Why not try a vacuum cleaner, rub a bit of mild disinfectant on the nozzle keep a little way from the machine. It will certainly lift all the loose flour/semolina around the base of the machine
Set the rollers to their widest setting, hold the tube close to the rollers and as you crank the machine it should also remove all the gunk.
Inspect, and if you ...
Personally I just use hot water and soap. Generally bacteria don't last long on surfaces that have been thoroughly cleaned with soap and dried.
Also, if you're using a wooden cutting board once it's dry 99.9% of any bacteria on there will be dead.
If you're concerned about this though this review recommends:
Keep the sponge away from raw meat. "If you're ...
(Assuming you wash by hand, if you have a dishwasher, just put everything in ... )
Just use plain'ol dishwasher soap and hot water.
If you have really dirty dishes, scrub them them first before washing them; so that the water you use to wash them after will be clean(er).
In general, Keep a clean cooking environment.
Your cleaning equipment (brush, ...