Maximizing EPS production from Pseudomonas aeruginosa and its application in Cr and Ni sequestration

Heavy metal contamination of water bodies has been a cause of grave concern around the globe. Analysis of various industrial effluents has revealed a perilous level of Cr (VI) and Ni (II). Pseudomonas aeruginosa is an extracellular polymeric substances (EPSs) producing bacterium. EPS has a great potential in the sequestration of heavy metal ions. In the present study efforts have been made to understand the effect of time, pH, and temperature on production of EPS by P. aeruginosa (MTCC 1688). The extracted EPS has been applied for removal of Ni (II) and Cr (VI) ions from aqueous system. The results revealed that highest EPS yield (26 mg/50 mL) can be obtained after 96 h of incubation at pH 6 and 32 degrees C temperature in 50 mL of culture. Treatment of 10 mg/L Cr (VI) and Ni (II) with 30 mg/L EPS resulted in the removal of 26% and 9% of Cr (VI) and Ni (II), respectively. Fourier-transform infrared spectral analysis revealed the involvement of -OH, -NH, C-O, diketone, and ester functional groups of EPS in the attachment of Cr (VI) ion while involvement of amide and -C=O groups in Ni (II) binding with EPS. Scaling-up the production of EPS using bioreactor may further help in developing an efficient process for treatment of water polluted with Cr and Ni.

Automated summary

The bacterium Pseudomonas aeruginosa produces extracellular polymeric substances (EPS) that have the potential to sequester heavy metal ions in water bodies contaminated with Cr (VI) and Ni (II). The study investigated the effect of time, pH, and temperature on EPS production and its ability to remove Cr (VI) and Ni (II) ions from aqueous systems. Results showed that specific functional groups of EPS were involved in binding with Cr (VI) and Ni (II) ions, demonstrating the potential for scaling up EPS production using a bioreactor for efficient treatment of water polluted with these heavy metals.