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Showing papers in "Acta Biotechnologica in 1988"



Journal ArticleDOI
TL;DR: The oxygen uptake rate (THE AUTHORS') was studied in a solid state fermentation process of dried citrus peel with the strain Aspergillus niger QH-2 in order to obtain the growth estimation of the microorganism in the system.
Abstract: The oxygen uptake rate (OUR) was studied in a solid state fermentation process of dried citrus peel with the strain Aspergillus niger QH-2 in order to obtain the growth estimation of the microorganism in the system. The relationship between OUR, the maintenance coefficient (m) and the yield for oxygen consumption YO2 allows the estimation of the biomass rate if we consider that both parameters are not constants in some periods of the process. It was estimated that in the first 24th the strain has an specific growth rate of 0.174 h−1 with values for YO2 and m in the order of 2.84 g-cell/g-oxygen and 0.006 g-oxygen/g-cell ·h respectively.

36 citations


Journal ArticleDOI
TL;DR: In this paper, l'activite lipolytique des microorganismes (bacteries, moisissures notamment) and la specificite des lipases vis-a-vis du substrat are discussed.
Abstract: Revue bibliographique sur l'activite lipolytique des microorganismes (bacteries, moisissures notamment) et la specificite des lipases vis-a-vis du substrat. Applications technologiques

33 citations




Journal ArticleDOI
TL;DR: The pectate beads are much more insensitive to those ions and chemical agents which destructively act on alginate beads (such as phosphate, citrate, gluconate, lactate as well as a high excess of sodium, potassium, and/or ammonium ions), even without addition of gelling cations to the liquid phase as mentioned in this paper.
Abstract: It is shown that Ca- and Al-pectate gel beads prepared by use of high molecular weight polygalacturonic acid (viz. polygalacturonic acid having a high STAUDINGER index) are well suited for cell immobilization. The pectate beads are much more insensitive to those ions and chemical agents which destructively act on alginate beads (such as phosphate, citrate, gluconate, lactate as well as a high excess of sodium, potassium, and/or ammonium ions), even without addition of gelling cations to the liquid phase.

17 citations


Journal ArticleDOI
TL;DR: Tween 80 and proteose peptone effect on cellulase production with Trichoderma spec.
Abstract: Tween 80 and proteose peptone effect on cellulase production with Trichoderma spec. was studied. Sugar cane pith was used in the medium as carbon source. Tween 80 increases cellulase production while proteose peptone has influence on enzyme adsorption. There is a combined effect on cellulase production between them.

16 citations


Journal ArticleDOI
TL;DR: In this paper, an autohydrolyzed and ethanol-alkali pulped wheat straw was examined as a candidate feedstock for both cellulase and xylanase production and enzymatic hydrolysis.
Abstract: Autohydrolyzed and ethanol-alkali pulped wheat straw was examined as a candidate feedstock for both cellulase and xylanase production and enzymatic hydrolysis. Submerged cultures of Trichoderma reesei F-522 grown on hydrothermally modified straw provided culture supernatants of the highest enzymatic activities, whereas the maximal efficiency of enzymatic hydrolysis was recorded in straw treated with ethanol-NaOH mixture. Some culture conditions were optimized to improve the growth and cellulase production by T. reesei on autohydrolyzed wheat straw.

16 citations


Journal ArticleDOI
TL;DR: The yeast Trichosporon adeninovorans secretes two multiple forms of β-glucosidase at a high rate if grown in a medium containing cellobiose and these enzymes displayed highest activity at pH of 4.5.
Abstract: The yeast Trichosporon adeninovorans secretes two multiple forms of β-glucosidase at a high rate if grown in a medium containing cellobiose. Following mutagenesis a mutant strain resistant to 2-deoxy-D-glucose was selected. This strain produced more β-glucosidase activity and had acquired a strong resistance against repression by glucose. The β-glucosidases were separated one from each other by chromatography on hydroxylapatite and by gel filtration. Both enzymes have similar properties. The optimal temperature for their activity was 60 to 63°C and the enzymes displayed highest activity at pH of 4.5. The molecular weight of β-glucosidase I was found to be 570,000 and that for β-glucosidase II was 525,000. The Km value for cellobiose was determined to be 4.1 mM for β-glucosidase I and 3.0 mM for β-glucosidase II.

