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Microbial Degradation of Chromium-Tanned Leather During Thermophilic Composting: A Multi-Scale Analysis of Microbial Communities and Structural Disruption

Summary

This study investigated how naturally occurring microorganisms can break down chromium-tanned leather waste through controlled composting at high temperatures. Researchers found that thermophilic composting successfully fragmented leather and selected specialized bacteria and fungi capable of surviving in chromium-rich environments. These microorganisms formed protective biofilms on leather surfaces, suggesting potential strategies for safer disposal of leather waste from the footwear and tannery industries.

Background

Chromium-tanned leather waste presents significant environmental challenges due to persistent collagen and chromium compounds that resist degradation. Traditional disposal methods like landfilling and incineration raise regulatory and environmental concerns. Biological treatment strategies through composting remain largely unexplored for chromium-tanned leather waste.

Objective

To establish a reproducible thermophilic composting system for characterizing microbial communities associated with chromium-tanned leather degradation and isolating cultivable microbial strains. The study aimed to understand leather-associated biofilm formation and identify thermophilic microorganisms capable of degrading collagen in chromium-rich environments.

Results

Thermophilic conditions induced marked structural alterations in chromium-tanned leather with 38.94% mass loss in small-scale systems and ~100% degradation in pilot-scale systems. Bacterial richness decreased in leather-containing samples, with enrichment of genera including Sinibacillus, Desulfotomaculum, Chelativorans, and Thermobifida. Extensive biofilm formation with extracellular polymeric substances was observed on leather surfaces, with 30 bacterial strains and 1 fungal strain successfully isolated.

Conclusion

Thermophilic composting creates selective conditions favoring chromium-tolerant and collagen-degrading microorganisms. Mature biofilms with extracellular polymeric substances suggest potential mechanisms for chromium tolerance and leather degradation. These findings provide a microbiological foundation for developing biotechnological approaches to manage chromium-tanned leather waste, though additional studies are needed before recommending this as a routine treatment option.
  • Published in:Biology (Basel),
  • Study Type:Experimental Research Study,
  • Source: PMID: 41463572
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