Microbial α-galactosidase preparations have implications in medicine and in the modification of various agricultural products as well. In this paper, four isolated fungal strains such as AL-3, WF-3, WP-4 and CL-4 from rhizospheric soil identified as Penicillium glabrum (AL-3), Trichoderma evansii (WF-3), Lasiodiplodia theobromae (WP-4) and Penicillium flavus (CL-4) based on their morphology and microscopic examinations, are screened for their potential towards α-galactosidases production. The culture conditions have been optimized and supplemented with specific carbon substrates (1%, w/v) by using galactose-containing polysaccharides like guar gum (GG), soya casein (SC) and wheat straw (WS). All strains significantly released galactose from GG, showing maximum production of enzyme at 7th day of incubation in rotary shaker (120？rpm) that is 190.3, 174.5, 93.9 and 28.8？U/mL, respectively, followed by SC and WS. The enzyme activity was stable up to 7days at ？20°C, then after it declines. This investigation reveals that AL-3 show optimum enzyme activity in guar gum media, whereas WF-3 exhibited greater enzyme stability. Results indicated that the secretion of proteins, enzyme and the stability of enzyme activity varied not only from one strain to another but also differed in their preferences of utilization of different substrates. 1. Introduction The α-galactosidases are the group of glycoside hydrolases (glycosidases or carbohydrases) (EC 3.2.1); the enzymes that catalyze hydrolytic cleavage of O-glycoside bond and belong to the enzymes of carbohydrate catabolism. The α-galactosidases (EC 3.2.1.22, α-D-galactoside galactohydrolase) hydrolyze the terminal α-1,6-linked nonreducing α-D-galactose residues from linear and branched oligosaccharides and polysaccharides like melibiose, raffinose, stachyose, short fragments of galacto(gluco)mannans, and galactolipid. According to their substrate specificities, α-galactosidases can be divided into two groups [1]. The first group contains α-galactosidases active only on oligosaccharides with low degree of polymerization, for example melibiose, raffinose, stachyose, and short fragments of galacto(gluco)mannans. These enzymes are usually very active on artificial substrates like p-nitrophenyl-α-D-galactopyranosides [2]. The second group of α-galactosidases is active on polymeric substrates. However, similar to the enzymes of the first group, they attack short oligosaccharides, mainly fragments of degraded polymers, as well as artificial α-galactosides. Galactose is found in many different oligo- and polysaccharides
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