Shading minimizes the effects of water deficit in Campomanesia xanthocarpa (Mart) O Berg seedlings / Sombreamento minimiza o efeito do déficit hídrico em mudas de Campomanesia xanthocarpa (Mart) O Berg

The objective of this study was to evaluate the activity of antioxidant enzymes, the functioning of the photosystem II and quality of C. xanthocarpa seedlings cultivated under intermittent water deficit and shading levels and the influence of shading on recovery potential after suspension of the stress conditions. The seedlings were subjected to three levels of shading (0, 30, and 70%), six periods of evaluation (start: 0 days; 1st and 2nd photosynthesis zero: 1st and 2nd P0; 1st and 2nd recovery: 1stand 2nd REC; and END), and two forms of irrigation (control: periodically irrigated to maintain 70% substrate water retention capacity, and intermittent irrigation: suspension of irrigation). The plants subjected to intermittent irrigation conditions at 0% shading showed a reduction in water potential (Ψw) and potential quantum efficiency of photosystem II (Fv/Fm) and maximum efficiency of the photochemical process (Fv/F0) and an increase in basal quantum production of the non-photochemical processes (F0/Fm). Superoxide dismutase (SOD) activity was higher in the leaves than in the roots. The C. xanthocarpa is a species sensitive to water deficit but presents strategies to adapt to an environment under temporary water restriction, which are more temporary are most efficient under shading. The seedlings with water deficit at all levels of shading exhibited higher protective antioxidant activity and lower quality at 0% shading. The shading minimizes prevents permanent damage to the photosystem II and after the re-irrigation, the evaluated characteristics showed recovery with respect to the control group, except POD and SOD activities in the leaves.

O objetivo deste estudo foi avaliar a atividade de enzimas antioxidantes, o funcionamento do fotossistema II e a qualidade de mudas de C. xanthocarpa cultivadas sob déficit hídrico intermitente e níveis de sombreamento e a influência do sombreamento sobre o potencial de recuperação após suspensão das condições de estresse. As mudas foram submetidas a três níveis de sombreamento (0, 30 e 70%), seis períodos de avaliação (início: 0 dias; 1ª e 2ª fotossíntese zero: 1ª e 2ª P0; 1ª e 2ª recuperação: 1ª e 2ª REC; e final), e duas formas de irrigação (controle: periodicamente irrigado para manter 70% da capacidade de retenção de água do substrato, e irrigação intermitente: suspensão da irrigação). As plantas submetidas às condições de irrigação intermitente a 0% de sombreamento apresentaram redução do potencial hídrico (Ψw) e eficiência quântica potencial do fotossistema II (Fv/Fm) e máxima eficiência do processo fotoquímico (Fv/F0) e aumento da produção quantica basal dos processos não fotoquímicos (F0/Fm). A atividade da superóxido dismutase (SOD) foi maior nas folhas do que nas raízes. C. xanthocarpa é uma espécie sensível ao déficit hídrico, mas apresenta estratégias para se adaptar a um ambiente com restrição hídrica temporária, sendo mais eficientes sob sombreamento. As mudas com déficit hídrico em todos os níveis de sombreamento exibiram maior atividade antioxidante protetora e menor qualidade no sombreamento 0%. O sombreamento minimiza danos permanentes ao fotossistema II e após a re-irrigação, as características avaliadas apresentaram recuperação em relação ao grupo controle, exceto atividades de POD e SOD nas folhas.

Produção de enzimas por fungos filamentosos / Production of enzymes by filamental fungi

Estudos utilizando fungos endofíticos como produtores de metabólitos secundários de interesse biotecnológico vem sendo explorados. Assim, o presente trabalho objetivou avaliar a produção de enzimas por fungos filamentosos endofíticos, sendo escolhida a cepa 50 (C50), proveniente da coleção de cultura do Laboratório de Produtos Naturais e Biotecnologia (LPNBio) da UESB. A produção das enzimas amilase, celulase, invertase, lipase e poligalacturonase foi avaliada pelo o índice enzimático, atividade enzimática e verificado o tempo de fermentação de maior produtividade. Com exceção da invertase, a C50 apresentou atividade para as demais enzimas, destaque para lipase e poligalacturonase no tempo de 96 horas de fermentação. Estes resultados mostraram que a C50 tem potencial para ser explorada como produtora de enzimas.

