| 1. |
- Birgisson, Hakon, et al.
(author)
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Cold adapted yeasts as producers of cold active polygalacturonases
- 2003
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In: Extremophiles. - : Springer Science and Business Media LLC. - 1433-4909 .- 1431-0651. ; 7:3, s. 185-193
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Journal article (peer-reviewed)abstract
- Eight cold-adapted, polygalacturonase-producing yeasts belonging to four species were isolated from frozen environmental samples in Iceland. They were identified as Cystofilobasidium lari-marini, Cystofilobasidium capitatum, Cryptococcus macerans and Cryptococcus aquaticus species by sequence analysis of rDNA regions. Growth behavior of the isolates was investigated. All strains could grow at 2°C. Addition of glucose to pectin-containing culture medium had a repressive effect on enzyme production except for C. aquaticus, which showed increased polygalacturonase activity. Optimal temperature for enzyme production for the Cystofilobasidium strains was 14°C, while that for the Cryptococcus strains was lower. Among the isolates, C. lari-marini S3B produced highest levels of enzyme activity at pH 3.2. Preliminary characterization of the polygalacturonases in the culture supernatant showed the enzyme from Cystofilobasidium strains to be optimally active at 40°C and pH 5, and that from the Cryptococcus strains at 50°C and pH 4. The polygalacturonase from C. macerans started to lose activity after 1 h of incubation at 40°C, while that from the other strains had already lost activity at 30°C. All the strains except C. aquaticus produced isoenzymes of polyglacturonase. In addition to polygalacturonase, the Cystofilobasidium strains produced pectin lyase, C. aquaticus pectin esterase, and C. macerans pectin lyase, pectate lyase and pectin esterase.
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| 2. |
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| 3. |
- Borde, X, et al.
(author)
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Synergistic relationships in algal-bacterial microcosms for the treatment of aromatic pollutants.
- 2003
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In: Bioresource Technology. - 1873-2976. ; 86:3, s. 293-300
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Journal article (peer-reviewed)abstract
- The potential of algal–bacterial microcosms was studied for the biodegradation of salicylate, phenol and phenanthrene. The isolation and characterization of aerobic bacterial strains capable of mineralizing each pollutant were first conducted. Ralstonia basilensis was isolated for salicylate degradation, Acinetobacter haemolyticus for phenol and Pseudomonas migulae and Sphingomonas yanoikuyae for phenanthrene. The green alga Chlorella sorokiniana was then cultivated in the presence of the pollutants at different concentrations, showing increasing inhibitory effects in the following order: salicylate85%) was recorded only in the systems inoculated with both algae and bacteria and incubated under continuous lighting. This study presents, to our knowledge, the first reported case of photosynthesis-enhanced biodegradation of toxic aromatic pollutants by algal–bacterial microcosms in a one-stage treatment.
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| 4. |
- Cirne, Dores, et al.
(author)
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Clostridium lundense sp nov., a novel anaerobic lipolytic bacterium isolated from bovine rumen
- 2006
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In: International Journal of Systematic and Evolutionary Microbiology. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 56:3, s. 625-628
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Journal article (peer-reviewed)abstract
- A strictly anaerobic, mesophilic, endospore-forming, lipolytic bacterium, designated strain R1(T), was isolated from bovine rumen fluid and characterized. Cells of this isolate were Gram-positive, non-motile rods that formed spherical terminal spores. The overall biochemical and physiological characteristics indicated that this strain should be placed in the genus Clostridium. The strain grew at temperatures between 25 and 47 degrees C (optimum, 37 degrees C), at pH between 5(.)0 and 8(.)5 (optimum pH 5(.)5-7(.)0) and in NaCl concentrations of 0-3% (w/v). The isolate was not able to utilize glucose or other carbohydrates as carbon sources. The DNA G+C content was 31(.)2 mol%. Sequence analysis of the 16S rRNA gene of R1(T) revealed that it has the closest match (98 % similarity) with Clostridium tetanomorphum DSM 4474(T). The highest levels of DNA-DNA relatedness of the isolate were 61(.)9 and 54(.)3 % with Clostridium pascui DSM 10365(T) and C. tetanomorphum DSM 4474(T), respectively. Based on 16S rRNA gene sequence similarity, phylogenetic analysis, DNA G+C content, DNA-DNA hybridization data and distinct phenotypic characteristics, strain R1(T) (=DSM 17049(T)=CCUG 50446(T)) was classified in the genus Clostridium, as a member of a novel species, for which the name Clostridium lundense sp. nov. is proposed.
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| 5. |
- Coronado, Liani, et al.
