Molecular Identification of Fungi Isolated From Tannery Wastes and Assessment of Their Chromium Reduction Ability

ABSTRACT High chromium content in tannery waste is a significant environmental concern because of its remarkable ecological hazards. However, while the potential of bacteria for bioremediation has been widely explored, research on fungal bioremediation remains relatively limited and underexplored. This study aimed to identify and examine chromium‐resistant fungi to determine their role in reducing chromium levels and observe their capability to help in remediation processes for cleaning up contaminated sites. Nine samples were collected from chromium‐contaminated tannery waste in Jhaowchar, Hemayetpur, Savar, Dhaka. These isolates were provisionally identified based on morphological traits. Then, subcultures of those isolates yielded four pure isolates. Finally, molecular identification was performed using PCR and sequence analysis, and the results were identified as Penicillium citrinum , P. janthinellum , Fusarium oxysporum , and Trichoderma harzianum . Subsequently, the chromium tolerance capacity of these isolates was evaluated after 72 h of incubation at 30°C. They all exhibited successful growth at concentrations of 500 and 1000 mg/L. At 1300 mg/L, P. janthinellum and T. harzianum developed while the others did not. At 1500 mg/L, only T. harzianum demonstrated growth. None of the fungal isolates could grow at 2000 mg/L. Notably, T. harzianum exhibited superior chromium tolerance at 1500 mg/L. The Cr (VI) reduction capacity of the four fungal isolates was quantitatively assessed using the diphenylcarbazide (DPC) method, with all isolates demonstrating approximately 95% reduction of 10 mg/L Cr (VI) to the less toxic Cr (III). For hexavalent chromium removal, contaminated soil containing 50 mg/L of Cr (VI) treated with all selected fungal isolates showed complete disappearance of Cr (VI) after incubation for 7 days. Therefore, these isolates can be employed in an economical and eco‐friendly manner to detoxify chromium and are promising for the removal of Cr (VI) contamination.