bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzymatic modification of yeast protein isolates
Authors: Einhorn‐Stoll U. , Kretzschmar U. , Lippert E. 
Published: December 2004

AbstractYeast protein isolate with 85% of pure protein and 1.2% of nucleic acids in dry matter was isolated fromSaccharomyces cerevisiaeby a procedure of two pre‐treatment steps, acidic extraction and isoelectric precipitation. The application of this yeast protein isolate was limited by its functionality resulting from the partially extreme isolating conditions.An enzymatic partial hydrolysis with Thermitase to a degree of hydrolysis of 5% not only improved the solubility and foaming properties, but also the water binding capacity and the emulsifying properties. The hydrolysate was free of bitter taste and could be applied either in two fractions of different solubility after centrifugation or as a whole product in food systems to improve the physiological and functional quality. The yeast protein hydrolysate had the same or even better properties than conventional protein products.
Intensification of transfer processes in biotechnology and chemical engineering using static mixers. (Review)
Authors: Gavrilescu M. , Tudose R. Z. 
Published: December 2004

AbstractA review of the intensification of moment, mass and heat transfer using an “unconventional” method, namely the application of static mixers, also known as “motionless mixers”, is presented in this paper.After the presentation of some structural types of static mixers, studies with particular emphasis on flow behaviour, pressure drop, mixing, mass and, heat transfer in the presence of static mixing devices, used in biotechnology and chemical engineering, were discussed.The suitability of static mixers to enhance the transfer process parameters was also justified by the low energy requirement, while the fluids might have different viscosities and because of this fact they could remove any mistakes made by the equipment.The article is not directed towards a comprehensive review, but it should serve as a landmark in future undertakings.
Behaviour of different Lactobacillus species in the production of lactic acid by the fermentation of whey
Authors: Rincón J. , Fuertes J. , Rodríguez L. , Monteagudo J. M. 
Published: December 2004

AbstractThe behaviour of different Lactobacillus casei and Lactobacillus plantarum species in the fermentation of Manchego whey was experimentally studied and the results were statistically analyzed using a hypothesis contrast method. The steadiness of the velocity of the production of lactic acid during the fermentation process allowed the use of this variable to compare the different microorganisms. From this comparison it was inferred that the individuals of the same population behave alike and that the L. casei population produces lactic acid at a higher rate than the L. plantarum population. A competitive effect among the members of the L. casei population was also observed.
“Macroscopic pattern analysis” based on formal analogies as a scientific methodology for complex systems
Authors: Moser A. 
Published: December 2004

AbstractBioprocess engineering at present concentrates on the enormous problems in the environment. What is therefore needed is a sound methodology, which should be based on the interactions between the physiology of biological reaction networks and physical processes in the environment and which should be an analogy to bioreactor performance. The conventional methodology is empirically oriented, using pilot plant data for the experimental estimates of process economics, where all further details are elucidated following the mechanistic approach on the microscopic level based on assumed mechanisms (causalities). According to the new view, the new systems‐based methodology uses mathematical models as approximations and includes all the interactions. Pilot plant data are needed for model falsification, using analogies on the formal macroscopic level. Bioreactor scale‐up as one application is a more rapid procedure of reasonable accuracy, where both the biokinetics as well as the fluid dynamics are quantified using formal macroscopic analogies.Model consistency and plausibility are the basic criteria when using model computer simulations as a decisive aid, while experiments lose their central role and are on longer the basis for evaluating the scientific work; they are simply the basis of the researcher's intuition. Another typical feature of complex systems is that model parameters are interdependent. The final decisive fact will be the mental experiment (“thinking” with the left and right side of the brain), which can be supported using computer simulations. This evolutionary interplay between the three realities of thinking, experimenting and simulating leads to a holistic progress towards the better understanding of highly complex systems. It offers the solution to the problems, which is needed in future.
Studies on the root nodules of leguminous plants: The production of indole acetic acid in culture by a Rhizobium sp. from a leguminous climbing shrub Derris scandens benth
Authors: De P. S. , Basu P. S. 
Published: December 2004