16 citations


Journal ArticleDOI
TL;DR: In this article, trichoderma reesei QM 9414 was grown in batch fermentation on wheat straw pretreated by different methods as the sole carbon source, and the results showed that the addition of fresh straw produced an elongation of the exponential phase or the beginning of a new exponential phase when the additions were carried out at 50 and 120 h, respectively.
Abstract: Trichoderma reesei QM 9414 was grown in batch fermentation on wheat straw pretreated by different methods as the sole carbon source. Cellulase production was maximal with NaOH treated wheat straw at a concentration of 10 g/l and an initial pH of 5.5. The addition of fresh straw produced an elongation of the exponential phase or the beginning of a new exponential phase when the additions were carried out at 50 and 120 h, respectively. Filter paper and carboxymethylcellulase activities decreased as an answer to the addition of wheat straw and the levels were regained at the end of fermentation. The decreases of activities were accompanied by the increases of soluble sugar levels, which decreased at the end of fermentation. β-glucosidase activity was stimulated by wheat straw addition at 50 h while not by addition at 120 h; however, at the end of the fermentation the levels of activities were both similar to control. The studies of pH stabilities of these enzymes allow assurance that the effect of the addition of wheat straw on the enzyme activities is not produced by the changes of the pH during the fermentation.

13 citations


Journal ArticleDOI
TL;DR: In this article, the potential use of enzyme hydrolysed cassava whey for ethanol production by Saccharomyces cerevisiae Aspergillus niger grown on wheat bran was investigated.
Abstract: Investigations were conducted into the potential use of enzyme hydrolysed cassava whey for ethanol production by Saccharomyces cerevisiae Aspergillus niger grown on whct bran was used as crude enzyme source to saccharify the whey starch. The whey with an initial HCN concentration of 54.0μg/ml was fermented at pH 4.5 and 30°C in a one-step process to produce ethanol. A maximum ethanol concentration of 4.5% (v/v) was obtained in 120 h with a decrease in HCN level to 4.0 μg/ml. In a two-stage fermentation, in which the raw whey was pre-hydrolysed and under the same fermentation conditions, the unsterilized hydrolysate yielded alcohol content of 5.5% (v/v), while the sterilized hydrolysate gave higher alcohol yield, 7.5% (v/v), in 48 h. No HCN was detected in the fermented liquour at the end of the two-stage process.

Journal ArticleDOI
TL;DR: A fungal strain suitable for protein enrichment of starchy raw materials was selected by evaluation of the growth rate, results of protein biosynthesis in solid state fermentation (SSF) and assessment of fungal biomass.
Abstract: A fungal strain suitable for protein enrichment of starchy raw materials was selected by evaluation of the growth rate, results of protein biosynthesis in solid state fermentation (SSF) and assessment of fungal biomass. The strain Aspergillus oryzae A.or. 11 selected for further studies was characterized by the radial growth rate Kr of about 300 μm/h and by the specific growth rate μ of about 0.100 h−1. Fungal biomass contained about 32% of crude protein in dry matter. The digestibility of this protein in vitro was close to 75%. Protein analysis for amino acids showed that the content of exogenous amino acids approached that in protein of the FAO standard. As a result of 34 — h culture of this strain in solid medium, net protein increased by about 5.0 g/100 g of starting medium d.m. at the cost of decomposition of about 20 g carbohydrates.

Journal ArticleDOI
TL;DR: The liquid chromatographic separations are based on self-packed highly efficient (approximately 80 000 theoretical plates per meter, N/m) glass columns as mentioned in this paper, which are optimized for HPLC analyses of mono-, di-, and oligomeric carbohydrates, organic acids (e.g., gluconic acid, α-ketoglutaric acid), and neutral lipids (squalene, cholesterol) are demonstrated.
Abstract: Suitable and optimized chromatographic separation systems for HPLC analyses of mono-, di- and oligomeric carbohydrates, organic acids (e.g. gluconic acid, α-ketoglutaric acid), phospholipids (PE, LPE, LPC, PC, SPH) and neutral lipids (squalene, cholesterol) are demonstrated. Applications of HPLC technique are separation examples of sugars from hydrolyzed starches which were isolated from potatos, calculations of organic acids in fermentation mediums and determinations of neutral lipids and phospholipids which were isolated from microbial biomass. The liquid chromatographic separations are based on self-packed highly efficient (approximately 80 000 theoretical plates per meter, N/m) glass columns.

