We would like to acknowledge Molly Lazar and Ver&#243;nica Delgado for assistance in testing the protocol, Kieran Sweeney for helpful discussions and editing, and Taylor Scott, My An-adirekkun, and Stephanie Geller for critical reading of the manuscript. Megan Nicole McClean, Ph.D. holds a Career Award at the Scientific Interface from the Burroughs Wellcome Fund.

<img alt="Figure 1" src="/files/ftp_upload/54894/54894fig1.jpg" />
Figure 1: The continuous culturing apparatus. This simplified diagram shows how the apparatus should be assembled when it is used to culture, illuminate, and measure optical properties of the microbes. <a href="http://cloudfront.jove.com/files/ftp_upload/54894/54894fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<p class="jove_content" fo:keep-togeth...

<ol>
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O., Taxis, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+LOV2+Domain-Based+Optogenetic+Tool+to+Control+Protein+Degradation+and+Cellular+Function.">A LOV2 Domain-Based Optogenetic Tool to Control Protein Degradation and Cellular Function.</a> Chemistry &amp; Biology. 20 (4), 619-626 (2013).</li><li>Novick, A., Szilard, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Description+of+the+chemostat.">Description of the chemostat.</a> Science (New York, N.Y.). 112 (2920), 715-716 (1950).</li><li>Monod, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=La+technique+de+culture+continue.+Th&#233;orie+et+applications.">La technique de culture continue. Th&#233;orie et applications.</a> Ann. Inst. Pasteur. 79 (4), 390-410 (1950).</li><li>Shimizu-Sato, S., Huq, E., Tepperman, J. M., Quail, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+light-switchable+gene+promoter+system.">A light-switchable gene promoter system.</a> Nature Biotechnology. 20, 1041-1044 (2002).</li><li>Kennedy, M. J., Hughes, R. M., Peteya, L. A., Schwartz, J. W., Ehlers, M. D., Tucker, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+blue-light-mediated+induction+of+protein+interactions+in+living+cells.">Rapid blue-light-mediated induction of protein interactions in living cells.</a> Nature Methods. 7, 973-975 (2010).</li><li>Olson, E. J., Tabor, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optogenetic+characterization+methods+overcome+key+challenges+in+synthetic+and+systems+biology.">Optogenetic characterization methods overcome key challenges in synthetic and systems biology.</a> Nature chemical biology. 10 (7), 502-511 (2014).</li><li>Botstein, D., Fink, G. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Yeast:+An+experimental+organism+for+21st+century+biology.">Yeast: An experimental organism for 21st century biology.</a> Genetics. 189 (3), 695-704 (2011).</li><li>Galanie, S., Smolke, C. 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A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alcoholic+fermentation+of+carbon+sources+in+biomass+hydrolysates+by+Saccharomyces+cerevisiae:+current+status.">Alcoholic fermentation of carbon sources in biomass hydrolysates by Saccharomyces cerevisiae: current status.</a> Antonie van Leeuwenhoek. 90 (4), 391-418 (2006).</li><li>Edelstein, A., Amodaj, N., Hoover, K., Vale, R., Stuurman, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computer+control+of+microscopes+using+&#181;Manager.">Computer control of microscopes using &#181;Manager.</a> Curr Protoc Mol Biol. , (2010).</li><li>Edelstein, A. D., Tsuchida, M. A., Amodaj, N., Pinkard, H., Vale, R. 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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthetic+gene+expression+perturbation+systems+with+rapid,+tunable,+single-gene+specificity+in+yeast.">Synthetic gene expression perturbation systems with rapid, tunable, single-gene specificity in yeast.</a> Nucleic Acids Research. 41 (4), 1-10 (2013).</li><li>McIsaac, R. S., Petti, A. A., Bussemaker, H. J., Botstein, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perturbation-based+analysis+and+modeling+of+combinatorial+regulation+in+the+yeast+sulfur+assimilation+pathway.">Perturbation-based analysis and modeling of combinatorial regulation in the yeast sulfur assimilation pathway.</a> Molecular biology of the cell. 23 (15), 2993-3007 (2012).</li><li>McIsaac, R. S., Silverman, S. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast-acting+and+nearly+gratuitous+induction+of+gene+expression+and+protein+depletion+in+Saccharomyces+cerevisiae.">Fast-acting and nearly gratuitous induction of gene expression and protein depletion in Saccharomyces cerevisiae.</a> Molecular biology of the cell. 22 (22), 4447-4459 (2011).</li><li>Melendez, J., Patel, M., Oakes, B. L., Xu, P., Morton, P., McClean, M. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+optogenetic+control+of+intracellular+protein+concentration+in+microbial+cell+cultures.">Real-time optogenetic control of intracellular protein concentration in microbial cell cultures.</a> Integrative biology quantitative biosciences from nano to macro. 6 (3), 366-372 (2014).</li><li>Brauer, M. J., Huttenhower, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coordination+of+growth+rate,+cell+cycle,+stress+response,+and+metabolic+activity+in+yeast.">Coordination of growth rate, cell cycle, stress response, and metabolic activity in yeast.</a> Molecular biology of the cell. 19 (1), 352-367 (2008).</li><li>Boer, V. M., Crutchfield, C. A., Bradley, P. H., Botstein, D., Rabinowitz, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth-limiting+intracellular+metabolites+in+yeast+growing+under+diverse+nutrient+limitations.">Growth-limiting intracellular metabolites in yeast growing under diverse nutrient limitations.</a> Molecular biology of the cell. 21 (1), 198-211 (2010).</li><li>Markham, B. E., Byrne, W. J., Methods, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Uptake,+storage+and+utilization+of+phosphate+by+yeast.">Uptake, storage and utilization of phosphate by yeast.</a> Journal of the Institute of Brewing. 73, 271-273 (1967).</li><li>Kazemi Seresht, A., Palmqvist, E. 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The authors have nothing to disclose.

