Evaluation of the antimicrobial activity of some bacteria-derived bio-active pigments

Abstract

There is a growing interest and concern for both the safety of the human population and the protection of the environment which has spurred renewed interest in the search for alternative chemicals from microbial origins which are biodegradable and environmentally friendly. Production of stable bio-products has been reported to be strain-dependent. The aim of this study was to evaluate the antimicrobial activity of pigments extracted from some pigmented native bacteria on some tomato spoilage pathogenic bacteria and fungi. In total, four pigment-producing bacteria spp. were isolated from samples including underneath tomato roots, soils from vegetation sites, wastewater from potato processing sites, tree liters, and tree bark using the enrichment culture and pour plating technique. The isolates were morphologically and biochemically identified as Serratia sp., Salinococcus sp., Exiguobacterium sp., and Xanthomonas sp. The crude bacteria pigments were tested for bio-activity (antimicrobial activity) against some tomato-derived spoilage bacteria (Xanthomonas sp. and Clavibacter sp.) and fungi pathogens (Alternaria alternata and Phytophthora infections) respectively. Among the isolates, pigments of Serratia sp had inhibition zones of 34.5mm and 32.1mm against Xanthomonas sp. and Clavibacter sp. bacteria and 27.8mm and 29.7mm against Alternaria alternata and Phytophthora infectans respectively. While Salinococcus sp. had 30.5mm and 34.2mm against the bacteria species and 27.9mm and 29.3mm against the fungi respectively. These are promising results. Therefore, further purification of the pigment should lead to discovering potent antimicrobial bio-active ingredients for drug development in the pharmaceutical industry.