After just more than 100 years of history of industrial acetone–butanol–ethanol (ABE) fermentation, patented by Weizmann in the UK in 1915, butanol is again today considered a promising biofuel alternative based on several advantages compared to the more established biofuels ethanol and methanol. Large-scale fermentative production of butanol, however, still suffers from high substrate cost and low product titers and selectivity. There have been great advances the last decades to tackle these problems. However, understanding the fermentation process variables and their interconnectedness with a holistic view of the current scientific state-of-the-art is lacking to a great extent. To illustrate the benefits of such a comprehensive approach, we have developed a dataset by collecting data from 175 fermentations of lignocellulosic biomass and mixed sugars to produce butanol that reported during the past three decades of scientific literature and performed an exploratory data analysis to map current trends and bottlenecks. This review presents the results of this exploratory data analysis as well as main features of fermentative butanol production from lignocellulosic biomass with a focus on performance indicators as a useful tool to guide further research and development in the field towards more profitable butanol manufacturing for biofuel applications in the future. Electronic supplementary material The online version of this article (10.1186/s13068-019-1508-6) contains supplementary material, which is available to authorized users.

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Efficient production of sugar monomers from lignocellulose is often hampered by serious bottle-necks in biomass hydrolysis. The present study reveals that ultra-sonication assisted pretreatment following autoclaving, termed as combined pretreatment, can lead to more efficient delignification of lignocellulosic biomass and an open, deformed polysaccharide matrix, found favorable for subsequent enzymatic hydrolysis, is formed. The pattern of inhibition for the enzymatic hydrolysis reaction on combined-pretreated saw dust is identified. Two main inhibition models (competitive and noncompetitive) are proposed and a better fit of experimental values with the theoretical values for the competitive inhibition model validates the proposition that in the present experiment, glucose inhibits the enzymes competitively. Additionally, accuracy of the inhibitory kinetics based models is estimated over a series of enzyme and substrate concentrations. A prominent departure in the range of residual concentrations from the competitive model supports the same proposition, in comparison to the non-competitive model.

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Background Butanol (n-butanol) has been gaining attention as a renewable energy carrier and an alternative biofuel with superior properties to the most widely used ethanol. We performed 48 anaerobic fermentations simultaneously with glucose and xylose as representative lignocellulosic sugars by Clostridium beijerinckii NCIMB 8052 in BioLector® microbioreactors to understand the effect of different sugar mixtures on fermentation and to demonstrate the applicability of the micro-cultivation system for high-throughput anaerobic cultivation studies. We then compared the results to those of similar cultures in serum flasks to provide insight into different setups and measurement methods. Results ANOVA results showed that the glucose-to-xylose ratio affects both growth and production due to Carbon Catabolite Repression. The study demonstrated successful use of BioLector® system for the first time for screening several media and sugar compositions under anaerobic conditions by using online monitoring of cell mass and pH in real-time and at unprecedented time-resolution. Fermentation products possibly interfered with dissolved oxygen (DO) measurements, which require a careful interpretation of DO monitoring results. Conclusions The statistical approach to evaluate the microbioreactor setup, and information obtained in this study will support further research in bioreactor and bioprocess design, which are very important aspects of industrial fermentations of lignocellulosic biomass.