How do I minimize the risk of bacteria growth in bean sprouts?
Some of my local supermarkets stopped selling sprouts because bacterial contamination was so widespread, but that's probably more of a problem for big batches. I'm thinking that the best things you can do at home to prevent unwanted bacterial growth might be:


Sanitize your jar before use. I think a hot water bath would work, or soak in a 10% bleach solution for 30 minutes (that's how I've sanitized in a lab).
Make sure to use beans that aren't old or of poor quality. This matters less when you're cooking them but is really important for sprouting.
Maybe try using a finer cover for the sprouts, like a layer or two of cheesecloth (I don't think this should matter too much though).
Use filtered water, not tap water to soak the beans.


I generally follow these rules when I'm sprouting and haven't had a problem. 

As a relevant side note I believe the beans themselves contain their own endophytes, or native microbes that live inside, which is something to consider when sprouting. Not all bacteria/fungi are bad, and having more of the good ones there could prevent pesky pathogens (which reinforces my suggestion of using "good beans").