Cristiana Torres - Academia.edu (original) (raw)

Papers by Cristiana Torres

Frontiers in Bioengineering and Biotechnology, Apr 5, 2022

Bioresource Technology, Dec 1, 2017

Although the ability to secrete exopolysaccharides (EPS) is widespread among microorganisms, only... more Although the ability to secrete exopolysaccharides (EPS) is widespread among microorganisms, only a few bacterial (e.g. xanthan, levan, dextran) and fungal (e.g. pullulan) EPS have reached full commercialization. During the last years, other microbial EPS producers have been the subject of extensive research, including endophytes, extremophiles, microalgae and Cyanobacteria, as well as mixed microbial consortia. Those studies have demonstrated the great potential of such microbial systems to generate biopolymers with novel chemical structures and distinctive functional properties. In this work, an overview of the bioprocesses developed for EPS production by the wide diversity of reported microbial producers is presented, including their development and scale-up. Bottlenecks that currently hinder microbial EPS development are identified, along with future prospects for further advancement.

CRC Press eBooks, Nov 5, 2020

International Journal of Biological Macromolecules, Jun 1, 2022

Process Biochemistry, Dec 1, 2018

Abstract The fucose-rich exopolysaccharide (EPS) producer Enterobacter A47 was cultivated in medi... more Abstract The fucose-rich exopolysaccharide (EPS) producer Enterobacter A47 was cultivated in medium containing different initial phosphate concentrations (3.0–8.8 g L−1) to evaluate the effect of this nutrient on EPS synthesis. Although cell growth was unaffected, a reduction of EPS production was observed upon lowering the phosphate concentration. The highest productivity, 1.57 g L−1 d−1, was achieved for a concentration of 8.8 g L−1, being reduced by 19 and 43% for the lower phosphate concentrations tested (5.8 and 3.0 g L−1, respectively). This decrease in bioproduction yield was also associated with modifications in composition and molecular weight (Mw) of the resulting polymers. The fucose content was reduced from 30 – 36%mol, for phosphate concentrations between 5.8 and 8.8 g L−1, to 26%mol for the lowest concentration tested. This change was concomitant with an increase of the polymer’s Mw. These results demonstrated for the first time that EPS synthesis by Enterobacter A47 is affected by the medium’s phosphate concentration, being favored by higher values that also result in unique polymers enriched in the rare sugar fucose.

Carbohydrate Polymers, Jul 1, 2018

The purpose of this work is the development and characterisation of new hybrid polysaccharide (Fu... more The purpose of this work is the development and characterisation of new hybrid polysaccharide (FucoPol) membranes. These membranes were prepared by incorporation of a SiO 2 network homogeneously dispersed by using a sol-gel method with GPTMS as a crosslinker silica precursor. They were further crosslinked with CaCl 2 for reinforcement of mechanical properties and improvement of their permeation performance. They were characterised in terms of their structural, mechanical and thermal properties. They presented a dense and homogeneous structure, resistant to deformation, with a Tg of 43°C and a thermal decomposition between 240 and 251°C. The hybrid FucoPol membranes were tested for ethanol dehydration by pervaporation and also for nitrogen dehydration. They exhibited high water selectivity values, similar to PERVAP ® 4101, however they lost their stability when exposed to solutions of 10.0 wt.% water in ethanol. In contrast, these membranes were stable when applied in N 2 dehydration, leading to reproducible performance and very high water selectivities.

Nanomaterials, Jan 31, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Environmental Science and Pollution Research, Nov 13, 2021

Large quantities of waste biomass are generated annually worldwide by many industries and are vas... more Large quantities of waste biomass are generated annually worldwide by many industries and are vastly underutilized. However, these wastes contain sugars and other dissolved organic matter and therefore can be exploited to produce microbial biopolymers. In this study, four selected Halomonas strains, namely, Halomonas caseinilytica K1, Halomonas elongata K4, Halomonas smyrnensis S3, and Halomonas halophila S4, were investigated for the production of exopolysaccharides (EPS) using low-cost agro-industrial wastes as the sole carbon source: cheese whey, grape pomace, and glycerol. Interestingly, both yield and monosaccharide composition of EPS were affected by the carbon source. Glucose, mannose, galactose, and rhamnose were the predominant monomers, but their relative molar ratio was different. Similarly, the average molecular weight of the synthesized EPS was affected, ranging from 54.5 to 4480 kDa. The highest EPS concentration (446 mg/L) was obtained for H. caseinilytica K1 grown on cheese whey that produced an EPS composed mostly of galactose, rhamnose, glucose, and mannose, with lower contents of galacturonic acid, ribose, and arabinose and with a molecular weight of 54.5 kDa. Henceforth, the ability of Halomonas strains to use cost-effective substrates, especially cheese whey, is a promising approach for the production of EPS with distinct physicochemical properties suitable for various applications.

