Innovative low-cost biosorption process of Cr⁶⁺ by Pseudomonas alcaliphila NEWG-2

Chromium is one of the heavy metal pollutants that causing risky health issues when discharged into the aquatic ecosystems. The current investigation focused on the bioremoval of Cr⁶⁺ depending on the bacterial sorption process by using Pseudomonas sp. NEWG-2 which was identified on the basis of morphological, cultural characteristics, 16S rRNA sequencing and phylogenetic analysis as Pseudomonas alcaliphila strain NEWG-2. It is clear from the FCCD experiments that the bacterium can grow normally and remove 96.60% of 200 mg/l of Cr⁶⁺ using yeast extract (5.6 g/l), glucose (4.9 g/l), pH (7) for 48 h incubation period. SEM and EDS analyses proved that the Cr⁶⁺ was biosorbed by P. alcaliphila NEWG-2. FTIR spectra indicated that the phenolic, carbonyl ester, acetyl, carboxylate, alkanes and carbonyl were the main groups involved in the chromium biosorption. Of the equilibrium isotherms models, the Langmuir model was more obedient, with a maximum uptake (q_max) of 10 mg/g (bacterial-alginate beads), than the Freundlich one. The findings reveal the efficiency of P. alcaliphila NEWG-2 in Cr⁶⁺ biosorption, with feasibility in the treatment of chromium-contaminated water as a green-technology tool. Interestingly, to the best of our knowledge, this is the first report on Cr⁶⁺ biosorption process by P. alcaliphila.