Recent advances and strategies in process and strain engineering for the production of butyric acid by microbial fermentation.

•Fermentative butyric acid production is an environmentally friendly process.•Feedstocks are primarily sugars but lignocellulose is a better long-term candidate.•Cell immobilized fermentation in the FBB increases butyric acid productivity.•Engineered C. tyrobutyricum capable of co-utilization of xylose and glucose.•Increasing butyric acid selectivity is important for process economic performance.