1. Water Baths Athikhun.suw (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

2. Why Water Baths? Growth of many microorganism require temperature control All enzymatic reactions have optimal temperature, usually 37 o C Some biochemical procedures such as nucleic acid hybridization require strict temperature control Many chemical reactions can be accelerated with temperature Heat transfer in a liquid is more efficient than in a air chamber at the same temperature Thermal capacity of water is greater than air Water is an excellent liquid, cheap, safe and plenty* *(Baths with substances such as polyethylene glycol (antifreeze) are used when temperature desired are below freezing point of water)

3. Types of Water Baths Static water baths vs. circulating water baths Above ambient (room) temperature- heater Below ambient temperature- refrigeration Shaker baths for growing microorganisms Boiling water baths Tissue baths for incubating tissues for biological studies

4. Google shopping (2015), Water Baths [screenshot]. Retrieved from google.com Athikhun.suw (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

5. Temperature Monitoring Thermistors Ansgar Hellwig (2005), NCT Thermistor [photograph]. Retrieved from https://commons.wikimedia.org/wiki/File:NTC_bead.jpg

6. Temperature Sensor Schematic Zach Hoeken (2011), Temperature Sensor Schematic [photograph]. Retrieved from https://www.flickr.com/photos/hoeken/2848762530

7. Immersion Water Circulators example Google Shopping (2016), Immersion circulator [screenshot]. Retrieved from google.com

8. Use and Care of Water Baths Maintain the minimum level with chemically pure water Do not use tap water which will cause salt deposit and corrosion and affect function Approved, non-corrosive antimicrobial agents should be added to avoid growth of bacterial and algae Always use a thermometer to check temperature accuracy Make sure that the substance being incubated is below the bath water surface It is a advisable to cover tubes, flasks, or plates during incubation to avoid contamination of the bath and also to avoid dilution of the tube/flask/plate contents by condensation Empty and clean the water bath regularly

9. Questions? ?