Highly Cr(vi)-tolerant Staphylococcus simulans assisting chromate evacuation from tannery effluent

Abstract

Chromium(vi) contaminated sites have been targeted for studying highly chromate-resistant bacteria. From a total of 23 Cr(vi)-resistant bacteria isolated on Luria-Bertani agar medium supplemented with K2CrO4 (1,500 μg/mL), only one strain UT8 (Staphylococcus simulans) was able to tolerate high concentration of chromate, i.e., up to 200 mg/mL in agar medium from tannery effluent. In acetate minimal medium (AMM), it showed maximum tolerance of up to 2,500 μg/mL. Cr(vi) removal potential was 94.6% after 24 h (K2CrO4 1,500 μg/mL). Parametric conditions were optimized in AMM to attain maximum chromate removal. Exopolysaccharides extracted from bacterial cells exposed to chromate exhibited major absorption shifts from 2,500 to 500 cm−1 revealed by Fourier transform infrared spectroscopy. Energy-disperse X-ray spectroscopy further confirmed the adsorption of oxyanions to the bacterial cells. Surface topography of the Cr(vi) treated cells showed transformation into concave shape by scanning electron microscopy. The presence of resistance genes, i.e., chromate reductase (chrR) and class I integrase (intI1), further confirmed tolerance toward chromate. Microarray data analysis of transcriptional gene expression suggested upregulation of cys gene cluster under chromate exposure. Concisely, the present investigations revealed the potential of S. simulans to be an effective candidate for chromate reclamation of wastewater.

Cr(VI) removal performance from wastewater by microflora isolated from tannery effluents in a semi-arid environment: a SEM, EDX, FTIR and zeta potential study

“…Additionally, Cr-specific peaks were detected in Bacillus vietnamensis, Bacillus lentus, Alcaligenes faecalis, Staphylococcus cohnii , and Staphylococcus saprophyticus treated with 3400 mg/L Cr 6+ (Selvakumar et al, 2021 ). Su et al ( 2021 ) and Kalsoom A. et al ( 2021 ) indicated that the presence of Cr peaks could be due to the complexation of Cr 3+ ions with molecules located on the cell surface or the presence of reduced Cr 3+ species precipitated on the outer surface of the strains. The peak observed by the scientists (Kalsoom A. et al, 2021 ) was in the biomass of Staphylococcus simulans treated with 1500 μg/mL Cr 6+ (0.19 wt.% Cr).…”

“…Su et al ( 2021 ) and Kalsoom A. et al ( 2021 ) indicated that the presence of Cr peaks could be due to the complexation of Cr 3+ ions with molecules located on the cell surface or the presence of reduced Cr 3+ species precipitated on the outer surface of the strains. The peak observed by the scientists (Kalsoom A. et al, 2021 ) was in the biomass of Staphylococcus simulans treated with 1500 μg/mL Cr 6+ (0.19 wt.% Cr).…”

“…The distinctive peaks observed on the cell surfaces of cells exposed to Cr are common in many scientific papers. This reflects the ability of microbial strains to sequester chromium on their cell surfaces (Jobby et al, 2019 ; Kalsoom A. et al, 2021 ; Mat Arisah et al, 2021 ; Sharma et al, 2022 ).…”

Characterization of multi-metal-resistant Serratia sp. GP01 for treatment of effluent from fertilizer industries

“…Aguilar-Barajas et al ( 2008) have reported the ChrR gene from Pseudomonas aeruginosa which is responsible for chromate resistance. Kalsoom et al (2021) have also reported the presence of chromate resistance genes (ChrR) from Staphylococcus simulans against chromate toxicity. It was evident that in the present study, the identi ed potent strain GP01 has the chromate reductase gene (ChR), which helps in the reduction of the Cr (VI) and helps the bacteria to withstand the extreme toxic conditions.…”

In Situ Bioreduction of Hexavalent Chromium‐Contaminated Water Using a Microbial Culture Barrier

“…Chromium (Cr) has been extensively used in many industrial applications (such as wood preservation, leather tanning, and textile dyeing) and is known to be one of the main toxic heavy metals [2]. Inappropriate disposal of effluent from these industrial activities has led to increased Cr(VI) concentrations in the environment, which triggered an alarming situation from the environmental safety perspective [3]. Cr exists in the form of chromium metal, hexavalent chromium (Cr(VI)), and trivalent chromium (Cr(III)).…”