Antimicrobial finishing of hide/leather by atmospheric pressure plasma and extracts of Cassia renigera and Cassia fistula bark

Abstract

In this study, pre-tanning stage goat hide was treated with atmospheric pressure air dielectric barrier discharge with the aim to provide an eco-friendly antimicrobial finishing. The untreated and the air plasma-treated hide pieces were incubated in sterilized agar media. Upon incubation, untreated sample showed noteworthy growth of fungus, while the plasma-treated piece remains unaffected which clearly reveals the sterilization capacity of the plasma treatment. The fungus grown on untreated sample was cultured and identified with fungal specific ITS rRNA gene sequence and Basic Local Alignment Search Tool and found to be strains of Curvularia sp. with 100% similarity to Curvularia caricae-papayae and 99% similarity to Curvularia pseudobrachyspora. The untreated and plasma-treated goat hide samples were subsequently dipped into the extract obtained from bark of two Cassia species: Cassia renigera and Cassia fistula to provide antifungal/antibacterial finishing. Effectiveness of this anti-fungal finishing was demonstrated by inoculating the samples with culture of the fungus and incubation. The obtained results indicate that samples treated with the plasma and the extracts finishing deliver substantial antifungal activity in comparison to that of untreated extract finished goat hide. Additionally, the plasma treated followed by plant extract finished samples provide evidence of antibacterial finish which has been confirmed by zone of inhibition against a Gram-positive bacteria Staphylococcus aureus. Activation of hide surface and generation of various functional groups due to the plasma treatment were accountable for better uptake of the extracts and thus imparting antimicrobial finish.