Need Help

John Bowman jbowman at
Tue Oct 11 12:59:59 EST 1994

In article <374v4n$j9d at> cray89 at (Chittaranjan Ray) writes:
>From: cray89 at (Chittaranjan Ray)
>Subject: Need Help
>Date: 8 Oct 1994 02:11:35 GMT

>I would like to have some information on compounds
>that might change color (visible to eye or camera)
>in the porous medium or soil under microbial action.
>I am expecting that the soil will be partly wet and at
>ambient temperature. 

>This is some thing I am interested to oberve microbial
>through an indirect means. I would like to know if such
>compounds are only acted upon by one or more specific
>types of organisms. Some one mentioned a compound like 

>I do not have much microbilogy in my traning. I have a degree
>in engineering. So, please respond so that it will be easy
>for a nonmicrobilogist to understand.

>Chittaranjan Ray
>Illinois State Water Survey
>Champaign, IL

Dear Chittaranjan

A possible compound useful for estimating cell biomass, numbers etc is called 
XTT. XTT is reduced by microbial oxidation to formazan which has a bright 
orange colour. I can can give you a reference to look up about the details of 
XTT methodology (Roslev & King, 1993. Application of a tetrazolium salt with a 
water-soluble formazan as an indicator of viability in respiring bacteria. 
Applied & Environmental Microbiology 59:2891-96).

XTT hasn't been applied to soil matrices yet maybe you can test it. You will 
need good negative controls if you do,

Best of luck

John Bowman Ph. D.

Univ Tennessee, Knoxville
jbowman at

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