Document Type : Original Article
Authors
Department of Agricultural Microbiology, Faculty of Agriculture, Ain Shams University, P.O. Box 68, Hadayek Shubra 11241, Cairo, Egypt
Abstract
Among 46 local bacterial isolates capable synthetized pigments, 26% produced extracellular of blue green and fluorescent whereas 74% produced intra-cellular pigments of red, brown, yellow, orange, and rose. Seven isolates were selected as a potential candidate for the synthesis of pigments. They were Pseudomonas fluoresces, P. aeruginosa, Serratia marcescens, Azotobacter chroococcum, Micrococcus kristinae, M. luteus, and M. roseus after their morphological and biochemical studies. They capable to produce fluorescent, blue green, red, brown, orange, yellow, and rose with maximum absorbance at 400, 520, 530, 320, 440, 460, and 470 nm, with an optical density of 0.62, 1.42,1.35, 1.11, 0.45, 0.98, and 0.40, respectively. Antibacterial activity of pigments was studied against 7 bacterial pathogenic strains namely P. aeruginosa ATCC27853, Escherichia coli 0157h7 ATCC25922, Klebsiella pneumonia ATCC00607, Salmonella typhimurium ATCC25566, Listeria monocytogenes ATCC19115, Staphylococcus aureus ATCC29737, and Bacillus cereus ATCC33018. The last tested strain behaved high significant (p≤ 0.05) sensitivity for blue green, fluorescent, brown, and rose pigments while, L. monocytogenes ATCC19115 was more susceptible for red, and yellow pigments and S. aureus ATCC29737 had more inhibited by orange pigment. These bacterial pigments seemed to have antioxidant activity which inhibited the formation of diphenyl-2-picrylhydrazyl radicals with percentage ranged from 40 % to 80 %. It could therefore be stated that the bacterial pigments tested had a broad impact on foodborne pathogens and had an antioxidant effect
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