Biotechnology Reports, Jun 1, 2021

Bacterial cellulose is one of the most promising biomaterials for the development of a wide array... more Bacterial cellulose is one of the most promising biomaterials for the development of a wide array of novel biotechnological solutions. Nevertheless, the commercial production of bacterial cellulose is still a challenge and obtaining novel strains presenting increased cellulose biosynthesis and stress resistance properties is of extreme importance. This work demonstrates the increased stress resistance, cellulose production abilities, and overall genomic properties of Komagataeibacter uvaceti FXV3, a novel cellulose-producing and stress resistant strain isolated from a fermented grape must. K. uvaceti FXV3 was able to grow under several stress conditions, including the presence of high concentrations of ethanol (up to 7.5 % v/v), a trait that is not observed in the model strain K. xylinus CECT 7351 T. Moreover, K. uvaceti FXV3 produced increased concentrations of cellulose (4.31 mg/mL, 7 days after inoculation-DAI) when compared to K. xylinus CECT 7351 T (1.42 mg/mL, 7 DAI). Moreover, the detailed analysis of strain FXV3 genome revealed the presence of several genes involved in cellulose and acetan biosynthesis, quorum-sensing and quenching mechanisms, carbohydrate, amino acid, alcohol and aldehyde metabolism, as well as several other genes involved in stress resistance. Additionally, comparative genomic analysis revealed the increased prevalence of stress resistance genes in K. uvaceti FXV3 when compared to K. xylinus CECT 7351 T. Ultimately, this study reveals the increased biotechnological potential of K. uvaceti FXV3 and brings new insights into the genetics behind Komagataeibacter stress resistance and cellulose production abilities.

International Journal of Polymeric Materials, Jan 8, 2016

ABSTRACT Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical charac... more ABSTRACT Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical characteristics that impart them diverse functional properties, including the ability to produce structures from nano- to macroscale (e.g., spheres, capsules, beads). Such structures may be specially designed to fulfill the requirements of specific applications in different areas, either alone or conjugated with other polymers by means of ionic interactions, hydrogen bonding, or chemical reactions. The interest on using such biomaterials has been increasing due to their unique functional properties, nontoxicity, biodegradability, and biocompatibility. The fields of application of bacterial polymers-based structures include drug delivery, biomedicine, food products, environment, and agriculture, among others. GRAPHICAL ABSTRACT

International Journal of Biological Macromolecules, Nov 1, 2017

The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobac... more The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobacter A47, as encapsulation matrix was explored. Spherical capsules with a smooth surface were produced by spray drying. The obtained microcapsules had average diameters ranging from 0.5 to 26.7 µm and presented thin walls (thickness from 222 to 1094 nm). The capsules were loaded with two bioactive compounds: gallic acid (GA) and oregano essential oil (OEO). Both bioactive materials were encapsulated in FucoPol particles, retaining their antioxidant activity after the drying process. Release studies showed that GA release in simulated gastric and intestinal fluids was faster than that of OEO, envisaging that the latter had established stronger interactions with the polymer matrix. These results suggest that FucoPol has a good potential for use as encapsulating material of bioactive compounds for application in several areas, including food, cosmetic or pharmaceutical products.

International Journal of Biological Macromolecules, May 1, 2011

The effect of temperature on the rheology of a new fucose-containing extracellular polysaccharide... more The effect of temperature on the rheology of a new fucose-containing extracellular polysaccharide (EPS) was evaluated. The steady state data revealed a shear-thinning behavior, with the viscosity being immediately recovered when the shear rate was decreased. The mechanical spectra indicated viscous solutions with entangled polymer molecules in the range of temperatures studied (from 15 • C to 65 • C). In addition, the Time-Temperature Superposition principle was successfully applied and the Cox-Merz rule was valid, reinforcing the idea of a thermorheologically simple behavior for the EPS in aqueous solution. Furthermore, the viscous and viscoelastic properties at 25 • C were maintained after consecutive heating and cooling cycles, indicating a good thermal stability under temperature fluctuations.

