Difference between revisions of "Part:BBa K1685011:Experience"

This part consists of Panama 2011's Biosurfactor biobrick (BBa_K653000) under T7lac promoter with strong RBS (BBa_K613010), and double terminator BBa_B0015. This part was in BioBasic's plasmid and it was transformed to E. coli BL21(DE3). A true transformant was used for expression.

We assembled out part in the BioBasic plasmid into pSB1C3 encoding RFP and then transformed it into E. coli DH5a. We used 2 ligation composition, and transformed each mix. Utilising red-white colony selection, we selected 4 white colonies candidate for colony PCR from each plate. Four of our selected colonies showed positive result: having a band around 2500-3000 kb.

Confirmation of this part successful assembly into pSB1C3 was done by isolating plasmid from selected positive colony (predicted by PCR colony). There was a band around 2500-300 kb

Rhamnolipid production

We transformed E. coli BL21(DE3) with rhamnolipid production module. After IPTG induction, the culture was centrifuged. The cell was collected and lysed for protein analysis by SDS-PAGE. It showed that there is a band that we assumed to be our rhlA and rhlB due to their size around 30 and 40 kDa respectively. The low concentration of putative rhlA and rhlB might be caused by the codon usage. But it needs more confirmation and further studies.

The supernatant was collected and tested for surfactant activity.

Rhamnolipid test

We tested our produced rhamnolipid for its characteristics and surfactant activites. Here we describe for the very first time the application of The Biosurfactor biobrick (BBa_K653000). The emulsification result showed that our supernatant has similar feature with positive control, Tween 20%, while our LB media (not from transformant’s supernatant) had similar property with negative control, water.

Using oil drop test, it was showed that supernatant from induced transformant (TI) has surfactant activity, almost similar to synthetic surfactant, Tween 20%. The uninduced transformant still created a clear zone. This maybe due to the leaky nature of lac operator. The negative control, LB media, had no clear zone. We used 40uL of the tested supernatant in 20 uL of crude oil.

We tested the supernatant in Lemigas, Indonesia’s national research and development centre for oil and gas technology. We tested the supernatant’s interfacial tension (IFT) in 60^oC and 70^oC. It is showed that the supernatant from induced transformant has lower IFT (which is better) in 60^oC. This IFT was even lower in higher temperature, 70^oC. The negative control (null) failed to separate the oil at 70^oC so it dosn't have IFT value.

The IFT was within the range of good quality surfactant. Therefore, Lemigas was interested to do more test, but we did not have enough time to receive the result before Wiki Freeze.