Journal ArticleDOI
TL;DR: In this article, white rot fungi were grown under solid substrate conditions in previously ensiled and pressed coffee pulp without adding additional sources of nitrogen, and six of them produced fruiting bodies.
Abstract: The presence of several antiphysiological factors limit the use of coffee pulp in monogastric and ruminant feeding. Twenty six white rot fungi were grown under solid substrate conditions in previously ensiled and pressed coffee pulp without adding additional sources of nitrogen. All grew and wholly covered the surface of the substrate. Six of them produced fruiting bodies. The weight loss interval ranged between 6.7–28.0% dry matter before fructification and from 17.0 to 48.7% after fructification. Some fungi biodegraded about 70, 55 and 47% of the total polyphenols, caffeine and permanganate lignin present in the original substrate.

Journal ArticleDOI
TL;DR: In this paper, several alkylaminated porous silica gels and acrylic type porous polymers have been used for covalent binding of fungal peroxidase from Trametes versicolor.
Abstract: Several alkylaminated porous silica gels and acrylic type porous polymers have been used for covalent binding of fungal peroxidase from Trametes versicolor. The immobilization efficiency expressed in terms of the bound protein content, specific enzyme activity, and enzyme storage stability have been determined for both types of supports used. The results indicate a better immobilization ability of organic polymers in comparison with silica gels.

Journal ArticleDOI
TL;DR: In this article, a HPLC technique for the analysis of organic acids in the production of α-ketoglutaric acid was developed, which was applied and optimized for the quantitative determination of citric acid, pyruvic acid, isocitric acid and α -ketoglutsuric acid in fermentation solutions.
Abstract: A HPLC technique for the analysis of organic acids in the production of α-ketoglutaric acid was developed. The method was applied and optimized for the quantitative determination of citric acid, pyruvic acid, isocitric acid and α-ketoglutaric acid in fermentation solutions. As microorganism the yeast Yarrowia lipolytica and as substrates glucose or paraffins were used. The chromatographic separations were carried out by means of 50 and 100 × 8 mm i.d. glass columns packed with an anion-exchange resin based on an 8% cross-linked polystyrene-divinylbenzene copolymer. The relative errors ranged from 2.1% (α-ketoglutaric acid) to 5.2% (isocitric acid). The percent recovery values varied between 94.4% (isocitric acid) and 107.7% (pyruvic acid). The contents of organic acids in fermentation solutions after the microbial synthesis based on paraffins or glucose were compared.

Journal ArticleDOI
TL;DR: In the late 70's an Austrian Consortium consisting of the StEYRERMUHL-Papierfabriks- und Verlags AG, the Voest-Alpine AG and the Universities of Graz was formed to develop a new process for the production of monosaccharides from renewable carbohydrate sources, in particular lignocellulosic material as mentioned in this paper.
Abstract: In the late 70's an Austrian Consortium consisting of the STEYRERMUHL-Papierfabriks- und Verlags AG, the Voest-Alpine AG and the Universities of Graz was formed to develop a new process for the production of monosaccharides from renewable carbohydrate sources, in particular lignocellulosic material. After detailed examination of various hydrolytic processes it was decided to intensify work on enzymatic hydrolysis. The composition of this group brought the great advantage that it could focus not only on one problem but could also research into the total process. This included pretreatment, enzyme production, hydrolysis, by-product utilization and energy supply. The raw materials studied most thoroughly on our program were waste paper and wheat straw, since these lignocellulosics are available in large quantities in Austria. Until now all endevour to produce ethanol out of lignocellulosic biomass on an industrial scale failed due to uneconomical production. Thus it is evident that the economy of such a process is very dependent not only on the yield of sugar, which is strongly affected by the respective pretreatment, but also on the utilization of the hemicellulose. Summarizing it can be said that the cellulose has to be degregated to a high extent and that the hemicellulose must be utilized to reach a feasible project.


