BRD School of Biosciences, Sardar Patel Maidan, Sardar Patel University, Satellite Campus, Vadtal Road, Vallabh Vidyanagar 388 120, Post Box No. 39, Gujarat, India.
Appl Biochem Biotechnol. 2010 Oct;162(3):766-79. doi: 10.1007/s12010-009-8852-0. Epub 2009 Dec 1.
Pentavalent arsenate reductase activity was localized and characterized in vitro in the cytosolic fraction of a newly isolated bacterial strain from arsenic-contaminated sites. The bacterium was gram negative, rod-shaped, nonmotile, non-spore-forming, and noncapsulated, and the strain was identified as Pseudomonas sp. DRBS1 following biochemical and molecular approaches. The strain Pseudomonas sp. DRBS1 exhibited enzymatic machinery for reduction of arsenate(V) to arsenite(III). The suspended culture of the bacterium reduced more than 97% of As(V) (40-100 mM) to As(III) in 48 h. The growth rate and total cellular yield decreased in the presence of higher concentration of arsenate. The suspended culture repeatedly reduced 10 mM As(V) within 5 h up to five consecutive inputs. The cell-free extracts reduced 86% of 100 microM As(V) in 40 min. The specific activity of arsenate reductase enzyme in the presence of 100 microM arsenate is 6.68 micromol/min per milligram protein. The arsenate reductase activity is maximum at 30 degrees C and at pH 5.2. The arsenate reductase activity increased in the presence of electron donors like citrate, glucose, and galactose and metal ions like Cd(+2), Cu(+2), Ca(+2), and Fe(+2). Selenate as an electron donor also supports the growth of strain DRBS1 and significantly increased the arsenate reduction.
五价砷酸盐还原酶活性在从砷污染场所新分离的细菌的胞质部分中进行了定位和体外表征。该细菌呈革兰氏阴性、杆状、非运动性、非孢子形成和无包膜，通过生化和分子方法鉴定为假单胞菌属 DRBS1 株。假单胞菌属 DRBS1 株表现出将砷酸盐（V）还原为亚砷酸盐（III）的酶机制。细菌的悬浮培养在 48 小时内将超过 97%的 As(V)（40-100 mM）还原为 As(III)。在较高浓度的砷酸盐存在下，生长速率和总细胞产量下降。悬浮培养在 5 小时内重复将 10 mM As(V)还原五次。细胞提取物在 40 分钟内将 100 microM As(V)还原 86%。在 100 microM 砷酸盐存在下，砷酸盐还原酶的比活性为 6.68 微摩尔/分钟/毫克蛋白。砷酸盐还原酶活性在 30°C 和 pH 5.2 时达到最大值。砷酸盐还原酶活性在存在电子供体如柠檬酸盐、葡萄糖和半乳糖以及金属离子如 Cd(+2)、Cu(+2)、Ca(+2)和 Fe(+2)时增加。作为电子供体的硒酸盐也支持 DRBS1 菌株的生长，并显著增加了砷酸盐的还原。
