Maybe it's worth noting that the only time Genesis was used on a planet, it was Regula, which had a massive cave teeming with lifeforms. If there really couldn't be "so much as a microbe", clearly Regula was a poor test subject.
It could be that Genesis functioned perfectly, but the only test was on an unsuitable world. The subsequent diplomatic flap with the Klingons, resulting in the deaths of all of Grissom's crew bar one, and all of Kruge's crew, bar one, meant the project was canned in the current round of peace talks.
Certainly we never hear of it again, which isn't surprising given that aside from Dr Marcus, all the scientists were dead, and their research station was obliterated. Given the secrecy of the project, it could be that Genesis died there and then. I doubt Marcus would be interested in continuing, given what it cost her personally.