Alpha-Galactosidase activity of rumen bacteria.

Abstract

IN a recent search for bacterial α-galactosidases, Carrere, Lambin and Courtois1 tested many organisms isolated from the intestinal tracts of a wide range of animals including several ruminants. Only one bacterial species, from the guinea pig, containing α-galactosidase was obtained. The authors commented on the apparent rarity of this enzyme in bacteria, although it is fairly widespread in yeasts and plant tissues2. Bacteria producing α-galactosidase might be expected in rumen micro-flora, particularly in animals grazing pasture, as small amounts of oligo- and poly-saccharides containing α-linked galactose are present in many pasture plants. In addition the leaves of plants such as red clover (Trifolium pratense) contain up to 1 per cent (dry wt. basis) of lipid bound galactose3, present either as monosaccharide or 6-O-α-D-galactopyranosyl-D-galactose glycosidically joined through a β-link to the lipid glycerol4. The ability of rumen bacteria to release this α- and β-linked galactose has not been demonstrated. One rumen organism, Streptococcus bovis, appears to be a potential producer of α-galactosidase, as an extract from cells of one strain of this species has been shown able to hydrolyse melibiose5. The action of cell extracts from mixed rumen bacteria and S. bovis on various compounds containing α-linked galactose has, therefore, been investigated.