Journal ArticleDOI
TL;DR: The aim of the investigations was to obtain selectants with an increased ability of cellulolytic enzymes biosynthesis from the parent strain Aspergillus niger A.n. 33 characterized by enhanced activities of saccharifying cellulase and endo-beta-1,4-glucanase.
Abstract: The aim of the investigations was to obtain — from the parent strain Aspergillus niger A.n. 33 — selectants with an increased ability of cellulolytic enzymes biosynthesis. Own selection methods allowed to receive two selectants A.n. 33/2 and A.n. 33/20 characterized by enhanced activities of saccharifying cellulase (respectively 0.11 and 0.14 FPU/cm3), endo-beta-1,4-glucanase (15.4 and 21.8 U/cm3) and cellobiase (0.6 and 1.4 IU/cm3) as compared with the parent strain (FPA — 0.09 IU, CMC — 8.2 U and CB — 0.1 IU/cm3). Moreover, the selectants differed in shape and size of conidial heads, in shape and colour of conidia, as well as in structure and shape of hyphae. Enzyme preparations obtained after ultrafiltration of liquid cultures were characterized by following activites: FPA-4–16 IU, CMC — 900–1800 U, CB — 60–120 IU and xylanase — 250–280 IU/cm3.

Journal ArticleDOI
TL;DR: From different fungal genera some mutant strains were selected which in cellulase formation exhibit reduced catabolite-repression related to several soluble carbon sources and these mutant strains are selected for cellulase production if a fed-batch-technique is used for feeding the substrate.
Abstract: From different fungal genera some mutant strains were selected which in cellulase formation exhibit reduced catabolite-repression related to several soluble carbon sources. The cellulase production by these mutant strains on the basis of soluble carbon sources is possible if a fed-batch-technique is used for feeding the substrate. The optimum procedure is an oscillating-fed-batch-technique (OFB) with feed-back-controlled intermittent addition of the substrate. The substrate concentration in the medium is adjusted in such a manner to realize oscillations between a limitation for mycelium growth and non-limiting conditions under a substrate concentration which is yet below the repressing concentration for cellulase formation. A suitable feed-back-parameter for the control of substrate addition is the specific CO2-formation of the mycelium. Using OFB the growth in cellulase activity is nearly proportional to the feeded substrate whereas the growth in mycelium is reduced. The productivity of cellulase formation is enhanced in comparison to continuous substrate addition as well as under limiting and non-limiting conditions for growth of mycelium.

Journal ArticleDOI
TL;DR: In this article, yeast were chemostatically cultivated on C2-substrates and the experimental yield figure was 0.94 g/g on hexadecane/ammonium.
Abstract: Yeasts were chemostatically cultivated on C2-substrates. Experimental yield figure were 0.77 g/g and 0.57 g/g on ethanol, 0.37 g/g and 0.29 g/g on acetate and ammonium and nitrate, respectively, as the nitrogen sources. Growth on hexadecane/ammonium yielded 0.94 g/g. Simultaneous utilization of formate lead to an increase of growth yield on acetate and hexadecane but not on ethanol. The experimental data were compared to theoretical figures. These results show that growth yield on ethanol/ammonium is carbon-limited, on ethanol/nitrate is NADPH-limited and on acetate with both nitrogen sources is energy-limited. With hexadecane/ammonium growth yield is energy-limited too. According to these results ethanol seems to be the only substrate from which an excess in energy can be obtained.


Journal ArticleDOI
TL;DR: In this article, the experimental technique for measurement of microbial culture heat evolution directly in fermenter has been described and its correctness analyzed, and the experimental data on the heat-to-oxygen ratio of synchronized yeast culture in the absence of fermentative metabolism has been found to be practically independent of a cell cycle phase and close to the theoretical constant predicted by the mass-energy balance theory.
Abstract: The experimental technique for measurement of microbial culture heat evolution directly in fermenter has been described and its correctness analysed. Heat-to-oxygen ratio, Q0, of synchronized yeast culture in the absence of fermentative metabolism has been found to be practically independent of a cell cycle phase and close to the theoretical constant predicted by the mass-energy balance theory. The collection of literature data on the heat-to-oxygen ratio is given. Energetic properties of cell biomass are discussed on the basis of the obtained and the surveyed values of Q0.


