Taxonomic and Functional Profiling of Bacterial Communities in Leather Biodegradation: Insights into Metabolic Pathways and Diversity

Leather biodegradation is a microbially driven process of increasing interest for the development of sustainable waste management strategies. In this study, bacterial communities involved in the biodegradation of leather tanned with different agents (chrome, zeolite, Biole®) were characterised using high-throughput sequencing. Taxonomic profiling based on 16S rRNA gene amplification revealed that Proteobacteria, Bacteroidetes, and Patescibacteria were the dominant phyla across samples. Functional analysis, carried out through metatranscriptomic sequencing of RNA molecules, identified a total of 1,302 expressed enzymes, of which 46 were classified as proteases. The most abundant proteases included Endopeptidase La, Endopeptidase Clp, and Methionyl aminopeptidase. Although collagen samples exhibited the lowest bacterial diversity, they showed the highest total enzyme expression, whereas chrome-treated samples displayed increased protease activity, indicating selective pressure associated with heavy metal content. Additionally, distinct functional enzyme sets were found to be either shared among or exclusive to specific tanning treatments. Genera such as Acinetobacter, Pseudomonas, and Sphingopyxis were identified as key contributors to enzymatic activity and potential metal resistance. These results provide new insights into how tanning agents shape microbial communities and their enzymatic functions, highlighting specific taxa and enzymes with potential applications in the bioremediation of leather waste and environmentally friendly processing technologies.