P. putida in Different Concentration of Iron - Week 8

Pyoverdine is a organic ligand that binds to iron molecules. At a low iron environment, Pseudomonas putida and some other bacteria produce pyoverdine to find iron for uptake. On top of our manganese research, we were also interested in looking at the pyoverdine secretion for this week’s experiment. I grew the P. putida in minimal medium A with 100uM manganese, Mn(II), and different concentration of iron (0.37, 18, and 100uM). There was only four time-points collected for this week.

On Monday, I prepared my minimal medium A. On Tuesday, I started the day by preparing the different concentration of iron to be added into the medium.  Then I inoculated the P. putida from LB medium into the medium with, manganese, iron, and all the trace elements added. At each time-point, there was six measurement was done, and they were: catalase activity, hydrogen peroxide concentration, presence of pyoverdine, dissolved and particulate manganese (total manganese), manganese oxide, and culture density. First of all, I had to filter some of the samples for the measurements, except for culture density, and pyoverdine, because I was trying to compare filtered and unfiltered of the medium.

Some of the results came out as expected, such as presence of pyoverdine, total manganese. And culture density. In the pyoverdine measurement, the fluorescence changed quicker over time in the medium with low concentration of  iron. This result was shown on both of the filtered and unfiltered samples. The culture density was measure to show at what growth phase the time-points were measured. The data showed that the time-points were measured at the P. putida’s stationary growth phase. Then on the total manganese measurements, the concentration of dissolved and particulate manganese came out roughly the same but the change was opposite of each other. As the dissolved manganese, Mn(II), decreased, the particulate manganese increased. This meant the Mn(II) was oxidized into particulate manganese. This was expected.

The other measurements, catalase activity, hydrogen peroxide concentration, manganese oxide, were all over the place. The graphs were very noisy making it hard to conclude much out of them. This experiment need to be repeated for more accurate data.