6 replies to this topic

[Micro]

Has anyone got any suggests for ways of quantifying cell density of filamentous bacteria?
I need to look at the growth curve, but normal OD600 analysis won't work due to the filamentous nature of the cells. I've been looking into packed cell density, protein production, DNA quantification and other spectro using the coloured pigments produced by the bacteria. Has anyone used any of these methods or have any other suggestions?

Cheers M    

[bob1]

I use DNA quantitation for mammalian cell growth assays using a fluorescent DNA binding dye.  It should work for bacteria too, but you would need to calibrate it for the individual types.

[Micro]

Hey Bob1. Thanks for the suggestion.

I have a couple of question: What brand/type of DNA binding dye do you use? Do you quantify your cells using spectro or microscopy?

Cheers M

[GeorgeWolff]

dry weight

[bob1]

I just use sybr green and a fluorescent plate reader.

[NWU99]

Try a microplate nephelometer, like the Nephelostar from BMG Labtech.  Nephelometry measures light scatter, not optical density, so it isn't affected by the extinction coefficient of anything in your wells.  This improves linearity and, sometimes, limit of detection.  Nephelometry can also remove artifacts from clumping or settling during growth.

[shanm]

measure is considered too expensive. An alternative is to generate conditions which prevent the excessive growth of filamentous bacteria like M. parvicella. Filamentous bacteria induced by CRAMP were subsequently incubated with chemical  of bacterial filamentation and growth arrest


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