We designed this apparatus with flexibility in mind. All the code used is free and open-source. The default image analysis process to segment cells is simple and runs quickly. Custom analysis could be implemented by recording user input while analyzing a representative image with the FIJI graphic user interface, converting the input to a beanshell script, and then setting the plugin to call the script. When it is called, this script will be sent a String array called &#34;images&#34; containing the file paths to the most...

Optogenetic systems use light to control a growing list of cellular processes including gene expression,1,2,3,4,5 protein localization,6 protein activity,6,7,8 protein binding,8,9,10 and protein degradation.11 A method for culturing cells in a controlled environment with programmed optical stimulation and for measuring their response over biologically relevant timescales is necessary to exploit the potential of these tools for research in cell biology and biotechnology. Our method takes advantage of chemostasis to maintain a constant cell growth rate in a well-mixed, aerated, and temperature-controlled glass culturing vessel12,13 that is exposed to programmed illumination. We image individual cells in the culture effluent with an inverted microscope to measure the response of the culture to programmed illumination. The culturing, sampling, imaging, and image analysis are fully automated so that the fluorescence intensity and cellular morphology of the effluent cell culture can be measured over multiple days without user input.
This protocol can be implemented in most labs familiar with growing cell culture and microscopy, and the apparatus used is inexpensive and made of readily available components. A transparent culturing vessel is placed above a matrix of light emitting diodes (LEDs) capable of emitting 1 &#181;W/cm2-10 mW/cm2 of light. Microbes are grown in the culturing vessel continuously; one peristaltic pump is used to add media at the dilution rate, another is used to withdraw culture at a lesser rate to the microscope, and the difference escapes through an overflow outlet. A heating pad maintains the temperature. Air is continually pumped into the culturing vessel to maintain a positive pressure as well as to mix and aerate the culture. Except for the air pump, power to these devices is regulated by a microcontroller that also receives input from a thermometer and a connected desktop computer. The effluent cell culture is pumped to a microfluidic device on the stage of an inverted microscope. Non-fluorescent and fluorescent images are automatically acquired. The cells in the images are characterized by an algorithm that locates each cell as a region of interest (ROI) and measures the properties of each ROI.
To demonstrate an application of this protocol, we measured the response to varying light intensities of Saccharomyces cerevisiae cells engineered with a blue-light responsive optogenetic system which controls the transcription of fluorescent protein. S. cerevisiae, commonly known as baker&#39;s yeast, was selected because multiple optogenetic systems for controlling gene expression in this system already exist14,15,16. Furthermore, this model organism is commonly used for studies in systems biology17 and as a chassis for biotechnological applications18,19,20. Our representative results demonstrate that this protocol can be used to control transcription of a culture over multiple days by varying input light intensities and measuring the production of a fluorescent reporter.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >Extensive lab manual</td>
			<td >GitHub</td>
			<td >NA</td>
			<td >An extensive, regularly updated lab manual is available in the &#8220;Optogenetic Chemostat Files&#8221; GitHub repository (https://github.com/McCleanResearch/Optogenetic-Chemostat-Files). This also includes a description of the microfluidic mold used to generate the representative results.</td>
		</tr>
		<tr >
			<td >Fritzing Design Viewer</td>
			<td >Fritzing</td>
			<td >NA</td>
			<td >The free, open-sourced software to view and edit the .fzz type circuit board designs is available at &#34;http://fritzing.org/download/&#34;</td>
		</tr>
		<tr >
			<td >Arduino Uno R3 (Atmega328 - assembled)</td>
			<td >Adafruit</td>
