Identifying interspecies interactions within a model methanotroph-photoautotroph coculture using semi-structured and structured modeling

Abstract

Methanotroph-photoautotroph (M-P) coculture has been demonstrated to be 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 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 this work, enabled by a novel experimental-computational protocol we developed recently to accurately characterize the M-P coculture in real time, we aim to elucidate the potential emergent metabolic interactions within a model coculture (Methylomicrobium buryatense – Arthrosipira platensis). Using designed experiments, we were able to confirm the existence of other interspecies metabolic interactions, in addition to the exchange of the in situ produced O2/CO2 within the model M-P coculture. Moreover, through semi-structured kinetic modeling, we were able to quantify the effect of these additional interspecies interactions, albeit unknown, on the growth of the model coculture. Finally, we developed the very first genome-scale model for the M-P coculture, which consistently predicts the top 8 metabolite being exchanged between the methanotroph and photoautotroph within the coculture, which contribute to the enhanced growth observed in the experiment.