Carbohydrate Polymers, Jul 1, 2010

Enterobacter sp. was grown on glycerol byproduct from the biodiesel industry for the production o... more Enterobacter sp. was grown on glycerol byproduct from the biodiesel industry for the production of a value-added exopolysaccharide (EPS). The culture broth was characterized in terms of its morphological and rheological properties throughout the cultivation run. Microscopic ...

Macromolecular Bioscience, Apr 9, 2008

The characterization of polyhydroxyalkanoates (PHA) produced by mixed cultures is fundamental for... more The characterization of polyhydroxyalkanoates (PHA) produced by mixed cultures is fundamental for foreseeing the possible final applications of the polymer. In this study PHA produced under aerobic dynamic feeding (ADF) conditions are characterized. The PHA produced shows a stable average molecular weight ($\overline M _{\rm w}$), in the range (1.0–3.0) × 106, along three years of reactor operation. Attempts to improve the amount of PHA produced did not introduce significant variations on the values of overlineMrmw\overline M _{\rm w}overlineMrmw. Along this period, the polydispersity indices (PDI) were between 1.3 and 2.2. The use of different carbon sources allowed the tailoring of polymer composition: homopolymers of poly(3‐hydroxybutyrate), P(3HB), were obtained with acetate and butyrate, whereas a mixture of acetate and propionate, and propionate and valerate, gave terpolymers of 3‐hydroxybutyrate (3HB), 3‐hydroxyvalerate (3HV), and 2‐methyl‐3‐hydroxyvalerate (2M3HV). All of these PHA had overlineMrmw\overline M _{\rm w}overlineMrmw between 2.0 × 106 and 3.0 × 106. Thermal characterization of the produced polymers showed values of glass transition temperature, melting temperature, melting enthalpy, and crystallinity slightly lower than those obtained for PHA from pure cultures. The introduction of a purification step during the polymer extraction process allowed the elimination of possible contaminants but did not significantly improve the polymer quality.magnified image

Carbohydrate Polymers, Aug 1, 2016

Highlights • FucoPol/chitosan bilayer films were prepared for application in food packaging. • Bi... more Highlights • FucoPol/chitosan bilayer films were prepared for application in food packaging. • Bilayer films showed good optical and mechanical properties. • Bilayer films are poor barriers to water vapour but excellent barriers to gases. • Bilayers presented enhanced properties comparing to FucoPol monolayer films.

Marine Drugs

Marine environments represent an enormous biodiversity reservoir due to their numerous different ... more Marine environments represent an enormous biodiversity reservoir due to their numerous different habitats, being abundant in microorganisms capable of producing biomolecules, namely exopolysaccharides (EPS), with unique physical characteristics and applications in a broad range of industrial sectors. From a total of 67 marine-derived bacteria obtained from marine sediments collected at depths of 200 to 350 m from the Estremadura Spur pockmarks field, off the coast of Continental Portugal, the Brevundimonas huaxiensis strain SPUR-41 was selected to be cultivated in a bioreactor with saline culture media and glucose as a carbon source. The bacterium exhibited the capacity to produce 1.83 g/L of EPS under saline conditions. SPUR-41 EPS was a heteropolysaccharide composed of mannose (62.55% mol), glucose (9.19% mol), rhamnose (19.41% mol), glucuronic acid (4.43% mol), galactose (2.53% mol), and galacturonic acid (1.89% mol). Moreover, SPUR-41 EPS also revealed acyl groups in its composi...

ACS Applied Bio Materials, 2021

Polymers, May 20, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Polymers

Biosurfactants synthesized by microorganisms represent safe and sustainable alternatives to the u... more Biosurfactants synthesized by microorganisms represent safe and sustainable alternatives to the use of synthetic surfactants, due to their lower toxicity, better biodegradability and biocompatibility, and their production from low-cost feedstocks. In line with this, the present study describes the physical, chemical, and functional characterization of the biopolymer secreted by the bacterium Burkholderia thailandensis DSM 13276, envisaging its validation as a biosurfactant. The biopolymer was found to be a glycolipopeptide with carbohydrate and protein contents of 33.1 ± 6.4% and 23.0 ± 3.2%, respectively. Galactose, glucose, rhamnose, mannose, and glucuronic acid were detected in the carbohydrate moiety at a relative molar ratio of 4:3:2:2:1. It is a high-molecular-weight biopolymer (1.0 × 107 Da) with low polydispersity (1.66), and forms aqueous solutions with shear-thinning behavior, which remained after autoclaving. The biopolymer has demonstrated a good emulsion-stabilizing cap...

