Hexavalent chromium detoxification by haloalkaliphilic Nesterenkonia sp strain NRC-Y immobilized in different matrices

Abstract

In order to develop a bioprocess for Cr(VI) detoxi cation in industrial e uent, a previously isolated potent Cr(VI) reducing haloalkaliphilic Nesterenkonia sp strain NRC-Y was immobilized in nine different matrices including natural polymer, modi ed natural, synthetic and mixtures of natural and synthetic polymers and investigated for Cr(VI) detoxi cation. Among the tested carriers and immobilization approaches, Nesterenkonia sp NRC-Y cells encapsulated in amidated pectin beads showed highest Cr(VI) reduction e ciency (58.4% of initial Cr(VI) concentration 150 mg/L after 20 h), followed by alginate, alginate-PVA, alginate-PVA-chitosan, PVA-PVP, and PVA respectively. Therefore, amidated pectin was selected for further investigation and immobilization of both whole cells and chromate reductase.Operational stability study revealed that immobilized whole cell was more e cient and stable than immobilized chromate reductase and the free cells retaining about 60%, 27.0% and 11.5% of its initial activity after four successive batches, respectively. The temperature and pH optima for the immobilized cells were 35 C and 7.0, respectively. The pH and thermal stability of Nesterenkonia sp NRC-Y cells were signi cantly enhanced upon immobilization in amidated pectin beads. The developed immobilized biocatalyst was applied for Cr(VI) reduction in industrial e uent samples, and was able to completely reduce Cr(VI) within 4 and 8 h for e uents for initial Cr(VI) concentrations of 10 and 30 mg/L, respectively. To the best of our knowledge, this is the rst report about of Cr(VI) detoxi cation by immobilized Nesterenkonia sp NRC-Y in amidated pectin beads. The developed immobilized biocatalyst is promising and has the potential for large-scale Cr(VI) detoxi cation application.

Description of Nesterenkonia aerolata sp. nov., an actinobacterium isolated from air of manufacturing shop in a pharmaceutical factory

“…could enhance aerobic conversion of starch to butanol (Ebrahimi et al 2020), the haloalkaliphilic Nesterenkonia sp. NRC-Y was applied in hexavalent chromium detoxi cation (Maany et al 2023)d lacusekhoensis EMLA3 can be used for removal of azo dyes as a low-cost ecofriendly approach for bioremediation of textile wastewaters (Prabhakar et al 2022).…”