الفهرس 
Microbial polysaccharides
Microbial polysaccharidesOnly 14 pages are availabe for public view
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Abstract
In this study, 50 bacterial isolates were isolated from different Egyptian soil locations, 36 Actinobacteria were isolated on starch nitrate medium and 14 Azotobacters were isolated on N- free medium. After screening all isolates for exopolysaccharides production by determining the dry weight of the produced EPSs, Actinobacteria no. 10 and Azotobacter no. 5 were the most effective EPS producers. The morphological, biochemical, physiological and genetic characters were identified the Actinobacteria no. 10 and Azotobacter no. 5 as Streptomyces plicatus and Azotobacter armeniacus under accession numbers (NR_ 043382.1) and (NR_ 041037.1), respectively. Various culture circumstances were examined to achieve the highest bacterial growth, and EPSs generation. The S. plicatus was achieved in a starchnitrate medium, with starch at 2% as the best carbon source, at 35ºC, pH 7, and shaking conditions at 120 rpm after 7 days. Whereas Az. armeniacus was achieved in N- free medium with sucrose at 1% as the best C-source, at 30°C, pH 7, under shaking conditions at 120 rpm after 4 days. Moreover chemical and physical analyses were performed for EPSs such as UV-Vis spectrophotometer, HPLC, FT-IR, 1H NMR and TGA analyses. The antitumor and antibacterial activities for EPSs from S. plicatus and Az. armeniacus were studied in vitro. Antitumor activity of produced EPSs showed that the two tested human cell lines: human hepatocellular carcinoma cell line (HepG-2), and human breast adenocarcinoma cell line (MCF-7) were more sensitive to the EPS from Az. armeniacus than EPS from S. plicatus. In addition, the (HepG-2) cell line is more sensitive to Az. armeniacus EPS than (MCF-7) cell Abstract line. The antibacterial activity of EPSs showed that the effect of EPS from Az. armeniacus was better than EPS from S. plicatus on the pathogenic bacteria Staphylococcus aureus and pseudomonas aeruginosa. Also, its effect on p. aeruginosa was better than S. aureus, but the commercial antibiotic Norfloxacin was the best when compared.