Separation and Purification Technology

Frontiers in Bioengineering and Biotechnology, Apr 5, 2022

Bioresource Technology, Dec 1, 2017

Although the ability to secrete exopolysaccharides (EPS) is widespread among microorganisms, only... more Although the ability to secrete exopolysaccharides (EPS) is widespread among microorganisms, only a few bacterial (e.g. xanthan, levan, dextran) and fungal (e.g. pullulan) EPS have reached full commercialization. During the last years, other microbial EPS producers have been the subject of extensive research, including endophytes, extremophiles, microalgae and Cyanobacteria, as well as mixed microbial consortia. Those studies have demonstrated the great potential of such microbial systems to generate biopolymers with novel chemical structures and distinctive functional properties. In this work, an overview of the bioprocesses developed for EPS production by the wide diversity of reported microbial producers is presented, including their development and scale-up. Bottlenecks that currently hinder microbial EPS development are identified, along with future prospects for further advancement.

CRC Press eBooks, Nov 5, 2020

International Journal of Biological Macromolecules, Jun 1, 2022

Process Biochemistry, Dec 1, 2018

Abstract The fucose-rich exopolysaccharide (EPS) producer Enterobacter A47 was cultivated in medi... more Abstract The fucose-rich exopolysaccharide (EPS) producer Enterobacter A47 was cultivated in medium containing different initial phosphate concentrations (3.0–8.8 g L−1) to evaluate the effect of this nutrient on EPS synthesis. Although cell growth was unaffected, a reduction of EPS production was observed upon lowering the phosphate concentration. The highest productivity, 1.57 g L−1 d−1, was achieved for a concentration of 8.8 g L−1, being reduced by 19 and 43% for the lower phosphate concentrations tested (5.8 and 3.0 g L−1, respectively). This decrease in bioproduction yield was also associated with modifications in composition and molecular weight (Mw) of the resulting polymers. The fucose content was reduced from 30 – 36%mol, for phosphate concentrations between 5.8 and 8.8 g L−1, to 26%mol for the lowest concentration tested. This change was concomitant with an increase of the polymer’s Mw. These results demonstrated for the first time that EPS synthesis by Enterobacter A47 is affected by the medium’s phosphate concentration, being favored by higher values that also result in unique polymers enriched in the rare sugar fucose.

Carbohydrate Polymers, Jul 1, 2018

The purpose of this work is the development and characterisation of new hybrid polysaccharide (Fu... more The purpose of this work is the development and characterisation of new hybrid polysaccharide (FucoPol) membranes. These membranes were prepared by incorporation of a SiO 2 network homogeneously dispersed by using a sol-gel method with GPTMS as a crosslinker silica precursor. They were further crosslinked with CaCl 2 for reinforcement of mechanical properties and improvement of their permeation performance. They were characterised in terms of their structural, mechanical and thermal properties. They presented a dense and homogeneous structure, resistant to deformation, with a Tg of 43°C and a thermal decomposition between 240 and 251°C. The hybrid FucoPol membranes were tested for ethanol dehydration by pervaporation and also for nitrogen dehydration. They exhibited high water selectivity values, similar to PERVAP ® 4101, however they lost their stability when exposed to solutions of 10.0 wt.% water in ethanol. In contrast, these membranes were stable when applied in N 2 dehydration, leading to reproducible performance and very high water selectivities.

Nanomaterials, Jan 31, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Environmental Science and Pollution Research, Nov 13, 2021

Large quantities of waste biomass are generated annually worldwide by many industries and are vas... more Large quantities of waste biomass are generated annually worldwide by many industries and are vastly underutilized. However, these wastes contain sugars and other dissolved organic matter and therefore can be exploited to produce microbial biopolymers. In this study, four selected Halomonas strains, namely, Halomonas caseinilytica K1, Halomonas elongata K4, Halomonas smyrnensis S3, and Halomonas halophila S4, were investigated for the production of exopolysaccharides (EPS) using low-cost agro-industrial wastes as the sole carbon source: cheese whey, grape pomace, and glycerol. Interestingly, both yield and monosaccharide composition of EPS were affected by the carbon source. Glucose, mannose, galactose, and rhamnose were the predominant monomers, but their relative molar ratio was different. Similarly, the average molecular weight of the synthesized EPS was affected, ranging from 54.5 to 4480 kDa. The highest EPS concentration (446 mg/L) was obtained for H. caseinilytica K1 grown on cheese whey that produced an EPS composed mostly of galactose, rhamnose, glucose, and mannose, with lower contents of galacturonic acid, ribose, and arabinose and with a molecular weight of 54.5 kDa. Henceforth, the ability of Halomonas strains to use cost-effective substrates, especially cheese whey, is a promising approach for the production of EPS with distinct physicochemical properties suitable for various applications.

