STUDIES ON THE PRODUCTION OF MICROBIAL B- GALACTOSIDASE 1. OPTIMIZATION OF B-GALACTOSIDASE EXTRACTION FROM Kluyveromyces fragilis AND Streptococcus salivarius SUBSP. thermophilus

Document Type : Original Article

Authors

1 Microbiol. Dept.I Fac. of Agric., Mansoura Univ.l Mansoura. Egypt.

2 Fac. of Agric., Omar EI-Mokhtar Univ.. El-Bieda, Libya

Abstract

Investigation of B-galactosidase production by three yeasts and five bacterial
species of lactose-fermenting microorganisms during different incubation periods was
carried out. K. fragilis and S. salivarius subsp. thermophiius. in shaken cultures.
proved to be the most potent and produced the highest B-galactosidase activity after
24 h incubation. Toluene was the most effective soiventin releasing B-galactosidase
from the microbial cells. B-Glactosidase release was increased with the solvent
concentration till it reached its maximum activity at2.0%(vlv). Higher concentrations
were correlated with a great decrease in B-galactosidase activity. Toluene released
B-galactosidase in higher yield after 15 min. The higher contact time was correlated
with a great decrease in activity. Maximum B-galactosidase activity was extracted at
37°C during suspensions of cells in 0.1-M phosphate buffer at pH 6.8. [3-
Galactosidase release was increased with the increase of the exposure time for
sonicalion till it reached its maximum after5minutes. The maximum release off}—
galactosidase was after 6 cycles of freezing and thawing of the cell pellets and cells in
buffer. Higher activity was obtained when the pellets were used.