Survival and growth of Bacillus cereus, Pseudomonas aeruginosa and Staphylococcus aureus in extreme environments present during the early stages of a conventional leather making process

Raw hides/skins used as a raw material for manufacturing leather contain various microorganisms including potential pathogens. The presence of hazardous chemicals during a conventional leather-making process may create extreme environmental conditions for the growth of the bacteria present on hides/skins. Bacteria, however, are known to survive harsh environmental conditions. This study was undertaken in order to determine the survival and growth of certain bacteria during a conventional pre-tanning and chromium-tanning process. Calfskin pieces were decontaminated and inoculated with log8 (108) to log10 (1010) colony forming units (cfu) of Bacillus cereus ATCC11778, Pseudomonas aeruginosa ATCC10145 and Staphylococcus aureus ATCC25923, and the survival was monitored following a conventional pre-tanning and chromium-tanning process. The presence of inoculated bacteria in effluent and on skins was determined. A higher bacterial growth was observed during the pre-soaking process, followed by a significant reduction (p≤0.05) during the main-soaking, unhairing and reliming processes. Although limited, bacterial growth was observed during the subsequent deliming, bating, pickling and tanning processes. The study showed that these bacterial species are not only capable of surviving a conventional leather-making process, but also showed the ability to proliferate if provided with suitable environmental conditions.