Isolation and identification of a new yeast isolate with high beta-galactosidase activity from Syrian dairy products

Beta-galactosidase (EC 3.2.1.23), has tremendous potential in research and application in various fields like food, bioremediation, biosensor, diagnosis and treatment of disorders. The main objective of this study was to isolate and select some yeast strains able to produce β- galactosidase from locally dairy products, the high producer strain coded DIYS 11 was belong to Kluyveromyces marxianus according to molecular method based on the sequence of the internal transcribed spacer (ITS) rDNA gene, and produced 338 U/min/cell estimated by the use of ONPG as substrate. The effect of six different extraction methods, isoamyl alcohol, acetone, SDS-chloroform, liquid nitrogen, glass beads and stainless beads on enzyme activity from this organism was studied. Our results showed the highest enzyme activity was obtained using isoamyl alcohol and reached 554 U/min/cell after nine minutes incubation with the substrate.