Pentavalent Arsenate Reductase Activity in Cytosolic Fractions of <Emphasis Type="Italic">Pseudomonas</Emphasis> sp., Isolated from Arsenic-Contaminated Sites of Tezpur,Assam |
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Authors: | Deepti Srivastava Datta Madamwar R B Subramanian |
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Institution: | (1) BRD School of Biosciences, Sardar Patel Maidan, Sardar Patel University, Satellite Campus, Vadtal Road, Vallabh Vidyanagar 388 120, Post Box No. 39, Gujarat, India; |
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Abstract: | 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 μM As(V) in 40 min. The specific activity of arsenate reductase enzyme in
the presence of 100 μM arsenate is 6.68 μmol/min per milligram protein. The arsenate reductase activity is maximum at 30 °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. |
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