Growth and photosynthetic down-regulation in Coffea arabica in response to restricted root volume

Coffee (Coffea arabica L.) plants were grown in small (3-L), medium (10-L) and large (24-L) pots for 115 or 165 d after transplanting (DAT), which allowed different degrees of root restriction. Effects of altered source : sink ratio were evaluated in order to explore possible stomatal and non-stomatal mechanisms of photosynthetic down-regulation. Increasing root restriction brought about large and general reductions in plant growth associated with a rising root : shoot ratio. Treatments did not affect leaf water potential or leaf nutrient status, with the exception of N content, which dropped significantly with increasing root restriction even though an adequate N supply was available. Photosynthesis was severely reduced when plants were grown in small pots; this was largely associated with non-stomatal factors, such as decreased Rubisco activity. At 165DAT contents of hexose, sucrose, and amino acids decreased in plants grown in smaller pots, while those of starch and hexose-P increased in plants grown in smaller pots. Photosynthetic rates were negatively correlated with the ratio of hexose to free amino acids, but not with hexose content. Activities of acid invertase, sucrose synthase, sucrose-P synthase, fructose-1,6- bisphosphatase, ADP-glucose pyrophosphorylase, starch phosphorylase, glyceraldehyde-3-P dehydrogenase, PPi : fructose-6-P 1-phosphotransferase and NADP : glyceraldehyde-3-P dehydrogenase all decreased with severe root restriction. Glycerate-3-P : Pi and glucose-6-P : fructose-6-P ratios decreased accordingly. Photosynthetic down-regulation was unlikely to have been associated directly with an end-product limitation, but rather with decreases in Rubisco. Such a down-regulation was largely a result of N deficiency caused by growing coffee plants in small pots.

Atividade das enzimas invertases e acúmulo de sacarose em cana-de-açúcar sob efeito do nitrato de potássio, etefon e etil-trinexapac

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

GROWTH AND FERMENTATION CHARACTERISTICS OF NEW SELECTED STRAINS OF SACCHAROMYCES AT HIGH-TEMPERATURES AND HIGH CELL DENSITIES

Maintenance of high cell viability was the main characteristic of our new strains of thermotolerant Saccharomyces. Total sugar conversion to ethanol was observed for sugarcane juice fermentation at 38-40-degrees-C in less than 10 h and without continuous aeration of the culture. Invertase activity differed among the selected strains and increased during fermentation but was not dependent on cell viability. Invertase activity of the cells and optimum temperature for growth, as well as velocity of ethanol formation, were dependent on medium composition and the type of strain used. At high sugarcane syrup concentrations, the best temperature for ethanol formation by strain 781 was 35-degrees-C. Distinct differences among the velocities of ethanol production using selected strains were also observed in sugarcane syrup at 35-38-degrees-C.

Purification and characterization of beta-fructosidase with inulinase activity from Aspergillus niger-245

Aspergillus niger - 245 a strain isolated from soil samples showed good beta -fructosidase activity when inoculated in medium formulated with dahlia extract tubers. The enzyme was purified by precipitation in ammonium sulphate and percolated in DEAE-Sephadex A-50 and CM-cellulose columns, witch showed a single peack in all the purification steps, maintaining the I/S ratio between 0.32 to, 0.39. Optimum pH for inulinase activity (I) was between 4.0 - 4.5 and for invertase activity (S) between 2.5 and 50. The optimum temperature was 60 degrees .C for both activities and no loss in activity was observed when it was maintained at this temperature for 30 min. The K-m value was 1.44 and 5.0 respectively, for I and S and V-m value 10.48 and 30.55 respectively. The I activity was strongly inhibited by Hg2+ and Ag+ and 2 x 10(-3) M of glucose, but not by fructose at the same concentration. The enzyme showed an exo-action mechanism acting on the inulin of different origins. In assay conditions total hydrolysis of all the frutans was obtained although it has shown larger activity on the chicory inulin than that one from artichoke Jerusalem and dahlia, in the first 30 min. The obtained results suggested that the enzyme presented good potential for industrial application in the preparing the fructose syrups.

