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The Use of Solar Radiation by the Photosynthetic Bacterium, Rhodopseudomonas palustris : Model Simulation of Conditions Found in a Shallow Pond or a Flatbed Reactor
Author(s) -
Ritchie Raymond J.
Publication year - 2013
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12124
Subject(s) - rhodopseudomonas palustris , photosynthesis , photoinhibition , photosynthetically active radiation , rhodopseudomonas , irradiance , photosystem ii , botany , oxygen evolution , oxygen , photochemistry , chemistry , biology , physics , bacteria , optics , genetics , organic chemistry , electrode , electrochemistry
Photosynthetic bacteria are attractive for biotechnology because they produce no oxygen and so H 2 ‐production is not inhibited by oxygen as occurs in oxygenic photoorganisms. Rhodopseudomonas palustris and Afifella marina containing BChl a can use irradiances from violet near‐ UV ( VNUV ) to orange (350–650 nm) light and near‐infrared ( NIR ) light (762–870 nm). Blue diode‐based pulse amplitude modulation technology was used to measure their photosynthetic electron transport rate ( ETR ). ETR vs Irradiance curves fitted the waiting‐in‐line model— ETR = (ETR max × E / E opt ) × exp (1 − E / E opt ). The equation was integrated over pond depth to calculate ETR of Afifella and Rhodopseudomonas in a pond up to 30 cm deep ( A 376 , 1 cm = 0.1). Afifella saturates at low irradiances and so photoinhibition results in very low photosynthesis in a pond. Rhodopseudomonas saturates at ≈15% sunlight and shows photoinhibition in the surface layers of the pond. Total ETR is ≈335 μmol (e − ) m −2 s −1 in NUV + photosynthetically active radiation light (350–700 nm). Daily ETR curves saturate at low irradiances and have a square‐wave shape: ≈11–13 mol (e − ) m −2 day −1 (350–700 nm). Up to 20–24% of daily 350–700 nm irradiance can be converted into ETR . NIR is absorbed by water and so competes with the bacterial RC ‐2 photosystem for photons.