			<td >50</td>
			<td >Microcontroller. 1 required.</td>
		</tr>
		<tr >
			<td >Arduino Stackable Header Kit</td>
			<td >SparkFun Electronics</td>
			<td >10007</td>
			<td >Female pin headers for connecting PCB to microcontroller. 1 required.</td>
		</tr>
		<tr >
			<td >Adjustable 30W 110V soldering iron - XY-258 110V</td>
			<td >Adafruit</td>
			<td >180</td>
			<td >For making electrical connections to the PCB. 1 required.</td>
		</tr>
		<tr >
			<td >Soldering iron stand</td>
			<td >Adafruit</td>
			<td >150</td>
			<td >For making electrical connections to the PCB. 1 required.</td>
		</tr>
		<tr >
			<td >Mini Solder spool - 60/40 lead rosin-core solder 0.031&#34; diameter - 100g</td>
			<td >Adafruit</td>
			<td >145</td>
			<td >For making electrical connections to the PCB. 1 required.</td>
		</tr>
		<tr >
			<td >0.1 &#956;F capacitor</td>
			<td >SparkFun Electronics</td>
			<td >COM-08375</td>
			<td >Stabilizes voltage in PCB. 1 required.</td>
		</tr>
		<tr >
			<td >10 &#956;F capacitor</td>
			<td >SparkFun Electronics</td>
			<td >COM-00523</td>
			<td >Stabilizes voltage in PCB. 1 required.</td>
		</tr>
		<tr >
			<td >MAX7219CNG LED Matrix/Digit Display Driver - MAX7219</td>
			<td >Maxim</td>
			<td >MAX7219CNG</td>
			<td >LED driver. 1 required.</td>
		</tr>
		<tr >
			<td >8 pin IC Socket</td>
			<td >Mouser Electronics</td>
			<td >575-144308</td>
			<td >16 required. These will be stacked on top of each other to support the culture vessel above the LED matrix.</td>
		</tr>
		<tr >
			<td >24 Pin IC socket</td>
			<td >Mouser Electronics</td>
			<td >535-24-3518-10</td>
			<td >Optional. Use this to reversibly attach the MAXIM 7219CNG driver to the PCB.</td>
		</tr>
		<tr >
			<td >Digital multimeter</td>
			<td >Adafruit</td>
			<td >2034</td>
			<td >For troubleshooting electronics. 1 required.</td>
		</tr>
		<tr >
			<td >Break Away Headers - 40-pin Male (Long Centered, PTH, 0.1&#34;)</td>
			<td >SparkFun Electronics</td>
			<td >PRT-12693</td>
			<td >Male pin headers for connected LED matrix to printed circuit board. Ends can be trimmed with wire cutters. 1 set required.&#160;</td>
		</tr>
		<tr >
			<td >Flush diagonal wire cutters</td>
			<td >Adafruit</td>
			<td >152</td>
			<td >For trimming long pin headers and cutting power cables. 1 required.</td>
		</tr>
		<tr >
			<td >Premium Female/Female Jumper Wires - 40 x 12&#34; (300mm)</td>
			<td >Adafruit</td>
			<td >793</td>
			<td >Wire ribbon for connecting breadboard to LED matrix. Can be connected end-to-end with male pin-headers to be longer. 1 required.</td>
		</tr>
		<tr >
			<td >Half-size breadboard</td>
			<td >Adafruit</td>
			<td >64</td>
			<td >The LED matrix will connect to this and the culturing vessel will rest above it.</td>
		</tr>
		<tr >
			<td >Miniature 8x8 Blue LED Matrix</td>
			<td >Adafruit</td>
			<td >956</td>
			<td >Light source. Dominant wavelength is 470nm (blue). 1 required. Alternative miniature LED matrices from the same vendor are available with dominant wavelengths: 624 nm (red), 588 nm (yellow), 525 nm (green), 572 nm (yellow-green), and white.</td>
		</tr>
		<tr >
			<td >Stackable header-3 pin</td>
			<td >SparkFun Electronics</td>
			<td >13875</td>
			<td >8 required.</td>
		</tr>
		<tr >
			<td >Resistor Kit - 1/4W (500 total)</td>
			<td >SparkFun Electronics</td>
			<td >10969</td>
			<td >For electronics. 1 required.</td>
		</tr>
		<tr >
			<td >&#160;IRL520N MOSFET</td>
			<td >International Rectifier</td>
			<td >IRL520N</td>
			<td >Voltage regulating switch for controlling DC current. 4 required.</td>
		</tr>
		<tr >
			<td >Hook-Up Wire - Assortment (Solid Core, 22 AWG)</td>
			<td >SparkFun Electronics</td>
			<td >PRT 11367</td>
			<td >Wire for electronics. 1 required.</td>
		</tr>
		<tr >
			<td >5V 2A (2000mA) switching power supply - UL Listed</td>
			<td >Adafruit</td>
			<td >276</td>
			<td >Power supply for the heating pad and Arduino. 2 required.</td>
		</tr>
		<tr >
			<td >12 VDC 1000mA regulated switching power adapter - UL listed</td>
			<td >Adafruit</td>
			<td >798</td>
			<td >For peristaltic pumps. 2 required.</td>
		</tr>
		<tr >
			<td >Electric Heating Pad - 10cm x 5cm</td>
			<td >Adafruit</td>
			<td >1481</td>
			<td >For heating the bioreactor. 1 required.</td>
		</tr>
		<tr >
