DSpace Angular :: Browsing by Author "Agosin, E"

Browsing by Author "Agosin, E"

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A neural network estimator for total biomass of filamentous fungi growing on two dimensional solid substrate
(KLUWER ACADEMIC PUBL, 1998) Acuna, G; Giral, R; Agosin, E; Jorquera, H; Perez Correa, R; Ferret, E; Molin, P; Thibault, J
A neural network dynamic model is proposed for the on-line estimation of total biomass during filamentous fungi cultures on two dimensional solid substrate. The neural network provides an accurate and robust estimation of biomass from macroscopic measurements of the colony radius evolution. Experiments were performed on Gibberella fujikuroi growing on Petri dishes under different conditions of temperature and water activity.
Aromatic potential of certain Muscat grape varieties important for Pisco production in Chile
(2000) Agosin, E; Belancic, A; Ibacache, A; Baumes, R; Bordeu, E; Crawford, A; Bayonove, C
Pisco is noted for its fruity, Muscat aroma. However, numerous different grape varieties, bearing distinct aromatic profiles, are used in the production of this unaged wine distillate. Hence, this work provides a quantification of the most significant terpenes (linalool, nerol and geraniol), and other aromatic components of the main aromatic grape varieties found in the Pisco-producing region of Chile. Moscatel de Alejandria and Moscatel Rosada both proved to be highly aromatic while the terpene profiles of two little-grown varieties, Early Muscat and Moscatel Amarilla, indicate that these could contribute much to the aroma of Pisco.
Biological and integrated control of Botrytis bunch rot of grape using Trichoderma spp.
(1996) Harman, GE; Latorre, B; Agosin, E; SanMartin, R; Riegel, DG; Nielsen, PA; Tronsmo, A; Pearson, RC
Field trials were carried out in upstate New York in 1990, 1992, 1998, and 1994 and in Chile in 1992-1993 and 1993-1994 in order to evaluate the ability of various strains of Trichoderma spp. to control bunch rot of grape, to assess the compatibility and possible additive effects of selected biocontrol fungi and dicarboximide fungicides, and to determine factors affecting biocontrol efficacy. In 1990, three strains of Trichoderma spp. were evaluated for their biocontrol ability, and all provided significant control of Botrytis cinerea. As few as two late applications of the biocontrol fungi were nearly as effective as up to five applications throughout bloom and fruit development. Trials in New York in 1992 and in Chile in 1992-1993 indicated that Trichoderma harzianum could replace some applications of iprodione or vinclozolin with little reduction in efficacy. In New York in 1993, we found that applications of T. harzianum at bloom and early fruit development followed by a tank-mix application of T. harzianum and half rates of iprodione gave extremely effective control of bunch rot. In 1994, less effective control was obtained than in earlier years. Addition of a nutritive adhesive (Pelgel, a mixture of carboxymethyl cellulose and gum arabic) applied with the biocontrol agent tended to improve results. Thus, biological control of bunch rot of grape with T. harzianum can be an effective method of management of this disease. (C) 1996 Academic Press, Inc.
Biomass content governs fermentation rate in nitrogen-deficient wine musts
(AMER SOC MICROBIOLOGY, 2004) Varela, C; Pizarro, F; Agosin, E
Problematic fermentations are common in the wine industry. Assimilable nitrogen deficiency is the most prevalent cause of sluggish fermentations and can reduce fermentation rates significantly. A lack of nitrogen diminishes a yeast's metabolic activity, as well as the biomass yield, although it has not been clear which of these two interdependent factors is more significant in sluggish fermentations. Under winemaking conditions with different initial nitrogen concentrations, metabolic flux analysis was used to isolate the effects. We quantified yeast physiology and identified key metabolic fluxes. We also performed cell concentration experiments to establish how biomass yield affects the fermentation rate. Intracellular analysis showed that trehalose accumulation, which is highly correlated with ethanol production, could be responsible for sustaining cell viability in nitrogen-poor musts independent of the initial assimilable nitrogen content. Other than the higher initial maintenance costs in sluggish fermentations, the main difference between normal and sluggish fermentations was that the metabolic flux distributions in nitrogen-deficient cultures revealed that the specific sugar uptake rate was substantially lower. The results of cell concentration experiments, however, showed that in spite of lower sugar uptake, adding biomass from sluggish cultures not only reduced the time to finish a problematic fermentation but also was less likely to affect the quality of the resulting wine as it did not alter the chemistry of the must.
