Isolation and characterization of a clay-dispersing polysaccharide produced by the phytopathogenic fungus, Colletotrichum gloeosporioides

The fungus, Colletotrichum gloeosporioides, which is pathogenic to peppers produced an extracellular polysaccharide in liquid culture which possessed clay-dispersing activity. The polysaccharide could bind cationic dyes, Ruth enium Red and Alcian Blue, indicating it to be polyanionic. The polysacchar ide dispersed kaolin in water and the dispersion was maintained for more th an 7 days at 25 degreesC. Kaolin dispersion by the polysaccharide was stabl e from pH 3 to 10 but the addition of divalent metals at 1 mM inhibited hal f of the dispersion activity comparing to the control. The polysaccharide c ould disperse bentonite, calcium carbonate and other fine particles but did not possess emulsifying activity.