			<td >Low flow variable flow peristaltic pump</td>
			<td >Fisher Scientific</td>
			<td >13-876-1</td>
			<td >For pumping media. 1 required</td>
		</tr>
		<tr >
			<td >Medium flow variable flow peristaltic pump</td>
			<td >Fisher Scientific</td>
			<td >13-876-2</td>
			<td >For pumping culture. 1 required.</td>
		</tr>
		<tr >
			<td >9 VDC 1000mA regulated switching power adapter - UL listed</td>
			<td >Adafruit</td>
			<td >63</td>
			<td >For microcontroller power supply. Order 1.</td>
		</tr>
		<tr >
			<td >High Temp Waterproof DS18B20 Digital temperature sensor + extras</td>
			<td >Adafruit</td>
			<td >642</td>
			<td >Thermometer for the bioreactor. 1 required.</td>
		</tr>
		<tr >
			<td >Micromanager</td>
			<td >Micromanager</td>
			<td >NA</td>
			<td >The free, open-sourced microscope control software is available at &#34;https://micro-manager.org/wiki/Download_Micro-Manager_Latest_Release&#34;</td>
		</tr>
		<tr >
			<td >FIJI</td>
			<td >ImageJ</td>
			<td >NA</td>
			<td >The free, open-sourced image analysis software is available at &#34;http://fiji.sc/&#34;</td>
		</tr>
		<tr >
			<td >Arduino Integrated Development Environment</td>
			<td >Arduino</td>
			<td >NA</td>
			<td >The free, open-sourced IDE is available at &#34;https://www.arduino.cc/en/Main/Software&#34;</td>
		</tr>
		<tr >
			<td >Custom code</td>
			<td >GitHub</td>
			<td >NA</td>
			<td >The custom microcontroller code and &#34;Bioreactor Controller&#34; plugin are available in the &#8220;Optogenetic Chemostat Files&#8221; GitHub repository (https://github.com/McCleanResearch/Optogenetic-Chemostat-Files).</td>
		</tr>
		<tr >
			<td >USB Cable A to B - 6 Foot</td>
			<td >SparkFun Electronics</td>
			<td >CAB-00512</td>
			<td >Used to download data to microcontroller. 1 required.</td>
		</tr>
		<tr >
			<td >bioreactorTimecourse_example.csv</td>
			<td >GitHub</td>
			<td >NA</td>
			<td >The advantage of loading LED matrix values from a CSV file is that a program can be called by the plugin to update those values based on image analysis results, and those values can be reloaded to the microcontroller, enabling feed-back control. It is available from the &#8220;Optogenetic Chemostat Files&#8221; GitHub repository (https://github.com/McCleanResearch/Optogenetic-Chemostat-Files).</td>
		</tr>
		<tr >
			<td >Tota-frost gels (diffusion paper)</td>
			<td >B&#38;H</td>
			<td >B&#38;H # LOFSFTL 
			MFR # T1-72</td>
			<td >For LED matrix. 1 required.</td>
		</tr>
		<tr >
			<td >Kitting Sheet Crosslink 1/4x12x24in</td>
			<td >Grainger, inc</td>
			<td >20JL37</td>
			<td >Black foam for culturing vessel enclosure. 4 required.</td>
		</tr>
		<tr >
			<td >Standard Photodiode Power Sensor, Si, 200 - 1100 nm, 50 mW&#160;</td>
			<td >Thorlabs</td>
			<td >S120VC</td>
			<td >For measuring light intensity. 1 required.</td>
		</tr>
		<tr >
			<td >Labelling Tape</td>
			<td >Fisher Scientific</td>
			<td >159015N</td>
			<td >For labelling and securing loose components. 1 required.</td>
		</tr>
		<tr >
			<td >Compact Power and Energy Meter Console, Digital 4&#34; LCD</td>
			<td >Thorlabs</td>
			<td >PM100D</td>
			<td >For measuring light intensity. 1 required.</td>
		</tr>
		<tr >
			<td >100mL GL45 hybridization glass bottle</td>
			<td >Bellco Glass, Inc.</td>
			<td >(7910-40150)</td>
			<td >Bioreactor vessel. 1 required.</td>
		</tr>
		<tr >
			<td >Six port assembly</td>
			<td >Bellco Glass, Inc.</td>
			<td >Custom&#160;</td>
			<td >For the bioreactor vessel. Tubing Specs: .125&#34; OD x .055&#34;ID. Port A: 1.0&#34; long above cap slug and to bottom of tube. Ports B,C,E,F: 1.0&#34; long above cap slug, 33 mm long below. Port D: 1.0&#34; long above cap slug, 65 mm&#160; long below. 1 required. Includes 45 mm diameter polypropylene open top screw cap and a white silicone gasket to ensure a tight seal between the cap and the vessel.&#160;</td>
		</tr>
		<tr >
			<td >Scotch Magic Tape 3105, 3/4 x 300 Inches, Pack of 3</td>
			<td >Amazon</td>
			<td >B0009F3P3U</td>
			<td >Clear scotch tape. This is available from many other vendors. It is used to cover markings on the culturing vessel and to secure the coverglass with the PDMS channel to the aluminum support frame.</td>
		</tr>
		<tr >
			<td >1/16&#34; ID x 3/16&#34; OD x 1/16&#34; Wall Tygon Sanitary Silicone Tubing</td>
