This is my first post on Feverbee … I’ve been searching for guidance on building communities and I stumbled upon this thread!
To answer the original query, there is a startup company in Waterloo, Canada that has a great service (which is free to start) and which allows you to search for Twitter and Instagram micro influencers. You can search using all kinds of filters, including keywords, hashtags, geographic region, etc. http://www.socialpeeks.com/
That might be a good way to help you find passionate people - the sort of founders you may be seeking!