Open AccessPhotosynthesis and respiration of a diatom biofilm cultured in a new gradient growth chamber
Author(s) -
Jensen Jørgen,
Revsbech Niels Peter
Publication year - 1989
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1989.tb03655.x
Subject(s) - photosynthesis , respiration , biofilm , diatom , chemistry , phototroph , oxygen , total inorganic carbon , dissolved organic carbon , environmental chemistry , carbon fibers , carbon dioxide , botany , biology , biochemistry , materials science , bacteria , genetics , organic chemistry , composite number , composite material
A diatom biofilm was grown in a chamber developed for culture of biofilms in chemical gradients. The diatoms grew on a polycarbonate membrane filter which separated a sterile reservoir, with added phosphate, from a reservoir without phosphate. Within 3 weeks of inoculation, a thick biofilm developed on the surface of the filter. The biofilms were homogeneous and therefore suitable for calculations of O 2 diffusion fluxes from concentration profiles of O 2 . Profiles of O 2 , pH, and gross photosynthesis at different light intensities and liquid medium concentrations of dissolved inorganic carbon and O 2 were measured with microelectrodes. Respiratory activity in a layer of the biofilm was determined as the difference between gross photosynthesis and outflux of O 2 from that layer. The photosynthetic activity in a well‐developed biofilm grown at 360 μEinst m −2 s −1 and 2.4 mM HCO 3 − was limited by the supply of inorganic carbon. Exposure to light above 360 μEinst m −2 s −1 stimulated gross photosynthesis as well as respiratory processes without affecting net outflux of O 2 . Higher concentrations of inorganic carbon, on the other hand, enhanced gross photosynthesis without concurrent increase in respiratory rate, resulting in an increased outflux of O 2 . High concentrations of O 2 in the liquid medium decreased the net outflux of O 2 with little effect on the gross photosynthesis. The effects of inorganic carbon and O 2 on the metabolic activities of the biofilm were consistent with the presence of photorespiratory activity.