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Bioactive compounds from Streptomyces nasri and its mutants with special reference to proteopolysaccharides

100%

Gohar Y., Beshay U., Daba A., Hafez E.

Polish Journal of Microbiology

2006

tom 55

nr 3

The use of microbial exopolysaccharides (EPS) in the food, pharmaceutical, and chemical industries has steadily increased during the past decade. A bioactive EPS producing microorganism, Streptomyces nasri was isolated from Kuwait tropical soil and the proteopolysaccharide was tested for its antimicrobial activity. The isolate was subjected to ultraviolet (UV) radiation and acridine orange (AO) treatment to select for superior proteopolysaccharide producers. Among eight (five derived from UV exposure and three from AO exposure) morphological variants of Streptomyces nasri, two mutants showed increased EPS production, from 1.8 g/l to 2.3 g/l. The SDS-PAGE profiles of exopolysaccharides were determined. The molecular weight of the proteopolysaccharide ranged from 18 to 200 kDa. Mutants derived from UV exposure produced polysaccharides with higher molecular weight than those derived from acridine orange exposure. Acridine orange derived mutants produced lower molecular weight polysaccharides. Culture super-natants have been partially characterized and they show antimicrobial activity against a wide range of microorganisms. The structure of the exopolysaccharide was determined using NMR spectroscopy. The polysaccharide was also tested for cytotoxic activity against human brain tumor cell line using SRB assay.

Beta-glucanase productivity improvement via cell immobilization of recombinant Escherichia coli cells in different matrices

88%

Beshay U., El-Enshasy H., Ismail I. M. K., Moawad H., Abd-El-Ghany S.

Polish Journal of Microbiology

2011

tom 60

nr 2

The studies have been performed to analyze the production of β-glucanase by a recombinant strain of Escherichia coli immobilized in different matrices. Porous sintered glass SIRAN®, Ceramic supporting matrices and Broken Pumice stone as well as SIRAN Raschig-rings were examined for the immobilization of whole bacterial cells. The β-glucanase activity of bacteria immobilized in CeramTec PST 5 (4–5 mm) was very low. CeramTec PST 5 (1.5–2.5 mm) was found to be the best carrier compared to all other matrices regarding glucanase production (630 U/ml) and compared to enzyme activity produced by free cells (500 U/ml). Different doses of matrices were applied (2, 5, 7, 10 g/lask) in the form of “matrix weight”. Using 2 g/flask of CeramTec PST 5 (1.5–2.5 mm) yielded enzyme activity of 630 U/ml). CeramTec gives highest operational stability of β-glucanase by repeated batch fermentation to 5 cycles, and activity reached 660 U/ml. Scanning electron microscopy observations showed a high number of vegetative cells that continued growth inside the matrices, indicating that β-glucanase activity improvement was due to the immobilization of the cells.

Ograniczanie wyników

2 Polish Journal of Microbiology

2 Beshay U.

1 Abd-El-Ghany S.

1 Daba A.

1 El-Enshasy H.

1 Gohar Y.

1 Hafez E.

1 Ismail I. M. K.

1 Moawad H.

1 2011

1 2006

Wyniki wyszukiwania

Bioactive compounds from Streptomyces nasri and its mutants with special reference to proteopolysaccharides

Beta-glucanase productivity improvement via cell immobilization of recombinant Escherichia coli cells in different matrices