Portable Anaerobic Microbioreactor Reveals Optimum Growth Conditions for the Methanogen Methanosaeta concilii

• Published in: Applied and Environmental Microbiology 2007-03, Vol.73 (5), p.1653-1658
• Main Authors: Steinhaus, Benjamin, Garcia, Marcelo L, Shen, Amy Q, Angenent, Largus T
• Format: Article
• Language: English
• Subjects: Ammonia - metabolism; Anaerobiosis; Archaea; Biological and medical sciences; Bioreactors; Culture Media; Fundamental and applied biological sciences. Psychology; Methane - metabolism; Methanosaeta concilii; Methanosarcinales - growth & development; Methanosarcinales - physiology; Methods; Microbiological Techniques; Microbiology; Microfluidics - instrumentation; Nitrogen - metabolism; Stress, Mechanical
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.01827-06

Conventional studies of the optimum growth conditions for methanogens (methane-producing, obligate anaerobic archaea) are typically conducted with serum bottles or bioreactors. The use of microfluidics to culture methanogens allows direct microscopic observations of the time-integrated response of growth. Here, we developed a microbioreactor (μBR) with ~1-μl microchannels to study some optimum growth conditions for the methanogen Methanosaeta concilii. The μBR is contained in an anaerobic chamber specifically designed to place it directly onto an inverted light microscope stage while maintaining a N₂-CO₂ environment. The methanogen was cultured for months inside microchannels of different widths. Channel width was manipulated to create various fluid velocities, allowing the direct study of the behavior and responses of M. concilii to various shear stresses and revealing an optimum shear level of ~20 to 35 μPa. Gradients in a single microchannel were then used to find an optimum pH level of 7.6 and an optimum total NH₄-N concentration of less than 1,100 mg/liter (