II)的最小抑制浓度(MIC)为10 microM，相比之下，在pH 7.2和8时为15 microM。这些MIC值比先前报道的SRB的MIC值低40倍。结果还表明，随着初始细胞蛋白质浓度(接种量)的增加，可溶性Pb(II)的去除率增加，并且Pb(II)导致延迟期增加的程度降低。在存在Pb(II)的情况下，在脱硫弧菌生长的所有情况下(即使经过312小时的延迟期)，最终细胞蛋白质浓度与无Pb对照的浓度相当。基于膜完整性的活/死染色表明，虽然Pb(II)抑制生长，但Pb(II)不会导致脱硫弧菌膜完整性丧失。
