Isolation and molecular characterization of the indigenous Staphylococcus aureus strain K1 with the ability to reduce hexavalent chromium for its application in bioremediation of metal-contaminated sites

Abstract

Background Urbanization and industrialization are the main anthropogenic activities that are adding toxic heavy metals to the environment. Among these, chromium (in hexavalent: Cr+6 and/or trivalent Cr+3) is being released abundantly in wastewater due to its uses in different industrial processes. It becomes highly mutagenic and carcinogenic once it enters the cell through sulfate uptake pathways after interacting with cellular proteins and nucleic acids. However, Cr+6 can be bio-converted into more stable, less toxic and insoluble trivalent chromium using microbes. Hence in this study, we have made efforts to utilize chromium tolerant bacteria for bio-reduction of Cr+6 to Cr+3. Methods Bacterial isolate, K1, from metal contaminated industrial effluent from Kala Shah Kaku-Lahore Pakistan, which tolerated up to 22 mM of Cr6+ was evaluated for chromate reduction. It was further characterized biochemically and molecularly by VITEK®2 system and 16S rRNA gene sequencing respectively. Other factors affecting the reduction of chromium such as initial chromate ion concentration, pH, temperature, contact-time were also investigated. The role of cellular surface in sorption of Cr6+ ion was analyzed by FTIR spectroscopy. Results Both biochemical and phylogenetic analyses confirmed that strain K1 was Staphylococcusaureus that could reduce 99% of Cr6+ in 24 hours at 35 °C (pH = 8.0; initial Cr6+ concentration = 100 mg/L). FTIR results assumed that carboxyl, amino and phosphate groups of cell wall were involved in complexation with chromium. Our results suggested that Staphylococcusaureus K1 could be a promising gram-positive bacterium that might be utilized to remove chromium from metal polluted environments.

Comparative Study of Polycaprolactone Electrospun Fibers and Casting Films Enriched with Carbon and Nitrogen Sources and Their Potential Use in Water Bioremediation

“…Chromium removal in water by P. aeruginosa has been reported extensively [ 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ], but to the best of our knowledge, no reports are found in the literature that use electrospun fibers as promoters of intended P. aeruginosa biofilm formation for the removal of chromium from water, and thus a comparison between the reported bioremediation potential of P. aeruginosa biofilms created with non-nanostructured substrates and our results is listed in Table 5 , in order to see the difference in the removal capacity with and without the use of nanostructured substrates.…”

The use of bacteria for bioremediation of environments contaminated with toluene: a molecular docking analysis

“…Zou et al (2014) analyzed metal-contaminated locals and reported the ability of S. aureus to resist and reduce chromium (VI) to chromium (III) and adsorb uranium (VI). Tariq et al (2019) confirmed through biochemical and phylogenetic analyses that the S. aureus K1 strain is promising and can remove chromium from metal-polluted environments. Furthermore, biofilms produced by S. aureus -one of the structures responsible for the bacterium's pathogenicity, have been tested for uranium bioremediation ability (SHUKLA et al, 2020).…”

Profiling of Indigenous Biosurfactant-Producing Bacillus Isolates in the Bioremediation of Soil Contaminated by Petroleum Products and Olive Oil

“…ese results are very important to show not only their importance in biodegradation but also to avoid any contamination of the soil with these pathogenic bacteria. Bioremediation of polluted oily sludge employing pathogenic bacteria including Pseudomonas aeruginosa, B. cereus, Staphylococcus sp., has been demonstrated [36,46,47]. Here, we showed the evidence that Bacillus could be the bright choice for bioremediation since strains are deeply considered like GRAS (generally recognized as safe) organisms.…”