Biotechnology Reports, Jun 1, 2021

Bacterial cellulose is one of the most promising biomaterials for the development of a wide array... more Bacterial cellulose is one of the most promising biomaterials for the development of a wide array of novel biotechnological solutions. Nevertheless, the commercial production of bacterial cellulose is still a challenge and obtaining novel strains presenting increased cellulose biosynthesis and stress resistance properties is of extreme importance. This work demonstrates the increased stress resistance, cellulose production abilities, and overall genomic properties of Komagataeibacter uvaceti FXV3, a novel cellulose-producing and stress resistant strain isolated from a fermented grape must. K. uvaceti FXV3 was able to grow under several stress conditions, including the presence of high concentrations of ethanol (up to 7.5 % v/v), a trait that is not observed in the model strain K. xylinus CECT 7351 T. Moreover, K. uvaceti FXV3 produced increased concentrations of cellulose (4.31 mg/mL, 7 days after inoculation-DAI) when compared to K. xylinus CECT 7351 T (1.42 mg/mL, 7 DAI). Moreover, the detailed analysis of strain FXV3 genome revealed the presence of several genes involved in cellulose and acetan biosynthesis, quorum-sensing and quenching mechanisms, carbohydrate, amino acid, alcohol and aldehyde metabolism, as well as several other genes involved in stress resistance. Additionally, comparative genomic analysis revealed the increased prevalence of stress resistance genes in K. uvaceti FXV3 when compared to K. xylinus CECT 7351 T. Ultimately, this study reveals the increased biotechnological potential of K. uvaceti FXV3 and brings new insights into the genetics behind Komagataeibacter stress resistance and cellulose production abilities.

International Journal of Polymeric Materials, Jan 8, 2016

ABSTRACT Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical charac... more ABSTRACT Bacterial polysaccharides and polyhydroxyalkanoates present physical and chemical characteristics that impart them diverse functional properties, including the ability to produce structures from nano- to macroscale (e.g., spheres, capsules, beads). Such structures may be specially designed to fulfill the requirements of specific applications in different areas, either alone or conjugated with other polymers by means of ionic interactions, hydrogen bonding, or chemical reactions. The interest on using such biomaterials has been increasing due to their unique functional properties, nontoxicity, biodegradability, and biocompatibility. The fields of application of bacterial polymers-based structures include drug delivery, biomedicine, food products, environment, and agriculture, among others. GRAPHICAL ABSTRACT

International Journal of Biological Macromolecules, Nov 1, 2017

The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobac... more The potential of a bacterial exopolysaccharide named FucoPol, produced by the bacterium Enterobacter A47, as encapsulation matrix was explored. Spherical capsules with a smooth surface were produced by spray drying. The obtained microcapsules had average diameters ranging from 0.5 to 26.7 µm and presented thin walls (thickness from 222 to 1094 nm). The capsules were loaded with two bioactive compounds: gallic acid (GA) and oregano essential oil (OEO). Both bioactive materials were encapsulated in FucoPol particles, retaining their antioxidant activity after the drying process. Release studies showed that GA release in simulated gastric and intestinal fluids was faster than that of OEO, envisaging that the latter had established stronger interactions with the polymer matrix. These results suggest that FucoPol has a good potential for use as encapsulating material of bioactive compounds for application in several areas, including food, cosmetic or pharmaceutical products.

International Journal of Biological Macromolecules, May 1, 2011

The effect of temperature on the rheology of a new fucose-containing extracellular polysaccharide... more The effect of temperature on the rheology of a new fucose-containing extracellular polysaccharide (EPS) was evaluated. The steady state data revealed a shear-thinning behavior, with the viscosity being immediately recovered when the shear rate was decreased. The mechanical spectra indicated viscous solutions with entangled polymer molecules in the range of temperatures studied (from 15 • C to 65 • C). In addition, the Time-Temperature Superposition principle was successfully applied and the Cox-Merz rule was valid, reinforcing the idea of a thermorheologically simple behavior for the EPS in aqueous solution. Furthermore, the viscous and viscoelastic properties at 25 • C were maintained after consecutive heating and cooling cycles, indicating a good thermal stability under temperature fluctuations.

