There's also Rifters' series by Peter Watts (great reads IMHO). With as little spoilers as possible: an ancient bacteria made of some sort of opposite-chirality

There's also Rifters' series by Peter Watts (great reads IMHO). With as little spoilers as possible: an ancient bacteria made of some sort of opposite-chirality proto-RNA is wrecking havoc across the planet, as no modern life form is prepared for it.