(645g) Invited Talk: Genome-Scale Understanding of the Emergent Metabolic Interactions within a Model Methanotroph-Cyanobacteria Coculture

Methanotroph-photoautotroph (M-P) coculture has been proposed as a highly promising biotechnology platform for biogas conversion. The metabolic coupling of methane oxidation and oxygenic photosynthesis within the coculture offers many benefits for the design of robust biotechnologies for biogas conversion. In addition, it has been postulated that the potential emergent interspecies interactions within the coculture could further enhance the growth of the coculture and play a pivotal role in determining the composition and function of the coculture. However, no knowledge on these emergent metabolic interactions within the M-P coculture is currently available. This is mainly due to the inherent complexity of the M-P coculture, and the lack of experimental tools to characterize the coculture in real time.

Recently, enabled by a novel experimental-computational protocol that we developed to accurately characterize the M-P coculture in real time, we were able to confirm the existence of the unknown emergent metabolic interactions within a model M-P coculture (Methylomicrobium buryatense 5GB1 – Arthrosipira platensis) through a series of designed experiments. Moreover, through a semi-structured kinetic model, we were able to quantify the effect of these interspecies interactions, albeit unknown, on the growth of the model coculture.

However, identifying what metabolites are exchanged within the M-P coculture is very challenging. Meta-transcriptomic analysis of various cocultures usually display a “messy” picture of global responses. It is almost impossible to identify a few key metabolic links that drive the function and behavior of the coculture. Although 13C labelling could potentially solve this problem, it requires a prior knowledge/hypothesis on what metabolite to target. To help address this challenge, we developed the very first genome-scale model for the model coculture, which consistently predicts the top 8 metabolites being exchanged between the methanotroph and photoautotroph within the coculture, which contribute to the enhanced growth observed in the experiment. To validate the model predictions, we conducted experiments where the individual microorganisms of methanotroph and cyanobacterial were cultured on the spent medium of the other. Finally, untargeted metabolomic analysis was conducted to compare the metabolomic profiles of the single culture supernatant with those of the coculture to corroborate the model predictions.