For what it's worth, I took Microbiology last fall after taking Chem I 6 years ago. And when I did take Chem I, I had taken it pass/fail, put in minimal effort, and didn't retain a thing (I'm not proud of it, I was a little more excited about some other things in my life seeing as how I was living away from home for the first time, getting the "college experience").
Micro last fall was a breeze. Easy "A" for me, and there was minimal chem knowledge needed in my course. I picked everything I needed (which wasn't much) back up really quickly. It was a *lot* of reading and application and critical thinking, but not very technical.
Now I'm taking Chem II in a fast-track summer session, and *that* is kicking my butt.
I'm really regretting my silly freshman ways now.
Maybe you can contact a micro professor at your school and ask their opinion? Ask what concepts they feel are really important for you to absorb before micro...otherwise, enjoy just getting chem over with!