Integrated Physical and Proteomic Approaches Dissect the Effect of Leather Degradation by Bacteria

Landfills
and incineration of leather wastes cause serious environmental
pollution. In contrast, leather biodegradation by microbes is an environmentally
friendly option for the disposal of leather. However, the microbial
degradation mechanism is not fully understood. In this study, Bacillus licheniformis (Gram-positive bacterium)
and Pseudomonas putida (Gram-negative
bacterium) were isolated from leather artifacts. The effects of leather
degradation by these two bacteria were systematically investigated. P. putida and B. licheniformis destroyed the morphology of the leather and caused obvious color
aberration by darkening, greening, and bluing the leather. The tensile
strength of sheep leather was significantly damaged by B. licheniformis. P. putida and B. licheniformis altered the
elemental contents and disrupted the collagen structure of cow and
sheep leathers to varying degrees. Proteomic profiling revealed a
significant depletion of structural proteins in cow and sheep leather
substrates mediated by B. licheniformis, including collagen alpha-1­(II) chain, collagen type VI, and fibrillar
collagen. In contrast, many proteases and peptidases of B. licheniformis were increased, such as acylaminoacyl
peptidase, aminopeptidase, and carboxypeptidase, suggesting that these
enzymes contribute to the degradation of leather proteins. These findings
highlighted that B. licheniformis can
effectively degrade leather by secreting proteases and peptidases.
This study provided new insights into the conservation and biodegradation
of leather, which will contribute to green development of the leather
industry.