Mold is not uncommon in conditions that occur with fridges and freezers. I'd definitely coat that bare wood with Urethane or your favorite finish and then clean it once in a while with a bit of bleach cleaner.
And I'm curious about that "Mold Armor" that RedBeard mentions. Might be worth looking into for a recurring problem area.
If your takin' your girlfriend out tonight
You better park the car well out of sight
'Cos if they catch you in the back seat trying to pick her locks
They're gonna send you back to mother in a cardboard box !