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The CO 2 ‐concentrating mechanism in the bloom‐forming cyanobacterium Microcystis aeruginosa (Cyanophyceae) and effects of UVB radiation on its operation 1
Author(s) -
Song Yanfang,
Qiu Baosheng
Publication year - 2007
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2007.00391.x
Subject(s) - microcystis aeruginosa , photosynthesis , bloom , total inorganic carbon , biology , cyanobacteria , carbon fibers , dissolved organic carbon , botany , nuclear chemistry , environmental chemistry , carbon dioxide , chemistry , bacteria , materials science , ecology , genetics , composite number , composite material
The bloom‐forming cyanobacterium Microcystis aeruginosa (Kütz.) Kütz. 854 was cultured with 1.05 W · m −2 ultraviolet‐B radiation (UVBR) for 3 h every day, and the CO 2 ‐concentrating mechanism (CCM) within this species as well as effects of UVBR on its operation were investigated. Microcystis aeruginosa 854 possessed at least three inorganic carbon transport systems and could utilize external HCO 3 − and CO 2 for its photosynthesis. The maximum photosynthetic rate was approximately the same, but the apparent affinity for dissolved inorganic carbon was significantly decreased from 74.7 μmol · L −1 in the control to 34.7 μmol · L −1 in UVBR‐treated cells. At 150 μmol · L −1 KHCO 3 and pH 8.0, Na + ‐dependent HCO 3 − transport contributed 43.4%–40.2% to the photosynthesis in the control and 34.5%–31.9% in UVBR‐treated cells. However, the contribution of Na + ‐independent HCO 3 − transport increased from 8.7% in the control to 18.3% in UVBR‐treated cells. The contribution of CO 2 ‐uptake systems showed little difference: 47.9%–51.0% in the control and 49.8%–47.2% in UVBR‐treated cells. Thus, the rate of total inorganic carbon uptake was only marginally affected, although UVBR had a differential effect on various inorganic carbon transporters. However, the number of carboxysomes in UVBR‐treated cells was significantly decreased compared to that in the control.