Extracellular alpha galactosidase (alpha galactnsidasc galactol~ydl-olase EC 3.2.1.22) producing bacteria wcre isolated fiom soil hy the enrichment culture techniyue using raffinose as the induce].. Six hacterial species were isolated hy this method hased on their morphological characteristics. Their raffinose ut.ilization rate varied fi-om 11 mgAl to 27 mgh. Enzyme acivity present in the supernatant varied from 2-11 mU/ml. Two of the isolated species did not show ally alpha galactosidase activily. Three hacterial species having 11ig11 alpha galactosidase activity were identified as K l c b s i ~l b u ~~~~. u ~~r ~~. o ~~. i i ~e ~Cifrobacter fieu~rtlii. andEsi;Ir.crichiix roli hy their colony morpholo~y and biochemical tests. They were cult,ivated a t different pH values with peptone and ammonium sulpllate as the nitrogen source. From t,l~ose studies, it was shown that the highest extracellular alpl~n galact,osidase activity of 14.7 mUIm1 could he obtained h.om Citmboclr!r frer1.17,rlii after 1811 o f cultivation in a culture medium with an i.nitial pH of 8 containing peptone as t l ~e nitrogen source. Extracellulai~ enzyme production was increased up to 1SmUIn1l hy the cullivation of Citrobur:ter f'rrlrlrdii in pH8 pllosphate Bufl'er li)~. 3611 with peptone as the nitrogen source.

Extracellular a-galactosidase producing bacteria were isolated from soil. Bacteria that showed a-galactosidase activity were identified as Escherichia coli, Klebsiella pneumonrae and Citrobacter freundii by morphological and biochemical tests. Citrobacter freundii showed the highest enzyme production of 19 milliunitsl ml after 36 h r s of cultivation i n p H 8 phosphate buffer containing peptone. a-Galactosidase from Citrobacter freundii was purified by ammonium sulphatefractionation and DEAE ion exchange chromatography. One a-galactosidase activity peak was observed indicating the presence of a single enzyme form. A 164 fold purification was obtained with a yield of 8%. Polyacrylamide gel electrophoresis of the enzyme showed 2 protein bands. The kinetic properties of the enzyme were studied using p-nitrophenyl a-D-galactopyranoside. The Michaelis constant and maximum reaction velocity obtained were 2.85 x M and 14/mmol/min/mg of protein respectively. Studies on the effect of pH on enzyme activity showed a broad pH optimum from 6.0 to 8.0 with maximum activity a t pH 7.5 a t 2g°C. The enzyme was stable between pH 5.5 to 8.0. The optimum enzyme activity was observed a t 40% a t pH 7.5. The enzyme was stable upto 40 OC. The enzyme preparation did not contain any invertase activity.