Biomarker evidence for the co-occurrence of three races (A, B and L) of Botryococcus braunii in El Junco Lake, Galapagos

摘要: In spite of the fact that individual races Botryococcus braunii are widely distributed in lakes, reports co-exis- tence different chemical rare. Here we report biomarker evidence for co-occurrence three B. (A, B and L) water column sediments El Junco Lake, a freshwater crater lake at 700 m elevation on San Cristobal Island, Galapagos. We also show existence lycopadienes lycopatrienes suspended particles sediments. Biomarker indicators were: cis trans C25-C31 n-alkadienes C29 triene race A, series C34H58 botryococcenes B, C40H78 hydrocarbon, trans,trans-lycopadiene accompanied by minor amounts isomers L. Epoxides derived from trans,trans-lycopadiene, specific to A L respectively, were detected. Several previously unreported identified both sediment, believed represent by-products intermediates, synthesis. Botryococcene lycopadiene concentrations reached 16.7 0.8 mg/g dry sediment near-surface sediments, varied over more than orders magnitude, while present trace quantities. Pyrolysates kerogen fraction contained alkadiene related lipids along with chemically resistant polymers cell walls. Apparently n-alkadienes, -trienes can survive oxic sedi- ments several decades, down core variation these likely reflects changes hydrology, alternately favoring bloom or near-extinction � 2007 Elsevier Ltd. All rights reserved.