Structural characterisation of unsaturated bacterial hopanoids by atmospheric pressure chemical ionisation liquid chromatography/ion trap mass spectrometry

Abstract

The production of bacteriohopanepolyols (BHPs) is widespread in many different groups of prokaryotes; however, unsaturated components are less common except amongst the acetic acid bacteria. Here we describe the characterisation of mono- (Delta(6) or Delta(11)) and diunsaturated (Delta(6,11)) bacteriohopanetetrols isolated from the acetic acid bacterium Gluconacetobacter xylinus (formerly Acetobacter aceti ssp. xylinum) by atmospheric pressure chemical ionisation ion trap mass spectrometry (APCI-MS(n)). APCI-MS(2) spectra are compared with equivalent electron ionisation (EI) spectra and differences in fragmentation pathways are discussed. Having established characteristic spectral features for a range of unsaturated BHPs we now have the ability to rapidly detect the presence of unsaturated BHPs in both natural environmental samples (soils, sediments, water columns) as well as in microbial cultures.

Identification of the Bacteriochlorophylls, Carotenoids, Quinones, Lipids, and Hopanoids of "Candidatus Chloracidobacterium thermophilum"

“…The APCI parameters were as follows: gas temperature, 325°C; vaporizer temperature, 350°C; drying gas (N 2 ) flow, 6 liters min Ϫ1 ; nebulizer (N 2 ) flow, 30 liter min Ϫ1 ; capillary voltage, 1,200 V; corona needle, 4 A; and fragmentor, 150 V. Data were recorded by scanning from m/z 100 to 1,600. Identification of the hopanoids was based on their exact mass and by comparison of retention times and mass spectra with published data (68,69).…”

Comparative microbial diversity and redox environments of black shale and stromatolite facies in the Mesoproterozoic Xiamaling Formation

“…We cannot exclude the possibility that the enhanced abundance of diahopanes could be attributable to the existence of a specific biological precursor. By analogy to the fact that diasteranes are derived from diasterenes, in turn originating from steroidal alkenes during early diagenesis (e.g., Peakman and Maxwell, 1988), it is possible that diahopanes are formed from unsaturated precursors such as the D-6 or D-11 unsaturated bacteriohopanes that have only been observed in a limited number of bacterial taxa (e.g., Rohmer and Ourisson, 1986;Talbot et al, 2007).…”

Euphotic zone bacterioplankton sources major sedimentary bacteriohopanepolyols in the Holocene Black Sea

“…BHPs with one or two double bonds -mostly at D6 and D11 -were found in several acetic acid bacteria, two cyanobacteria and two Methylosinus strains (Rohmer et al, 1984;Zundel and Rohmer, 1985;see Talbot et al, 2007b for recent review). For instance, Methylocaldum szegediense was found to produce a D11 unsaturated 35-aminobacteriohopanepentol derivative (Cvejic et al, 2000), and more recently a careful revisiting of the hopanoid inventory of Rhodopseudomonas palustris (a-proteobacteria) demonstrated the presence of minor amounts of a 35-aminobacteriohopenetriol (Talbot et al, 2007b). R. palustris is an anoxygenic phototroph, but if oxygen is present, photosynthesis is repressed and aerobic heterotrophy or chemoautotrophy is the preferred lifestyle.…”