Reduction of hexavalent chromium by Micrococcus endophyticus isolated from leather industry wastewater

Christina Saran¹, Arya Arun Kumar¹, Anuradha Devi¹, Luiz Fernando Romanholo Ferreira², Ganesh Dattatraya Saratale³ and Ram Naresh Bharagava¹

¹Laboratory of Bioremediation and Metagenomics Research (LBMR), Department of Environmental Microbiology (DEM), Babasaheb Bhimrao Ambedkar University, VidyaVihar, Raebareli Road, Lucknow-226 025 (U.P.), India.

²Graduate Program in Genomic Sciences and Biotechnology, Catholic University of Brasília, Brasília 71966-700, Brazil 

³Department of Food Science and Biotechnology, Dongguk University-Seoul, Ilsandong-gu, Goyang-si, Gyeonggido 10326, Republic of Korea

 

Cite this article: Saran, C., Kumar, A.A., Devi, A., Ferreira, L.F. R., Saratale, G.D., Bharagava., R.N., 2025. Reduction of hexavalent chromium by Micrococcus endophyticusisolatedfrom leather industry wastewater. J. Appl. Sci. Innov. Technol. 4 (2), 64-78.

Highlights

1. LIWW was the main source of Cr⁶⁺ contamination in nature.
2. Cr⁶⁺ was highly toxic to humans, plants, microbes, and environment.
3. Micrococcus endophyticus was identified from LIWW using 16S rRNA sequencing.
4. Bacteria reduced 2000 ppm of Cr⁶⁺ within 96 hours under optimal conditions.
5. Reduced  product was analysed using DPC, SEM, FT-IR, and GC-MS techniques.

Abstract

The study aimed to isolate and characterize bacteria capable of reducing hexavalent chromium (Cr⁶⁺) present in wastewater discharged from the leather industry (LIs).The bacterial isolate AAKC5 was successfully obtained and characterized using 16S rRNA sequencing. The isolate demonstrated a tolerance capacity of up to 2000 mg/L Cr⁶⁺.Phylogenetic analysis of the 16S rRNA gene sequence identified the strain as Micrococcus endophyticus (PP830646). The study presents a novel finding wherein isolated bacterium demonstrated the ability to reduce Cr⁶⁺ at greater concentrations higher than previously reported. In experiment involving Cr⁶⁺reduction across varying concentrations ranging from (250-2000) mg/L, the bacterium exhibited notable reduction efficiencies ranging from 89.9% (250 mg/L) to 81.02% (2000 mg/L) over a period of 96-120 hours. Scanning electron microscope (SEM) analysis comparing control cells with those exposed to 2000 mg/L Cr⁶⁺revealed an increase in cell size, which was likely due to adsorption or precipitation of reduced Cr³⁺ on the bacterial surface. Fourier transform infrared spectroscopy (FT-IR) spectroscopy further indicated that biomass carboxylate and amino conjugates played a key role in the bio reduction of Cr⁶⁺.Additionally, Gas chromatography mass spectrometry (GC-MS) analysis of untreated and Micrococcus endophyticus (AAKC5) treated leather industry wastewater (LIWW) showed a significant reduction in toxic compounds, demonstrating effective microbial bioremediation. Overall, the study showed that an isolated strain of Micrococcus endophyticus effectively reduced Cr⁶⁺present in LIssediments and could be applied for the detoxification of heavy metal contaminated leather effluent sites.

Keywords: Leather industry wastewater; Chromium reduction ; Micrococcus endophyticus; SEM analysis; FT-IR analysis

Scope: Environmental Microbiology 

References

Akhzari, F., Naseri, T., Mousavi, S.M., Khosravi-Darani, K., 2024. A sustainable solution for alleviating hexavalent chromium from water streams using LactococcuslactisAM99 as a novel Cr(VI)-reducing bacterium. J. Environ. Manage. 353, 120190.

Baird, R., Rice, E., Eaton, A., 2017. Standard methods for the examination of water and wastewaters. Water Environ. Fed., Am. Public Health Assoc., Am. Water Works Assoc., 1, 71-90.