Capture of volatile metabolites for tracking the evolution of gibberellic acid in a solid-state culture of Gibberella fujikuroi
(2000) González-Sepúlveda, M; Agosin, E
The evolution of volatile compounds produced during solid substrate cultivation (SSC) of Gibberella fujikuroi on wheat bran was tracked looking for volatile metabolites related with GA(3) production. Ethyl acetate and isoamyl acetate gave identical profiles and sharp increases that abated as the production of GA(3) began, while ent-kaurene displayed a profile matching that of the development of GA(3). ent-Kaurene is a precursor in the synthesis of gibberellins and was the most abundant compound found.
Chemical markers for tracking the sensory contribution of production stages in muscat wine distillates
(WILEY, 2005) Lillo, MPY; Agosin, E; Latrille, E
The main sensory contribution of each post-fermentation production stage of muscat wine distillates can be tracked by following the concentration of just 1 corresponding chemical marker. Matching sample clusters of sensory and chemical data by using principal components analysis (PCA) revealed potential chemical markers. The data used in this study correspond to 12 sensory attributes that showed significant differences among products (P < 0.05) and concentrations of 23 volatile compounds of 14 distillate fractions and 15 finished. Piscos. Artificial fruit attribute, characteristic of the head fraction (FR1) can be tracked with esters. Linalool, main odor attribute of the 1st part of the heart (FR2) can be tracked with linalool molecule. The 2nd part of the heart (FR3) can be tracked with octanoic acid, decanoic acid, furfural and ethyl lactate, accounting for tails attribute. In blended and aged finished products, chemical markers accounting for the effects of distillate fractions were similar but not identical to the markers from samples obtained from the purely distilled samples. Chemical markers for FR1 are ethyl hexanoate, ethyl octanoate, ethyl decanoate. Differentiation between FR1 and FR2 is less evident than in the purely distilled samples due to the linalool and artificial fruit attribute correlation. Chemical markers for FR2, therefore, include linalool and esters ethyl hexanoate, ethyl octanoate, and ethyl decanoate. The blending of the 2nd, part of the heart (FR3) can be tracked with 2-phenylethanol, ethyl lactate, and decanoic acid. Oak aging was tracked with eugenol and whisky lactones, while 5-hydroxy-methyl-2-furfural accounted for added caramel.
Comparison between odour and aroma profiles of Chilean Pisco spirit
(ELSEVIER SCI LTD, 2005) Lillo, MPY; Latrille, E; Casaubon, G; Agosin, E; Bordeu, E; Martin, N
Precise sensory measurements of odour (orthonasal) and aroma (retronasal olfactory perception) are time and resource consuming. The aim of this work was to develop improved olfactory tasting procedures. Odour and aroma profiles of 13 Pisco spirits and 14 distillation fractions were obtained through descriptive analysis by a panel of 12 trained subjects. The samples were discriminated by 12 odour and 11 aroma attributes out of 13, with odour being slightly more discriminant at a panel and individual level. Samples were differentiated according to the type of distillation fraction and maturation process. None of the tasting modes induced significantly higher intensity judgement, with the exception of linalol whose average sample odour intensity was higher. However, there were differences in intensity scores between modes due to subject-mode interactions for all attributes except linalol and, to a lesser extent, to product-mode interactions for tails, ethyl acetate and linalol. Partial least square (PLS) models gave a good prediction of aroma from odour scores, except for oak attribute which exhibited a non-linear behaviour. Overall, Pisco olfactory perception can be limited to odour assessment. (C) 2004 Elsevier Ltd. All rights reserved.
Control strategies for intermittently mixed, forcefully aerated solid-state fermentation bioreactors based on the analysis of a distributed parameter model
(PERGAMON-ELSEVIER SCIENCE LTD, 2004) von Meien, OF; Luz, LFL; Mitchell, DA; Perez Correa, JR; Agosin, E; Fernandez Fernandez, M; Arcas, JA
This paper tests different control strategies based on classic proportional integral derivative (PID) and advanced dynamic matrix control (DMC) algorithms for an intermittently stirred, forcefully aerated solid-state fermentation bioreactor. The study was done using a distributed parameter model to reproduce the main operating features of this type of bioreactor. There is predicted to be a remarkable improvement in the bioreactor productivity when control strategies are implemented. For this type of bioreactor, the temperature and water content of the substrate bed can be controlled by saturating the air at the air inlet but manipulating its temperature, coupled with a strategy of water replenishment when the water content of the bed falls below a threshold. Dynamic matrix control is superior to PID control; however, a specific convolution matrix for different stages of the fermentation is necessary due to the changing behavior of the system. This work shows the benefit of mathematical modeling, since the many different operating conditions investigated via simulations would not have been economically feasible to undertake experimentally with a large-scale bioreactor. The results obtained provide an excellent starting point for such large-scale experimental work. (C) 2004 Elsevier Ltd. All rights reserved.
