I haven't used anything other than water on my rides to work, but am now looking into something to hold my hot tea and the suggestions here look good.

But for that creepy looking growing stuff... I regularly fill my bottles with warm water, drop a denture cleaner tablet in and let it sit for 20 minutes or so. Cleans, kills bacteria and removes any lingering smell from my electrolyte drinks, so I haven't had to toss any bottles due to aliens growing in it, or funny smells. I get the denture cleaner at the .99c store so it is cheap to do.