Barrow, G.I., Feltham, R.K.A., 1993. Cowan and Steel’s manual for the identification of medical bacteria, 3rd ed. Cambridge Univ. Press, Cambridge.

Bharagava, R.N., Chandra, R., Rai, V., 2009. Isolation and characterization of aerobic bacteria capable of the degradation of synthetic and natural melanoidins from distillery effluent.World J. Microbiol.Biotechnol. 25, 737-744.

Bharagava, R.N., Mishra, S., 2018. Hexavalent chromium reduction potential of Cellulosimicrobium sp. isolated from common effluent treatment plant of tannery industries. Ecotoxicol. Environ. Saf. 147, 102-109.

Bharagava, R.N., Saxena, G., Mulla, S.I., Patel, D.K., 2018. Characterization and identification of recalcitrant organic pollutants (ROPs) in tannery wastewater and its phytotoxicity evaluation for environmental safety. Arch. Environ. Contam.Toxicol. 75, 259-272.

Bruno, W.J., Socci, N.D., Halpern, A.L., 2000. Weighted neighbor joining: a likelihood-based approach to distance-based phylogeny reconstruction. Mol. Biol. Evol. 17(1), 189-197.

Central Pollution Control Board (CPCB), 2013. Pollution assessment: River Ganga. Status of grossly polluting industries (GPI).

Chen, J., Tian, Y., 2021. Hexavalent chromium reducing bacteria: mechanism of reduction and characteristics. Environ. Sci. Pollut. Res. 28, 20981-20997.

Chowdhary, P., Singh, A., Chandra, R., Kumar, P.S., Raj, A., Bharagava, R.N., 2022. Detection and identification of hazardous organic pollutants from distillery wastewater by GC-MS analysis and its phytotoxicity and genotoxicity evaluation by using Allium cepa and Cicerarietinum L. Chemosphere 297, 134123.

De Marco, E., Savarese, M., Paduano, A., Sacchi, R., 2007. Characterization and fractionation of phenolic compounds extracted from olive oil mill wastewaters. Food Chem. 104(2), 858–867.

Devi, A., Ferreira, L.F.R., Saratale, G.D., Mulla, S.I., More, N., Bharagava, R.N., 2022. Microbe-assisted phytoremediation of environmental contaminants. In: Advances in Microbe-Assisted Phytoremediation of Polluted Sites. Elsevier, 3-26.

Devi, A., Saran, C., Bharagava, R.N., 2023a. Use of secondary treated tannery wastewater as nutrient source to grow cyanobacteria and microalgae and evaluation of its effectivityas liquid biofertilizer on Vignaradiata L. seeds.  J. Appl. Sci. Innov. Technol. 2(2), 82-89.

Devi, A., Saran, C., Ferreira, L.F.R., Mulla, S.I., Bharagava, R.N., 2024. Sustainable approaches to algal biofuels: Opportunities, key challenges and current status. In: Value Added Products from Bioalgae-Based Biorefineries: Opportunities and Challenges. Springer Nature, Singapore, 163-188.

Devi, A., Verma, M., Saratale, G.D., Saratale, R.G., Ferreira, L.F.R., Mulla, S.I., Bharagava, R.N., 2023b. Microalgae: A green eco-friendly agent for bioremediation of tannery wastewater with simultaneous production of value-added products. Chemosphere 336, 139192.

Devi, A., Jain, V., Patel, D.K., VenkataSatyanarayan, G.N., Bharagava, R.N., 2025a. Bioremediation of tannery wastewater using Tetradesmusdeserticola: A sustainable approach. J. Exp. Biol. Agric. Sci. 13(2), 190-203.

Devi, A., Singh, V., Raj, A., Saratale, G.D., Ferreira, L.F.R., Mulla, S.I., Bharagava, R.N., 2025b. Optimization of lipid production in Tetradesmusdimorphus using response surface methodology with tannery wastewater for biodiesel production. Bioresour.Technol.430, 132585.

Fajri, J.A., Nurmiyanto, A., Sa’adah, N.N., Sagita, N.D., Nuryana, I., Rahayu, A., Lathifah, A.N., 2025.Selection of endophyte and indigenous bacteria degrading textile wastewater in floating treatment wetland. Int. J. Environ. Sci. Technol. 22(1), 319-330.