(author)
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Investigation of chronic and persistent classical swine fever infections under field conditions and their impact on vaccine efficacy
- 2019
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In: BMC Veterinary Research. - : BioMed Central (BMC). - 1746-6148. ; 15:1
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Journal article (peer-reviewed)abstract
- Background: Recent studies have hypothesized that circulation of classical swine fever virus (CSFV) variants when the immunity induced by the vaccine is not sterilizing might favour viral persistence. Likewise, in addition to congenital viral persistence, CSFV has also been proven to generate postnatal viral persistence. Under experimental conditions, postnatal persistently infected pigs were unable to elicit a specific immune response to a CSFV live attenuated vaccine via the mechanism known as superinfection exclusion (SIE). Here, we study whether subclinical forms of classical swine fever (CSF) may be present in a conventional farm in an endemic country and evaluate vaccine efficacy under these types of infections in field conditions.Results: Six litters born from CSF-vaccinated gilts were randomly chosen from a commercial Cuban farm at 33 days of age (weaning). At this time, the piglets were vaccinated with a lapinized live attenuated CSFV C-strain vaccine. Virological and immunological analyses were performed before and after vaccination. The piglets were clinically healthy at weaning; however, 82% were viraemic, and the rectal swabs in most of the remaining 18% were positive. Only five piglets from one litter showed a specific antibody response. The tonsils and rectal swabs of five sows were CSFV positive, and only one of the sows showed an antibody response. After vaccination, 98% of the piglets were unable to clear the virus and to seroconvert, and some of the piglets showed polyarthritis and wasting after 36 days post vaccination. The CSFV E2 glycoprotein sequences recovered from one pig per litter were the same. The amino acid positions 72(R), 20(L) and 195(N) of E2 were identified in silico as positions associated with adaptive advantage.Conclusions: Circulation of chronic and persistent CSF infections was demonstrated in field conditions under a vaccination programme. Persistent infection was predominant. Here, we provide evidence that, in field conditions, subclinical infections are not detected by clinical diagnosis and, despite being infected with CSFV, the animals are vaccinated, rather than diagnosed and eliminated. These animals are refractory to vaccination, likely due to the SIE phenomenon. Improvement of vaccination strategies and diagnosis of subclinical forms of CSF is imperative for CSF eradication.
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| 6. |
- de las Nieves Montano, Damarys, et al.
(author)
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Influenza aviar. Oportunidades de mejora del sistema de vigilancia activa basado en riesgo en Cuba
- 2020
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In: Revista de Salud Animal. - : SciELO Cuba. - 0253-570X .- 2224-4700. ; 42:3
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Journal article (peer-reviewed)abstract
- El perfeccionamiento continuo de la vigilancia y el control de la influenza aviar (IA) son prioridades a nivel mundial debido a la permanencia de esta amenaza a escala global. El objetivo del presente trabajo fue identificar oportunidades de mejora en el sistema de vigilancia activa de la IA establecido en Cuba. Mediante análisis geoespacial multicriterio se mapeó con resolución de 1 km2. Adicionalmente, se tuvo en cuenta la existencia de zonas de contigüidad entre granjas avícolas (< 3 km) donde pudiera verse favorecida la difusión del agente causal en caso de introducción. Como resultado, se identificaron áreas con muy alto riesgo de ocurrencia, ya sea por exposición o difusión que, en ocasiones, se favoreció por la contigüidad entre granjas avícolas comerciales. A partir de estos hallazgos se logró refinar el criterio preexistente para la selección de granjas a ser investigadas durante la vigilancia activa, lo cual pudiera mejorar la capacidad de detección de casos positivos. La precisión y el manejo del riesgo de difusión son de gran importancia porque suele ser el principal determinante de la magnitud de la epidemia. Se concluye que existen áreas estratégicas y de marcada importancia hacia donde se deben dirigir, prioritariamente, los principales recursos para fortalecer la bioseguridad y la vigilancia encaminada a la alerta rápida.
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| 7. |
- Delgado, Osvaldo, et al.
(author)
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Chromosomal integration and expression of green fluorescent protein in Zymomonas mobilis
- 2002
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In: Biotechnology Letters. - 1573-6776. ; 24:15, s. 1285-1290
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Journal article (peer-reviewed)abstract
- An integrative vector was constructed to allow expression of heterologous proteins into the adhB locus of Zymomonas mobilis. As a reporter gene, the ORF of a bright variant of green fluorescent protein from Aequorea victoria (GFPuv) was fused to the adhB strong promoter from Z. mobilis by using a two-step PCR strategy. Z. mobilis recombinant strains that were stably marked by precise gene replacement at adhB locus with a single chromosomal copy of gfpuv. Protein expression was confirmed by fluorescence microscopy and measured by fluorescence spectroscopy, showing high expression levels (12 to 30 times higher than those obtained in E. coli) without affecting the host growth.
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| 8. |
- Delgado, Osvaldo, et al.
