Biomats that flourished in a fumarole located on the geothermal site Los Azufres (Mexico) were used as inocula to select aerobic and sulfate-reducing bacteria consortia for studying their capacity to reduce hexavalent chromium [Cr(VI)], aiming to use these consortia in biotransformation technologies. The sample site is characterized by slightly warm (nearly 27 \(^\circ\)C), acid (pH 3) and about hypoxic (1.8 mg L\(^{-1}\) of dissolved oxygen) conditions. Four culture systems (2 aerobic and 2 anaerobic) were investigated, including their enzymatic activity, capacity to produce biofilms, and an analysis of the total bacterial populations. For the anaerobic condition (using sulfate and sulfur as electron acceptors), four pH values (from 2 to 8) and four carbon sources (pyruvate, glycerol, Na-lactate and Na-acetate) were probed. Significant biological Cr(VI) removal was observed for all the pH values probed, particularly during the first 12 h, being more effective at the most acid conditions. At a pH value of 4 and using pyruvate as carbon source, 100 mg L\(^{-1}\) of Cr(VI) were completely depleted in less than 12 h, while the use of Na-lactate was less effective but still reasonable. These results indicate that sulfate-reducing bacteria consortia from geothermal sites like the one studied here are capable of biotransforming Cr(VI) and have the potential to provide metal bioremediation technologies.

在位于地热站点Los Azufres（墨西哥）的喷气孔中生长的生物垫被用作接种物，以选择需氧和硫酸盐还原菌菌群，以研究其还原六价铬[Cr（VI）]的能力，旨在将这些菌群用于生物转化技术。示例站点的特征在于微温（近27 \（^ \ CIRC \） C），酸（pH为3）和大约低氧（1.8毫克的L \（^ { - 1} \）溶解氧条件）。研究了四个培养系统（两个有氧和两个厌氧），包括其酶活性，产生生物膜的能力以及对总细菌种群的分析。对于厌氧条件（使用硫酸盐和硫作为电子受体），检测了四个pH值（从2到8）和四个碳源（丙酮酸，甘油，乳酸钠和乙酸钠）。对于所有探测到的pH值，尤其是在最初的12小时内，均观察到了显着的生物Cr（VI）去除，在大多数酸性条件下更有效。在pH值为4且使用丙酮酸作为碳源的情况下，100 mg L \（^ {-1} \）在不到12小时的时间内，Cr（VI）中的六价铬完全耗尽，而乳酸钠的使用效果不佳，但仍然合理。这些结果表明，来自地热场所的硫酸盐还原菌群（如本文研究的群）能够生物转化Cr（VI），并具有提供金属生物修复技术的潜力。