			<td >United States Plastic Corp.</td>
			<td >57288</td>
			<td >Tubing. ~25&#39; required.</td>
		</tr>
		<tr >
			<td >Cole-Parmer Twistit white rubber stopper, size 10</td>
			<td >Cole-Parmer</td>
			<td >EW-62992-32</td>
			<td >Media flask stopper and effluent flask stopper. 2 required.</td>
		</tr>
		<tr >
			<td >2L Laboratory Flask</td>
			<td >Pyrex</td>
			<td >4980</td>
			<td >Media flask and effluent flask. 2 required.</td>
		</tr>
		<tr >
			<td >Day pinchcock</td>
			<td >Fisher Scientific</td>
			<td >5867</td>
			<td >For pinching tubes shut. 3 required.</td>
		</tr>
		<tr >
			<td >Replacement tubing assembly 1/16&#34; ID</td>
			<td >Traceable Products</td>
			<td >3372</td>
			<td >The peristaltic pumps come with a set of tubes, but they wear out after weeks of use.</td>
		</tr>
		<tr >
			<td >Replacement tubing assembly 1/50&#34; ID</td>
			<td >Traceable Products</td>
			<td >3371</td>
			<td >The peristaltic pumps come with a set of tubes, but they wear out after weeks of use.</td>
		</tr>
		<tr >
			<td >Male luer with lock ring x 1/16&#34; hose barb, Nylon, 25/pk</td>
			<td >Cole-Parmer</td>
			<td >EW-45505-00</td>
			<td >Connectors. ~10 luers are required.</td>
		</tr>
		<tr >
			<td >Male luer with lock ring x 1/8&#34; hose barb, Nylon, 25/pk</td>
			<td >Cole-Parmer</td>
			<td >EW-45505-04</td>
			<td >Connectors. 5 required, one for each rubber stopper hole to fill with tubing.</td>
		</tr>
		<tr >
			<td >Female luer x 1/16&#34; hose barb adapter, Nylon, 25/pk</td>
			<td >Cole-Parmer</td>
			<td >EW-45502-00</td>
			<td >Connectors. ~10 luers required.</td>
		</tr>
		<tr >
			<td >Female luer x 3/16&#34; hose barb adapter</td>
			<td >Cole-Parmer</td>
			<td >EW-45502-08</td>
			<td >Connectors. ~10 luers required.</td>
		</tr>
		<tr >
			<td >Cole-Parmer Luer Accessory, Female Luer Cap, Nylon, 25/Pk</td>
			<td >Cole-Parmer</td>
			<td >SC-45502-28</td>
			<td ></td>
		</tr>
		<tr >
			<td >Cole-Parmer Luer Accessory, Male Luer Lock Plug, Nylon, 25/Pk</td>
			<td >Cole-Parmer</td>
			<td >EW-45505-56</td>
			<td ></td>
		</tr>
		<tr >
			<td >Microbore PTFE Tubing, 0.022&#34;ID x 0.042&#34;OD, 100 ft/roll</td>
			<td >Cole-Parmer</td>
			<td >EW-06417-21</td>
			<td >Tubing. 1 roll required.</td>
		</tr>
		<tr >
			<td >Masterflex platinum-cured silicone tubing, L/S 13, 25 ft</td>
			<td >Cole-Parmer</td>
			<td >EW-96410-13</td>
			<td >Tubing. ~25&#39; required.</td>
		</tr>
		<tr >
			<td >3/16&#34; ID x 1/4&#34; OD x 1/32&#34; Wall Tygon Sanitary Silicone Tubing</td>
			<td >United States Plastic Corp.</td>
			<td >57293</td>
			<td >Tubing. ~1&#39; required.</td>
		</tr>
		<tr >
			<td >Vacuum filter</td>
			<td >Fisher Scientific</td>
			<td >974107</td>
			<td >Nalgene vacuum filter for sterile filtering media.</td>
		</tr>
		<tr >
			<td >Aquel Oxy-Boost 200</td>
			<td >Rena Aquatic Supply</td>
			<td >AP200</td>
			<td >Dual diaphram adjustable flow air pump for aerating and mixing media. 1 required.&#160;</td>
		</tr>
		<tr >
			<td >0.2 &#956;m pore syringe filter</td>
			<td >Corning International</td>
			<td >431229</td>
			<td >This ensures that air from the aquarium pump does not contaminate the apparatus. 1 required.</td>
		</tr>
		<tr >
			<td >Slygard 184 Silicone Elastomer Kit</td>
			<td >Dow Corning</td>
			<td >Slygard 184</td>
			<td >For microfluidic device. 1 required.</td>
		</tr>
		<tr >
			<td >American Safety Razor GEM Scientific Single-Edge Razor Blades</td>
			<td >Fisher Scientific</td>
			<td >17989000</td>
			<td >For cutting tubes and PDMS. 1 blade required.</td>
		</tr>
		<tr >
			<td >Harris Uni-Core hole puncher 1.2mm ID</td>
			<td >Sigma-Aldrich</td>
			<td >WHAWB100028 ALDRICH</td>
			<td >For punching inlet/outlet in microfluidic device. 1 required.</td>
		</tr>
		<tr >
			<td >Microscope cover glass 22x60-1.5</td>
			<td >Fisher Scientific</td>
			<td >12-544-G</td>
			<td >For microfluidic device. 1 required.</td>
		</tr>
		<tr >
			<td >Rectangular aluminum frame with a square window</td>
			<td >Custom</td>
			<td >Custom</td>
			<td >To support the microfluidic channel. Outer dimensions: 3 inches x 1.25 inches. 
			Inner dimmensions (cut out portion): 7/8 inches x 7/8 inches 
			Thickness: ~1/32 inches</td>
		</tr>
	</tbody>
</table>