Carbohydrate Polymers, Jul 1, 2010

Enterobacter sp. was grown on glycerol byproduct from the biodiesel industry for the production o... more Enterobacter sp. was grown on glycerol byproduct from the biodiesel industry for the production of a value-added exopolysaccharide (EPS). The culture broth was characterized in terms of its morphological and rheological properties throughout the cultivation run. Microscopic ...

Macromolecular Bioscience, Apr 9, 2008

The characterization of polyhydroxyalkanoates (PHA) produced by mixed cultures is fundamental for... more The characterization of polyhydroxyalkanoates (PHA) produced by mixed cultures is fundamental for foreseeing the possible final applications of the polymer. In this study PHA produced under aerobic dynamic feeding (ADF) conditions are characterized. The PHA produced shows a stable average molecular weight ($\overline M _{\rm w}$), in the range (1.0–3.0) × 106, along three years of reactor operation. Attempts to improve the amount of PHA produced did not introduce significant variations on the values of overlineMrmw\overline M _{\rm w}overlineMrmw. Along this period, the polydispersity indices (PDI) were between 1.3 and 2.2. The use of different carbon sources allowed the tailoring of polymer composition: homopolymers of poly(3‐hydroxybutyrate), P(3HB), were obtained with acetate and butyrate, whereas a mixture of acetate and propionate, and propionate and valerate, gave terpolymers of 3‐hydroxybutyrate (3HB), 3‐hydroxyvalerate (3HV), and 2‐methyl‐3‐hydroxyvalerate (2M3HV). All of these PHA had overlineMrmw\overline M _{\rm w}overlineMrmw between 2.0 × 106 and 3.0 × 106. Thermal characterization of the produced polymers showed values of glass transition temperature, melting temperature, melting enthalpy, and crystallinity slightly lower than those obtained for PHA from pure cultures. The introduction of a purification step during the polymer extraction process allowed the elimination of possible contaminants but did not significantly improve the polymer quality.magnified image

Carbohydrate Polymers, Aug 1, 2016

Highlights • FucoPol/chitosan bilayer films were prepared for application in food packaging. • Bi... more Highlights • FucoPol/chitosan bilayer films were prepared for application in food packaging. • Bilayer films showed good optical and mechanical properties. • Bilayer films are poor barriers to water vapour but excellent barriers to gases. • Bilayers presented enhanced properties comparing to FucoPol monolayer films.

Marine Drugs

Marine environments represent an enormous biodiversity reservoir due to their numerous different ... more Marine environments represent an enormous biodiversity reservoir due to their numerous different habitats, being abundant in microorganisms capable of producing biomolecules, namely exopolysaccharides (EPS), with unique physical characteristics and applications in a broad range of industrial sectors. From a total of 67 marine-derived bacteria obtained from marine sediments collected at depths of 200 to 350 m from the Estremadura Spur pockmarks field, off the coast of Continental Portugal, the Brevundimonas huaxiensis strain SPUR-41 was selected to be cultivated in a bioreactor with saline culture media and glucose as a carbon source. The bacterium exhibited the capacity to produce 1.83 g/L of EPS under saline conditions. SPUR-41 EPS was a heteropolysaccharide composed of mannose (62.55% mol), glucose (9.19% mol), rhamnose (19.41% mol), glucuronic acid (4.43% mol), galactose (2.53% mol), and galacturonic acid (1.89% mol). Moreover, SPUR-41 EPS also revealed acyl groups in its composi...

ACS Applied Bio Materials, 2021

Polymers, May 20, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Polymers

Biosurfactants synthesized by microorganisms represent safe and sustainable alternatives to the u... more Biosurfactants synthesized by microorganisms represent safe and sustainable alternatives to the use of synthetic surfactants, due to their lower toxicity, better biodegradability and biocompatibility, and their production from low-cost feedstocks. In line with this, the present study describes the physical, chemical, and functional characterization of the biopolymer secreted by the bacterium Burkholderia thailandensis DSM 13276, envisaging its validation as a biosurfactant. The biopolymer was found to be a glycolipopeptide with carbohydrate and protein contents of 33.1 ± 6.4% and 23.0 ± 3.2%, respectively. Galactose, glucose, rhamnose, mannose, and glucuronic acid were detected in the carbohydrate moiety at a relative molar ratio of 4:3:2:2:1. It is a high-molecular-weight biopolymer (1.0 × 107 Da) with low polydispersity (1.66), and forms aqueous solutions with shear-thinning behavior, which remained after autoclaving. The biopolymer has demonstrated a good emulsion-stabilizing cap...

Separation and Purification Technology