Poly(DL-lactide)-degrading enzyme production by immobilized Actinomadura keratinilytica strain T16-1 in a 5-L fermenter under various fermentation processes

Background: Poly(DL-lactic acid), or PDLLA, is a biodegradable polymer that can be hydrolyzed by various types of enzymes. The protease produced by Actinomadura keratinilytica strain T16-1 was previously reported to have PDLLA depolymerase activity. However, few studies have reported on PDLLA-degrading enzyme production by bacteria. Therefore, the aims of this study were to determine a suitable immobilization material for PDLLA-degrading enzyme production and optimize PDLLA-degrading enzyme production by using immobilized A. keratinilytica strain T16-1 under various fermentation process conditions in a stirrer fermenter. Results: Among the tested immobilization materials, a scrub pad was the best immobilizer, giving an enzyme activity of 30.03 U/mL in a shake-flask scale. The maximum enzyme activity was obtained at aeration 0.25 vvm, agitation 170 rpm, 45°C, and 48 h of cultivation time. Under these conditions, a PDLLA-degrading enzyme production of 766.33 U/mL with 15.97 U/mL·h productivity was observed using batch fermentation in a 5-L stirrer fermenter. Increased enzyme activity and productivity were observed in repeated-batch (942.67 U/mL and 19.64 U/mL·h) and continuous fermentation (796.43 U/mL and 16.58 U/mL·h) at a dilution rate of 0.013/h. Scaled-up production of the enzyme in a 10-L stirrer bioreactor using the optimized conditions showed a maximum enzyme activity of 578.67 U/mL and a productivity of 12.06 U/mL·h. Conclusions: This research successfully scaled-up the enzyme production to 5 and 10 L in a stirrer fermenter and is helpful for many applications of poly(lactic acid).

Bacterial selection for biological control of plant disease: criterion determination and validation

Abstract This study aimed to evaluate the biocontrol potential of bacteria isolated from different plant species and soils. The production of compounds related to phytopathogen biocontrol and/or promotion of plant growth in bacterial isolates was evaluated by measuring the production of antimicrobial compounds (ammonia and antibiosis) and hydrolytic enzymes (amylases, lipases, proteases, and chitinases) and phosphate solubilization. Of the 1219 bacterial isolates, 92% produced one or more of the eight compounds evaluated, but only 1% of the isolates produced all the compounds. Proteolytic activity was most frequently observed among the bacterial isolates. Among the compounds which often determine the success of biocontrol, 43% produced compounds which inhibit mycelial growth of Monilinia fructicola, but only 11% hydrolyzed chitin. Bacteria from different plant species (rhizosphere or phylloplane) exhibited differences in the ability to produce the compounds evaluated. Most bacterial isolates with biocontrol potential were isolated from rhizospheric soil. The most efficient bacteria (producing at least five compounds related to phytopathogen biocontrol and/or plant growth), 86 in total, were evaluated for their biocontrol potential by observing their ability to kill juvenile Mesocriconema xenoplax. Thus, we clearly observed that bacteria that produced more compounds related to phytopathogen biocontrol and/or plant growth had a higher efficacy for nematode biocontrol, which validated the selection strategy used.

