Simultaneous Transport of CO2 and HCO3− by the Cyanobacterium Synechococcus UTEX 625 1

AUTOR(ES)

Espie, George S.

RESUMO

A mass spectrometer was used to simultaneously follow the time course of photosynthetic O2 evolution and CO2 depletion of the medium by cells of the cyanobacterium Synechococcus leopoliensis UTEX 625. Analysis of the data indicated that both CO2 and HCO3− were simultaneously and continuously transported by the cells as a source of substrate for photosynthesis. Initiation of HCO3− transport by Na+ addition had no effect on ongoing CO2 transport. This result is interpreted to indicate that the CO2 and HCO3− transport systems are separate and distinctly different transport systems. Measurement of CO2-dependent photosynthesis indicated that CO2 uptake involved active transport and that diffusion played only a minor role in CO2 acquisition in cyanobacteria.

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