A facultative anaerobe is growing photoheterotrophically in sterile water, covered with a thick layer of oil inside a test-tube containing 1g fructose. It has been observed that the bacteria are growing at the water/oil interface, and appear to be growing inside the oil layer. Which of these (can choose more than one) possibilities is the most likely: a) The bacteria are growing on the oil while partly in the water. b) They may only grow in water and might migrate into the oil to feed. c) The oil may not be pure i.e. contains water. d) The bacteria are utilizing the oil as a source of energy and the biofilm they have created floats on the water, but is trapped under the oil. I think that these are all likely possibilities, but am unsure which would be the most probable. I was also thinking that the solution may be saturated with fructose. I know that too much sugar can kill bacteria, so maybe they are moving as far away from the fructose at the bottom of the test-tube as they can. I really need some help with this.