Ferrando, V. | Search bioRxiv

bioRxiv2026

FluOpti: an open-source system for programmable whole-plate optogenetics and multi-fluorescence imaging

Bacteria are able to self-organize into complex spatial communities, such as colonies, biofilms and swarms. Probing cells and gene networks with dynamic stimuli while preserving their spatial organization is therefore essential for understanding how bacterial communities organize across spatial and temporal scales. Optogenetics offers a powerful approach for such a task given the precise control of stimulus delivery without the perturbations normally associated with the addition of liquid inducers. However, most optogenetics devices have been developed to work with liquid cell cultures or to deliver a spatial pattern without the concurrent recording of gene responses and colony growth. Here, we describe FluOpti, an open source, low-cost device for controlling gene expression, through programmable light inputs, and recording multi-fluorescence responses and colony growth across whole petri dishes. White light LEDs are used for brightfield imaging while green and red LEDs are used as optogenetic inputs to activate and inactivate target genes via the CcaS/R two component system in E. coli. Low cost blue and orange acrylic are used as excitation and emission filters for fluorescence imaging, respectively. We developed custom software to analyze colony growth and optogenetic responses from 72-hour time-lapse experiments. A mathematical model was developed to predict gene expression levels in response to green-to-red light ratio stimuli. We use FluOpti to reveal a spatially structured response to optogenetic stimuli, with gene activation rates differing in cells located at the center and edge of colonies. to validate its use at a whole petri dish scale, FluOpti was used to depict how Voronoi territories can act as predictors of colony size, in congruence with previous studies. Together, these results demonstrate the utility of the device for studying gene networks at multiple spatio-temporal scales, from individual colonies to the whole petri dish. Performing optogenetics studies in whole petri dishes while preserving spatial arrangements could offer valuable insights into the spatial biology of gene networks in microbial populations.

bioengineering↗

bioRxiv2024

Open Educational Resources for distributed hands-on teaching in molecular biology

The urgent need to develop a more equitable bioeconomy has positioned biotechnology capacity building at the forefront of international priorities. However, in many educational institutions, particularly in low-and middle-income countries, this remains a major challenge due to limited access to reagents, equipment, and technical documentation. In this work, we describe Open Educational Resources (OER) composed of locally produced biological reagents, open source hardware and free software to teach fundamental techniques in biotechnology such as LAMP DNA amplification, RT-PCR RNA detection, enzyme kinetics and fluorescence imaging. The use of locally produced reagents and devices reduces costs by up to one order of magnitude. During the pandemic lockdowns, these tools were distributed nationwide to students homes as a lab-in-a-box for remote teaching of molecular biology. To test their performance, a total of 93 undergraduate students tested these resources during a biochemistry practical course. 27 out of 31 groups ([~]87%) successfully achieved the objectives of the PCR activity, while 28 out of 31 groups ([~]90%) correctly identified the target using LAMP reactions. To assess the potential application in secondary school, we organized three workshops for high school teachers from different institutions across Chile and performed an anonymous questionnaire, obtaining a strong agreement on how these OER broaden teachers perspectives on the techniques and facilitate the teaching of molecular biology topics. This effort was made possible through a close collaboration with open source technology advocates and members of DIYbio communities, whose work is paving the way for low-cost training in biology. All the protocols and design files are available under open source licenses.

molecular biology↗