Chemical composition and production of exopolysaccharides from representative members of heterocystous and non-heterocystous cyanobacteria

Exopolysaccharide (EPS) production and chemical composition of heterocystou s and non-heterocystous cyanobacteria of subgroups 3, 4, and 5 together wit h four new species isolated from Pantelleria (Italy) hard sands and from a lake in the proximity of Edmonson Point in Antarctica were studied. The yie ld of extracellular soluble polysaccharides (RPS) and slime layers (CPS) sh owed a significant variation from one strain to another; generally RPS were more abundant than CPS with the exception of Anabaena torulosa and Scytone ma hoffmanni. Phormidium sp. was the best producer of EPS. Among heterocyst ous cyanobacteria belonging to Nostocaceae the new species Anabaena WSAF an d,4. torulosa were found to produce the highest level of EPS. Among heteroc ystous cyanobacteria other than Nostocaceae, the best producer of EPS was C hlorogloeopsis sp. 6912. Four species were chosen for studying the effects of growth conditions, nutritional, physical and chemical, on total EPS form ed. Glucose and galactose were the neutral sugars widely present in the spe cies examined, although other sugars such as mannose and xylose were plenti ful in some species. Amino-sugar, as glucosamine, and uronic acids were als o found in EPS of some cyanobacteria. Finally the inhibition of avarol, a s esquiterpene hydroquinone, toxicity on Artemia salina by EPS of some specie s was analysed. (C) 1999 Elsevier Science Ltd. All rights reserved.