Cr(VI) Reduction and Fe(II) Regeneration by Penicillium oxalicum SL2-Enhanced Nanoscale Zero-Valent Iron

Nanoscale zero-valent iron (nZVI) faces significant challenges in Cr­(VI) remediation through aggregation and passivation. This study identified a Cr­(VI)-resistant filamentous fungus (Penicillium oxalicum SL2) for nZVI activation and elucidated the synergistic mechanism in chromium remediation. P....

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Published in:Environmental science & technology 2023-08, Vol.57 (30), p.11313-11324
Main Authors: Luo, Yating, Pang, Jingli, Peng, Cheng, Ye, Jien, Long, Bibo, Tong, Jianhao, Shi, Jiyan
Format: Article
Language:English
Subjects:
Adsorption
Antioxidants
Bioinformatics
Catalase
Chromium
Chromium - analysis
Ferrous Compounds
Fungi
Gene sequencing
Glyoxylate cycle
Harsh environments
Intracellular
Iron
Organic acids
Oxidative stress
Penicillium oxalicum
Physico-Chemical Treatment and Resource Recovery
Reductases
Reduction
Regeneration
Remediation
Riboflavin
Solubilization
Toxicity
Water Pollutants, Chemical - analysis
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Summary:Nanoscale zero-valent iron (nZVI) faces significant challenges in Cr­(VI) remediation through aggregation and passivation. This study identified a Cr­(VI)-resistant filamentous fungus (Penicillium oxalicum SL2) for nZVI activation and elucidated the synergistic mechanism in chromium remediation. P. oxalicum SL2 and nZVI synergistically and effectively removed Cr­(VI), mainly by extracellular nonenzymatic reduction (89.1%). P. oxalicum SL2 exhibited marked iron precipitate solubilization and Fe­(II) regeneration capabilities. The existence of the Fe­(II)–Cr­(V)-oxalate complex (HCrFeC4O9) indicated that in addition to directly reducing Cr­(VI), iron ions generated by nZVI stimulated Cr­(VI) reduction by organic acids secreted by P. oxalicum SL2. RNA sequencing and bioinformatics analysis revealed that P. oxalicum SL2 inhibited phosphate transport channels to suppress Cr­(VI) transport, facilitated iron and siderophore transport to store Fe, activated the glyoxylate cycle to survive harsh environments, and enhanced organic acid and riboflavin secretion to reduce Cr­(VI). Cr­(VI) exposure also stimulated the antioxidative system, promoting catalase activity and maintaining the intracellular thiol/disulfide balance. Cr­(VI)/Fe­(III) reductases played crucial roles in the intracellular reduction of chromium and iron, while nZVI decreased cellular oxidative stress and alleviated Cr­(VI) toxicity to P. oxalicum SL2. Overall, the P. oxalicum SL2–nZVI synergistic system is a promising approach for regenerating Fe­(II) while reducing Cr­(VI).
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.3c01390