Production of Exopolysaccharides by Diverse Bacterial Strains Isolated from Cheese Whey

Abstract

Background and objectivesMicooraganism's ability to produce exopolysaccharides (EPS) has drawn special attention from the food sector. EPS enhance the rheological characteristics of fermented foods and considered as natural thickener. The objective of this study was to evaluate the ability of some bacterial strains isolated from cheese whey to produce EPS under different environmental conditions and to select the most potent EXP producing candidates. Materials and methodsBased on their physical characteristics and 16S rRNA gene sequencing, the selected bacterial isolates Priestia aryabhattai (PC) and Bacillus pumilus (MC) were identified as non-similar strains. The one-factor-at-a-time approach was adopted to customize cultivation environments to maximize the EPS production for the isolated strains.Results and conclusionThe EPS maximum yield of 12.09 and 8.91 g/l were achieved by the isolates Priestia aryabhattai and Bacillus pumilus, respectively. Both extract's infrared (FT-IR) spectra showed the usual patterns of polysaccharide absorption. Furthermore, HPLC analysis showed that EPSs are heteropolysaccharides composed of glucose, galactose, rhamnose, and arabinose. The produced polysaccharide was composed of high ratios of carbon, oxygen, phosphorus, calcium, and chloride, as confirmed by Scanning electron microscope (SEM) and Energy dispersive X-ray (EDX). The EPS showed antioxidant activity as well as strong antibacterial effect against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella typhimurium as hazardous human pathogens, suggesting their application in the food industry. Also, the produced EPS had nontoxic effect on Brine shrimp toxicity (Artemia salina).