Specific growth rates for cyanobacteria were calculated for exponential phase using selected equation. In the literature, most often appears the equation (and its combinations):
GR = ln(Nt-N₀)/∆t,
where:
N₀ and Nt it is chl-a or optical density values at the beginning and the end of the exponential growth phase
∆t - is the period of the exponential phase expressed in days
any else equations?
Hello Agnieszka Brzozowska,
I don't work with cyanobacteria but I have some experience working with seaweed cultures. The equation that you present is quite common for GR calculations, however there are several other equations used for this purpose. Yong et al. (2013) compared the accuracy and reliability of these formulae. They conclude that GR can be best calculated using the following formula:
[(Wt/W0)1/t−1]
Where:
Wt = initial wet weight (or in your case initial Chla or optical density)
W0 = final wet weight (or in your case final Chla or optical density)
t = days in culture
I recommend you to check the paper (DOI 10.1007/s10811-013-0022-7) so you can decide by youserlf which formula is the best. I also recommend you this paper (Article Determination of first order rate constants by natural logar...
) which explores deeper the analysis of the exponential phase in batch cultures of AspergillusBest regards
recommend
https://scholarworks.umass.edu/cgi/viewcontent.cgi?article=1045&context=cee_ewre
In press
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CALCULATION OF THE SPECIFIC GROWTH RATE OF MICROALGAE
R.P. Trenkenshu
Abstract. The work focuses on techniques of quantifying the specific growth rate of microalgae in both batch and continuous culture. It is shown, that to prove that the specific growth rate is a constant value, both the ratio of two chemical biomass characteristics and dimensional structure of cell population must be constant. Critical analysis of the correctness of using of a logarithmic formula for estimating the specific growth rate (m) of microalgae in the exponential phase of growth of batch culture: m = (lnB2 – lnB1) / (t2 – t1). Where B1 and B2 - density (concentration) of culture at a moment of time t1 and t2, respectively. This formula is widely used by most microalgae researchers without proving exponential growth character. Availability of such proofs makes the applying of the logarithmic formula meaningless. Examples of quantitative description of the experimental data obtained for two types of marine microalgae in the exponential and linear phases of culture growth are given.
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