Optimizing sample pretreatment for compound-specific stable carbon isotopic analysis of amino sugars in marine sediment

Abstract

Abstract. Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compoundspecific isotopic analysis of amino sugars in marine sediment, employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e., equivalent to ∼ 8 ng of amino sugar carbon. Compoundspecific stable carbon isotopic analysis of amino sugars obtained from marine sediment extracts indicated that glucosamine and galactosamine were mainly derived from organic detritus, whereas muramic acid showed isotopic imprints from indigenous bacterial activities. The δ 13 C analysis of amino sugars provides a valuable addition to the biomarker-based characterization of microbial metabolism in the deep marine biosphere, which so far has been lipid oriented and biased towards the detection of archaeal signals.

Stable carbon isotopic composition of amino sugars in heterotrophic bacteria and phytoplankton: Implications for assessment of marine organic matter degradation

“…Pretreatment of amino sugar samples followed the method of Zhu et al (2014). Briefly, materials on glass fiber filters or ground sediments were hydrolyzed using 6 M HCl at 105 C for 8 h. The hydrolysates were then neutralized with 6 M potassium hydroxide to pH $ 6.8 and centrifuged immediately.…”

Evaluation of Sedimentary Organic Carbon Reactivity and Burial in the Eastern China Marginal Seas

“…The pretreatment and analysis of total hydrolyzable amino sugars (THAS) followed modified procedures from Zhu et al (2014). Briefly, the sediment sample was hydrolyzed with 6 M HCl for 8 h at 105°C, neutralized (pH ∼6.8) with 6 M KOH and then centrifuged.…”

Avanços Recentes Na Química Dos Aminoaçúcares: Ocorrência, Biossíntese, Síntese E Aplicação

“…2 Os aminoaçúcares que são sem dúvida os mais importante açúcares modificados existentes, são os constituintes fundamentais 3,4 de muitos compostos biologicamente ativos, como antibióticos 5,6 e biopolímeros. 7 Aminoaçúcares são definidos como aldoses ou cetoses que têm seu grupo hidroxila substituído por grupo amino nos C2, C3 ou C4 do anel hexose ou pentose, exceto no carbono anomérico. 8,9 As propriedades físico-químicas dessas moléculas podem afetar fortemente suas atividades biológicas.…”