George completed his bachelor’s degree at University of Illinois at Urbana-Champaign (USA) in the field of Integrated Biology in 2015. Then went on to complete his master’s degree at Uppsala University (Sweden) in Ecology and Conservation in 2019. And now he is currently working towards completing his PhD degree in Microbiology, here at the Swedish University of Agricultural Sciences.
BI1278 Microbiology: 2020-2021
Acetogens are responsible for one of the four steps in the biogas process, acetogenesis. These microbes are capable of fixing carbon via the Wood-Ljungdahl pathway (WLP), which is highly conserved across Bacteria and Archaea. An important distinction in the definition for acetogens, that is acetyl-CoA being produced from two molecules of CO2. Key enzymes from the WLP, i.e., formyltetrahydrofolate synthetase (FTHFS) and carbon monoxide dehydrogenase/acetyl-CoA synthetase (CODH/ACS), were used to screen through metagenomic assembled genomes (MAGs). A recently established database dedicated for FTHFS by Abhijeet Singh, called AcetoBase, was used to identify potentially acetogens from recovered MAGs. To further corroborate the presence of the WLP, the CODH/ACS is required to also be present. However, there is no similar dedicated databases for acetogenic CODH/ACS.
The systems that have been explored so far include thermophilic high-ammonia biogas reactors and syngas trickle bed reactor. The thermophilic high-ammonia biogas reactors operated with slaughter-house waste and food waste or waste water. Within these reactors, several MAGs revealed the presence of FTHFS except many of them missing CODH/ACS; or rather the MAGs did not match in similarity to already known CODH/ACS genes. There could be two potential explanations; first being that the MAGs do not possess the CODH/ACS complex and utilize a different pathway, i.e., the glycine cleavage system pathway. Second, the genes for the CODH/ACS complex within the genomes are different from the ones that are already established. The goal now is to determine if there is a hypothetical protein that is functioning the same as the CODH/ACS or if these MAGs utilize and alternative pathway to WLP.