Thank you so much! Your channel is a gem for me! I study biotechnologies, and my professor does not explain the topics in such great detail. I will share your content with my classmates.
It is important to mention that the O.D. is a relative quantity. In order to use it you first need to perform a time-consuming calibration step that requires taking volume samples, diluting said volumes to exact dilution factors, plating in petri dishes, incubating the petri dishes, counting the resulting colonies, repeating the process and taking averages. All while making sure the bacterial population density is within 10 +/- 3 million cells per mL so the O.D. stays under 1.0 units for a 1 cm optical path.
good resources: IMPLEN, “OD600 (Cell Density, Bacterial Growth, Yeast Growth)“ www.implen.de/od600-diluphotometer/od600/ BiteSizeBio, “Is Your Bacterial Culture Still Growing? A Primer on OD600 Measurements” by Adrienne Huntress, July 28, 2021 bitesizebio.com/41100/is-your-bacterial-culture-still-growing/#:~:text=Optical%20density%20measures%20the%20degree,more%20the%20light%20is%20scattered Eppendorf, “OD600 Measurements Using Different Photometers Why does the absorbance value of turbidity measurements vary using different photometers?’, September 2015 www.eppendorf.com/product-media/doc/en/148370/Detection_White-Paper_028_BioPhotometer-D30_BioSpectrometer-family_OD600-Measurements-Different-Photometers.pdf more on recombinant protein expression in bacteria: bit.ly/bacterialproteinoverexpression ; longer video: ruclips.net/video/ePwVeXxU26w/видео.html ; just the gist version… ruclips.net/video/vcCApiKl80I/видео.html more on absorbance: bit.ly/dnauvbeer ; RUclips: ruclips.net/video/cUxh2DCqYBo/видео.html
more about all sorts of things: #365DaysOfScience All (with topics listed) 👉 bit.ly/2OllAB0 or search blog: thebumblingbiochemist.com
Hello. I'm working on measurements of E Coli in LB media (200 ml) in an Erlenmeyer Flask. We are keeping it in the incubator without stirring at 37 °C. And then we do the measuremnt extracting 4 ml aprox cause' this what the spectrophotometer needs for measuring. I was wondering if it's important to mix the culture before taking the measurement. I read in one of the resources from the comments that advice. Also, I don't know if it's necessary stirring during the growth or if it's better to let the bacteria to growth by its own. I've search for explanation about stirring but I didn't find it, just some papers say they do and others not.
Thank you so much! Your channel is a gem for me! I study biotechnologies, and my professor does not explain the topics in such great detail. I will share your content with my classmates.
Thanks so much! I'm so glad I could help!
It is important to mention that the O.D. is a relative quantity. In order to use it you first need to perform a time-consuming calibration step that requires taking volume samples, diluting said volumes to exact dilution factors, plating in petri dishes, incubating the petri dishes, counting the resulting colonies, repeating the process and taking averages.
All while making sure the bacterial population density is within 10 +/- 3 million cells per mL so the O.D. stays under 1.0 units for a 1 cm optical path.
good resources:
IMPLEN, “OD600 (Cell Density, Bacterial Growth, Yeast Growth)“ www.implen.de/od600-diluphotometer/od600/
BiteSizeBio, “Is Your Bacterial Culture Still Growing? A Primer on OD600 Measurements” by Adrienne Huntress, July 28, 2021
bitesizebio.com/41100/is-your-bacterial-culture-still-growing/#:~:text=Optical%20density%20measures%20the%20degree,more%20the%20light%20is%20scattered
Eppendorf, “OD600 Measurements Using Different Photometers Why does the absorbance value of turbidity measurements vary using different photometers?’, September 2015 www.eppendorf.com/product-media/doc/en/148370/Detection_White-Paper_028_BioPhotometer-D30_BioSpectrometer-family_OD600-Measurements-Different-Photometers.pdf
more on recombinant protein expression in bacteria: bit.ly/bacterialproteinoverexpression ; longer video: ruclips.net/video/ePwVeXxU26w/видео.html ; just the gist version… ruclips.net/video/vcCApiKl80I/видео.html
more on absorbance: bit.ly/dnauvbeer ; RUclips: ruclips.net/video/cUxh2DCqYBo/видео.html
more about all sorts of things: #365DaysOfScience All (with topics listed) 👉 bit.ly/2OllAB0 or search blog: thebumblingbiochemist.com
Hello. I'm working on measurements of E Coli in LB media (200 ml) in an Erlenmeyer Flask. We are keeping it in the incubator without stirring at 37 °C. And then we do the measuremnt extracting 4 ml aprox cause' this what the spectrophotometer needs for measuring. I was wondering if it's important to mix the culture before taking the measurement. I read in one of the resources from the comments that advice. Also, I don't know if it's necessary stirring during the growth or if it's better to let the bacteria to growth by its own. I've search for explanation about stirring but I didn't find it, just some papers say they do and others not.
typically you grow the cells with shaking
@@thebumblingbiochemist Thanks :)
Can we count colonies of bacteria?
Yes