Bacterioviridins: novel sedimentary chlorins providing evidence for oxidative processes affecting palaeobacterial communities

A series of novel sedimentary transformation products of bacteriochlorophyll a, 7,8-didehydro derivatives (bacterioviridins), has been identified using high performance liquid chromatography with photodiode array detection and atmospheric pressure chemical ionisation liquid chromatography-multistage mass spectrometry. The derivatives occur in a range of sediments including Priest Pot (UK), les Salines de la Trinital, Ebre delta (Spain), Sutton-on-the-Forest (UK) and Certes (France). The bacterioviridins are products of oxidative transformation of bacteriochlorophyll a, and their presence in sediments indicates exposure of the bacterial community to oxygen.