I do a lot of food prep while running hospitality suites for conventions. Are wood surfaces safer than plastic when it comes bacteriological contamination? Which clean easier?
Plastic.
There is some idea that wood has natural disinfectants in it, but I wouldn’t count on it. I would stick with plastic.
I worked as a professional cook/caterer for some time, and I stuck with plastic. You could run it through the dishwashers or bleach the hell out of it. Wood? Not so much. If you bleach wood, it tends to hang on to the smell of bleach. Plastic isn’t so prone to do that.
Most sources that I have consulted give a slight edge to plastic and other nonporous cutting surfaces but the general consensus seems to be that avoiding cross contamination is the most important factor to consider so you should use two separate boards. One for meats and fish and the other for produce.
Research has shown that both types of board has its drawbacks but it ultimately depends on human interaction. Simply put, does the user take all of the necessary precautions? If you are cautious and aware it should not matter much. Personally, plastics ability to stand up to disinfectants makes it my top choice for meat and fish. Less room for human error in the cleaning process
Ideally you should have separate colour-coded cutting boards:
Red: Raw meat
Blue: Raw Fish
Brown: Raw vegetables
Green: Salad/Fruit
White: Bakery/Dairy
Yellow: Cooked Meat
I’m not sure there is a Straight Dope answer here, too many competing claims.
Seperate boards are inarguably a good thing.
If you do food prep that must conform to any health code, the best thing is compliance to the letter of the law.
Staff Report by Hawk: What’s better, a wooden cutting board or a plastic one?
And a link from a thread in Staff Reports: http://faculty.vetmed.ucdavis.edu/faculty/docliver/Research/cuttingboard.htm
I never bother with this, although my set is indeed color-coded, with a handy little picture in the corner to remind me which is which! 
I can use different flexies in the same prep for different foods, or I can bleach in between, or I can order my prep- veggies/fruit first, then raw meat or fish, then the flexie goes into the sink.
I NEVER use wood anymore for meat or fish- only fruit or veggies.
ETA- a squirt bottle of bleach solution is very handy to have at the sink…
What I posted is what a commercial kitchen in the UK is supposed to do. They often have separate colour-coded knives too, unless the chef/cook has their own knives. When I worked as a kitchen porter in a hospital, which is a job at which I lasted one week, they had the coloured boards and the coloured knives.
What’s the reasoning behind cutting “raw vegetables” on the brown board and “salad”, which is generally a mix of raw vegetables, on the green one? For that matter, why separate cutting boards for vegetables and fruit, is it taste cross-contamination perhaps? (Nobody wants to cut an apple on a board that’s just been used to cut onions…)
Ah- of course a commercial kitchen (hopefully, please God…) is held to a much higher standard than my kitchen.
Raw veggies might have dirt, containing who knows what, on them. It doesn’t matter too much if they’re going to be cooked, but you wouldn’t want to contaminate your fresh salad leaves or fruit that will be eaten raw. Raw carrots, say for a salad, would be washed and peeled and then cut on the green board, where as carrots to be cooked, would be peeled and then chopped on the brown board.