AbstractThe Rhizobium sp. When isolated form the root nodules of a leguminous climbing shrub Derris scandens produced a high amount of indole acetic acid (IAA) (135.2 μg/ml) from the tryptophan‐supple‐mented basal medium. Growth and IAA production started simultaneously, and the maximum amount of IAA was produced as a secondary metabolite in the stationary phase of growth. The IAA production by the Rhizobium sp. was increased by 503% when the medium was supplemented with mannitol (2%), KNO3 (0.2%), nicotinic acid (0.1 μg/ml) and MnSO4 (1 μg/ml) in addition to tryptophan (4 mg/ml)/The possible role of the rhizobial production of IAA on the rhizobia‐legume symbiosis is also discussed.
Effect of oleic acid on the production of ethanol and fructose from glucose/fructose mixtures in an immobilized cell reactor
Authors: Guénette M. E. , Duvnjak Z. 
Published: December 2004

AbstractSaccharomyces cerevisiae ATCC 39859 was immobilized onto small cubes of wood to produce ethanol and very enriched fructose syrup from glucose/fructose mixtures through the selective fermentation of glucose. A maximum ethanol productivity of 21.9 g/l‐h was attained from a feed containing 9.7% (w/v) glucose and 9.9% (w/v) fructose. An ethanol concentration, glucose conversion and fructose yield of 29.6 g/l, 62% and 99% were obtained, respectively. This resulted in a final fructose/glucose ratio of 2.7. At lower ethanol productivity levels the fructose/glucose ratio increases, as does the ethanol concentration in the effluent. The addition of 30 mg/l oleic acid to the medium increased the ethanol productivity and its concentration by 13% at a dilution rate of 0.74 h−1.
Media for the detection of Bacillus larvae spores in honey
Authors: Steinkraus K. H. , Morse R. A. 
Published: December 2004

AbstractBacillus larvae, the causative agent of American foulbrood in honey bees completes its life cycle of germination, outgrowth and sporulation in young honey bee larvae by killing them and often bringing about the destruction of the entire hive. While B. larvae germinates and outgrows on complex organic media in vitro, the literature suggests, for reasons that are not at all clear, that a relatively large number of spores of B. larvae are required to yield each visible colony (colony forming units, CFU) on media. Various researchers have reported that from 16 to 3,000 or more spores of B. larvae are required to yield a single colony on an agar plate. HANSEN in Denmark designed a useful method of spreading approximately 80 mg of honey directly on the surface of a PETRI plate containing “J” agar medium to determine if B. larvae spores are present in the honey. In the present study, selected media were tested for the ability to recover B. larvae spores in honeys in the form of visible colonies (CFU) using HANSEN's strek method. A modification of a medium (TMYGP) developed by DINGMAN and STAHLY, (T‐HCL‐YGP agar), recovered considerably more viable B. larvae spores in the form of visible colonies (CFU) than HANSEN's “J” medium. When “J” medium was fortified with 0.1% sodium pyruvate, it was comparable to modified T‐HCL‐YGP medium in its recovery of B. larvae spores. Brain heart infusion agar (BHIA) with the addition of thiamine recovered more spores in the form of viable colonies than did “J” medium but it was not as efficient as T‐HCL‐YGP medium. Serial dilution from 100 to 10,000 times of weighed samples of honey with deionized water led to higher spore counts (CFU per g honey) than that indicated by undiluted honeys plated at 80 mg levels directly onto the surface of media by the HANSEN procedure.
Production of citrinin by Monascus ruber submerged culture in chemically defined media
Authors: Pastrana L. , Loret M. O. , Blanc P. J. , Goma G. 
Published: December 2004

AbstractFollowing our investigations on citrinin production by Monascus ruber in a chemically defined medium, the kinetic behaviour of this toxin in the fermenter was studied with relation to production of pigments, biomass and nutrient consumption. Showing a secondary metabolite pattern, citrinin was produced when dμ/dt and dQs/dt were ≤ 0, while a high specific production rate of pigments occurred when dμ/dt and dQs/dt were > 0. No trophophase‐idiophase transition was detected during the cuitivation, and the behaviour of pigment production was similar to that of a primary metabolite.
Sucrose medium osmolality as a regulator of anabolic and catabolic parameters in Zymomonas culture
Authors: Vigants A. , Zikmanis P. , Bekers M. 
Published: December 2004