design and implementation of an automated illuminating, culturing, and sampling system for microbial optogenetic applications

Optogenetic systems utilize genetically-encoded proteins that change conformation in response to specific wavelengths of light to alter cellular processes. There is a need for culturing and measuring systems that incorporate programmed illumination and stimulation of optogenetic systems. We present a protocol for building and using a continuous culturing apparatus to illuminate microbial cells with programmed doses of light, and automatically acquire and analyze images of cells in the effluent. The operation of this apparatus as a chemostat allows the growth rate and the cellular environment to be tightly controlled. The effluent of the continuous cell culture is regularly sampled and the cells are imaged by multi-channel microscopy. The culturing, sampling, imaging, and image analysis are fully automated so that dynamic responses in the fluorescence intensity and cellular morphology of cells sampled from the culture effluent are measured over multiple days without user input. We demonstrate the utility of this culturing apparatus by dynamically inducing protein production in a strain of Saccharomyces cerevisiae engineered with an optogenetic system that activates transcription.

This apparatus was used to stimulate a culture of S. cerevisiae expressing yellow fluorescent protein (YFP) in response to blue-light via an inducible optogenetic transcription system based on the CRY2/CIB1 protein pair30. Cells were grown chemostatically in phosphate-limited media with an average dilution rate of 0.2 &#177; 0.008. Phosphate limitation is commonly used in S. cerevisiae chemostat experiments to control growth rate and the effects o...

