Biomass Measurement of Methanogens in the Sediments of Tokyo Bay Using Archaeol Lipids

Abstract

An archaeal ether-linked lipid, archaeol, was determined to be a biomass indicator for methanogens both in the laboratory enriched culture and in marine sediments. The archaeol measurement method described by Ohtsubo et al. in 1993 was modified and applied to marine sediments. We compared the amount of archaeol with the cell number of methanogens or methane concentration in laboratory enriched culture of methanogens from marine sediment. Good correlations were obtained as follows: (Methane, mmol) = 11.2 x (Archaeol, mg): r =.996 or (Cell number) = 1.13 x 10(11) x (Archaeol, mg): r =.995, respectively. In the sediments of Tokyo Bay, archaeol was measured from approximately 46 to 561 ng/dry g sediment at the entrance to 267 to 4160 ng/dry g sediment at the innermost area. Using the coefficient from the laboratory experiment, these data corresponded to cell numbers of 5.2 x 10(6) to 4.7 x 10(8)/dry g sediment. These values were 1 or 2 orders of magnitude higher than those obtained by culture methods in previous studies. Although dead or decomposed cells might be detected, archaeol measurement is useful for estimating the biomass of methanogens because of the good correlation between methane concentration and archaeol content in marine environments. In this study, we found a correlation of (Methane, mmol) = 0.012 x (Archaeol, mg): r =.932, n = 17 in marine sediments.

Molecular and isotopic evidence reveals the end-Triassic carbon isotope excursion is not from massive exogenous light carbon

“…For example, phytane-related isoprenoids released after the cleavage of polar lipids have been detected in abundance in the hypersaline microbial mats of Shark Bay, Western Australia, and Laguna Guerrero Negro, Mexico (53,54). Originating from archaeol, such compounds are indicative of methanogens found in a range of environments including microbial mats (55)(56)(57). In algae, n-alkyl lipids (e.g., C 17-19 n-alkanes) are depleted in 13 C compared to the cooccurring isoprenoids by ∼1.5‰, whereas in bacteria, the opposite pattern is observed (ref.…”

Recent Advances in Structural Research on Ether Lipids from Archaea Including Comparative and Physiological Aspects

“…These findings strongly suggest new archaea species producing these lipids in marine environments at not high temperatures and ubiquitous distribution of archaea on Earth in accordance with 16S rRNA ecology. 60,61) HPLC analysis of archaeal core lipids was applied to quantitation of cell masses of methanogenic archaea in given environmental samples, such as anaerobic sewage sludge, 62) paddy field soil, 63) and marine sediments of Tokyo Bay, 64) and information was obtained. This method is inevitably accompanied by the weakness that it cannot discriminate whether detected core lipids were derived from living cells, or were accumulated lipid released from dead cells.…”

Archaeol: An Indicator of Methanogenesis in Water-Saturated Soils

“…Archaeal diether core lipids have been proposed as a methanogen biomarker or to estimate quantitatively methanogen biomass in natural systems. Respective studies have predominantly been restricted to highly anaerobic environments exhibiting significant CH 4 emissions such as rice paddies [16, 17], digester sludge [18, 19], marine sediment [20], faecal material [21], permafrost [22, 23], and peatlands [24–26]. Wachinger et al [27] observed that absolute Archaea cell numbers in mineral soils, calculated using the approximate ether lipid concentration 2.5  μ mol g −1 dry weight of methanogen cells [28], also reflected CH 4 productivity.…”