Team:UC Chile/Results/Growthcurve

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Standardizing growth conditions

While we managed to acquire an inoculum of Synechocystis PCC 6803, no conditions were set for working with Synechocystis PCC 6803 in our faculty. We proceeded to standardize our own growth conditions by building a custom made cyanobacterial incubator based on growth conditions described in the literature (References?)

Here we show our growth curve for Synechocystis PCC 6803 using the conditions set in our DIY shaking incubator (40uE/s/m²), 90 RPM, 30°C.

Methods for the growth curve characterization of Synechocystis PCC 6803 over here.

Results

Model for Synechocystis growth at OD 600 nm and 730 nm

After analyzing the experimental data, a polinomial growth model was obtained by function curve fitting. We used Excel's Solver tool for data processing

Model at 600 nm :

Model at 730 nm :

Exponential phase growth curve

As we wanted to see the behaviour of cells in exponential phase, we analysed the part of the prior curves which best fitted the exponential function. We considered a first order kinetics growth.

The expression that governs the exponential growth is given by the expression:

Where File:Xsubzero uc chile.jpg is the initial amount of bacteria, File:Timetime.jpg is time and File:Muuuuuu uc chile.jpgis the specific speed constant.

Adjustment of File:Muuuuuu uc chile.jpg parameter was obtained using Solver's algorithm of least squares.

Then we have these parameters for exponential growth at 600 nm and 730 nm

Exponential growth at 600 nm

Exponential growth at 730 nm

The exponential model allows us to express duplication time as the independent variable by equation rearragement.

This was the duplication time we obtained

Relation of measurements at 600 nm and 730 nm

In other data analysis, we wanted to check of we could move from one OD to the other. This is, that we can predict OD at 730 nm with 600 nm data. As it happens, this is possible and the linear model between measurements is given by

Where x is the OD measurement at 600 nm and y is the function of OD measurement at 730 nm.