198 research outputs found
Production of short-chain fatty acids (SCFAs) as chemicals or substrates for microbes to obtain biochemicals
No full text[Abstract] Carboxylic acids have become interesting platform molecules in the last years due to their versatility to act as carbon sources for different microorganisms or as precursors for the chemical industry. Among carboxylic acids, short-chain fatty acids (SCFAs) such as acetic, propionic, butyric, valeric, and caproic acids can be biotechnologically produced in an anaerobic fermentation process from lignocellulose or other organic wastes of agricultural, industrial, or municipal origin. The biosynthesis of SCFAs is advantageous compared to chemical synthesis, since the latter relies on fossil-derived raw materials, expensive and toxic catalysts and harsh process conditions. This review article gives an overview on biosynthesis of SCFAs from complex waste products. Different applications of SCFAs are explored and how these acids can be considered as a source of bioproducts, aiming at the development of a circular economy. The use of SCFAs as platform molecules requires adequate concentration and separation processes that are also addressed in this review. Various microorganisms such as bacteria or oleaginous yeasts can efficiently use SCFA mixtures derived from anaerobic fermentation, an attribute that can be exploited in microbial electrolytic cells or to produce biopolymers such as microbial oils or polyhydroxyalkanoates. Promising technologies for the microbial conversion of SCFAs into bioproducts are outlined with recent examples, highlighting SCFAs as interesting platform molecules for the development of future bioeconomy.This article is based upon work from COST Action Yeast4Bio (CA18229), supported by COST (European Cooperation in Science and Technology). Open access funding provided by Swedish University of Agricultural Sciences. CK, NOL, MCV from the BIOENGIN group, are grateful to Xunta de Galicia for its financial support to Competitive Reference Research Groups (ED431C 2021/55). They also thank the Spanish Ministry of Science and Innovation and European FEDER funding (PID2020-117805RB-I00) for financing ongoing research, at the BIOENGIN group, on the topic of this paper. ETP, CGF and SG acknowledge the projects BIOMIO + H2 (PID2020-119403RBC21) funded by MCIN/AEI/http://dx.doi.org/10.13039/501100011033 and OLEOFERM (EraBoBiotech; PCI2021-121936) funded by MCIN/AEI/http://dx.doi.org/10.13039/501100011033 and “European Union NextGenerationEU/PRTR”. ETP also acknowledges the grant RYC2019-027773-I funded by MCIN/AEI/http://dx.doi.org/10.13039/501100011033 and by “ESF Investing in your future”. VP and BM were supported by the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (Formas) [grant number 2018–01877]Xunta de Galicia; ED431C 2021/55Suecia. Research Council for Environment, Agricultural Sciences and Spatial Planning (Formas); 2018–0187
Physiology and gene expression profiles of Dekkera bruxellensis in response to carbon and nitrogen availability
No full textThe assimilation of nitrate, a nitrogenous compound, was previously described as an important factor favoring Dekkera bruxellensis in the competition with Saccharomyces cerevisiae for the industrial sugarcane substrate. In this substrate, nitrogen sources are limited and diverse, and a recent report showed that amino acids enable D. bruxellensis to grow anaerobically. Thus, understanding the regulation of nitrogen metabolism is one fundamental aspect to comprehend the competiveness of D. bruxellensis in the fermentation environment. In the present study, we evaluated the physiological and transcriptional profiles of D. bruxellensis in response to different carbon and nitrogen supplies to determine their influence on growth, sugar consumption, and ethanol production. Besides, the expression of genes coding for nitrogen permeases and enzymes involved in the biosynthesis of glutamate and energetic metabolism were investigated under these conditions. Our data revealed that genes related to nitrogen uptake in D. bruxellensis are under the control of nitrogen catabolite repression. Moreover, we provide indications that glutamate dehydrogenase and glutamate synthase may switch roles as the major pathway for glutamate biosynthesis in D. bruxellensis. Finally, our data showed that in nonoptimal growth conditions, D. bruxellensis leans toward the respiratory metabolism. The results presented herein show that D. bruxellensis and S. cerevisiae share similar regulation of GDH-GOGAT pathway, while D. bruxellensis converts less glucose to ethanol than S. cerevisiae do when nitrogen is limited. The consequence of this particularity to the industrial process is discussed
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