BIOREMEDIATION OF HEXAVALENT CHROMIUM BY FREE AND IMMOBILIZED BIOMASS OF CHLORELLA AND PSEUDOMONAS

Abstract

Hexavalent chromium is a toxic heavy metal and carcinogen. The purpose of present study was to analyze Cr(VI) resistant bacterial strain S7 in combination with Cholera for observing the mutualistic relationship for remediation processes. By 16S rRNA sequencing technique, the strain S7 was identified to be Pseudomonas species (KR095629). It was able to tolerate Cr(VI) stress up to 600μg/mL and showed an optimum Cr(VI) reduction of 100μg/mL. Sodium alginate (2%) was used for immobilization of S7 and Chlorella. Chromium (VI) removal by immobilized cells of S7 and Chlorella was 4.5mg/g and 6.20mg/g, with reduction potential of 58% and 60%, respectively. A direct relation between Cr(VI) concentration and root length of Chlorella was observed. Maximum root length was observed for Chlorella and S7 i.e. 1.9cm at 500μg/ml Cr(VI) concentration. The presence of several absorption peaks in the Fourier transform infrared spectroscopy (FTIR) of the biomass indicated its complex nature. This technique revealed the involvement of hydroxyl group, N-H and C- O group. The Cr(VI) was effectively removed by bacterial strain when used with Chlorella.