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Author Torrella Barrufet, Joan |
Abstract Over the last decades, due to the limited availability of refined sugars worldwide, numerous research efforts have focused on the implementation of a range of non-sugar, renewable feedstocks for the production of biofuels and biochemicals. However, the microbial growth characteristics and bioprocessing challenges and opportunities of each of them have not been compared yet. With the aim to highlight the most promising feedstocks, here we have analyzed a set of experimentally measured growth parameters of microorganisms growing under different feedstocks. These alternative carbon sources can be classified into three simple groups: lignocellulosic-derived biomass, C1 feedstocks, including CO2, methanol and methane, and C2 feedstocks, comprising acetic acid. Based on a comprehensive literature search, we have also classified the most critical challenges of the implementation of these feedstocks on industrialscale bioprocesses into specific categories, which we used to establish a comparative analysis across carbon sources. Based on its miscibility, the ease of generating strains with improved acetate assimilation or tolerance, its wide host availability and low cost, we determined that acetate is one of the most promising alternative feedstocks to be used in industrial-scale fermentations in the near future. We hope that the analysis we provide in this review will serve as a roadmap for the sustainable and economically feasible bioproduction from a non-sugar feedstock. In parallel to establishing a transversal comparison across carbon sources, the second underlying aim of this project was to develop a production system of glycoglycerolipids in recombinant E.coli, using the previously mentioned feedstock: acetate; and a selection system based on functional complementation of the acetate assimilation pathway. Former master student Xavier Carol successfully developed an ΔaceA mutant E. coli strain (i.e. aceA is an essential gene for acetate assimilation). Plasmids carrying the aceA gene to complement the auxotrophy were also generated and named pLaceA and pSaceA. The sequence of these plasmidic vectors was verified here. The growth behavior of the ΔaceA mutant and wild type strains under minimal medium with glucose or acetate was also analyzed in this work. Results indicate that after a first overnight incubation in LB medium, an overnight incubation in M9.1 medium prior to the growth analysis is strictly necessary to reduce variability. Moreover, the in silico design of the cloning strategy of the MG517 gene, encoding for a glycosyltransferase, into the pSaceA and pLaceA was successfully developed. Future experiments should focus on performing the designed cloning strategy, analyzing the glycoglycerolipids yield of the transformed ΔaceA strain and eventually testing the performance of the developed platform in a bioreactor. |
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Director Carnicer Heras, Marc |
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Degree IQS SE - Master’s Degree in Bioengineering |
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Date 2020-07-21
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