How do methane-producer and methane-consumer microorganisms are distributed in the Amazon River floodplains: a molecular and biogeochemical approach

• Grant number: 24/21564-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2025
• End date: February 28, 2026
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Gustavo Maruyama Mori
• Grantee: Vinícius Tesch Mazotti
• Host Institution: Instituto de Biociências (IB-CLP). Universidade Estadual Paulista (UNESP). Campus Experimental do Litoral Paulista. São Vicente , SP, Brazil
• Associated research grant: 22/02804-9 - Evaluating adaptation, epigenetic variation, and dispersal to unveil the response of mangrove in a changing world, AP.PNGP.PI

Abstract

The Amazonian floodplains are responsible for ~8% of the global methane (CH¿) emissions. CH¿ fluxes in these environments are primarily determined by the balance between its production and oxidation. This balance, in turn, is intrinsically linked to the activity of anaerobic archaea that produce the gas (methanogenic) and microorganisms that consume it (methanotrophic). The community structure of these organisms is regulated by abiotic factors, such as the characteristics of organic matter (OM) in the sediment, and biotic factors, such as the structure of the prokaryotic community in which they are embedded. Therefore, identifying and describing the factors that modulate the presence and abundance of these microorganisms in floodplains requires an integrated assessment of both abiotic and biotic regulators. Based on the hypothesis that spatially separated floodplain areas exhibit distinct prokaryotic community structures influenced by local environmental variables, this research project aims to identify and quantify the influence of OM and the general prokaryotic community on the distribution of methanogenic and methanotrophic organisms across the mouth of the Amazon Basin and the Pará River estuary. To achieve this, we will characterize the microbial community associated with methanogenesis and methanotrophy through the quantification of the mcrA and pmoA genes, respectively, as well as through 16S metabarcoding. Additionally, geochemical analyses of sedimentary OM will be conducted to determine its quality, quantity, and origin using isotopic analyses, total organic carbon (TOC), and C/N ratios. This study will complement ongoing scientific endeavors that aim to measure carbon, methane and other environmental components and their impacts on the biodiversity in the studied region. Thus, we expect that it will allow us to refine and expand the discussion about the distribution of methanogenic and methanotrophic microbial communities in the floodplains in the Amazon hydrological system.