# Abstract

This year, SMS_Shenzhen built two models in total. The first one is a chitinase-activity prediction model and the second is a convenient math tool that can help other teams to use ABS to obtain the concentration of E. coli.

# The First Model: Cultivation Time Model

## I Problem

- In this year SMS_Shenzhen project, we are aiming at producing a biological pesticide for farmers to use in their field. In our design, farmers cultivate our bacteria and then spread the culture to the field. However, instruction of how long and under what condition should our engineered E. coli should be cultivated is needed. In our model, we talked about the fundamental relationship between the time of cultivation and the enzyme activity of chitinase.

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## II Hypothesis

- The activity of chitinase should increase in the few days when the bacteria is going through the K1 period. There should be a stop of increasing and a decline when the nutriment is declining.

## III Variables

1. T: Days of cultivation

1. A: Enzyme Activity defined by active unit divided by bacteria population.

## IV Result

## V Modeling

## VI Analysis

- From the above set of data, we can reach an agreement that our TOP10 Expression System is suitable for the expression of plasmid K2224001, which CDS is the modified chitinase. But the chitinase activity curve with insufficient data only shows an uncertain relationship with time. We can define this relationship as a liner relationship but since it is weak and uncertain, further research and experiment should be taken, until a confirmation can be done.

- From our model, we suggest that the farmers should cultivate our engineered bacteria for at least 120 hours to make sure that there is a significant activity of chitinase. However, the cultivation should be no longer than one week since the phage may grow and the E. coli may mutate.

# The Second Model: The ABS-Concentration Model

## I Problem

- For many iGEM teams, obtaining the concentration of E. coli is a troublesome process since there is not a uniform method. In our modeling, we construct a tool for other teams to calculate the concentration if they use our method of cultivating E. coli.

## II Variables and Constriction

- In our modeling, there are two variables: ABS value and the actual cell concentration.

- To use our model, there are several constrictions of the cultivation environment. First, the bacteria should be E. coli (TOP 10 strain). Second, the cultivation condition is 37 ℃，LB culture media, and monoclonal.

## III Method of Obtaining Variables

- The ABS value is obtained by using a spectrophotometer.

- The actual cell concentration is obtained by dilution plating procedure.

## IV Result

Raw Material:

Model:

-According to the paper we used for reference, the relationship between ABS value and concentration of sample bacteria fluid is positive and liner.