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Subject: Re: Growth rate calculation
From: "Niels T. Eriksen" <[log in to unmask]>
Reply-To:Niels T. Eriksen
Date:Wed, 7 Nov 2007 11:23:39 +0100
Content-Type:text/plain
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The same issue has also been a subject of discussion for filamentous 
fungi. In these organisms, growth curves are often very different from 
the exponential growth curve because the cultures tend to become 
inhomogeneous and all cells don't grow at similar rates. However, if 
homogenous cultures are established these will grow exponentially until 
nutrient depletion and otherwise follow Monod's growth model, see

Larsen et al. (2004) Homogeneous batch cultures of /Aspergillus oryzae/ 
by elimination of wall growth in the Variomixing bioreactor. Appl. 
Microbiol. Biotechnol. 64: 192-198
http://www.springerlink.com/content/gdv10k7q9c6d3uka/?p=f578c88db46e4b5e92c3fc23bb64ea46&pi=2

The same should be true for multicellular filamentous algae.

Niels Eriksen



Philippe Vandevivere skrev:
> Right, but the way I understand the question is whether this equation 
> actually holds for _multicellular filamentous_ microalgae, as opposed 
> to unicellular non-filamentous ones.  Interesting question. 
>  
> I believe this equation holds for all organisms reproducing by binary 
> fission, or even multiple fission for that matter (eg 
> chlorococcales).  So the equation would hold for (multicellular) 
> filamentous algae, provided _all_ cells within a filament undergo 
> cellular division, and at the same rate.  I don't know whether that's 
> the case but I assume it is. 
>  
> Just my 2 cents.
>  
> Dr Philippe Vandevivere 
>
> */"Henley, Bill" <[log in to unmask]>/* wrote:
>
>     Hussain,
>      
>     The exponential growth equation should work for any biomass
>     measure.  However, it assumes growth is really exponential
>     throughout the period of measurement; the calculated rate will not
>     be accurate if the culture is approaching stationary phase.  Thus
>     it would be best to measure on several successive days to confirm
>     this, at least in a pilot experiment, so you know the appropriate
>     range of days over which to calculate.
>      
>     Bill
>      
>     William J. Henley
>     Professor and Head
>     Dept. of Botany (http://botany.okstate.edu/)
>     104 Life Science East
>     Oklahoma State University
>     Stillwater, OK 74078-3013 USA
>     405-744-6674; -5956 lab (FAX -7074)
>     www.okstate.edu/artsci/SPMO
>     ------------------------------------------------------------------------
>     *From:* Forum for marine, freshwater and terrestrial algae. Open
>     to all interested in algae. [mailto:[log in to unmask]]
>     *On Behalf Of *hussain alrekabi
>     *Sent:* Tuesday, November 06, 2007 11:29 AM
>     *To:* [log in to unmask]
>     *Subject:* Growth rate calculation
>      
>
>     Hi all,
>
>     I  know  we use the following equation for calculate the growth rate [[1]]and doubling time [[2]]:     
>
>                               Ln (X_1  /X_0  )                                  ln2
>
>           [[1]]      = -----------------          [[2]]     G = ----------
>
>                                      T
>                                                       
>
>     when: X_0  : cell number in beginning of experiment
>
>              X_1  :  cell number in end of
>      experiment                                       
>
>          *That's for unicellular*
>
>     * algae*
>
>     The question: I
>      ask if we could use that's equations (above) for *filamentous algae* by substitute or replace the *cells numbers* with other growth measurements like *chlorophyll content* or *dry weight*(please tell me if there is other equations   with its reference)
>
>     If so, please inform me.
>
>     Thanks,
>
>     Hussain Yousif Al-Rekabi
>
>     Technical instutue Al-Nassiria
>
>     Iraq
>
>     [log in to unmask]
>
>      
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