Natural Organic Matter Reduction Fuels Anaerobic Oxidation Of Methane In Sediments From A Tropical Wetland E. I. Valenzuela1*, A. Prieto-Davó2, N. E. López-Lozano1, A. Hernández-Eligio3, L. Vega-Alvarado4, K. Juárez3, A.S. García5, M. G. López5, F. J. Cervantes1*. 1División
de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica A.C. 2Facultad de Química Unidad Sisal, Universidad Nacional Autónoma de México. 3Dpto. De Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México. 4Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México.
[email protected] [email protected]
1. Introduction ◙ Wetlands release a
3rd
CO2
CO2
CH4
Tg/year)[1].
of total global CH4 emissions (164
ATMOSPHERE
CH4
CO2
O2
CO2 Aerobic methane oxidation
◙ Around ~50% of CH4 produced (in wetlands) is oxidized via anaerobic processes[2].
O2
◙ Natural organic matter (NOM) a.k.a. humus, prevails in wetlands and participates in biological oxidation/reduction processes[3].
Plant matter (high in carbon)
Hemicellulose, cellulose, starch, sugars, fats, proteins, amino acids…
Plant matter (high in carbon)
decay Biological and chemical transformations
Anaerobic methane oxidation (AOM)
◙ Due to is redox properties NOM could drive AOM by functioning as terminal electron acceptor (TEA) for methanotrophic biota (Fig. 1).
decay
Natural organic matter (NOM)
NOM driven AOM
NOM anaerobic oxidation
Objective: To document the CH4 anaerobic oxidation coupled to NOM reduction by means of isotopic tracing, spectroscopy and molecular tools.
Microcosms inoculation
AOM kinetics
• Amendment with 13CH4, humus and/or Na2MoO4.
• Gaseous and liquid measurements (Fig. A).
3. Results
𝐂𝐇𝟒
¹³CH₄ + SR-INH Killed
3
𝐒𝐎𝟐𝟒
𝐇𝐒
■ Sediment + HS
𝐇𝐂𝐎𝟑
♦ Sediment + HS + SR-INH
HS or NOM 7%
2 1
𝐇𝟐 𝐎
0
10
20
𝐂𝐇𝟒
Undetermined 90%
𝐍𝐎𝐌𝐨𝐱
𝐇𝟐 𝐎
𝐂𝐎𝟐
𝐍𝐎𝐌𝐫𝐞𝐝
0
pMC2A209 (Thaumarchaeota) unclassified..pMC2A209.
Anaerolineae
Others Others
Marine_Benthic_Group_B unclassified..Marine_Benthic_Group_B.
Bacteroidetes_vadinHA17
Methanogenium Methanogenium unclassified_SM1K20 unclassified..SM1K20.
Acidobacteria
Halomarina Halomarina
Parcubacteria_Incertae_Sedis
unclassified_Fe.A.9 (Euryarchaeota) unclassified..Fe.A.9.
unclassified_Aminicenantes Bacteroidetes_BD2.2 α-proteobacteria Cytophagia
Y Pixel
2162 2035 1978 1800
712 631 872
1407
40 4500
4000
3500
3000
2500
2000
1500
1000
500
-1
Wavelength (cm )
15
Binding Energy (eV)
4. Conclusions
◙ Presence and reduction of quinone moieties of sediment’s intrinsic NOM was detected displaying it’s availability and microbial utilization.
Take-home message!
5. Bibliography
Candidatus_Iainarchaeum Candidatus_Iainarchaeum
AOM supported by NOM reduction is a
Miscellaneous Euryarchaeotic Group unclassified..Miscellaneous_Euryarchaeotic_Group.MEG.. AMOS4A-452-E11 (Euryarchaeota) unclassified..SMS.sludge.7.
ε-proteobacteria
unclassified_SMS-sludge.7 (Euryarchaeota) unclassified..AMOS4A.452.E11.
Acidimicrobiia
unclassified..MHLsu47.B8A. unclassified_MHLsu47-B8A
Deferribacteres_Incertae_Sedis
Methanomicrobium Methanomicrobium
Latescibacteria_Incertae_Sedis unclassified_Atribacteria
unclassified_Group-C3 (Thaumarchaeota) unclassified..Group_C3.
Gemmatimonadetes Phycisphaerare
After incubation
◙ Known anaerobic methanotrophic biota (ANME) abundance was unexpectedly low (
