Our projects in the summer of 2015 focused on two main questions:
Where can Delftia acidovorans be found in the environment?
Environmental swabs were taken from multiple sources on and off of NCSU’s campus. The gene DACI_4753, which encodes for the non-ribosomal peptide delftibactin. This gene is only found in Delftia acidovorans, making it ideal as a means of detection. Samples were amplified using SYBR green qPCR as well as a TaqMan Probe. Positives and negatives were determined. 16S RNA was amplified in positive samples and barcodes were added to distinguish each sample from the other. Samples were then sent off for deep sequencing.
Figure 1. The locations of samples collected on the NCSU campus, and whether the samples contained Delftia acidovorans as determined by qPCR.
Does Delftia acidovorans contain specific genes that allow it to cope with/resist toxic heavy metals?
Minimal Inhibitory Concentration (MIC) assays were performed with all five strains using both copper and cobalt. Consistently, the 396R strain was the most resistant of the strains, so it was used for cloning. Using the SPH-1 genome as a reference, three cobalt resistance genes were identified and amplified from the 396R template. These genes were cloned and over-expressed in competent E. coli, and then the MIC assays were repeated with the transformants. The transformants containing resistance genes were able to grow at a higher concentration of cobalt when compared to the cloning control that had no cobalt resistance gene. This indicates that the genes are involved in Delftia acidovorans heavy metal resistance.