# Synchronous Culture Simulation

A rather simple-minded approach to modeling synchronous
culture is to assume that substrate uptake will be
proportional to the number of organisms. Our equation for
rate of change of substrate is:**
**

**dS/dt = -K ×
X**

where **S** = concentration of limiting nutrient

**K** = some coefficient

**X** = concentration of organisms

The number of organisms doubles at
regular time intervals. This is shown in the figure below drawn by the program SYNCH.BAS.
Inspection of the program reveals some tricks to prevent S from
going negative because the cells have a doubling time not dependent on
substrate concentration.

Think about the graph and try the following:

- Can you see that the sugar curve is constructed of straight-line segments ?
Click here if your answer is
**NO**
- Can you detect the faulty assumption in Equation 1 ? Click on the same NO as in #1.

**Continue to discussion of realistic behavior**
**Dept. of Chemical Engr.**

#### 15-Aug-95