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Biobased 2-butanol offers high potential as biofuel, but its toxicity toward microbial hosts calls for efficient techniques to alleviate product inhibition in fermentation processes. Aiming at the selective recovery of 2-butanol, the feasibility of a process combining in situ vacuum stripping followed by vapor adsorption has been assessed using mimicked fermentation media. The experimental vacuum stripping of model solutions and corn stover hydrolysate closely aligned with mass transfer model predictions. However, the presence of lignocellulosic impurities affected 2-butanol recovery yields resulting from vapor condensation, which decreased from 96 wt % in model solutions to 40 wt % using hydrolysate. For the selective recovery of 2-butanol from a vapor mixture enriched in water and carbon dioxide, silicalite materials were the most efficient, particularly at low alcohol partial pressures. Integrating in situ vacuum stripping with vapor adsorption using HiSiv3000 proved useful to effectively concentrate 2-butanol above its azeotropic composition (>68 wt %), facilitating further product purification., OLD BT/Cell Systems Engineering, BT/Bioprocess Engineering, Applied Sciences, ChemE/Catalysis Engineering

(Poly)methyl methacrylate is a valuable thermoplastic with wide application in several fields. Currently, methyl methacrylate (MMA) can be produced from ethene via methyl propionate using the Alpha technology, a more environmentally friendly method than the typical acetonecyanohydrin route. Nevertheless, the use of lignocellulosic materials as feedstock to produce bio‐based MMA would potentiate the recycling of agricultural waste biomass, theoretically resulting in zero‐carbon emissions, contrasting with the current use of petrochemical feedstocks. This would also mitigate the industrial impact on climate change. In the present thesis, a bio‐based approach for the production of methyl propionate, the precursor of MMA, has been proposed. The overall process involves a two‐step biotransformation, starting with the anaerobic fermentation of lignocellulosic sugars into 2‐ butanol, pursuing a metabolic route via butanone (a.o.). 2‐Butanol is further used as chemical precursor in a cascade enzymatic reaction, where methyl propionate and ethyl acetate are formed from the Baeyer‐Villiger (BV) oxidation of butanone. The techno‐economic feasibility of this bio‐based approach has been assessed, and critical issues affecting the practicability of the proposed process have been identified at a very early stage of strain engineering and process design…, BT/Bioprocess Engineering

A new approach was studied for bio-based production of methyl propionate, a precursor of methyl methacrylate. Recombinant E. coli cells were used to perform a cascade reaction in which 2-butanol is reduced to butanone using alcohol dehydrogenase, and butanone is oxidized to methyl propionate and ethyl acetate using a Baeyer-Villiger monooxygenase (BVMO). Product was removed by in situ stripping. The conversion was in line with a model comprising product formation and stripping kinetics. The maximum conversion rates were 1.14 g-butanone/(L h), 0.11 g-ethyl acetate/(L h), and 0.09 g-methyl propionate/(L h). The enzyme regioselectivity towards methyl propionate was 43% of total ester. Starting from biomass-based production of 2-butanol, full-scale ester production with conventional product purification was calculated to be competitive with petrochemical production if the monooxygenase activity and regioselectivity are enhanced, and the costs of bio-based 2-butanol are minimized., Accepted Author Manuscript, BT/Bioprocess Engineering

This paper describes the effect of several inhibiting components on three potential hosts for the bio-based production of methyl propionate, namely, wild-type Escherichia coli and Bacillus subtilis, and evolved Saccharomyces cerevisiae IMS0351. The inhibition by the lignocellulose-derived products 5-hydroxymethyl-2-furaldehyde, vanillin, and syringaldehyde and the fermentation products 2-butanol, 2-butanone, methyl propionate, and ethyl acetate has been assessed for these strains in defined medium. Multiple screenings were performed using small-scale cultures in both shake flasks and microtiter plates. Technical drawbacks revealed the limited applicability of the latter in this study. The microbial growth was characterized by means of a lag-time model, and the inhibitory thresholds were determined using product-inhibition models. The lignocellulose-derived products were found to be highly inhibitory, and none of the strains could grow in the presence of 2.0 g L−1 of product. From the fermentation products tested, methyl propionate had the most severe impact resulting in complete inhibition of all the strains when exposed to concentrations in the range of 12–18 g L−1. In general, S. cerevisiae and B. subtilis were comparatively more tolerant than E. coli to all the fermentation products, despite E. coli’s lower sensitivity towards vanillin. The results suggest that, overall, the strains investigated have good potential to be engineered and further established as hosts for the bio-based production of methyl esters., BT/Bioprocess Engineering, OLD BT/Cell Systems Engineering