Pigment production and isotopic fractionations in continuous culture: okenone producing purple sulfur bacteria Part II

摘要: Okenone is a carotenoid pigment unique to certain members of Chromatiaceae, the dominant family purple sulfur bacteria (PSB) found in euxinic photic zones. Diagenetic alteration okenone produces okenane, only recognized molecular fossil PSB. The vivo concentrations and bacteriochlorophyll (Bchl a) on per cell basis were monitored quantified as function light intensity continuous cultures bacterium Marichromatium purpuratum (Mpurp1591). We show that okenone-producing PSB have constant ratios light-harvesting antenna complexes. Bchl a, 0.151 ± 0.012 fmol cell^(−1), okenone, 0.103 not dependent average (10–225 Lux) at both steady non-steady states. This observation revealed autotrophic Mpurp1591, there was ratio for 1:1.5. therefore constitutively produced planktonic PSB, regardless intensity. confirms legitimacy signature by extrapolation water column euxinia. measured δ^(13)C, δ^(15)N, δ^(34)S bulk biomass values from cells collected daily determined isotopic fractionations Mpurp1591. There no statistical relationship isotope measurements or stable density under non-steady-state conditions. carbon fractionation between with respect overall (^(13)e_pigment – biomass) 2.2 0.4‰ −4.1 0.9‰, respectively. (^(13)e_pigment-CO_2) production pigments more variable than previously thought our reported −15.5 1.2‰ −21.8 1.7‰ a.