From 2010.igem.org

Arginine is an amino acid that is acidic. Therefore if B. subtilis 168 is able to take up arginine, it will cause a pH change in the media. This would result in an increase in pH.

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Figure 1: Arginine test using pH indicator stick to measure pH changes of the media.

Time (in minutes)	Control (1)	Control (2)	Control (3)	Test (1)	Test (2)
0	pH 7	pH 7	pH 7	pH 7	pH 7
30	pH 7	pH 7	pH 7	pH 7	pH 7
60	pH 7	pH 7	pH 7	pH 7	pH 7
90	pH 7	pH 7	pH 7	pH 7	pH 7
120	pH 7	pH 7	pH 7	pH 8	pH 8
150	pH 7	pH 7	pH 7	pH 8	pH 8
180	pH 7	pH 7	pH 7	pH 9	pH 9
210	pH 7	pH 7	pH 7	pH 9	pH 9
240	pH 7	pH 7	pH 7	pH 9	pH 9
270	pH 7	pH 7	pH 8	pH 9	pH 9
300	pH 7	pH 7	pH 8	pH 9	pH 9

Table 1: Arginine test using pH indicator stick to measure pH changes of the media. Table represents the change in pH over the time span of 300 minutes i.e. 5 hours. Here,

Control (1) - LB media
Control (2) - LB media with 10 mM of arginine
Control (3) - LB media plus B. subtilis 168
Test (1) - LB media with 10 mM of arginine plus B. subtilis 168
Test (2) - LB media with 10 mM of arginine plus B. subtilis 168

Conclusion

B. subtilis 168 breakdowns arginine to urea by producing arginase. The urea is then further broken down to ammonia and carbonate. This will lead to an increase in pH. Both the test 1 and test 2, which contain B. subtilis 168 and 10 mM of arginina show an increase in pH from 7 to 9. While the control 1 and control 2, which contain no B. subtilis 168 remains at pH 7. The control 3 which contain B. subtilis 168 but without addition of arginine show an increase in pH from 7 to 8. This could be due to unidentified products that are secreted by the bacteria.

Therefore this experiment have shown that B. subtilis 168 is able to utilise arginine, and thus increase the overall pH of the media. The overalll change in pH will cause calcium ions to precipitate with carbonate, forming calcium carbonate.

Team:Newcastle/23 July 2010

From 2010.igem.org

Contents

Arginine experiment

Aim

Procedure

Results

Conclusion