TY - JOUR

T1 - Growth of green sulphur bacteria in experimental benthic oxygen, sulphide, pH and light gradients

AU - Pringault, Olivier

AU - Kühl, Michael

AU - De Wit, Rutger

AU - Caumette, Pierre

PY - 1998

Y1 - 1998

N2 - The green sulphur bacterium Prosthecochloris aestuarii (strain CE 2401) was cultured in a benthic gradient chamber to study its growth and photosynthetic activity in experimental gradients of oxygen, sulphide and light. An axenic biofilm was obtained within evenly inoculated artificial sediment after 5 weeks of incubation. The phototrophic biofilm was located 2.2-3.5 mm below the sediment surface, i.e. below the maximal penetration depth of oxygen, thus confirming that growth of P. aestuarii was restricted to strictly anoxic sediment layers. The activity was limited by the diffusive flux of sulphide, showing the role of molecular diffusion in growth of this benthic species. Scalar irradiance was attenuated strongly in the biofilm, with distinct attenuation maxima at 750 nm corresponding to bacteriochlorophyll c (Bchl c) absorption and at 800 nm corresponding to bacteriochlorophyll a (Bchl a) absorption. Using radiance attenuation data as a proxy for photopigment contents it was shown that the ratio Bchl a/Bchl c changed with depth. This indicates chromatic adaptation to changing light climates in the sediment. Total sulphide oxidation was estimated from the sulphide fluxes from below into the reaction zone. Measurements of sulphide oxidation as a function of scalar irradiance in the reaction zone showed that anoxygenic photosynthesis of the biofilm was saturated at a scalar irradiance (430-830 nm) > 2 μmol photons m-2 s-1.

AB - The green sulphur bacterium Prosthecochloris aestuarii (strain CE 2401) was cultured in a benthic gradient chamber to study its growth and photosynthetic activity in experimental gradients of oxygen, sulphide and light. An axenic biofilm was obtained within evenly inoculated artificial sediment after 5 weeks of incubation. The phototrophic biofilm was located 2.2-3.5 mm below the sediment surface, i.e. below the maximal penetration depth of oxygen, thus confirming that growth of P. aestuarii was restricted to strictly anoxic sediment layers. The activity was limited by the diffusive flux of sulphide, showing the role of molecular diffusion in growth of this benthic species. Scalar irradiance was attenuated strongly in the biofilm, with distinct attenuation maxima at 750 nm corresponding to bacteriochlorophyll c (Bchl c) absorption and at 800 nm corresponding to bacteriochlorophyll a (Bchl a) absorption. Using radiance attenuation data as a proxy for photopigment contents it was shown that the ratio Bchl a/Bchl c changed with depth. This indicates chromatic adaptation to changing light climates in the sediment. Total sulphide oxidation was estimated from the sulphide fluxes from below into the reaction zone. Measurements of sulphide oxidation as a function of scalar irradiance in the reaction zone showed that anoxygenic photosynthesis of the biofilm was saturated at a scalar irradiance (430-830 nm) > 2 μmol photons m-2 s-1.

KW - Benthic gradient chamber

KW - Microsensors

KW - P vs I curve

KW - Photoadaptation

KW - Prosthecochloris aestuarii

U2 - 10.1099/00221287-144-4-1051

DO - 10.1099/00221287-144-4-1051

M3 - Journal article

AN - SCOPUS:2642671981

VL - 144

SP - 1051

EP - 1061

JO - Microbiology

JF - Microbiology

SN - 1350-0872

IS - 4

ER -