If the oil has Joules of energy in it, which I guess it must have (otherwise it wouldn't be fuel!), then those bugs have to be getting the Joules from somewhere. They have to be either consuming something else with Joules in it, to transfer to the fuel, or they are absorbing them from sunlight. The scientists who worked on it missed something fundamental if they didn't identify the source of Joules.

In the case of hydrogen generation from solar, the Joules in hydrogen obviously come direct from sunlight, no bugs needed, just some panels and an electrolyser.

Something else you might be interested in is "Solein" (Easily found in Google). That is a kind of hydrogen activated human edible food (70 percent protein, 30 percent carbohydrate), which does use some kind of bio process, in a "Bioreactor", to convert hydrogen into energy rich food.

In the case of Solein, the fuel is for humans, and the source of Joules is easily traced to the energy used to power the bio-reactor.