The HaloEd Project

A web site dedicated to biotechnology education

Introduction

VJC

Pictures from our Field Trip:

The Bay was picture perfect-looking…

At the beach, we grouped up for

a presentation about the local wild

life by the National Aquarium’s

Tammy Robertson.

We were surprised at the condition of the beach which had just been through a cleanup the week before.

We tried to clean it up some.

We were shown how fish-sampling was done.

Volunteered to go out and collect some for a quick look.

Then we did some analysis of the water.

And soil.

Finally, we reeled in the net and were ready to pack up and return to the college.

Several exciting and promising projects resulted in the laboratory, including:

Looking at the effects of:

1. “Pollutants” such as vegetable oil, olive oil, canola oil, safflower oil, gasoline, kerosene, used and unused motor oil and diesel fuel –

They found that, when grown on plates, different organisms had different zones of inhibition depending on which “pollutants” were used on the test-discs.

One group of students found that diesel fuel was more toxic to the microbes than the other materials tested. No microbes were isolated that seemed to grow on the diesel fuel and would have been candidates for bioremediation, though certain microbes seemed less inhibited by it than others.

Another group testing some pollutants on agar plates found that they might have isolated microbes that may be capable of degrading certain hydrocarbons, including kerosene, diesel oil and gasoline and used and unused motor oil. These students also found that by lowering the temperatures, decreased the zones of inhibition, indicating that some organisms were less affected by the pollutants at lower temperatures.

Students predicted that when the Fort McHenry isolates were grown in minimal media, with only the chosen hydrocarbons available as carbon sources, these may be more readily degraded. They found that the microbes grew more readily at higher concentrations of vegetable, canola and olive oil than in the motor oil, indicating that this may be more toxic to the organisms. The fact that cultures could be grown in its presence was indeed promising.

2. Temperature and Salinity–

Students tested growth of their isolates from the fort at 7, 37, 55 and 70^oC. Growing cultures in 5 to 10% NaCl-containing media, students discovered that the optimum growth temperature for their isolates was 37^oC, even though their hypothesis was that 45-55^oC would be the optimum.

Other students tried to find a correlation between the isolate growth rate at various temperatures and the salt concentrations. They predicted that the microbes would grow optimally on 15%NaCl plates. They grew cultures in 0, 0.8, 5, 15, and 25% NaCl-containing media at 7, 37, 55 and 70^oC. They found optimum growth at temperatures between 6 and 37^oC and no growth at 55^oC and above.

Other students believed that high salt optima correlated with high salt optima. They found that their isolates with optima at 5% NaCl did well at broad ranges of temperature, while those with a salt optimum of 10% only grew at the lower temperatures, and those with a salt optimum of 15%, did well only at 70^oC.

3. pH and Salinity–

Students did some literature searches and predicted that halophiles prefer high pH values. And tested this hypothesis by culturing their isolated in media with ph values ranging from 0-7. They found that the optimum for their isolates from the 3 testing sites, grown at 5 and 15% NaCl, were pH 7 and 9 and 5,7, and 9 respectively, with more growth at the 5% vs the 15% NaCl concentrations.