Carbon isotopic fractionation in lipids from methanotrophic bacteria II: the effects of physiology and environmental parameters on the biosynthesis and isotopic signatures of biomarkers

Changing redox conditions at cold seeps as revealed by authigenic carbonates from Alaminos Canyon, northern Gulf of Mexico

“…Moreover, the various types of cultured methanotrophs use different carbon assimilation pathways (see Hanson and Hanson, 1996 for a review). Type I methanotrophs use the ribulose monophosphate (RuMP) carbon assimilation pathway, whereas Type II methanotrophs use the serine pathway (Summons et al, 1994;Hanson and Hanson, 1996;Jahnke et al, 1999). Type X methanotrophs use the RuMP pathway as well as the Rubisco and serine pathways (Jahnke et al, 1999).…”

“…Type I methanotrophs use the ribulose monophosphate (RuMP) carbon assimilation pathway, whereas Type II methanotrophs use the serine pathway (Summons et al, 1994;Hanson and Hanson, 1996;Jahnke et al, 1999). Type X methanotrophs use the RuMP pathway as well as the Rubisco and serine pathways (Jahnke et al, 1999). The major difference of the various assimilation pathways of Type I/X and Type II results in significant differences in carbon isotope fractionation between the carbon source and the lipids synthesized, with a greater fractionating in Type I and X methanotrophs (cf.…”

“…The major difference of the various assimilation pathways of Type I/X and Type II results in significant differences in carbon isotope fractionation between the carbon source and the lipids synthesized, with a greater fractionating in Type I and X methanotrophs (cf. Summons et al, 1994;Jahnke et al, 1999). While 4α-methylcholesta-8(14),24-dien-3β-ol suggests the former presence of methanotrophic bacteria of Type I/X, the BHPs aminotetrol and aminotriol suggest the presence of Type II methanotrophs.…”

“…Compoundspecific carbon isotopes may allow a further discrimination (cf. Summons et al, 1994;Jahnke et al, 1999).…”

“…: −21‰) for M. capsulatus (Type X), and −12 to +10‰ (av. : −1‰) for M. trichosporium (Type II; Jahnke et al, 1999; Table 6). The results revealed that δ 13 C values of hopanoids and steroids can both be used to differentiate between Type I/X and Type II methanotrophs.…”