Probably not within the timescale needed. Lipids are definitely open-season for all sorts of creatures (If a molecule is synthesized to store energy, after all, you can be fairly sure that it contains enough energy to be worth cracking); but it would be a truly alarming bacterial metabolism that can cut through a large chunk of fat as fast as a guy with a shovel.
Wet wipes are probably a harder case. If made of cellulose, there certainly are agents that will attack them, albeit relatively slowly. If made of a synthetic polymer, they aren’t immortal; but could last for multiple decades, or even centuries, depending on UV exposure.
For areas of the sewer with lower input rates, bacteria and friends are probably already helping keep congestion down; but in high-input areas, or areas where material collects for whatever perverse reasons of fluid dynamics, we are probably talking several orders of magnitude faster than bacteria can handle it(and you wouldn’t want to see what bacteria that can cut through fat fast enough could do to human fatty tissues upon exposure…)
