Colonización fungica de lentes de contacto

En la presente tesis doctoral se han estudiado los factores implicados en el proceso de colonización fúngica (adhesión e invasión) de lentes de contacto nuevas y procedentes de usuarios.Para ello se ha diseñado una fase experimental en la que se han observado, mediante microscopía óptica, las lentes procedentes de usuarios a fin de determinar la presencia o ausencia de hongos. Cuando se detectaron, y para poder proceder a su identificación taxonómica, se procedió a la realización de cultivos.Las lentes nuevas fueron cultivadas con diferentes cepas de hongos y se valoró la frecuencia y densidad de colonización según las condiciones de cultivo establecidas.La caracterización morfológica de las diferentes especies fúngicas, experimentadas y encontradas, se realizó utilizando microscopía óptica, confocal y electrónica de barrido.Los resultados obtenidos indican que: el 11,82% de las lentes procedentes de usuarios mostraban contaminación. Entre los hongos contaminantes encontrados se describen tres nuevas citas, Gliomastix, Humicola y Phoma. Así mismo, se ha establecido que únicamente las cepas 93150 de Candida albicans y 2700 de Aspergillus niger fueron cepas de colonizar las lentes nuevas.Por otra parte, se ha comprobado que la composición de los medios de cultivo, su evaporación y las características quimicas de las lentes (ionicidad e hidrofilia), son factores que influyen en la frecuencia de colonización y en la densidad de las hifas invasoras.Finalmente, la microscopía confocal por reflexión de luz ha permitido visualizar las colonias internas y su grado de penetración en el material de la lente.Las conclusiones obtenidas representan una contribución al conocimiento de los fenómenos determinantes del desarrollo de hongos en los diferentes polímeros estudiados. Suponen, además, un avance en el campo de la contactología clínica y explican algunos de los problemas

Novi soj bakterije, izoliran iz bolivijskog slanog jezera, prikladan za proizvodnju poli[(R)-3-hidroksibutirata]

Poly[(R)-3-hydroxybutyrate] (PHB) constitutes a biopolymer synthesized from renewable resources by various microorganisms. This work focuses on finding a new PHB-producing bacterium capable of growing in conventional media used for industrial biopolymer production, its taxonomical identification, and characterization of its biopolymer. Thus, a bacterial isolation process was carried out from environmental samples of water and mud. Among the isolates, strain S29 was selected and used in a fed-batch fermentation to generate a biopolymer. This biopolymer was recovered and identified as PHB homopolymer. Surprisingly, it featured several fractions of different molecular masses, and thermal properties unusual for PHB. Hence, the microorganism S29, genetically identified as a new strain of Bacillus megaterium, proved to be interesting not only due to its growth and PHB accumulation kinetics under the investigated cultivation conditions, but also due to the thermal properties of the produced PHB.Poli[(R)-3-hidroksibutirat] (PHB) je biopolimer kojega sintetiziraju različiti mikroorganizmi iz obnovljivih izvora. Težište je rada bilo na pronalasku novog soja bakterije koji može proizvesti PHB na različitim industrijskom podlogama, te provesti taksonomsku identifikaciju soja i karakterizaciju biopolimera. Stoga su iz uzoraka vode i mulja izolirani sojevi bakterija, te je šaržnim postupkom fermentacije s pritokom supstrata pomoću odabranog soja S29 proizveden biopolimer, kasnije određen kao homopolimer PHB. Iznenađujuće je što je biopolimer imao više frakcija različitih molekularnih masa i termička svojstva neuobičajena za PHB. Time je potvrđeno da je novi soj bakterije Bacillus megaterium S29 zanimljiv ne samo zbog kinetičkih značajki rasta i akumulacije PHB, već i zbog termičkih svojstava proizvedenog biopolimera

Novel Poly[(R)-3-Hydroxybutyratel-producing bacterium isolated from a bolivian hypersaline lake

Poly [ ( R )-3-hydroxybutyrate ] (PHB) constitutes a biopolymer synthesized from renew- able resources by various microorganisms. This work focuses on finding a new PHB-produc- ing bacterium capable of growing in conventional media used for industrial biopolymer production, its taxonomical identification, and characterization of its biopolymer. Thus, a bacterial isolation process was carried out from environmental samples of water and mud. Among the isolates, strain S29 was selected and used in a fed-batch fermentation to gene- rate a biopolymer. This biopolymer was recovered and identified as PHB homopolymer. Surprisingly, it featured several fractions of different molecular masses, and thermal prop- erties unusual for PHB. Hence, the microorganism S29, genetically identified as a new strain of Bacillus megaterium , proved to be interesting not only due to its growth and PHB accumulation kinetics under the investigated cu ltivation conditions, but also due to the thermal properties of the produced PHBPostprint (published version

