Chromatic photoacclimation, photosynthetic electron transport and oxygen evolution in the Chlorophyll d -containing oxyphotobacterium Acaryochloris marina

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作者：

RS Gloag，RJ Ritchie，C Min，AWD Larkum，RG Quinnell

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摘要：

Changes in photosynthetic pigment ratios showed that the Chlorophyll d -dominated oxyphotobacterium Acaryochloris marina was able to photoacclimate to different light regimes. Chl d per cell were higher in cultures grown under low irradiance and red or green light compared to those found when grown under high white light, but phycocyanin/Chl d and carotenoid/Chl d indices under the corresponding conditions were lower. Chl a , considered an accessory pigment in this organism, decreased respective to Chl d in low irradiance and low intensity non-white light sources. Blue diode PAM ( P ulse A mplitude M odulation) fluorometry was able to be used to measure photosynthesis in Acaryochloris . Light response curves for Acaryochloris were created using both PAM and O 2 electrode. A linear relationship was found between electron transport rate (ETR), measured using a PAM fluorometer, and oxygen evolution (net and gross photosynthesis). Gross photosynthesis and ETR were directly proportional to one another. The optimum light for white light (quartz halogen) was about 206±51μmol m 2 s 1 (PAR) ( P hotosynthetically A ctive R adiation), whereas for red light (red diodes) the optimum light was lower (109±27μmol m 2 s 1 (PAR)). The maximum mean gross photosynthetic rate of Acaryochloris was 73±7μmol mg Chl d 1 h 1 . The gross photosynthesis/respiration ratio ( P g / R ) of Acaryochloris under optimum conditions was about 4.02±1.69. The implications of our findings will be discussed in relation to how photosynthesis is regulated in Acaryochloris .

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关键词：

Acaryochloris Oxyphotobacteria Photosynthesis Chlorophyll d Photo adaptation Oxygen electrode PAM Light saturation curve Induction curve