Non-sterile fermentations for the economical biochemical conversion of renewable feedstocks

Heavy reliance on petroleum-based products drives continuous exploitation of fossil fuels, and results in serious environmental and climate problems. To address such an issue, there is a shift from petroleum sources to renewable ones. Biochemical conversion via fermentation is a primary platform for converting renewable sources to biofuels and bulk chemicals. In order to provide cost-competitive alternatives, it is imperative to develop efficient, cost-saving, and robust fermentation processes. Non-sterile fermentation offers several benefits compared to sterile fermentation, including elimination of sterility, reduced maintenance requirements, relatively simple bioreactor design, and simplified operation. Thus, cost effectiveness of non-sterile fermentation makes it a practical platform for low cost, large volume production of biofuels and bulk chemicals. Many approaches have been developed to conduct non-sterile fermentation without sacrificing the yields and productivities of fermentation products. This review focuses on the strategies for conducting non-sterile fermentation. The challenges facing non-sterile fermentation are also discussed.