By logical means, the optical density (OD) of any microbial culture can be interpreted as an approximation to its number of colony forming units (CFU). However, once stationary phase (or even the mortality phase) is reached and held for 'too' long, such a relationship would not hold any longer due to the fact that OD is measuring the absorbance of a given amount of biomass that will contain dead and live cells. My question is, may anyone help me with a reference where this fact has been documented and explained?
Thanks in advance
Hey there Mauricio,
I would check out the below citation, there are also some papers cited within it that maybe helpful also.
Kim DJ, Chung SG, Lee SH, Choi JW. Relation of microbial biomass to counting units for Pseudomonas aeruginosa. African Journal of Microbiology Research. 2012 Jun 9;6(21):4620-2.
The link below should work too
http://www.academicjournals.org/article/article1380721635_Kim%20et%20al.pdf
Cheers,
Ceth
And some more links, which may help you: http://www.academicjournals.org/article/article1380721635_Kim%20et%20al.pdf http://www.microbiologynetwork.com/content/JVT_2011_v17n1_Measurement-of-Microbial-Cells-by-Optical-Density.pdf
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2672.2005.02727.x/pdf
Best regards
Vit
Braz J Microbiol. 2013 May 31;44(1):287-9. doi: 10.1590/S1517-83822013000100042. eCollection 2013.
Measuring of Mycobacterium tuberculosis growth. A correlation of the optical measurements with colony forming units.
Peñuelas-Urquides K1, Villarreal-Treviño L, Silva-Ramírez B, Rivadeneyra-Espinoza L, Said-Fernández S, de León MB.
Author information
Abstract
The quantification of colony forming units (cfu), turbidity, and optical density at 600 nm (OD600) measurements were used to evaluate Mycobacterium tuberculosis growth. Turbidity and OD600 measurements displayed similar growth curves, while cfu quantification showed a continuous growth curve. We determined the cfu equivalents to McFarland and OD600 units.
KEYWORDS: McFarland; Mycobacterium tuberculosis; bacterial growth; colony forming units; optical density
PMID: 24159318
PMCID: PMC3804212
DOI: 10.1590/S1517-83822013000100042
No se porque me llego su pregunta. Yo trabajo en Aisladores Sismicos. Disipadores de Energia Sismicos.....
Dr. Roberto Aguiar
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