Thermostable invertases from Paecylomyces variotii produced under submerged and solid-state fermentation using agroindustrial residues

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Exploiting Cascade Reactions in Bienzyme Layer-by-Layer Films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evidence for involvement of Saccharomyces cerevisiae protein kinase C in glucose induction of HXT genes and derepression of SUC2

The PKC1 gene in the yeast Saccharomyces cerevisiae encodes protein kinase C that is known to control a mitogen-activated protein (MAP) kinase cascade consisting of Bck1, Mkk1 and Mkk2, and Mpk1. This cascade affects the cell wall integrity but the phenotype of Pkc1 mutants suggests additional targets which have not yet been identified. We show that a pkc1Δ mutant, as opposed to mutants in the MAP kinase cascade, displays two major defects in the control of carbon metabolism. It shows a delay in the initiation of fermentation upon addition of glucose and a defect in derepression of SUC2 gene after exhaustion of glucose from the medium. After addition of glucose the production of both ethanol and glycerol started very slowly. The V max of glucose transport dropped considerably and Northern blot analysis showed that induction of the HXT1, HXT2 and HXT4 genes was strongly reduced. Growth of the pkc1Δ mutant was absent on glycerol and poor on galactose and raffinose. Oxygen uptake was barely present. Derepression of invertase activity and SUC2 transcription upon transfer of cells from glucose to raffinose was deficient in the pkc1Δ mutant as opposed to the wild-type. Our results suggest an involvement of Pkc1p in the control of carbon metabolism which is not shared by the downstream MAP kinase cascade. © 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

Composition of stingless bee honey: Setting quality standards

Compositional data from 152 stingless bee (Meliponini) honey samples were compiled from studies since 1964, and evaluated to propose a quality standard for this product. Since stingless bee honey has a different composition than Apis mellifera honey, some physicochemical parameters are presented according to stingless bee species. The entomological origin of the honey was known for 17 species of Meliponini from Brazil, one from Costa Rica, six from Mexico, 27 from Panama, one from Surinam, two from Trinidad & Tobago, and seven from Venezuela, most from the genus Melipona. The results varied as follows: moisture (19.9-41.9g/100g), pH (3.15-4.66), free acidity (5.9-109.0meq/Kg), ash (0.01-1.18g/100g), diastase activity (0.9-23.0DN), electrical conductivity (0.49-8.77mS/cm), HMF (0.4-78.4mg/Kg), invertase activity (19.8-90.1IU), nitrogen (14.34-144.00mg/100g), reducing sugars (58.0-75.7g/100g) and sucrose (1.1-4.8g/100g). Moisture content of stingless bee honey is generally higher than the 20% maximum established for A. mellifera honey. Guidelines for further contributions would help make the physicochemical database of meliponine honey more objective, in order to use such data to set quality standards. Pollen analysis should be directed towards the recognition of unifloral honeys produced by stingless bees, in order to obtain standard products from botanical species. A honey quality control campaign directed to both stingless beekeepers and stingless bee honey hunters is needed, as is harmonization of analytical methods. © 2007 Asociación Interciencia.

Extracellular β-fructofuranosidase from Fusarium graminearum: Stability of the spray-dried enzyme in the presence of different carbohydrates

Microbial enzymes have been used for various biotechnological applications; however, enzyme stabilization remains a challenge for industries and needs to be considered. This study describes the effects of spray-drying conditions on the activity and stability of β-fructofuranosidase from Fusarium graminearum. The extracellular enzyme β-fructofuranosidase was spray dried in the presence of stabilizers, including starch (Capsul) (SC), microcrystalline cellulose (MC), trehalose (TR), lactose (LC) and β-cyclodextrin (CD). In the presence of TR (2% w/v), the enzymatic activity was fully retained. After 1 year of storage, 74% of the enzymatic activity was maintained with the CD stabilizer (10% w/v). The residual activity was maintained as high as 80% for 1 h at 70°C when MC, SC and CD (5% w/v) stabilizers were used. Spray drying with carbohydrates was effective in stabilizing the F. graminearum β-fructofuranosidase, improved enzymatic properties compared to the soluble enzyme and demonstrated a potential use in future biotechnology applications. © 2013 Informa UK Ltd. All rights reserved.

Caracterização bioquímica de leveduras industriais produtoras de etanol cultivadas em diferentes açúcares

Pós-graduação em Biotecnologia - IQ

Avaliação da desidratação de mamão utilizando métodos combinados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Expressão gênica diferencial em palmitos de cana-de-açúcar submetida a diferentes períodos de estresse hídrico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Filmes nanoestruturados para a detecção de glicose e sacarose em bebidas comerciais

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influência da fonte e do dreno de fotoassimilados no metabolismo glicídico de plantas de milho

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Maturadores associados à boro e silício aplicados via foliar em cana-de-açúcar (Saccharum spp.)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)