[wickedfrags]

I should provide a little info as I worked as a hazardous materials management consultant for 10 years (asbestos, mould, PCBs and the like), and still deal with similar issues in my current role. So if you have any other questions just post them here and I can give you my opinion.

If you are short on cash, the bathroom silicone is your best bet. Also be mindful that much of the info you find on the internet on mould is inaccurate and blown out of proportion. Ensure the surface is clean and dry before you apply the caulking. I would not recommend the use of bleach. Bleach is not used by mould removal/abatement companies because of how harsh the chemical is, and at the end of the day there is no "guarantee" that you killed all the mould because you used bleach. Any disinfectant cleaner suitable for the bathroom should do the trick.

Mould essentially requires three things to grow, moisture, a relatively dark cool location, and a food source. Take any of the 3 elements away, and the mould will stop growing.

The food source on drywall is the cellulose-based paper on the back of the drywall. It is for this reason drywall is no longer used in locations that expect water throughout the life cycle of the building, such as bathrooms in houses. Cement board replaces drywall in modern homes. Generally, 90% of mould on drywall is on the back of the drywall and not visible.

Also (an FYI for those reading this about mould), the "musty" smell you may notice in some basements when you enter, well this is evidence of mould actively growing somewhere in the basement. MVOC's is what creates that odour, microbial volatile organic compounds, the by-product of active mould growth.

Ironically I did my bathroom reno about 3 months back and found ample mould. Be certain to wear a respirator/dust mask with a N95 rating before significantly disturbing mould contaminated materials.