Antimicrobial Activity of Natural and Synthetic Dyes Used in Leather Dyeing: A Comparative Study

Both natural and synthetic dyes have gained increasing attention in the leather dyeing process due to environmental and health considerations. This research was designed to determine and compare the antimicrobial efficacy of four natural dyes (Acacia catechu, Trema orientalis, Camellia sinensis, Swietenia macrophylla) with four synthetic dyes (brown BFR, brown NG, brown EDK, red G) to develop safer leather dyeing process. The above eight dyes were evaluated against eight prevalent pathogenic and opportunistic pathogenic bacteria Bacillus megaterium, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Salmonella sp., Escherichia coli, Shigella sp., Pseudomonas aeruginosa, and four fungi. Dyestuff from Acacia catechu, Trema orientalis, and Swietenia macrophylla was effective against the three Bacillus strains, and Staphylococcus aureus with an inhibition zone extending from 6.3 mm to 11 mm. Synthetic dye brown BFR was effective against the three Bacillus strains, and Staphylococcus aureus with zone diameter of 14.8 mm to 19.7 mm. Brown EDK and Red G showed activity against Bacillus megaterium and Bacillus cereus. Camellia sinensis and brown NG showed no antimicrobial efficacy. Also, all eight dyes showed no antifungal activity. For both types of dyes, the zone of inhibition increased approximately linearly as dye concentrations increased. Of the natural dyes, Acacia catechu showed the highest activity. Brown BFR showed the maximum zone diameter of the eight dyes tested. The results indicated that both natural and synthetic dyes were quite effective. Synthetic dyes had remarkable antibacterial properties compared to natural dyes. These dyes having antimicrobial activity can be used in a safer leather dyeing process.