Microorganisms from tannery wastewater: Isolation and screening for potential chromium removal

Chromium is a chemical element that enables many industries to function. However, its hexavalent form can cause serious problems. The current methods used to remove Cr are expensive and cause environmental damages, hence the need to set up the most envi-ronment friendly methods like the biological methods. The main objectives of this study were isolation, characterization of hexavalent chromium removing microorganisms from Marrakech tannery wastewater. Four microbial strains namely Bacillus licheniformis, Bacillus megaterium, Byssochlamys sp. and Candida maltosa were selected and identified using molecular methods. Candida maltosa and Byssochlamys sp. produce antimicrobial metabolites that have a microbiostatic effect. Bacillus licheniformis, Bacillus megaterium and Candida maltosa removed 92.75; 75.48 and 43.27% of hexavalent chromium at the concentration of 50 mg/L in 96 h respectively. In contrast, Byssochlamys sp. removed 100% of 50 mg/L of hexavalent chromium concentration in 72 h. At 100 mg/L of hexavalent chromium, it was recorded that Bacillus licheniformis, Bacillus megaterium, Byssochlamys sp., Candida maltosa, consortium C reduced 41.20; 50.88; 64.44; 31.88; 57.30% in 96 h respectively. Byssochlamys sp. strain could be the best candidate for bioremediation of chromium contaminated leather industry effluent and metal recovery in mining process.(c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).