Microbial applications and tools for environmental management and assessment

Different microbial applications and tools were developed for environmental management and assessment. We lead applied research working at different scales, beginning with projects at a laboratory scale, but as well experimenting with demonstrative projects (pilot plants). We work to discern about mechanisms related to pathogen removal, water treatment and reuse, and biomaterials production, both combining traditional and molecular microbiology techniques. We also work in the production, characterization and processing of biopolymers, as well as in the analysis of their degradation by microorganismsPeer Reviewe

Visible light enhances the antimicrobial effect of some essential oils

The photodisinfection is a topical, broad spectrum antimicrobial technology, targeting bacteria, virus, fungi, and protozoa effective for single cells as for biofilms. Natural molecules have been studied less than synthetic agents in the process but they are currently receiving great interest. Therefore, the aim of this study is to evaluate for the first time if non-coherent blue and red light enhances the antimicrobial activity of some essential oils when standard strains for antibiotic or fungicide tests are enlightened in vitro. Staphylococcus epidermidis, Pseudomonas aeruginosa and Candida albicans collection strains were irradiated with monochromatic visible light from light emitting diodes in the presence of 5% and 0.5% eucalyptus (Eucalyptus globulus), clove (Eugenia caryophyllata), and thyme (Thymus vulgaris) essential oils. Microbial levels were measured by plate count on culture media. In this preliminary report, the results differ according to the kind and concentration of antimicrobial oils, the wavelength of light, and the prokaryotic or eukaryotic microorganism. The results support the idea that mainly blue light enhances the innate antimicrobial activity of the essential oils, especially phenols, and could offer a very efficient and natural way to combat microorganisms in several industries and medical applications.Postprint (author's final draft

Poly[(R)-3-hydroxybutyrate] production under different salinity conditions by a novel Bacillus megaterium strain

Bacillus megaterium uyuni S29, isolated from the Bolivian salt lake Uyuni, displays a high capability to produce poly[(R)-hydroxybutyrate] (PHB) in industrial culture media. In order to analyze the influence of salt on biomass formation and PHB production, cultivations at different NaCl concentrations were carried out according to the salinity conditions of the habitats of the strain’s original isolation. In this preliminary report, the strain showed considerable adaptability to media of different salinity, obtaining the best results for both cellular growth and PHB production in media containing 45 g/L NaCl. The strain grew at 100 g/L NaCl and PHB production was observed even at high salt levels of 250 g/L without unwanted concurrent spore formation. Its tolerance to high salt concentrations together with auspicious PHB productivity makes this strain appealing not only for PHB production, but also for other biotechnological applications such as the treatment of salty wastewater; additional studies will be needed to further increase PHB productivity.Postprint (published version

Estudio comparativo de la carrera académica del profesorado en las universidades públicas politécnicas españolas desde un perspectiva de género

Postprint (published version

Conjunctival Short-term Evolution after Pterygium Excision

Purpose To analyze conjunctival cytological features 1 month after pterygium excision using limbo-conjunctival autograft (LCA) with and without intraoperative mitomycin C and to assess tissue short-term evolution in both situations.; Methods Fifty-nine primary nasal pterygia from 59 patients were excised with LCA. Twenty-nine were treated with intraoperative mitomycin C 0.02% (MMC+) and 30 were treated without it (MMC-). Impression cytology was performed in nasal and temporal conjunctiva before and 1 month after the excision. Goblet cell density (GCD) and nucleus-to-cytoplasm nongoblet epithelial cell ratio were quantified.; Results Surgical strategy comparisons (intergroup comparisons): All the preoperative data were, in mean, within the reference range, except for a slight goblet cell hyperplasia in the area of the lesion in MMC+ but no significant differences were found between the groups (p = 0.079 for GCD and p = 0.245 for nucleus-to-cytoplasm ratio; analysis of variance). Clinically relevant differences after surgery were only shown in nasal GCD that was significantly lower in MMC+ than in MMC- (p = 0.000; analysis of variance), with the mean value in MMC+ slightly below normal values whereas that in MMC- remained normal. Tissue evolution (intragroup comparisons): No clinically relevant changes were found in MMC-. Data from MMC+ displayed no changes 1 month after surgery, except for nasal GCD that showed a significant reduction (p = 0.000; paired t test). Nevertheless, this GCD decrease was more modest than that previously described using mitomycin C without autograft, because in the present study, nasal GCD was not lower but similar to postoperative temporal data of the same eye (p = 0.164; paired t test).; Conclusions Limbo-conjunctival autograft is a good technique for conjunctiva early recovery. When mitomycin C was added, the GCD reduction was lower than described using other surgical techniques. Mitomycin C, in optimal concentration and exposure, associated with LCA could be a good clinical option to minimize pterygium recurrence.Postprint (author's final draft

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

Influence of glycerol on poly(3-hydroxybutyrate) production by Cupriavidus necator and Burkholderia sacchari

Glycerol is a co-product of many industrial processes and is generated in large quantities from different origins. In this study, glycerol is used as a cheap carbon source for the production of poly(3- hydroxybutyrate) (PHB) with two different collection strains, Cupriavidus necator and Burkholderia sacchari, in order to provide an alternative outlet for glycerol and produce value-added bioproducts. The objective of this work was to study the influence of this carbon source on their growth kinetics, on their polymer production, and on the molecular mass of the produced biopolymer. Therefore, fermentations in bioreactors were carried out with these strains. Different results for both strains were obtained showing, for the first time, a high cell dry mass and growth rate, when glycerol was used together with glucose in the fermentation with C. necator. In the first fermentation with B. sacchari using glycerol as a sole carbon source, the strain properly developed synthesizing PHB. The biopolymers obtained from both fermentations with glycerol showed low molecular masses about 300 kDa with a polydispersity of 4.72 with C. necator, and 200 kDa with polydispersity of 2.50 with B. sacchari.Postprint (author's final draft

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