Watch this Scientific Journal Video about Design and Implementation of an Automated Illuminating, Culturing, and Sampling System for Microbial Optogenetic Applications at JoVE.com

Design and Implementation of an Automated Illuminating, Culturing, and Sampling System for Microbial Optogenetic Applications

We designed a continuous culturing apparatus for use with optogenetic systems to illuminate cultures of microbes and regularly image cells in the effluent with an inverted microscope. The culturing, sampling, imaging, and image analysis are fully automated so that dynamic responses to illumination can be measured over several days.

Optogenetic systems utilize genetically-encoded proteins that change conformation in response to specific wavelengths of light to alter cellular ...

The overall goal of this procedure is to assemble a continuous culturing vessel, in which the response to illumination of optogenetic microbes can be measured with a microscope automatically in real time and over multiple days. This method can help answer key questions in cellular biology and metabolic engineering, such as how dynamic gene expression can elicit responses which differ from static gene expression. The main advantage of this method it that continuous culture enables measurements to be collected for multiple days.To begin, solder the ground line, the data line, and the positive voltage line of the digital thermometer to the printed circuit board. Clip off one pin from a female three pin header and trim the remaining two pins. Solder this in the pair of holes labeled R2, and connect the two soldered pins by inserting a 4.7 kilo ohm resistor in the pin header.Next connect the remaining components to the circuit board. Overlay the circuit board on to the micro controller. Set up the light proof enclosure, and install all software as described in the accompanying text protocol.First, place the long end of the aluminum port through the gasket into the culturing vessel and screw on the cap. Cover one short aluminum port outlet with medium diameter silicone tubing. Plug the distill end by inserting a female luer lock, and then connecting a male luer lock plug.This outlet is supplementary and will not be used. Connect two short segments of medium diameter silicone tubing with male and female luer locks. Then connect one end to a short aluminum port outlet, and plug the distill end.The vessel will be inoculated through this tube. Next, connect two medium tubes to the ends of the medium diameter peristaltic tubing and connectors. Connect one end to a short aluminum port, and plug the other.Later, this will be connected to the media flask. Connect a medium diameter silicone tube to the longest aluminum port. The tube should be long enough to reach the media flask.Connect another short segment a few inches long to the end, and then insert it into the rubber stopper on the media flask. Clamp the tube. When later unclamped, this connection allows the culture to be mixed, aerated, and kept at a positive pressure by the incoming bubbles.Insert a medium diameter tube long enough to reach the bottom of the flask into the stopper through which media will be transferred. Connect another medium diameter tube to this one, and then a wide diameter tube on the end. Plug the distill end.Fill the third hole in the stopper with a short segment of medium diameter tubing, connected to two other segments of medium diameter tubing, and plugged at the distill end. This will be connected to a vacuum pump, and later to an aquarium pump. Insert a male luer lock into a segment of narrow diameter silicone tubing and then firmly insert PTFE tubing.Then attach a female luer lock to a medium diameter tube. Thread the female lock along the PTFE tube to connect the locks and the other to a short aluminum port. Ensure that the PTFE tube inside the culturing vessel dangles below the second longest aluminum tube, and above the bottom.Trim as needed. Media will be sampled from here to the imaging channel, and the narrow tubing minimizes the intermediate volume. Next, connect the exposed narrow silicone tube to the narrow peristaltic tube and connectors.To this connect three segments of narrow diameter tubing and two segments of PTFE tubing, alternating them. Connect this to the effluent flask, via medium diameter tubing. Then connect one end of a medium diameter silicone tube to the second longest tube of the aluminum port in the other end of the effluent flask.This aluminum tube sets the culture volume, and excess culture overflows into the effluent container. Wrap the lids of the flask with aluminum foil, and then autoclave the assembly for 30 minutes at 121 degrees Celsius and 15 PSI. Attach the vacuum filter to a 100 milliliter bottle.Remove the nipple cover, and then remove the white plug from the nipple of the vacuum filter with sterile tweezers. Connect the wide silicone tube to the nipple, the media flask's other free tube to a vacuum pump, and ensure that the third tube connecting the media flask to the culturing vessel is clamped shut. Fill the filter with media, turn on the vacuum pump, and then filter the rest of the media.Clamp the medium silicone tubing connected to