Farag, S., Zaki, S., 2010.Identification of bacterial strains from tannery effluent and reduction of hexavalent chromium. J. Environ. Biol. 31(5), 877.

Gautam, A., 2022. Polymerase chain reaction (PCR). In: DNA and RNA Isolation Techniques for Non-Experts. Techniques in Life Science and Biomedicine for the Non-Expert. Springer, Cham.

Hoorzook, K.B., Barnard, T.G., 2022. Culture independent DNA extraction method for bacterial cells concentrated from water. Methods X 9, 101653.

Ismail, I., Moustafa, T., 2016.Biosorption of heavy metals. In: Heavy Metals: Sources, Toxicity and Remediation Techniques. 131-174.

Kashyap, B.K., Saran, C., Solanki, M.K., Divvela, P.K., 2023. Emerging frontiers of microbes as liquid waste recycler. In: Kashyap, B.K., Solanki, M.K. (Eds.), Current Research Trends and Applications in Waste Management. Springer, Singapore.

Khan, M.T.A., Al-Battashi, H., Al-Hinai, M., Almdawi, M., Pracejus, B., Elshafey, E.S.I., Abed, R.M., 2025.Isolation of aerobic heterotrophic bacteria from a microbial mat with the ability to grow on and remove hexavalent chromium through biosorption and bioreduction. Appl. Biochem. Biotechnol. 197(1), 94-112.

Khanam, R., Al Ashik, S.A., Suriea, U., Mahmud, S., 2024. Isolation of chromium resistant bacteria from tannery waste and assessment of their chromium reducing capabilities -A bioremediation approach. Heliyon 10(6).

Lin, W.H., Chien, C.C., Ou, J.H., Yu, Y.L., Chen, S.C., Kao, C.M., 2023.Cleanup of Cr (VI)-polluted groundwater using immobilized bacterial consortia via bioreduction mechanisms. J. Environ. Manag.339, 117947.

Lipps, W.C., Baxter, T.E., Braun-Howland, E.B. (Eds.), 2023. Standard methods for the examination of water and wastewater. Am. Public Health Assoc., Am. Water Works Assoc.

Maurya, A., Kumar, R., Raj, A., 2025. Effective treatment of tannery effluent by biofilm-forming bacteria and evaluation of their toxicity reduction.Water Air Soil Pollut. 236 (2), 84.

Mishra, S., Chen, S., Saratale, G.D., Saratale, R.G., Ferreira, L.F.R., Bilal, M., Bharagava, R.N., 2021. Reduction of hexavalent chromium by Microbacteriumparaoxydans isolated from tannery wastewater and characterization of its reduced products. J. Water Process Eng. 39, 101748.

MOWR (Ministry of Water Resources), 2013. Report of the committee: Pollution caused by leather tanning industries to the water bodies/ground water in Unnao District of Uttar Pradesh, 90.

Patil, A., Arya, M., Yadav, B.K., Nahar, M., Rajamohan, N., 2025. Removal of toxic arsenic and chromium from soil using biochar-immobilized Geobacillus and Bacillus species: A review. Int. J. Environ. Sci. Technol. 1-24.

Priya, A.K., Gnanasekaran, L., Dutta, K., Rajendran, S., Balakrishnan, D., Soto-Moscoso, M., 2022. Biosorption of heavy metals by microorganisms: Evaluation of different underlying mechanisms. Chemosphere 307, 135957.

Qasem, N.A., Mohammed, R.H., Lawal, D.U., 2021. Removal of heavy metal ions from wastewater: A comprehensive and critical review. NPJ Clean Water 4(1), 1-15.

Rahman, Z., Thomas, L., 2021. Chemical-assisted microbially mediated chromium (VI) reduction under the influence of various electron donors, redox mediators, and other additives: An outlook on enhanced Cr(VI) removal. Front. Microbiol.11, 619766.

Ramli, N.N., Othman, A.R., Kurniawan, S.B., Abdullah, S.R.S., Hasan, H.A., 2023. Metabolic pathway of Cr(VI) reduction by bacteria: A review. Microbiol.Res. 268, 127288.

