Frontiers in Microbiology | www.frontiersin.org 1 June 2019 | Volume 10 | Article 1135 TECHNOLOGY REPORT published: 05 June 2019 doi: 10.3389/fmicb.2019.01135 Edited by: Roland Hatzenpichler, Montana State University, United States Reviewed by: Grayson L. Chadwick, California Institute of Technology, United States Tim Sandle, University of Manchester, United Kingdom *Correspondence: Joseph J. Grzymski joe.grzymski@dri.edu Specialty section: This article was submitted to Microbial Physiology and Metabolism, a section of the journal Frontiers in Microbiology Received: 01 February 2019 Accepted: 03 May 2019 Published: 05 June 2019 Citation: Vuono DC, Lipp B, Staub C, Loney E, Harrold ZR and Grzymski JJ (2019) A Real-Time Multiplexed Microbial Growth Intervalometer for Capturing High-Resolution Growth Curves. Front. Microbiol. 10:1135. doi: 10.3389/fmicb.2019.01135 A Real-Time Multiplexed Microbial Growth Intervalometer for Capturing High-Resolution Growth Curves David C. Vuono 1 , Bruce Lipp 1 , Carl Staub 2 , Evan Loney 1 , Zoë R. Harrold 1 and Joseph J. Grzymski 1 * 1 Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, NV, United States, 2 Lumenautix, LLC, Reno, NV, United States Batch cultures are a low maintenance and routine culturing method in microbiology. Automated tools that measure growth curves from microorganisms grown in traditional laboratory glassware, such as Balch-type tubes, are not commercially available. Here, we present a new MicrobiAl Growth Intervalometer (MAGI) that measures optical density as it correlates to microbial growth by utilizing photo-conduction as opposed to photo- attenuation used by traditional OD measurement equipment. Photo-attenuation occurs when biomass in suspension within a medium blocks and/or diffuses light directed at the detector, such that an increase in biomass results in a decrease in the measured signal. Photo-conduction differs in which the biomass contained in a medium conducts light from the emitter to the detector, where an increase in the biomass results in a corresponding increase in the measured signal. MAGI features software-driven automation that provides investigators with a highly sensitive, low-background noise growth measurement instrument with added capabilities for remote visualization and data acquisition. It is a low maintenance, cost effective, versatile, and robust platform for aerobic/anaerobic cultivation. We demonstrate the versatility of this device by obtaining growth curves from two common laboratory organisms Escherichia coli K-12 and Bacillus subtilis. We show that growth rates and generation times in E. coli K-12 are reproducible to previously published results and that morphological changes of B. subtilis during growth can be detected as a change in the slope of the growth curve, which is a function of the effects of cell size on photo- conduction through the medium. We also test MAGI to capture growth curves from an environmental organism, Intrasporangium calvum C5, under various media compositions. Our results demonstrate that the MAGI platform accurately measures growth curves in media under various redox conditions (aerobic, microaerobic, and anaerobic), complex and minimal medias, and resolving diauxic growth curves when I. calvum is grown on a disaccharide. Lastly, we demonstrate that the device can resolve growth curves for μM concentrations of resources that yield low biomass. This research advances the tools available to microbiologists aiming to monitor growth curves in a variety of disciplines, such as environmental microbiology, clinical microbiology, and food sciences. Keywords: anaerobic growth, aerobic growth, batch culture, growth curves, growth rates