Team:Washington/Alkanes/Future/Vector

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Growth Optimization

Using our initial, non-optimized growth conditions, we were able to obtain alkane/ene yields of approximately 2 mg/L. In order to make analysis easier, and to make it easier to determine the effects of the addition of additional modules, we wanted to increase yield. Our efforts focused on how by varying system conditions, we could increase yield.

Effect of Trace metals on yield

We had suspected that the trace metals in the original media may be inhibiting alkane production. We analyzed alkane production of cells transformed with the basic Petrobrick in medias of varying trace metal concentration.

Trace metals inhibit alkane production.

Based upon this test, we determined that trace metals have a negative effect on alkane yield, and that all future tests would be conducted in an M9 media without additional trace metals.

Use of Different strains

We had suspected that different strains of E. coli would produce varying amounts of alkane. Initial experiments were done in MG1655, and we decided to test XL-1 blue( a commercial supercopentent variant of DH5a) for the ability to produce alkane.

Effects of different strains on alkane yield.

XL-1 blue was able to produce more alkane than MG1655. In addition, XL-1 blue did not produce detectable levels of C16 alcohol. This makes C17 alkene analysis easier, and would mean a purer alkane product.


Sealed vs. Open Tubes

We were concerned that alkane evaporation may have been evaporating, reducing apparent yield. Therefore, we performed tests were the tubes were either capped like normal, or capped with foil coverting the opening, redcing evaporation.

Effect of sealing culture tubes on alkane yield.

Covered tubes showed significantly more alkane, so all further tests would be conducted in sealed tubes.

Aerobic vs Microaerobic growth

In many industrial production applications, growth in conditions with little or no oxygen can improve yield. Therefore, we tested alkane yield in cultures grown in airtight vials with only a small amount of air on the top in order to severely limit oxygen availability.

Effect of Oxygen on alkane yield.

Based upon this data, aerobic growth appears to be better for alkane yield. Note that this difference is not likely due to differences in growth rate, as both cultures were inoculated to a high OD600 of 1. 1C3 vs 3D4R


TB vs M9


and more...