Team:WPI-Worcester/Results


Results

Biofilm Assay Results

Ultimately, we tested the effects of 11 untagged and 9 BclA-tagged antifreeze proteins on biofilm formation in EMG2:K λ. Of the 20 antifreeze proteins,12 exhibited biofilm enhancing properties, while 8 exhibited biofilm inhibiting properties. Many of the antifreeze proteins that inhibited biofilm formation were untagged, and were either secreted or internally expressed, while antifreeze proteins that enhanced biofilm formation were typically targeted to the cell surface by the BclA tag. The graphs below show the average OD595 of the crystal violet stain for biofilms formed by EMG2:K λ expressing each of the antifreeze proteins normalized to OD595 of the crystal violet stain for biofilms formed by standard EMG2:K λ. The promoter BBa_J23117 is included on both graphs to demonstrate that incorporation of an empty vector does not impact biofilm formation.

Antifreeze proteins that increased biofilm formation relative to standard EMG2:Kλ, plus or minus standard error (line at 1).

Antifreeze proteins that decreased biofilm formation relative to standard EMG2:Kλ, plus or minus standard error (line at 1). Error vars indicate +/- standard error.

Freeze Assay Results

Preliminary results from our antifreeze protein assay are shown below. Antifreeze protein efficacy was measured at -20 ℃ and -80 ℃ via an MTS assay adapted from Wang et al. 2013, details of which can be found on the Protocols page. Due to time constraints, three replicates were not able to be completed for every assay. The graphs are color-coded accordingly: green bars indicate those using three data points, orange bars use two data points, and red bars indicate that just one data point went into that value. Standard error bars are shown on the graphs.

Percent survival of AFPs compared to control at -20 ℃.

Percent survival of AFPs compared to control at -80 ℃.

The data shows that several AFPs, including all the versions of IAFGP that were tested, and the BclA-tagged version of EpAFP, show improved survival in E. coli over transformation with an empty vector. TiAFP also shows promise, but since the assay was performed only once, it is difficult to draw conclusions. At this time, we have a preliminary understanding of how our antifreeze proteins respond to -20 ℃ and and -80 ℃ temperatures, but more testing is needed to draw concrete conclusions.