Polysaccharases for microbial exopolysaccharides

Microbial exopolysaccharides (EPS) are the substrates for a wide range of e nzymes most of which are highly specific. The enzymes are either endoglycan ases or polysaccharide lyases and their specificity is determined by carboh ydrate structure with uronic acids often playing a major role. The presence of various acyl substituents frequently has little effect on the action of many of the polysaccharases but markedly inhibits some of the polysacchari de lyases including alginate and gellan lyases, The commonest sources of su ch enzymes can be either microorganisms or bacteriophages. These specific p olysaccharide-degrading enzymes can yield oligosaccharide fragments, which are amenable to NMR and other analytical techniques. They have thus proved to be extremely useful in providing information about microbial polysacchar ide structures and were routinely used in many such studies. Complex system s containing various mixtures of enzymes may also be effective in the absen ce of single enzymes but may be difficult to obtain with reproducible activ ities. Such preparations may also cause extensive degradation of the polysa ccharide structure and thus prove less useful in providing information. Com mercially available enzyme preparations have seldom proved capable of degra ding microbial heteropolysaccharides, although some are active against bact erial alginates and homopolysaccharides including bacterial cellulose and c urdlan. (C) 1999 Elsevier Science Ltd. All rights reserved.