Developments in biobutanol production: New insights

Biobutanol will become an attractive, economic and sustainable fuel as petroleum oil leads towards expensive fuel due to diminishing oil reserves and an increase of green house gases in the atmosphere. The major challenges in biobutanol production are low butanol titer, availability of compatible feedstocks, and product inhibition. These hurdles are being resolved using several genetic engineering techniques, metabolic engineering strategies, and promising integrated continuous fermentation processes with efficient product recovery techniques (like gas stripping). Adequate success in utilizing renewable and cost-effective cellulosic materials as feedstocks has opened up novel grounds for the advancement in economic biobutanol production. In this direction, Clostridium beijerinckii is being explored as promising strain to produce biobutanol from cellulosic materials. Moreover, high biobutanol titer is being focused through genetic modifications of Clostridia and non-Clostridia organisms (e.g., Escherichia coli, Saccharomyces cerevisiae, Pseudomonas putida, and Bacillus subtilis) in both aerobic and anaerobic fermentation. Further, application of various novel genetic tools and genome sequencing of hyper-butanol-producing Clostridial organism will enhance the scope of genetic engineering for biobutanol production. Therefore, consolidation of academic and industrial research towards economic synthesis of biobutanol illustrates the possibility of substantial breakthrough in future. In this review, we focus on (i) selection of suitable bacterial strain (ii) availability of cheaper biomass to produce butanol (iii) metabolic engineering strategies of various microorganisms (iv) attempts at process development and (v) biobutanol recovery techniques that provide future direction of economical biobutanol fermentation. © 2010 Elsevier Ltd.