Effect of culture conditions on spore shelf life of the biocontrol agent Trichoderma harzianum
(1997) Agosin, E; Volpe, D; Munoz, G; SanMartin, R; Crawford, A
The influence of pH, carbon:nitrogen (C:N) ratio, carbon content and harvesting time on spore attributes of the biocontrol agent Trichoderma harzianum was evaluated. The effect of these culture parameters on viability, shelf-life and ultrastucture was also assessed. pH was a key parameter to manipulate for both growth and sporulation, while carbon concentration and C:N ratio strongly affected spore production time. At fixed pH, the C:N ratio had a limited influence on production yield, but was critical for spore shelf-life. The highest spore longevity was found in a medium with a C:N ratio of 14 and a pH of 7.0, when most resulting spores were still alive after 45 d storage. These spores also remained viable during storage under a broad range of relative humidities, indicating that they would be more sustainable in the field.
Effect of water activity on gibberellic acid production by Gibberella fujikuroi under solid-state fermentation conditions
(ELSEVIER SCI LTD, 2005) Corona, A; Saez, D; Agosin, E
The evolution of water activity during solid-state cultivation of Gibberella fujikuroi was followed. A typical organic substrate, wheat bran and soluble starch, was used. Culture sorption isotherms were determined verifying that, as culture evolves, higher moisture contents were necessary to maintain the same water activity level. Optimal values for Gibberella fujikuroi growth and gibberellic acid production rates and yields were established, around a(w) 0.99. A non-linear model, based on neural networks, is proposed to represent the sorption curves of the substrate during the fermentation process. (c) 2005 Elsevier Ltd. All rights reserved.
Effectiveness of conidia of Trichoderma harzianum produced by liquid fermentation against Botrytis bunch rot of table grape in Chile
(ELSEVIER SCI LTD, 1997) Latorre, BA; Agosin, E; SanMartin, R; Vasquez, GS
Over 100 isolates of Trichoderma harzianum Rifai were obtained from soil samples and from the phylloplane of kiwifruit (Actinidia chinensis Planchon), grape (Vitis vinifera), orange (Citrus sinensis (L.) Osbeck), eucalyptus (Eucalyptus globulus Labill.), and apricot (Prunus armeniaca L.) in Chile. A subsample of 48 isolates were tested and found to be antagonistic to Botrytis cinerea Pers. ex Fr. on apple fruits. Isolate S10B from soil in Chile provided similar control of Botrytis bunch rot under field conditions to reference isolate P1 (ATCC 74058) and T39 (Trichodex 25 WP). However, field trials conducted during four growing seasons (1992-1995) with preparations of conidia of formulated or non-formulated T. harzianum P1 provided only partial control of Botrytis bunch rot of 'Thomson Seedless' table grape. Disease incidence was significantly different (p < 0.05) from untreated controls, but equal to or less than the control achieved with vinclozolin (Ronilan 50 WP, 1.5 kg ha(-1)) and similar to captan (Captan 80 WP, 4 kg ha(-1)). This level of control is insufficient considering that tolerance for B. cinerea is very low (< 0.5%) on table grapes. Nevertheless, the antagonistic activity of T. harzianum may be effective if it is integrated with other control practices, and may result in acceptable levels of disease control with reduced levels of pesticide use. (C) 1997 Elsevier Science Ltd.
Gibberellic acid decomposition and its loss of biological activity in aqueous solutions
(1996) Perez, FJ; Vecchiola, A; Pinto, M; Agosin, E
In addition to gibberellic acid (GA(3)), significant amounts of iso-GA(3), an isomer of GA(3), accumulated in cultures media of the fungus Gibberella fujikuroi. It has been reported that iso-GA(3) is an intermediate in the decomposition of GA(3) to gibberellenic acid, a dicarboxylic acid lacking the gamma-lactone ring. In this work, we studied the decomposition of GA(3) in buffered aqueous solutions at pH 5 and 7, both by spectrophotometry, measuring the appearance of gibberellenic acid at 254 nm, and using a bioassay by measuring the induction of alpha-amylase in barley endosperm. Results indicate that at both pH values, biological inactivation of GA(3) is more rapid than the appearance of gibberellenic acid, suggesting that inactivation is largely due to conversion to the intermediate, iso-GA(3). Furtheremore, no induction of alpha-amylase activity in barley endosperm was obtained in bioassays with iso-GA(3).
