| Congresso Brasileiro de Microbiologia 2023 | Resumo: 664-1 | ||||
Resumo:Carbon fixation, an essential process for life on Earth, involves the conversion of inorganic carbon to organic molecules. Seven cycles of autotrophic carbon fixation have been described so far, however it is rare to find an autotrophic bacterium that exhibit more than one carbon fixation pathway. Here, we present the genes expression of Calvin-Benson-Bassham (CBB) cycle and an alternative Reductive Citrate Cycle (rTCA) in Carbonactinospora thermoautotrophica strain StC. This thermophilic chemolithoautotrophic aerobic bacterium was isolated from a burning organic pile and thrives at temperatures between 55° and 65° C. To better understand the carbon fixation mechanisms and potential biotechnological applications, we conducted transcriptomic analysis on autotrophically and heterotrophically grown bacterial cells using Illumina HiSeq technology. Four biological replicates were used for the experiment aiming to report the genes expressed in two cultivation conditions: mineral culture medium N-fix with an atmosphere gas (CO/CO2/N2/O2) versus oligotrophic culture medium R2A. Our results revealed the overexpression of genes related to both CBB cycle and a variant of the rTCA cycle in autotrophically cultivated cells. Genes encoding key enzymes of CBB cycle, including RuBisCo form I, phosphoribulokinase (PRK) and Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were expressed, along with genes which encoding proteins phosphoenolpyruvate carboxylase and 2-oxoglutarate/2-oxoacid ferredoxin oxidoreductase, crucial components for the rTAC cycle. These findings suggests that Carbonactinospora thermoautotrophica StC employs both pathways (CBB and rTCA cycles) and may be working simultaneously for carbon fixation within single symbiont cells, However, further investigations are required to ascertain this. Previously, only sulfur-oxidizing, tubeworm symbionts, and possibly also large sulfur bacteria was described to possess both CBB and rTCA cycle to fix carbon; however, their study has been limited due to cultivation challenges. Our study significantly enhances the understanding of the physiology and metabolic potential of C. thermoautotrophica strain StC by uncovering the coexistence of two carbon fixation pathways. Ongoing analyses involving proteomics and biochemistry data aim to provide deeper understanding of the presence of both pathways in this bacterium and shed light on why this strain possess dual carbon fixation pathways, because its request more energy or potentially indicating an energetic advantage at certain stages of its lifecycle. Palavras-chave: thermophilic bacteria, extremophiles, carbon fixation pathways, transcriptomic analysis Agência de fomento:CAPES, King Abdullah University of Science and Technology (KAUST) | |||||