the vacuum and turn off the vacuum pump. Remove the luers from the intermediate segment of medium silicone tubing connected to the vacuum pump and insert the blue end of a sterile syringe air filter into this tube. Then clamp the wide silicone tube and disconnect the male luer from it.Disconnect the plug from the female luer of the culturing vessel's media inlet tube. Connect these luers to enable media to be pumped into the culturing vessel. Then, remove the filter from the 100 milliliter bottle, and attach the bottle cap.Use this media to prepare a starter culture. Set the continuous culturing assembly near a microscope with the media flask higher than the culturing vessel, and the effluent flask lower than the culturing vessel to prevent back flow. Securely tape down the rubber stoppers on the media and effluent flasks.Next unplug the ends of the PTFE tube from the narrow silicone tube connecting them and plug these ends into the inlet and outlet of a prepared microfluidic device. Then push media into the culturing vessel, by connecting the white end of the syringe air filter to the aquarium pump. When media reaches the level of the effluent port wrap the medium media inlet tubing and connectors around the slow peristaltic pump, and the narrow sample outlet tubing and connectors around the fast peristaltic pump.Aerate the media by unclamping the air tube between the media flask and culturing vessel. Then, tape the heating pad and thermometer to the culturing vessel so that it's temperature can be controlled. Coil the media tubing around the culturing vessel, so the entering media will be at the same temperature as the vessel.Then insert the culturing vessel into the black foam enclosure over the LED matrix and ensure that the tubes are not pinched. Use the bioreactor controller plugin to set the slow media pump on for one tenth of every 30 second interval. The flow rate will be very low, but greater than the rate of evaporation.Clamp the incoming air tube between the media flask and culturing vessel. Use a pipette to inoculate the culturing vessel with one milliliter from a starter culture. Then clamp the distill end of this tube, and unclamp the air tube.Let the culture grow overnight. Cover the enclosure so that no light enters. The next day, use the bioreactor controller plugin to set the peristaltic pumps to rotate for a greater proportion of time, corresponding to the desired media and sampling flow rates.Let the culture density equilibrate overnight. The next day fill the stage position list and micro manager with a set of non overlapping positions where cells pumped into the microfluidic channel will be in the focal plane. Then open the bio reactor controller plugin.Select the desired LED matrix time course, imaging channels, and other experimental settings from the prompts, and then begin collecting data. This apparatus was used to stimulate a culture of saccharomyces cerevisiae, expressing yellow fluorescent protein in response to blue light via an inducible optogenetic transcription system. Base contrast and fluorescent images of the microfluidic channel were acquired.Cell outlines were identified from the phase contrast images, mapped to the fluorescent images, and the fluorescent images were recorded in real time. The heat map here shows the fluorescence distribution of a culture due to yellow fluorescent protein production upon activation of the optogenetic system. The fluorescence of approximately of 170, 000 cells was analyzed from over 30, 000 images, acquired from 28 stage positions over 70 hours.During this study, the culture was exposed to varying intensities of blue light for six hour intervals, followed by six hours of complete darkness. Cells had been exposed to light prior to the first measurement which is why it's fluorescence intensity is decreasing during the first dark period. Once mastered, this technique can be done in eight hours, over the course of three days, if it is performed properly.While attempting this procedure, it's very important to use sterile technique. Following this procedure, other methods, like real time feedback control, can be used to control protein concentration. This technique will enable organisms with optogenetic constructs to be studied dynamically, over longer periods of time, longer than what is possible using plates or batch culture.After watching this video, you should have a good understanding of how to integrate a continuous culturing apparatus, a light, and a microscope, to stimulate and study optogenetic microbes.

design-implementation-an-automated-illuminating-culturing-sampling

Research

JoVE Journal

Bioengineering

9.6K Görüntüleme.  University of Wisconsin-Madison. The overall goal of this procedure is to assemble a continuous culturing vessel, in which the response to illumination of optogenetic microbes can be measured with a microscope automatically in real time and over multiple days. This method can help answer key questions in cellular biology and metabolic engineering, such as how dynamic gene expression can elicit responses which differ from static gene expression. The main advantage of this method it that continuous culture enables measurements...