Journal ArticleDOI
TL;DR: Preparation et proprietes cinetiques de cette enzyme immobilisee sur verre obtenue a partir d'Aspergillus niger Application a la saccharification de l'amidon dans trois systemes de conditions de fonctionnement en discontinu, en semi-continu ou en continu
Abstract: Preparation et proprietes cinetiques de cette enzyme immobilisee sur verre obtenue a partir d'Aspergillus niger Application a la saccharification de l'amidon dans trois systemes de conditions de fonctionnement en discontinu, en semi-continu ou en continu

Journal ArticleDOI
TL;DR: Investigation of the feasibility of using the ATP concentration for the monitoring of the growth of Escherichia coli K 12 W 3350 in different cultivation conditions showed that the ATP content of the culture is as suitable characteristic as the optical density of theculture, total cell number per ml or total cell volume per ml.
Abstract: The relative constancy of ATP content per unit of dry biomass in different microorganisms enables to use the specific, sensitive and quick luciferin-luciferase method for ATP assay for indirect quantitation of microbial biomass by measuring the ATP content in biomass samples.The aim of this work was to investigate the feasibility of using the ATP concentration for the monitoring of the growth of Escherichia coli K 12 W 3350 in different cultivation conditions. Statistically significant high correlation coefficients (r > 0.9) between the ATP content (ATP/ml) and the other growth characteristics examined showed that the ATP content of the culture is as suitable characteristic as the optical density of the culture, total cell number per ml or total cell volume per ml for the monitoring of the growth of E.coliin batch culture in mineral medium with glucose at different growth temperatures (27–42 °C) as well as in fed-batch culture.

Journal ArticleDOI
TL;DR: The ethanol-inhibitory behavior of the yeast Saccharomyces cerevisiae Sc 5 was found to be characterized by a continual linear relation between the specific ethanol formation rate and the ethanol concentration as mentioned in this paper.
Abstract: The ethanol-inhibitory behaviour of the yeast Saccharomyces cerevisiae Sc 5 was found to be characterized by a continual-linear relation between the specific ethanol formation rate and the ethanol concentration. Therefore the simple equation could be applied for it. It is shown that this model is correct only then, if all of the process parameters are in their optimum. Out of the optimum temperature range the characteristics of the function ν = f(P) change in such a way that in regard to the ethanol concentration P twc linear relations exist for each suboptimum temperature: and a non-linear equation is current for each superoptimum temperature: where bT is also a function of the temperature and always less than 1. Taking as a basis these equations the specific ethanol formation rate of the used strain can be calculated for the whole biokinetic P/T-sphere of ethanol production.

Journal ArticleDOI
TL;DR: Fast and simple methods of determination of L -lysine by a potentiometric enzyme electrode based on a CO2 electrode and L-lysine decarboxylase are described in this paper.
Abstract: Fast and simple methods of determination of L-lysine by a potentiometric enzyme electrode based on a CO2 electrode and L-lysine decarboxylase are described. Measuring devices for manual and automated operation for steady state response measurement as well as kinetic measurement are compared. Sample frequency may be increased by decreasing the time of a measuring cycle.

Journal ArticleDOI
TL;DR: It is stated that the specific product formation rate in the case of fermentations negligibly influenced by diffusion hindrance is related to the total surface of the viable cells but not to their total number, total volume or total dry weight.
Abstract: S. cerevisiae cells immobilized in alginate beads show in many cases an increase of mean single cell volume during long-time fermentations (successive batch cycles). The biomass loading capacity of the gel beads is characterized by a maximum volume but not by a maximum number of cells occupying the gel volume. In our system this loading capacity, i.e. the maximum volume fraction of cells per volume of beads, amounted to about 0.54. As a more important result it must be stated that the specific product formation rate in the case of fermentations negligibly influenced by diffusion hindrance is related to the total surface of the viable cells but not to their total number, total volume or total dry weight.