New PHB-producing Bacillus Strain from Environmental Samples

Many microorganisms are known to synthesize poly[(R)-3-hydroxybutyrate] (PHB) from renewable resources. This biocompatible and biodegradable biopolyester possesses similar properties to some of the conventional plastics such as polypropylene. However, PHB is not competitive with the polymers from the oil industry so far due to its high production costs. An aproach to overcome this problem is to discover new microorganisms with higher polymer productivity. Therefore, the main objectives of this chapter are focused on finding a new PHB-producing bacterium from environmental samples capable of growing in different salts conditions, and on characterizing the biopolymer produced. A bacterial isolation process was carried out with environmental samples of water and mud from different Bolivian salt lakes. One bacterium from the Uyuni salt lake fulfilled the selection conditions and was consequently used in an initial fermentation to generate biopolymer in order to identify and characterize it via Fourier transform infrared microscopy (FTIR), nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DS) analyses. Then, the microorganism was tested in different fed-batch fermentation processes to determine its PHB production potential, and to analyse the influence of salt content in the medium on both, the cell growth and the PHB production. The selected biopolymer synthetised in a conventional medium used for industrial biopolymer production was identified as PHB homopolymer. Surprisingly, it featured several fractions of different molecular masses and thermal properties unusual for PHB. The results of fermentation in the 3L-bioreactor showed a high specific growth rate. The highest polymer content ever reached for the genus Bacillus was up to 70% PHB of cell dry mass. The strain turned out to be appealing not only due to its growth and PHB accumulation kinetics under the cultivation conditions investigated, but also due to the thermal properties of the PHB produced. Also, the strain shows a high adaptability to media with high salt concentrations, constantly synthesizing PHB. The strain was taxonomically identified by molecular processes as the novel strain of Bacillus megaterium uyuni S29. It is deposited in the Spanish Type Culture Collection and its nucleotide sequence is deposited at GenBank. The tolerance to the salt, together with the production of biopolymer, makes this strain viable for its utilization in the biotechnological production of PHA as well as for other applications such as the treatment of salty wastewater

New PHB-producing Bacillus Strain from Environmental Samples

Many microorganisms are known to synthesize poly[(R)-3-hydroxybutyrate] (PHB) from renewable resources. This biocompatible and biodegradable biopolyester possesses similar properties to some of the conventional plastics such as polypropylene. However, PHB is not competitive with the polymers from the oil industry so far due to its high production costs. An aproach to overcome this problem is to discover new microorganisms with higher polymer productivity. Therefore, the main objectives of this chapter are focused on finding a new PHB-producing bacterium from environmental samples capable of growing in different salts conditions, and on characterizing the biopolymer produced. A bacterial isolation process was carried out with environmental samples of water and mud from different Bolivian salt lakes. One bacterium from the Uyuni salt lake fulfilled the selection conditions and was consequently used in an initial fermentation to generate biopolymer in order to identify and characterize it via Fourier transform infrared microscopy (FTIR), nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DS) analyses. Then, the microorganism was tested in different fed-batch fermentation processes to determine its PHB production potential, and to analyse the influence of salt content in the medium on both, the cell growth and the PHB production. The selected biopolymer synthetised in a conventional medium used for industrial biopolymer production was identified as PHB homopolymer. Surprisingly, it featured several fractions of different molecular masses and thermal properties unusual for PHB. The results of fermentation in the 3L-bioreactor showed a high specific growth rate. The highest polymer content ever reached for the genus Bacillus was up to 70% PHB of cell dry mass. The strain turned out to be appealing not only due to its growth and PHB accumulation kinetics under the cultivation conditions investigated, but also due to the thermal properties of the PHB produced. Also, the strain shows a high adaptability to media with high salt concentrations, constantly synthesizing PHB. The strain was taxonomically identified by molecular processes as the novel strain of Bacillus megaterium uyuni S29. It is deposited in the Spanish Type Culture Collection and its nucleotide sequence is deposited at GenBank. The tolerance to the salt, together with the production of biopolymer, makes this strain viable for its utilization in the biotechnological production of PHA as well as for other applications such as the treatment of salty wastewater.Postprint (published version