Expression of phenazine biosynthetic genes during the arbuscular mycorrhizal symbiosis of Glomus intraradices

To explore the molecular mechanisms that prevail during the establishment of the arbuscular mycorrhiza symbiosis involving the genus Glomus, we transcriptionally analysed spores of Glomus intraradices BE3 during early hyphal growth. Among 458 transcripts initially identified as being expressed at presymbiotic stages, 20% of sequences had homology to previously characterized eukaryotic genes, 30% were homologous to fungal coding sequences, and 9% showed homology to previously characterized bacterial genes. Among them, GintPbr1a encodes a homolog to Phenazine Biosynthesis Regulator (Pbr) of Burkholderia cenocepacia, an pleiotropic regulatory protein that activates phenazine production through transcriptional activation of the protein D isochorismatase biosynthetic enzyme phzD (Ramos et al., 2010). Whereas GintPbr1a is expressed during the presymbiotic phase, the G. intraradices BE3 homolog of phzD (BGintphzD) is transcriptionally active at the time of the establishment of the arbuscular mycorrhizal symbiosis. DNA from isolated bacterial cultures found in spores of G. intraradices BE3 confirmed that both BGintPbr1a and BGintphzD are present in the genome of its potential endosymbionts. Taken together, our results indicate that spores of G. intraradices BE3 express bacterial phenazine biosynthetic genes at the onset of the fungal-plant symbiotic interaction.

Influencia del a-Factor sobre la expresión de IDShr en Pichia pastoris: Revisión sistemática de literatura y análisis computacional / Influence of a-Factor over the expression of hrIDS in Pichia pastoris: Literature review and computational analysis

En la búsqueda de alternativas para mejorar la expresión de la enzima Iduronato Sulfatasa (IDSh) en la levaduraPichia pastoris, se realizó una Revisión Sistemática de la Literatura con el fin de recopilar información quepermitiera relacionar los niveles de expresión de proteínas humanas recombinantes con la señal de secreción y las características propias de la molécula a expresar. Se hallaron 349 publicaciones de las cuales sólo 7 (2)porciento reportaron la expresión de proteínas que cumplían con los criterios de inclusión manejados en el estudio. Con la información obtenida en los 7 artículos se realizó una prueba de hipótesis tomando como muestras los datos recopilados y un análisis cualitativo de la información, con los cuales se evidenció que al reemplazar la señal de secreción nativa por el a-Factor como péptido líder se incrementa el nivel de expresión de proteínas humanas recombinantes en P. pastoris (p=0.053). Se encontró que la eliminación de la secuencia que codifica para el péptido nativo heterólogo en el ADNc de la proteína, es imprescindible para que el a-Factor pueda favorecer la secreción de proteínas heterólogas y por consiguiente incrementar el nivel de expresión. En el caso de la IDShr se halló que en la construcción GS115/pPIC9-IDS, aparecen dos secuencias de péptido señal al mismo tiempo, la nativa de la IDSh y la putativa proveniente de Saccharomyces cerevisiae; sin embargo, se han obtenidos expresiones hasta de ~30mmol/h mg de proteína, lo que deja la incógnita de un posible conflicto en el reconocimiento erróneo de una u otra señal de secreción, teniendo en cuenta el grado de hidrofobicidad de ambas.

Production of industrially important enzymes by some actinomycetes producing antifungal compounds.

Seventeen strains of actinomycetes antagonistic to yeast and moulds have been tested for their ability to produce amylase, lipase, gelatinase and caseinase using solid media containing starch, Tween-20, gelatin and skimmed milk, respectively, Enzyme producing potential of test strains is expressed in ternis of relative enzyme activity (REA). Actinomycetes strain Streptomyces somaliensis GS 1242 and Streptomyces sampsonii GS 1322 showed higher amylase production (REA 6.5) while maximum lipase activity was noted in Streptomyces strain SAP 1089 (REA 7.0). Gelatinase activity was noted higher is S. sampsonii GS 1322 (REA 9.6) and S. somaliensis GS 1242 (REA 8.8). Enzyme producing potential of these strains has been discussed in terms of their industrial significance.

