Identification of the bacteriochlorophyll homologues of Chlorobium phaeobacteroides strain UdG6053 grown at low light intensity.

Detailed APCI LC-MS/MS analysis using an improved HPLC separation reveals the green sulphur bacterium Chlorobium phaeobacteroides strain UdG6053 to contain a wider range of distinct bacteriochlorophyll homologues than has been previously recognised in Chlorobiaceae. The diversity in the homologue distribution is confirmed as arising from differences in the extent of alkylation of the macrocycle and variation in the nature of the esterifying alcohol and a novel series of bacteriochlorophyll structures has been recognised. Homologues containing esterifying alcohols other than farnesol, a number of which have not previously been reported in Chlorobiaceae, are present in high relative abundance. Confirmation of the structures of the esterifying alcohols has been obtained by hydrolysis and analysis by GC-MS.