Integrated bioprocess approach for the production of xylooligosaccharides

The demand of prebiotic ingredients has been growing over the years as consumers pay more attention to their health. Xylooligosaccharides (XOS) are considered emergent and competitively priced prebiotics, presenting high potential as food ingredients. As a result, the industry is focused on developing new approaches to improve their production efficiency to meet the increasing demand while reducing costs. Hence, the main purpose of this work was to develop an integrated bioprocess, based on one-step fermentation, for the production of prebiotic XOS, towards the simplification and cost reduction of the process. The one-step fermentation of 13 agro-residues was done using two Trichoderma species. The most promising results were found for T. reesei using brewers spent grain (BSG) as substrate. BSG is an inexpensive and abundant agroindustrial residue that was proven interesting for the production of arabino-xylooligosaccharides (AXOS). In order to reduce the production time obtained with T. reesei (3 d), the Bacillus subtilis 3610 wild type (wt) was successfully used to produce AXOS through direct fermentation of BSG, reducing the production time to 12 h. Genetic engineering was used to further optimize the microorganism performance, by cloning the T. reesei xylanase gene coupled with a secretion tag into the B. subtilis chromosome (B. subtilis 3610 clone 2). This strategy led to a yield increase of 33 % comparing to the wt, and 29 % comparing to the T. reesei. B. subtilis 3610 clone 2 was also selected for downscale production of XOS by direct fermentation of commercial beechwood xylan. The maximum production yield, 306 ± 4 mg/g (XOS/xylan), was achieved after 8 h of fermentation operating under one-time impulse fed-batch regimen. In vitro studies using human fecal inocula were performed to evaluate and compare the potential prebiotic effect of commercial lactulose and the XOS herein produced. The significant increase in the production of short chain fatty acids and CO2, added to the reduction of pH and ammonia concentration suggest that the XOS hold potential functional properties for human health. The results gathered provide important insights for the development of new integrated strategies for XOS production from agro-residues.info:eu-repo/semantics/publishedVersio

Gibbs free energy of transfer of a methylene group on {UCON + (sodium or potassium) phosphate salts} aqueous two-phase systems: Hydrophobicity effects

The Gibbs free energy of transfer of a suitable hydrophobic probe can be regarded as a measure of the relative hydrophobicity of the different phases. The methylene group (CH2) can be considered hydrophobic, and thus be a suitable probe for hydrophobicity. In this work, the partition coefficients of a series of five dinitrophenylated-amino acids were experimentally determined, at 23 °C, in three different tie-lines of the biphasic systems: (UCON + K2HPO4), (UCON + potassium phosphate buffer, pH 7), (UCON + KH2PO4), (UCON + Na2HPO4), (UCON + sodium phosphate buffer, pH 7), and (UCON + NaH2PO4). The Gibbs free energy of transfer of CH2 units were calculated from the partition coefficients and used to compare the relative hydrophobicity of the equilibrium phases. The largest relative hydrophobicity was found for the ATPS formed by dihydrogen phosphate salts.Fundação para a Ciência e a Tecnologia (FCT) - Programa "Ciência 2007", SFRH/BD/43439/2008LSREFEDER/POCI/201

Bonding of fiber posts with different cements

Poster presented at the “From Basic Sciences to Clinical Research” - First International Congress of CiiEM. Caparica, Portugal, 27-28 November 2015"Since their development in 1989 the use of fiber posts on endodontically treated teeth has become common on dentistry and it is supported by clinical evidence. There has been many developments by the different manufactures improving the reliability and durability of the cements used with the fiber posts.Objectives: Measure the bond strength of cement with the push-out test in different root thirds (cervical, middle and apical) at 24h and at 6 months with and without restoration and with different cements.

Cation effect on the (PEG 8000 + sodium sulfate) and (PEG 8000 + magnesium sulfate) aqueous two-phase system: Relative hydrophobicity of the equilibrium phases

The partitioning of four dinitrophenylated (DNP-) amino acids in aqueous two-phase systems of polyethylene glycol (PEG)-8000sodium sulfate and polyethylene glycol (PEG)-8000magnesium sulfate in five different tie-lines was experimentally determined at 298.15 K. The Gibbs free energy of transfer of a methylene group between the two phases was calculated from the measured partition coefficients. This characterizes the relative hydrophobicity of the equilibrium phases. Values of G(CH2) were in range from (-0.674 to -1.012) kJ·mol-1. A comparison of both systems was carried out. The results show that the cation type has a strong influence on the amino acids partitioning process. The largest relative hydrophobicity was noted for the ATPS system formed by sodium sulfate. This showed to be a better system for the separation.FCT/MEC and FEDER under Programe PT2020 (Project UID/EQU/50020/2013), and co-financed by QREN, ON2 and FEDER (Projects NORTE-07-0162-FEDER-000050 and NORTE-07-0124-FEDER-0000011

Laccase partition in ATPS: finding some molecular descriptors

Aqueous Two-Phase Systems (ATPS) are known since 1896, when Beijerinck reported the formation of a biphasic system after mixing aqueous solutions of gelatine and agar or gelatine and starch. However, only in the 50’s, Albertsson showed the potential of these systems in the separation and purification of several biological constituents.1 In general, ATPS are obtained by mixing two aqueous solutions of different constituents that become immiscible above certain critical conditions, like temperature, concentration, etc. Both phases are composed mainly by water (>80%) and each one is enriched in a different component. ATPS formed by two polymers or a polymer and a salt represent the traditional systems. Nevertheless, other alternative biphasic systems can be obtained using surfactants, micellar compounds or ionic liquids

Exploitation of olive oil mil wastewater for esterase production

[Excerpt] Development of bio-sustainable and renewable resource technologies is extremely important on environmental contexts. Waste can contain many valuable substances and, through a suitable process or technology, this material can be converted into value-added products or raw materials that can be used in secondary processes. To reduce the environmental problems caused by olive oil mill wastewater (OOMW), which is the liquid effluent produced during the extraction process of olive oil, this waste can be applied to bioproducts production. (...