Heterologous expression of Escherichia coli ppsA (phosphoenolpyruvate synthetase) and galU (UDP-glucose pyrophosphorylase) genes in Corynebacterium glutamicum, and its impact on trehalose synthesis
(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2005) Padilla, L; Agosin, E
Trehalose is a disaccharide with a wide range of applications in the food industry. We recently proposed a strategy for trehalose production based on a Corynebacterium glutamicum strain expressing the Escherichia coli enzyme UDP-glucose pyrophosphorylase (GalU).
Hydrophobin gene srh1, expressed during sporulation of the biocontrol agent Trichoderma harzianum
(1997) Munoz, G; NakariSetala, T; Agosin, E; Penttila, M
A cDNA clone encoding a spore-related hydrophobin, SRHI, was isolated from a cDNA bank prepared from mRNA induced in sporulating cultures of Trichoderma harzianum by heterologous hybridization using the hfb2 gene encoding a spore-bound hydrophobin of Trichoderma reesei as a probe. Based on sequence similarity the predicted protein was identified as a new member of the class-II hydrophobin family. Including the signal sequences, SRHI has 65% and 56% amino-acid similarity with the T. reesei hydrophobins HFBII and HFBI, respectively, being less similar with other hydrophobins. srh1 is present as one copy in the T. harzianum genome. It is highly expressed under sporulating conditions, both in submerged as well as in aerial cultures. Moreover, nutrient limitation induces srh1 expression.
Impact of heterologous expression of Escherichia coli UDP-glucose pyrophosphorylase on trehalose and glycogen synthesis in Corynebacterium glutamicum
(AMER SOC MICROBIOLOGY, 2004) Padilla, L; Morbach, S; Kramer, R; Agosin, E
Trehalose is a disaccharide with a wide range of applications in the food industry. We recently proposed a strategy for trehalose production based on improved strains of the gram-positive bacterium Corynebacterium glutamicum. This microorganism synthesizes trehalose through two major pathways, OtsBA and TreYZ, by using UDP-glucose and ADP-glucose, respectively, as the glucosyl donors. In this paper we describe improvement of the UDP-glucose supply through heterologous expression in C. glutamicum of the UDP-glucose pyrophosphorylase gene from Escherichia coli, either expressed alone or coexpressed with the E. coli ots genes (galU otsBA synthetic operon). The impact of such expression on trehalose accumulation and excretion, glycogen accumulation, and the growth pattern of new recombinant strains is described. Expression of the galU otsBA synthetic operon resulted in a sixfold increase in the accumulated and excreted trehalose relative to that in a wild-type strain. Surprisingly, single expression of galU also resulted in an increase in the accumulated trehalose. This increase in trehalose synthesis was abolished upon deletion of the TreYZ pathway. These results proved that UDP-glucose has an important role not only in the OtsBA pathway but also in the TreYZ pathway.
Indirect measurement of water content in an aseptic solid substrate cultivation pilot-scale bioreactor
(JOHN WILEY & SONS INC, 2001) Lillo, MPY; Perez Correa, R; Agosin, E; Latrille, E
A lack of models and sensors for describing and monitoring large-scale solid substrate cultivation (SSC) bioreactors has hampered industrial development and application of this type of process. This study presents an indirect dynamic measurement model for a 200-kg-capacity fixed-bed SSC bioreactor under periodic agitation. Growth of the filamentous fungus Gibberella fujikuroi on wheat bran was used as a case study. Real data were preprocessed using previously reported methodology. The model uses CO, production rate and inlet air conditions to estimate average bed water content and average bed temperature. The model adequately reproduces the evolution of the average bed water content and can therefore be used as an on-line estimator in pilot-scale SSC bioreactors. To obtain a reasonable fit of the bed temperature, however, inlet air humidity measurements will have to be adjusted with a data reconciliation algorithm. Good estimation of temperature is important for the future design of improved water content estimation using state observers. The model also provides insight into understanding the complex behavior of the dynamic system, which could prove useful when establishing advanced model-based operational and control strategies. (C) 2001 John Wiley & Sons, Inc.