(author)
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Nesterenkonia aethiopica sp nov., an alkaliphilic, moderate halophile isolated from an Ethiopian soda lake
- 2006
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In: International Journal of Systematic and Evolutionary Microbiology. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 56:6, s. 1229-1232
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Journal article (peer-reviewed)abstract
- T Strain DSM 17733(T), isolated from the shore of Lake Abjata in Ethiopia, is a heterotrophic, alkaliphilic, moderately halophilic, Gram-positive, strictly aerobic, non-motile, non-endospore-forming bacterium. The organism grows optimally at 30-37 degrees C, pH 9 and 3 % (w/v) NaCl. Analysis of the cell wall showed the presence of murein of the type L-Lys-Gly-L-Glu, variation A4 alpha. The G + C content of the genomic DNA was 69(.)0 mol%. Sequence analysis of 16S rRNA gene sequence of strain DSM 17733(T) placed the isolate in the genus Nesterenkonia. DNA-DNA hybridization of DSM 17733(T) with those organisms with the closest phylogenetic affiliation, i.e. Nesterenkonia halobia, Nesterenkonia facusekhoensis and Nesterenkonia xinjiangensis, gave relatedness values of 48.5 %, 63(.)7 % (repetition, 57(.)2 %) and 35(.)7 % (repetition, 29(.)3 %), respectively. On the basis of both phenotypic and phylogenetic criteria and the low levels of DNA-DNA relatedness with the phylogenetically closest species N. xinjiangensis and N. halobia, it is proposed that the isolate be classified in a novel species, Nesterenkonia aethiopica sp. nov. The type strain is DSM 17733(T) (=CCUG 48939(T)).
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| 9. |
- Fernandes, S, et al.
(author)
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Beta-galactosidase from a cold-adapted bacterium: purification, characterization and application for lactose hydrolysis.
- 2002
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In: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 1432-0614 .- 0175-7598. ; 58:3, s. 313-321
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Journal article (peer-reviewed)abstract
- The enzyme beta-galactosidase was purified from a cold-adapted organism isolated from Antarctica. The organism was identified as a psychrotrophic Pseudoalteromonas sp. The enzyme was purified with high yields by a rapid purification scheme involving extraction in an aqueous two-phase system followed by hydrophobic interaction chromatography and ultrafiltration. The beta-galactosidase was optimally active at pH 9 and at 26 degrees C when assayed with o-nitrophenyl-beta-D-galactopyranoside as substrate for 2 min. The enzyme activity was highly sensitive to temperature above 30 degrees C and was undetectable at 40 degrees C. The cations Na+, K+, Mg2+ and Mn2+ activated the enzyme while Ca2+, Hg2+, Cu2+ and Zn2+ inhibited activity. The shelf life of the pure enzyme at 4 degrees C was significantly enhanced in the presence of 0.1% (w/v) polyethyleneimine. The pure beta-galactosidase was also evaluated for lactose hydrolysis. More than 50% lactose hydrolysis was achieved in 8 h in buffer at an enzyme concentration of 1 U/ml, and was increased to 70% in the presence of 0.1% (w/v) polyethyleneimine. The extent of lactose hydrolysis was 40-50% in milk. The enzyme could be immobilized to Sepharose via different chemistries with 60-70% retention of activity. The immobilized enzyme was more stable and its ability to hydrolyze lactose was similar to that of the soluble enzyme.
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| 10. |
- Hashim, Suhaila, et al.
(author)
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Alkaline active maltohexaose-forming α-amylase from Bacillus halodurans LBK 34
- 2005
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In: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229. ; 36:1, s. 139-146
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Journal article (peer-reviewed)abstract
- The gene encoding Amy 34, a maltohexaose-forming α-amylase from Bacillus halodurans LBK 34 isolated from Lake Bogoria, Kenya, was cloned and sequenced. The mature peptide consists of 958 amino acids with a theoretical molecular weight of 107.2 kDa and pI 4.41, respectively. The gene was expressed in Escherichia coli and the recombinant enzyme purified to homogeneity by a combination of metal chelate affinity and size exclusion chromatography. The pure enzyme exhibited optimum activity at 60 °C and pH 10.5–11.5. The enzyme retained over 60% activity after incubation at 55 °C for 4 h and was most stable at pH 9.0. Complete inhibition of enzyme activity was observed in presence of 5 mM Cu2+, Fe2+, Fe3+, Mn2+ and 5 mM EDTA. The enzyme displayed 80% of its original activity in presence of 1% (w/v) SDS and was stable in presence of up to 5 mM DTT. Maltohexaose (G6) was the main initial product of starch hydrolysis while other products formed were G4 > G2 > G5 > G3 and G1. The main end product of the enzyme's action on amylose, amylopectin and maltodextrin is maltotetraose. Amy 34 could not hydrolyse pullulan, α and β-cyclodextrin but could hydrolyse γ-cyclodextrin to produce glucose, maltose and maltotetraose. Maltotetraose was the smallest α-(1–4) linked maltooligosaccharide that could be hydrolysed by the enzyme.
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