AN IMPROVED METHOD FOR THE ISOLATION OF ARTIFACT-FREE ALGAENANS FROM MICROALGAE

A new process for the isolation of algaenans (insoluble non-hydrolysab le, highly aliphatic biopolymers of microalga cell walls) which avoids their contamination with melanoidin-like polymer artifacts is present ed and the algaenans of two species from the Chlorophyceae (Scenedesmu s communis and Botryococcus braunii) are re-examined. Preliminary rele ase of the polysaccharides from these microorganisms by trifluoroaceti c acid hydrolysis affords a pure, or much less contaminated, algaenan for the two species. Re-examination of the pyrolysate of S. communis a lgaenan indicates that the long-chain n-alkylnitriles, previously dete cted when the algaenan was isolated by the usual process (Berkaloff et al., 1983), do not actually originate from this biopolymer. We sugges t that some nitrogen-containing molecules present in S. communis (or i n other Chlorophyceae species) are incorporated into the structure of the melanoidin-like polymers generated when the algaenan is isolated b y the usual process which lead, upon pyrolysis, to nitriles. Considera tion of previous data, on the pyrolysates of numerous kerogens, sugges ts that a similar process occurs under natural conditions during early diagenesis. (C) 1998 Elsevier Science Ltd. All rights reserved.