Induction of trehalose in spores of the biocontrol agent Trichoderma harazianum
(1997) Pedreschi, F; Aguilera, JM; Agosin, E; SanMartin, R
Spores of the biocontrol agent Trichoderma harzianum P1 produced in liquid media and harvested in the stationary sporulation stage SSS (after 60 h), had higher viability after slow (>4x) and fast drying (>12x) than their counterparts harvested in the exponential sporulation stage, ESS (after 30 h). The trehalose content of SSS spores was almost 20x higher than that of ESS spores (0.16 vs. 3.4 mg/100 mg, respectively). Heat shock (40 degrees C x 90 min) effectively increased the trehalose content 2.5x with respect to untreated SSS spores. The trehalose content achieved in heat-treated SSS spores was almost 60% higher than the maximum reached by holding the spores under water-stress at 97% relative humidity prior to drying.
Influence of a mixed culture with Debaryomyces vanriji and Saccharomyces cerevisiae on the volatiles of a Muscat wine
(INST FOOD TECHNOLOGISTS, 2002) Garcia, A; Carcel, C; Dulau, L; Samson, A; Aguera, E; Agosin, E; Gunata, Z
A non-Saccharomyces yeast strain, Debaryomyces vanriji, isolated from grape berry flora was found to Influence wine volatiles of the cv. Muscat of Frontignan when co-cultured with native or inoculated with a selected strain of Saccharomyces cerevisiae during fermentation. The concentrations of several volatiles were significantly different (p < 0.05) between the control and the 2 wines inoculated with D. vanriji. The latter were richer in fatty acids, esters, and terpenols. The increase in geraniol concentration In D. vanriji wines could be attributed to the hydrolysis of the corresponding glucosidic precursor by D. vanriji β-glucosidase. D. vanriji inoculated musts showed higher levels of β-glucosidase activity through fermentation compared to the control sample.
Influence of sun exposure on the aromatic composition of Chilean Muscat grape cultivars Moscatel de Alejandria and Moscatel rosada
(AMER SOC ENOLOGY VITICULTURE, 1997) Belancic, A; Agosin, E; Ibacache, A; Bordeu, E; Baumes, R; Razungles, A; Bayonove, C
The effect of sun exposure on the aromatic composition of two Muscat grape cultivars, Moscatel de Alejandria and Moscatel rosada, was monitored over two seasons. Fully exposed and artificially shaded clusters permitting 20% (shaded) and 50% (semi-shaded) sun exposure were used to assess the impact of shading in fruit aroma composition. Both cultivars contained similar levels of total free terpenols (2100 mu g/L), although Moscatel de Alejandria was richer in total bound terpenols. The highest concentration of free terpenols was obtained from the semi-shaded treatment, although for Moscatel de Alejandria, the resulting difference between exposed and semi-shaded treated grapes was negligible. Shaded grapes had the lowest concentration of terpenols, with poor Muscat typicity. The content of one of the most important terpenols from the aromatic perspective, linalool, appeared to be the most sensitive to sun exposure. Berry temperature appeared to be critical for maximizing monoterpene levels and muscat flavor in the fruit.
Metabolic engineering of Corynebacterium glutamicum for trehalose overproduction: Role of the TreYZ trehalose biosynthetic pathway
(AMER SOC MICROBIOLOGY, 2006) Carpinelli, J; Kramer, R; Agosin, E
Trehalose has many potential applications in biotechnology and the food industry due to its protective effect against environmental stress. Our work explores microbiological production methods based on the capacity of Corynebacterium glutainicum to excrete trehalose. We address here raising trehalose productivity through homologous overexpression of maltooligosyltrehalose synthase and the maltooligosyltrehallose trehalohydrolase genes. In addition, heterologous expression of the UDP-glucose pyrophosphorylase gene from Escherichia coli improved the supply of glycogen. Gene expression effects were tested on enzymatic activities and intracellular glycogen content, as well as on accumulated and excreted trehalose. Overexpression of the treY gene and the treY/treZ synthetic operon significantly increased maltooligosyltrehalose synthase activity, the rate-limiting step, and improved the specific productivity and the final titer of trehalose. Furthermore, a strong decrease was noted in glycogen accumulation. Expression of galU/treY and galU/treYZ synthetic operons showed a partial recovery in the intracellular glycogen levels and a significant improvement in both intra- and extracellular trehalose content.

Browsing by Author "Agosin, E"

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