Perspectives on the biotechnological production and potential applications of lactosucrose: A review

Lactosucrose is a synthetic trisaccharide composed of galactose, glucose and fructose. This compound is obtained through enzymatic synthesis using lactose and sucrose as substrates. The enzymes involved in the process are able to catalyse both hydrolysis and transfer reactions. The yield and productivity of the process are usually affected by the occurrence of parallel hydrolysis of the newly formed product (lactosucrose). Therefore, it is important to find efficient strategies to avoid or minimize product degradation. Furthermore, in the last decades the demand for lactosucrose has significantly increased. This compound is considered a potential prebiotic and several beneficial effects associated to its consumption have been described. As a result, it has been included in the formulations of functional foods. This review covers the most relevant information about lactosucrose, including its synthesis and purification, beneficial effects at physiological level, and also its potential applications.Fundação para a Ciência e a Tecnologia (FCT) Strategic Project of UID/BIO/04469/2013 unit, the project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and the project “BioInd – Biotechnology and Bioengineering for im- proved Industrial and Agro-Food processes”, REF. NORTE-07- 0124-FEDER-000028 co-funded by the Programa Operacional Regional do Norte (ON. 2–ONovo Norte), QREN, FEDER

Biocatalytic approaches using lactulose: end product compared with substrate

Lactulose is a lactose-based carbohydrate with well-known prebiotic effect and recognized medical applications. Currently, the commercially available lactulose is chemically synthesized. Nevertheless, the process leads to low yields and high levels of by-products. Alternatively, lactulose can be produced by enzymatic synthesis, which provides a cleaner production under mild conditions. Two different enzymatic routes were reported for lactulose production. Lactulose can be obtained through hydrolysis and transfer reactions catalyzed by a glycosidase. Alternatively, lactulose can be produced by direct isomerization of lactose to lactulose catalyzed by cellobiose-2-epimerase. An interesting characteristic of lactulose is also its capacity to act as substrate in additional enzymatic synthesis which leads to the formation of attractive compounds, such as lactulose-based oligosaccharides and lactulose esters. Besides increasing the interest and potential of lactulose, these lactulose-based compounds can also offer new and promising functionalities and applications. Herein, we review the enzymes involved in the synthesis of lactulose, as well as the reaction conditions and yields. The potential of different enzymes is discussed and it is shown that reaction conditions and composition of products depend on the type of enzyme and its microbial source. The conversion of lactulose into lactulose-based compounds is also covered, describing in detail the biocatalysts involved, the reaction conditions used, and the potential of the final products obtained.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684). The authors also thank the FCT for the financial support under the scope of the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462). SCS also acknowledges her post doc grant (SFRH/BPD/88584/2012) from FCT

Relative hydrophobicity of (PEG or Ucon)-salt ATPSs

Aqueous Two-Phase Systems (ATPSs) are biphasic systems composed mainly by water. ATPSs are obtained upon mixing of two aqueous solutions of certain polymers or a polymer and a salt (above certain critical conditions, e.g. concentration, temperature). These systems are commonly indicated for the extraction of biomolecules. In this work, the partition coefficients for a series of five dinitrophenylated amino-acids (ranging from glycine to amino-caprylic acid) were determined experimentally in five different polymer-salt ATPSs (polymers: PEG or Ucon; salts: Na2SO4, Li2SO4 or (NH4)2SO4) at 23ºC. Values of the free energy of transfer of a methylene group, ΔG(CH2), for the five ATPSs were obtained from the partition coefficients and compared with ΔG(CH2) previously obtained for PEG-Na2SO4 (Rodríguez et al., 2007). Ucon-salt ATPSs presented higher values of ΔG(CH2) than the corresponding PEG-salt systems, witch indicates that the Ucon-rich phase is more hydrophobic than the PEG-rich phase

Production of Natural Pigments by Penicillium brevicompactum Using Agro-Industrial Byproducts

The demand for natural pigments for industrial applications has significantly increased. Penicillium brevicompactum was recently reported as a promising pigments producer using submerged fermentation and a synthetic culture medium containing lactose. In this work, pigment production by P. brevicompactum was studied under different fermentation conditions, namely, submerged fermentation with free (SmF) and immobilized mycelium (SmFi), and solid-state fermentation (SSF). The potential of culture media composed of agro-industrial byproducts (cheese-whey (CW) and corn steep liquor (CSL)) was investigated for the first time as low-cost alternatives to pigment production by P. brevicompactum. The fungus showed great adaptability to the different culture media and types of fermentation, being able to synthesize pigments under all the tested conditions. A culture medium composed of 34.6 g/L of CW and 8 g/L of CSL proved to be the most suitable alternative to the synthetic medium, especially under SmF and SmFi. Our data also show that different mixtures of pigments (yellow, orange, and red) can be produced depending on the medium composition and the type of fermentation. Additionally, the immobilization and reuse of biomass to produce pigments by P. brevicompactum were demonstrated for the first time, suggesting the possibility of operating under repeated batch mode at an industrial scale