Papageorgiou M, Tselios C, Varotsis C. Photoreduction of carotenoids in the aerobic anoxygenic photoheterotrophs probed by real time Raman spectroscopy.
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2020;
213:112069. [PMID:
33152639 DOI:
10.1016/j.jphotobiol.2020.112069]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 11/28/2022]
Abstract
The Aerobic anoxygenic phototrophic bacteria (AAPB) Roseobacter denitrificans and Roseobacter litoralis are widespread in the bacterioplankton community with a particular role in the marine carbon cycle. Measurements of carotenoids isolated from dark-grown cells indicated the presence of spheroidenone (SO, N = 11) and of 3,4 dihydrospheroidenone (N = 10) in the carotenoids isolated from illuminated cells. Time-dependent Raman 514 nm excitation experiments of R. denitrificans and R. litoralis cells grown under illumination demonstrated that v1 (C=C) of SO exhibits a time-dependent substantial frequency upshift relative to its frequency in the dark-grown cells, in a manner resembling shorting the conjugation length (N). We suggest that the irreversible dark-SO to light- 3,4 dihydrospheroidenone transition observed in the intact carotenoids of R. denitrificans and R. litoralis cells is an operative photoreduction strategy of SO containing AAPB that affects the energy transfer mechanism.
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