What is the Non-GMO enzyme alternative to rennet that is used for Organic Whey? Marzyme Vegetarian Rennet. Marzyme Vegetarian Rennet is used in cheese making as an alternative to animal extract coagulants. Marzyme is microbial in origin and produced by fermentation of a purified culture of Mucor miehei. Have more questions? Submit a request 0 Comments Article is closed for comments.