Sudeep Joshi1 Manu Mannoor1

1, Stevens Institute of Technology, Hoboken, New Jersey, United States

A characteristically well-diverse assemblage of myriad micro-organisms operating in a synergic environment, constitutes a microbiotic consortium. It possesses a complex spatial and temporal microbial arrangement, which is self-sustained and perform multitudinous task by effective communicative functionality. The ability to custom-tailor a well-diversified microbiotic consortia permitting re-programmability of the microbial composition possess potential application prospects in bacteriology, drug-screening, clinical diagnostics, and therapeutic purposes. Additive manufacturing technique accomplished via 3D printing can serve as an efficient tool to realize such a functional microbiotic consortia.

In the present article, we have utilized 3D printing technique to custom-tailor different genera of cyanobacterial cells within biofriendly hydrogel materials to realize a living microbiotic consortium. Moreover, these cyanobacterial colonies were seamlessly merged with abiotic nanomaterials for creating a functional microbiota capable of photosynthetic energy generation. Specifically, we demonstrate 3-dimensional interweaving of 2 genera of cyanobacteria (Anabaena and Nostoc Sp.) pre-seeded in a hydrogel matrix with electronic nanomaterial (graphene nanoribbons, GNRs) into various complex spatial geometries to enable harvesting of photosynthetic bio-electrons. Fluorescence and scanning electron microscopic studies were performed to examine the spatial distribution of cyanobacterial cells and their interaction with GNRs, respectively. Photo-electrochemical studies verified highly-conducting GNRs helped in efficient transfer of bio-electrons generated due to the water-splitting reaction during photosynthesis. UV-visible spectroscopy and standard plate counting methods were used to determine the growth of cyanobacterial cells in microbiotic consortium, hence confirming the cytocompatibility of hydrogel matrix. Significantly, the proposed 3D-printing strategy can organize cyanobacteria in complex arrangements to investigate the influence of spatial and environmental parameters in social behaviors for creating photosynthetically active microbiotic consortia.

Techniques developed in this research can also be extended to 3D print other genera of bacterial species with smart hydrogel materials to determine mutualistic relationships between bacteria, designing of synthetic organisms, and post-biotic products. Taken together, our experimental efforts lead towards the better comprehension and understanding of complex microbial arrangement and associated functionality of a robust microbiota.