Production of glucoamylase by fed-batch culture of Aspergillus awamori NRRL3112

A produçäo de amiloglicosidase por Aspergillus awamori NRRL3112 em processo descontínuo alimentado é 92 por cento superior em relaçäo ao processo descontínuo em cultivos com 20g/l de concentraçäo total de fonte de carbono oriunda de farinha de mandioca. Uma análise da velocidade específica de produçäo mostra ser este resultado decorrente da reduçäo do efeito repressivo causado pela glicose, já que o efeito indutivo, relacionado à concentraçäo de polissacarídeo, também foi reduzido

Alteración de las ARN-polimerasas de núcleos de células cerebrales en ratones infectados con el virus de la encefalitis venezolana / Cellular RNA-polymerases alterations in brain nuclei in EEV virus infected mice

La infección de ratones jóvenes (34 semanas de edad) con 100 DL50 del virus de la Encefalitis Equina Venezolana, por vía intraperitoneal, produce una inhibición de las enzimas nucleares ARN-polimerasas dependientes de ADN, tipo I y II. La determinación enzimática efectuada en la fracción nuclear, en condiciones de baja fuerza iónica, demostró que las 2 enzimas tienen un patrón de sensibilidad diferente en las primeras 15 horas posteriores a la infección: ARN-polimerasa tipo II presentó un 50 por ciento de inhibición contra sólo un 25 por ciento de inhibición de la tipo I; sin embargo, a las 24 horas, esta diferencia desaparació por aumento en el nivel de inhibición de la última igualándose los valores de ambas enzimas en un 50 por ciento de inhibición. Estos valores se mantuvieron hasta las 48 horas después de la infección. Durante el período de determinaciones enzimáticas, ninguno de los animales del grupo infectado mostró signos clínicos de la enfermedad pero al cabo de 5 días, todos murieron con parálisis del tren posterior

Purificaçäo e caracterizaçäo de amiloglicosidase extracelular de Candida sp. e sua utilizaçäo na produçäo de xarope de glicomaltose / Purification and characterization of extracelullar amyloglusidase from Candida sp. and its use for the production of glucomaltose syrup

A enzima amilolítica de Candida sp. ATCC 90238 foi purificada e suas características enzimáticas foram estudadas. O peso molecular da enzima purificada foi estimado em 120.000. A cromatografia em papel do hidrolizado de amido solúvel indicou que a enzima é uma amiloglicosidase. Maltotriose e amido solúvel foram eficientemente hidrolisados a glicose pela enzima, enquanto que a maltose foi menos eficiente como substrato. A enzima apresenta características diferentes quando comparada à amiloglicosidase de Aspergillus e Rhizopus sp. que hidrolisam completamente a maltose. Esta enzima é adequada para a produçäo de xarope de glicomaltose.

Androgenic regulation of glycolytic and HMP pathway in epididymis and vas deferens of rhesus monkey.

The androgenic regulation of the eleven enzymes of glycolytic pathway and two key enzymes of HMP pathway was studied in the initial segment, caput, corpus and cauda regions of the epididymis and in the vas deferens of rhesus monkey. The specific activities of enzymes were expressed as units of activity per mg DNA. Results in control animals indicate a marked difference in energy metabolism of epididymis and vas deferens. However, the epididymal duct itself did not show much regional variation in enzyme activities along its length. All the enzymes of the two pathways studied showed significant reduction after castration, the regulatory enzymes being affected more severely. On treatment with exogenous dihydrotestosterone, most of these enzymes showed stimulation in castrated monkeys, but none of them could be restored to normal level. The stimulation of these enzymes on treatment with exogenous dihydrotestosterone varied along the epididymal duct itself being maximum in the initial segment and minimum in the cauda region. The changes in the vas deferens were less marked as compared to the epididymis following castration and androgen replacement.

Effect of hybridization on the production of cellulolytic enzymes by aspergillus niger

Two non cellulolytic auxotrophic mutants of Aspergillus niger were crossed together. From 20 obtained prototrophs, the segregants of 4 only could give prototrophs indicating that they were stable heterocaryons or diploids. The 4 prototrophs grew well and produced true cellulolytic activity on avicel as a sole carbon source. Cellulase production by the 4 isolates growing in liquid medium in shaken flask cultures has been investigated. In general A. niger isolates were found to be inducible for the enzymes of the cellulase complex [exoglucanase, endoglucanase, and B-glucosidase], and isolate No I was the most potent mold, and it showed about 3 fold that in B-glucosidase production [8.851 unit/ml] when Na NO[3]was used as a nitrogen source