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Item type:Publication, Access status: with files , Tropical agroindustrial biowaste revalorization through integrative biorefineries—review part II: pineapple, sugarcane and banana by-products in Costa RicaBiorefineries are a model for greener production processes, based on the concept of bioeconomy. Instead of targeting first-generation biofuels—that compete with food supply—the focus relies on lignocellulosic material, considering many aspects, such as sustainable fuel production, as well as valorization of waste, as an alternative to the traditional petrochemical approach of goods production. Especially, in tropical countries agricultural activities lead to tremendous amounts of biomass, resulting in waste that has to be dealt with. In the case of Costa Rica, the five major crops cultivated for export are coffee, oil palm, pineapple, sugarcane, and banana. Traditional ways of waste treatment cannot cope with the increasing amount of biomass produced and therefore, bear various challenges often related to increased pollution. This review aims to bring up the recent state of waste treatment but even more, stress potential opportunities of adding value to not used residues; thus, improve sustainability in the agro industrial sector. Part I of the review already highlighted the potential of producing promising bioactive chemical compounds by novel biorefinery concepts from agricultural waste originating from coffee and oil palm cultivation. This second part focuses on the lignocellulose-rich biowaste from pineapple, sugarcane, and banana, showing biorefinery concepts, where fuel and energy production, as well as establishment of novel products and new applications, play an important role.Publicationtype: Review ArticleScopus© Citations 10 75 114 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Tropical agroindustrial biowaste revalorization through integrative biorefineries—review part I: coffee and palm oil by-products(Springer, 2021-04-13); ; ; ; Tropical crops are an important source of wealth in many countries. The current agribusiness model is based on the production of a final commodity, leading to the production of organic by-products (biowastes) that in many cases contain bioactive compounds with a potential added value. The exploitation of these by-products is the foundation of the circular economy that leads to the generation of greener bioprocesses for the industry with foreseeable economic improvements in production systems. This review aims to point out the idle opportunities of agricultural production systems and their associated biowastes to contribute to the establishment of a bioeconomy. Hence, the focus lies on five tropical extensive crops: coffee, oil palm, sugar cane, banana, and pineapple. This first part of the review explores agricultural wastes originated from the coffee and oil palm industrial process and is oriented on the potential use of these by-products as a starting material for the alternative obtention of chemicals, otherwise obtained from petrochemistry. The second part of the review focuses on prospective use of lignocellulosic rich biowaste that is derived from the industrialization of sugar cane, banana, and pineapple. A fundamental difference for the use of coffee biomass compared to other crops is the presence of numerous bioactive compounds that are not yet properly utilized, such as antioxidants (i.e., caffeic acid, chlorogenic acid, ferulic acid), as well as their possible use in the manufacture of products of interest in the cosmetic (i.e., quinic acid) or pharmaceutical industry (i.e., caffeic acid phenethyl ester). In the case of oil palm, its potential lies in obtaining chemicals such as glycerol and carotenoids, or in the bioenergy production.Publicationtype: Review ArticleScopus© Citations 16 110 110 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Synthetic pathways and processes for effective production of 5-hydroxytryptophan and serotonin from glucose in Escherichia coliTryptophan derivatives such as 5-hydroxytryptophan (5HTP) and serotonin are valuable molecules with pharmaceutical interest. 5HTP is presently mainly obtained by extraction from the plant Griffonia simplicifolia and serotonin is produced by chemical synthesis. A simple biotechnological method for the production of these compounds is desired.Publicationtype: Journal ArticleScopus© Citations 31 370 351 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Protein engineering and synthetic pathways in Escherichia coli for effective production of 5-hydroxytryptophan and serotoninMetabolic engineering has improved the production of tryptophan in E. coli during the last two decades, opening itself a plethora of opportunities for the production of tryptophan derivatives. 5-Hydroxytryptophan (5HTP) and serotonin are two important derivatives not only important for their pharmaceutical value but also because they could serve as a precursor of other molecules which includes sleep cycle regulator, anti-migraine medications, sedatives, anticonvulsants, antitumors, antimicrobials, antivirals, among others. To the present, 5HTP is mainly obtained by extraction from the plant Griffonia simplicifolia and serotonin is produced by chemical synthesis. In both cases, the processes involve the use of organic solvents and high temperature during the procedure. Moreover, in the case of serotonin, its chemical synthesis starts from a complex molecule (5-benzyloxyindole). A simple biotechnological method for the production of these compounds is desired. This dissertation presents the work done in the extension of the tryptophan metabolism for the production of 5HTP and serotonin. For this purpose, serotonin production via tryptamine and via 5HTP were compared and analyzed. In both cases, the hydroxylation step seemed to be the bottleneck due to the low activity of the enzymes when expressed in E. coli and the requirement of a cofactor, plus its regeneration pathway. The serotonin production pathway via 5HTP was chosen, and for this purpose, an aromatic amino acid hydroxylase from Cupriavidus taiwanensis (CtAAAH) was selected using an in silico structure-based approach. Several substrate-determining residues were predicted and selected using sequence, phylogenetic and functional divergence analyses. Whole cells analysis with the wild-type and variants were done to study the shift of the enzyme preference from phenylalanine to tryptophan. All the variants increased the tryptophan hydroxylation activity in detriment to phenylalanine. The best performer, CtAAAH-W192F, was transformed into a strain that had the tryptophanase A gene disrupted and carried a human tetrahydrobiopterin (BH4) regeneration pathway. The resulting strain was capable of synthesizing 2.5 mM 5HTP after 24 hours in medium supplied with tryptophan. After this first rational design round, a second semi-rational approach was selected to improve the efficiency of the enzyme. A tryptophan intracellular concentration sensor was used to screen two independent libraries, and the variants found in the best performer of each library were combined to create CtAAAH-LC. This double mutant showed higher activity and reaction velocity than its predecessor. CtAAAH-LC was transformed into a tryptophan producer strain (S028), which had been previously modified by the addition of a pterin (a cofactor that is consumed during hydroxylation) regeneration pathway. In this case, 5HTP was synthesized from glucose. Tryptophan decarboxylase (TDC) was incorporated in the 5HTP producer strain to produce serotonin from glucose. However, the serotonin production was low and undesired side reactions were identified. To circumvent this problem, a two-step system was constructed in which the 5HTP production and the serotonin conversion are separated. In this work, results of the highest biotechnologically produced concentration of 5HTP reported so far are presented, for this purpose protein engineering was done in CtAAAH and a synthetic pathway was incorporated in E. coli. Afterwards, 5HTP was decarboxylated to produce serotonin in a second fermentation. This is the first report of serotonin production from glucose. Still, the process can be further optimized by combining the hydroxylation and decarboxylation reaction in one strain. TDC selectivity can be engineered to shift the preference toward 5HTP in detriment of tryptophan. In this case, the development of a novel biosensor sensitive to 5HTP is critical for selection.Publicationtype: Doctoral Thesis479 1087