Not mentioned. Of course, back in the 1990s when most of the ED-canonical lore (FE2/FFE) was written, we didn't yet know that Enceladus was interesting at all, and Titan and Europa were still largely unknown; the assumption was that if Mars was dead, then there was nowhere else life could be in the solar system. Titan was "interesting" enough for them to put a station in orbit there, but there's no mention of life; the space stations around Io and Titan were first founded as space holiday destinations for tourists, back before the invention of the hyperdrive.
The only ecosystems yet revealed in the Elite universe, both the traditional lore and in ED, are Earth-like (water-based) and Thargoid-like (ammonia-based). Titan's hydrosphere is methane-based.
The lore states that the first planet on which they found alien life was in Tau Ceti.
Here's the FE2 Gazzetteer, if you haven't seen it yet.
