Chromium VI Detoxification by <i>P. fluorescens </i>Adopted from Tannery Effluent under Optimal Condition

Abstract

The present study is aimed to isolate and evaluate chromium reduction by the indigenous bacterium Pseudomonas fluorescens in tannery effluents collected from airport, Tiruchirappalli. Chromium resistant pattern was studied by plate method and reduction was studied by shake flask method. Isolate Pseudomonas fluorescens biochemically characterized as Gram negative siderophore producing bacteria and found to tolerate 1000 ppm Cr VI. Among the pH best growth was found at pH 6 showed Lag Growth phase was observed on 4 h at nonchromium condition and 6 h for chromium supplemented medium at 100 ppm and 7 h at 1000ppm. The growth was retreated by chromium but not arrested. The yield of the bio-surfactant was relatively higher in pH 8. Medium with yeast extract, pH 8 comparatively better than other nitrogen in chromium reduction. Maximum Chromium removal efficiency was 82% under chitosan and 78% by EDTA supplemented medium. Other nitrogen sources were less significant. In pH 8 under yeast extract and glucose with EDTA and 68% chromium reduction was noted without EDTA. Medium with chitosan showed enhanced reduction from 55 % to 88%. Other nitrogen sources like peptone, casein, ammonium nitrate showed 60-70% reduction in the presence of EDTA and reduction was reduced to 50% without EDTA. The increase of dextrose strength does not influence the reduction of chromium and maximum activity was found at 2% same as 10%.