title: Optimization of alpha-galactosidase production in Streptomyces erythrus.
abstract: Physiological studies on Streptomyces erythrus NRRL ISP 5517 grown on fourteen different media have revealed that the enzyme was formed and released in the medium with different levels depending upon the type of the medium and the carbon source used. The results indicate that S. erythrus produced the highest level of extracellular and endocellular enzyme when grown in modified Czapek-Dox's medium (containing 2% D-galactose as the only carbon source). The highest levels of enzyme formation was obtained upon using D-galactose (9.94 Units/ml and 2.92 Units/ml), raffinose (8.87 Units/ml and 2.69 Units/ml) or melibiose (8.14 Units/ml and 2.52 Units/ml) at a final concentration of 2% as inducers for extra- and endocellular enzyme, respectively. With respect to nitrogen sources tested, sodium nitrate produced the highest level of alpha-galactosidase in both fractions optimally at 2.0 g/l. Studies revealed that the extracellular enzyme levels were produced optimally at initial pH in culture of 7.0 and air:medium ratio in flasks corresponding to 1:5 and after 5 days of incubation at 30 degrees C. On testing the effect of the addition of eight leguminous seeds powders (at a final concentration of 2%), it was found that soybean powder gave the highest induction effect. The addition of sodium nitrate at a concentration of 2 g/l to Dox's soybean medium, the adjustment of initial pH value of the medium to 7.0 and the air:medium ratio in flasks to 1:5 for an incubation period of 4 days produced the highest level of extracellular alpha-galactosidase.
authors.affiliation: Dept. of Microbial Chemistry, National Research Centre, Dokki, Cairo, Egypt.
authors.forename: A M
authors.initials: AM
authors.lastname: Elshafei
authors.forename: M S
authors.initials: MS
authors.lastname: Foda
authors.forename: E
authors.initials: E
authors.lastname: Abdel-Mobde
authors.forename: N H
authors.initials: NH
authors.lastname: Ali
mesh_terms: D003470:Culture Media; D007218:Industrial Microbiology; D013302:Streptomyces / Q000201:enzymology*; D000519:alpha-Galactosidase / Q000378:metabolism*
chemical_list: D003470:Culture Media; D000519:alpha-Galactosidase