Evolution is the oldest engineering method
Variation, selection, inheritance. Repeat for four billion years.
Nature's design loop has three steps. Try many variations. Keep what survives. Pass it on. Run it long enough and you get the nautilus, the pear and the ibex: each one a solution that passed every test so far.
One of the oldest solutions is a partnership. Plants feed the microbes around their roots with a share of the carbon they fix from the air, and those microbes repay them by unlocking nutrients from the soil. The arrangement has run for hundreds of millions of years.
Some of those microbes breathe by passing electrons to whatever they touch. Give them an electrode and they will pass electrons to that.
Fyto doesn't invent a power source. It joins a partnership that already works, and takes a little of what flows through it. Our job is to be a good guest: take little, disturb nothing, and stay out of the way of the plant.