New PHB-producing Bacillus Strain from Environmental Samples

Many microorganisms are known to synthesize poly[(R)-3-hydroxybutyrate] (PHB) from renewable resources. This biocompatible and biodegradable biopolyester possesses similar properties to some of the conventional plastics such as polypropylene. However, PHB is not competitive with the polymers from the oil industry so far due to its high production costs. An aproach to overcome this problem is to discover new microorganisms with higher polymer productivity. Therefore, the main objectives of this chapter are focused on finding a new PHB-producing bacterium from environmental samples capable of growing in different salts conditions, and on characterizing the biopolymer produced. A bacterial isolation process was carried out with environmental samples of water and mud from different Bolivian salt lakes. One bacterium from the Uyuni salt lake fulfilled the selection conditions and was consequently used in an initial fermentation to generate biopolymer in order to identify and characterize it via Fourier transform infrared microscopy (FTIR), nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DS) analyses. Then, the microorganism was tested in different fed-batch fermentation processes to determine its PHB production potential, and to analyse the influence of salt content in the medium on both, the cell growth and the PHB production. The selected biopolymer synthetised in a conventional medium used for industrial biopolymer production was identified as PHB homopolymer. Surprisingly, it featured several fractions of different molecular masses and thermal properties unusual for PHB. The results of fermentation in the 3L-bioreactor showed a high specific growth rate. The highest polymer content ever reached for the genus Bacillus was up to 70% PHB of cell dry mass. The strain turned out to be appealing not only due to its growth and PHB accumulation kinetics under the cultivation conditions investigated, but also due to the thermal properties of the PHB produced. Also, the strain shows a high adaptability to media with high salt concentrations, constantly synthesizing PHB. The strain was taxonomically identified by molecular processes as the novel strain of Bacillus megaterium uyuni S29. It is deposited in the Spanish Type Culture Collection and its nucleotide sequence is deposited at GenBank. The tolerance to the salt, together with the production of biopolymer, makes this strain viable for its utilization in the biotechnological production of PHA as well as for other applications such as the treatment of salty wastewater

Enzymatic degradation of poly(3-hydroxybutyrate) by a commercial lipase

Polyesters such as poly(3-hydroxybutyrate) (PHB) have attracted commercial and academic interest as new biotechnological materials. In previous studies it was confirmed that two commercial lipases hydrolyzed the ester bonds from the 3HB fractions of P(3HB-co-4HB) copolymer. In this study, one of the previously used commercial lipases has been used for the enzymatic degradation of PHB homopolymer obtained via fermentation with Cupriavidus necator in order to obtain low molecular mass polymer. The results confirmed the enzymatic reaction of the used lipase with this PHB and show a controlled decrease of the molecular mass from 300,000 Da–4000 Da.Peer ReviewedPostprint (published version

Enzymatic degradation of poly(3-hydroxybutyrate) by a commercial lipase

Polyesters such as poly(3-hydroxybutyrate) (PHB) have attracted commercial and academic interest as new biotechnological materials. In previous studies it was confirmed that two commercial lipases hydrolyzed the ester bonds from the 3HB fractions of P(3HB-co-4HB) copolymer. In this study, one of the previously used commercial lipases has been used for the enzymatic degradation of PHB homopolymer obtained via fermentation with Cupriavidus necator in order to obtain low molecular mass polymer. The results confirmed the enzymatic reaction of the used lipase with this PHB and show a controlled decrease of the molecular mass from 300,000 Da–4000 Da.Peer Reviewe

Modification of titanium surfaces by adding antibiotic-loaded PHB spheres and PEG for biomedical applications

Novel researches are focused on the prevention and management of post-operative infections. To avoid this common complication of implant surgery, it is preferable to use new biomaterials with antibacterial properties. Therefore, the aim of this work is to develop a method of combining the antibacterial properties of antibiotic-loaded poly(3-hydroxybutyrate) (PHB) nano-and micro-spheres and poly(ethylene glycol) (PEG) as an antifouling agent, with titanium (Ti), as the base material for implants, in order to obtain surfaces with antibacterial activity. The Ti surfaces were linked to both PHB particles and PEG by a covalent bond. This attachment was carried out by firstly activating the surfaces with either Oxygen plasma or Sodium hydroxide. Further functionalization of the activated surfaces with different alkoxysilanes allows the reaction with PHB particles and PEG. The study confirms that the Ti surfaces achieved the antibacterial properties by combining the antibiotic-loaded PHB spheres, and PEG as an antifouling agent

Modification of titanium surfaces by adding antibiotic-loaded PHB spheres and PEG for biomedical applications

Novel researches are focused on the prevention and management of post-operative infections. To avoid this common complication of implant surgery, it is preferable to use new biomaterials with antibacterial properties. Therefore, the aim of this work is to develop a method of combining the antibacterial properties of antibiotic-loaded poly(3-hydroxybutyrate) (PHB) nano-and micro-spheres and poly(ethylene glycol) (PEG) as an antifouling agent, with titanium (Ti), as the base material for implants, in order to obtain surfaces with antibacterial activity. The Ti surfaces were linked to both PHB particles and PEG by a covalent bond. This attachment was carried out by firstly activating the surfaces with either Oxygen plasma or Sodium hydroxide. Further functionalization of the activated surfaces with different alkoxysilanes allows the reaction with PHB particles and PEG. The study confirms that the Ti surfaces achieved the antibacterial properties by combining the antibiotic-loaded PHB spheres, and PEG as an antifouling agent