Resistant biomacromolecules in marine microalgae of the classes Eustigmatophyceae and Chlorophyceae: Geochemical implications

The impact of oxygen exposure on long-chain alkyl diols and the long chain diol index (LDI) – a long-term incubation study

“…1) following the work-up procedures of e.g. Gelin et al (1997) or Goossens et al (1986). E1 contains freely occurring and -extractable lipids, while E2 contains free-extractable lipids from E1 as well as extractable lipids which are ester-bound or bound by glycosidic ether-or amide bonds.…”

“…The particulate matter was subsequently freeze dried and processed using the analytical scheme outlined in Fig. 1, which is an approach modified from Gelin et al (1997) and Goossens et al (1986).…”

“…The most likely source for these LCDs is the insoluble biopolymer algaenan, which is produced in substantial amounts by Eustigmatophyte algae. Based on chemical degradation methods such as RuO 4 and/or HI, or thermal degradation methods such as pyrolysis GC/MS (Gelin et al, 1997(Gelin et al, , 1999Blokker et al, 1998bBlokker et al, , 2000Blokker et al, , 2006, this algaenan is thought to be composed of LCDs linked by ether bonds (Zelibor et al, 1988;Tegelaar et al, 1989a;de Leeuw and Largeau, 1993;Gelin et al, 1997;Blokker et al, 1998aBlokker et al, , 2000. If so, it is difficult to envisage how oxidation of ether-linked diols would result in the release of LCDs themselves, i.e.…”

“…C 28 to C 32 1,13-and 1,15-LCDs have been identified in cultures of freshwater and marine Eustigmatophyte algae, e.g. Nannochloropsis oculata and Nannochloropsis oceanica (Volkman et al, 1992Gelin et al, 1997;Mejanelle et al, 2003;Shimokawara et al, 2010;Rampen et al, 2014a;Balzano et al, 2017;Zhang and Volkman, 2017), but the diol distributions in marine environments are dissimilar to those of cultured algae (Volkman et al, 1992;Versteegh et al, 1997;Rampen et al, 2012Rampen et al, , 2014a, suggesting unknown marine sources. LCDs in algal cell material of Eustigmatophytes and in the sediment have been shown to occur in different forms, i.e.…”

“…LCDs in algal cell material of Eustigmatophytes and in the sediment have been shown to occur in different forms, i.e. as free-extractable, extractable-bound (released by hydrolysis of the extract) and residually-bound lipids (released by hydrolysis of the residual biomass left after extraction) (Gelin et al, 1997;Ahmed et al, 2000;Grossi et al, 2001;Hoefs et al, 2002;Shimokawara et al, 2010). Additionally, they are also thought to be the building blocks of the insoluble biopolymer algaenan, which occurs in the cell wall of Eustigmatophytes (de Leeuw et al, 1981;Tegelaar et al, 1989b;Gelin et al, 1997;Volkman et al, 1998;Scholz et al, 2014;Zhang and Volkman, 2017).…”