Enzyme functionalized microgels enable precise regulation of dissolved oxygen and anaerobe culture

• Published in: Materials today bio 2021-01, Vol.9, p.100092-100092, Article 100092
• Main Authors: Jeevarathinam, A.S., Guo, F., Williams, T., Smolen, J.A., Hyde, J.A., McShane, M.J., de Figueiredo, P., Alge, D.L.
• Format: Article
• Language: English
• Subjects: Afterglow; Anaerobic culture; Bioreactor; Full Length; Gut microbe; Hydrogel; Imaging
• ISSN: 2590-0064; 2590-0064
• DOI: 10.1016/j.mtbio.2020.100092

Anaerobes are a major constituent of the gut microbiome and profoundly influence the overall health of humans. However, the lack of a simple, cost-effective, and scalable system that mimics the anaerobic conditions of the human gut is hindering research on the gut microbiome and the development of therapeutics. Here, we address this gap by using glucose oxidase and catalase containing gelatin microparticles (GOx-CAT-GMPs) to precisely regulate dissolved oxygen concentration [O2] via GOx-mediated consumption of oxygen. Fluorescence images generated using conjugated polymer afterglow nanoparticles showed that [O2] can be tuned from 257.9 ​± ​6.2 to 0.0 ​± ​4.0 ​μM using GOx-CAT-GMPs. Moreover, when the obligate anaerobe Bacteroides thetaiotaomicron was inoculated in media containing GOx-CAT-GMPs, bacterial growth under ambient oxygen was comparable to control conditions in an anaerobic chamber (5.4 ​× ​105 and 8.8 ​× ​105 colony forming units mL−1, respectively). Finally, incorporating GOx-CAT-GMPs into a bioreactor that permitted continuous radial diffusion of oxygen and glucose generated a gut-mimetic [O2] gradient of 132.4 ​± ​2.6 ​μM in the outer ring of the reactor to 7.9 ​± ​1.7 ​μM at the core. Collectively, these results indicate that GOx-CAT-GMPs are highly effective oxygen-regulating materials. These materials can potentially be leveraged to advance gut microbiome research and fecal microbiota transplantation, particularly in low-resource settings. [Display omitted] •A large number of anaerobes are not studied owing to the limitations of current anaerobic culturing techniques.•Here, we describe a novel but simple materials-based approach to culture anaerobes on a benchtop.•The proposed approach eliminates the need for an anaerobic chamber or complex equipment.•Oxygen-gradients generated in a bioreactor are verified by imaging oxygen-sensitive fluorescent nanoparticles.•Suitability for anaerobic culture is demonstrated using the obligate anaerobe Bacteroides thetaiotaomicron.