Sanchez-Hachair, A., Hofmann, A., 2018. Hexavalent chromium quantification in solution: Comparing direct UV-visible spectrometry with 1,5-diphenylcarbazide colorimetry. C. R. Chim. 21(9), 890-896.

Sanjay, M.S., Sudarsanam, D., Raj, G.A., Baskar, K., 2020. Isolation and identification of chromium reducing bacteria from tannery effluent. J. King Saud Univ. Sci. 32, 265-271.

Saran, C., Devi, A., Saratale, G.D., Saratale, R.G., Ferreira, L.F.R., Mulla, S.I., Bharagava, R.N., 2024a. Bacterial treatment of industrial wastewaters: Applications and challenges. In: Microbes-Based Approaches for the Management of Hazardous Contaminants, 171-189.

Saran, C., Devi, A., Saratale, G.D., Ferreira, L.F.R., Bharagava, R.N., 2024b.Bioenergy generation and cogeneration from algae-based biorefineries. In: Value Added Products from Bioalgae-Based Biorefineries: Opportunities and Challenges. Springer Nature, Singapore, 189-211.

Saran, C., Devi, A., Verma, M., Saratale, G.D., Ferreira, L.F.R., More, N., Bharagava, R.N., 2024c.A continuous system of biofuel production from microalgal biomass. In: Recent Trends and Developments in Algal Biofuels and Biorefinery. Springer Nature, Cham, 77-106.

Saran, C., Purchase, D., Saratale, G.D., Saratale, R.G., Ferreira, L.F.R., Bilal, M., Bharagava, R.N., 2023. Microbial fuel cell: A green eco-friendly agent for tannery wastewater treatment and simultaneous bioelectricity/power generation. Chemosphere 312, 137072.

Saran, C., Patel, D.K., Jain, V., Satyanarayana, G.N.V., Saratale, G.D., Ferreira, L.F.R., Bharagava, R.N., 2025a.Characterization and identification of potential microbial fuel cells capable for the detoxification of hexavalent chromium from leather industry wastewater with power generation. Next Energy 7, 100299.

Saran, C., Singh, V., Bharagava, R.N., 2025b. Development and optimization of a microbial fuel cells consortium by response surface methodology for the effective reduction of hexavalent chromium with power generation. J. Exp. Biol. Agric. Sci. 13(2), 239-257.

Satpati, G.G., Devi, A., Kundu, D., Dikshit, P.K., Saravanabhupathy, S., Banerjee, R., Davoodbasha, M., 2024.Synthesis, delineation and technological advancements of algae biochar for sustainable remediation of the emerging pollutants from wastewater – a review. Environ. Res. 258, 119408.

Sharma, V.K., Shah, M.P., Parmar, S., Kumar, A., 2021. Fungi bio-prospects in sustainable agriculture, environment and nanotechnology. Academic Press.

Sophia, A.C., Saikant, S., 2016.Reduction of chromium (VI) with energy recovery using microbial fuel cell technology. J. Water Process Eng. 11, 39-45.

Suresh, G., Balasubramanian, B., Ravichandran, N., Ramesh, B., Kamyab, H., Velmurugan, P., Ravi, A.V., 2021. Bioremediation of hexavalent chromium-contaminated wastewater by Bacillus thuringiensis and Staphylococcus capitis isolated from tannery sediment. Biomass Convers.Biorefin. 11, 383-391.

Tan, H., Wang, C., Zeng, G., Luo, Y., Li, H., Xu, H., 2020. Bioreduction and biosorption of Cr(VI) by a novel Bacillus sp. CRB-B1 strain. J. Hazard. Mater. 386.

Thacker, U., Madamwar, D., 2005. Reduction of toxic chromium and partial localization of chromium reductase activity in bacterial isolate DM1. World J. Microbiol.Biotechnol. 21, 891-899.

Zahoor, A., Rehman, A., 2009. Isolation of Cr(VI)-reducing bacteria from industrial effluents and their potential use in bioremediation of chromium-containing wastewater. J. Environ. Sci. 21(6), 814–820.