AbstractThis study focuses on the growth of Zymomonas mobilis strain 113 S and its ethanol and levan production under the conditions of increasing sucrose medium osmolality caused by NaCl, KCl, sorbitol or maltose. The increase in medium osmolality (700–1,500 mosml/kg) was accompanied by the inhibition of growth (growth rate, biomass yield) and ethanol production (specific productivity and yield) In contrast, levan synthesis was less affected or even stimulated and, as a consequence, levan specific productivity was increased significantly. A decrease in the anabolic growth parameters correlated with a parallel inhibition of glucose‐6‐P dehydrogenase and alcohol dehydrogenase (isoenzyme ADH II) activities. A significant inverse linear relationship (r = − 0.932, 1 − P = 0.01) was observed between the values of the specific productivities of ethanol and levan. This relationship was confirmed independently by a controlled reduction of growth and ethanol productivity (3.75–4.75 mM sodiumbisulphite as an acceptor of acetaldehyde formed in the pyruvate decarboxylase reaction). As further support of this relationship, a significant inverse correlation was observed between levan specific productivity and ATP concentration in Zymomonas mobilis cells, most probably demonstrating that a reduced level of energetic metabolism is favourable for levan production.
Formation of aminium lactates in lactic acid fermentation preparation and characterization of 1,4‐piperazinium‐(L,L)‐dilactate obtained fromL(+)‐lactic acid (part I)
Authors: Kamm B. , Kamm M. , Richter K. 
Published: December 2004

AbstractThe potential for the production of 1,4‐piperazinium‐(L, L)‐dilactate fromL(+)‐lactic acid preparations obtained by fermentation was studied. Piperazinium dilactate was found to be a very suitable source material for poly(lactic acid) production. In a novel polymerization process, the intermediate dilactide was directly formed in the salt melt at a moderate temperature. High‐performance cultivation ofLactobacillus paracaseion a glucose‐MRS medium was carried out using high‐viability inocula. After the cell mass had been removed from the fermentation broth by centrifugation and/or ultrafiltration, the lactic acid solution was concentrated to 45% [w/w] by a two‐stage electrodialysis process. Two methods of preparing 1,4‐piperazinium dilactate were developed: the first from the medium‐concentrated lactic acid (45%) and the second from a highly‐concentrated lactic acid (85%) obtained by evaporation from the first one. Because there were no physical data on 1,4‐piperazinium‐(L, L)‐dilactate in specialized literature, the pure product was characterized according to its solubility characteristics, melting point and spectroscopic analysis.
Selection of yeast strain and fermentation conditions for high‐yield ethanol production from lactose and concentrated whey
Authors: Szczodrak J. , Szewczuk D. , Fiedurek J. , Rogalski J. 
Published: December 2004

AbstractA total of 65 yeast strains were screened for their ability to grow and ferment lactose in a standard DURHAM tube test at 30 °C. Based on the kinetic parameters for lactose and whey lactose fermentations in shake flask cultures, the strain Candida psedotropicalis 65 was chosen for further studies.Some of the cultural parameters affecting ethanolic fermentations on lactose were standardized. At an initial lactose concentration of 100–120 g/l in the medium containing concentrated whey or lactose, at 40 °C and within 48 h, the selected strain reached an ethanol concentration of 41–59 g/l, an ethanol productivity of 1.3–3.0 g/l/h, a lactose consumption of 99%, an ethanol yield 0.4–0.49 g/g and a biomass yield of 0.027 g/g.
Correlation between hypericin content and the ploidy of somaclones of Hypericum perforatum L.
Authors: Čellárová E. , Brutovská R. , Bruňáková K. , Daxnerová Z. , Weigel R. C. 
Published: December 2004

AbstractAn altered ploidy level was observed in plants regenerated by adventitious shoot formation from seedlings of Hypericum prformatum L. (2n = 4x = 32). Among the somaclones of the Ro generation, the presence of diploids (2n = 2x = 16), triraploids (2n = 3x = 24), tetraploids (2n = 4x = 32) and mixoploids was detected. Cytogenetic analyses of the R1 and R2 progenies showed that the chromosomal instability of the Ro somaclones was transferred onto the next generation.While almost all the seed progeny of diploids (100% in R1 and 94% in R2) progenies showed that the chromosomal instability of the Ro somaclones was transferred onto the next generations.While almost all the seed progeny of diploids (100% in R1 and 94% in R2) and more than 60% of tetraploids (61% in R1 and 73% in R2) retained their chromosome number, cytogenetic diversity was observed in the progeny of triploids, mixoploids and some tetraploids.Somaclones and their offspring were analyzed for hypericin content. Statistical evaluation showed a correlation between hypericin content and ploidy during a two‐year cultivation of R0 somaclones and in their R1 and R2 progenies.
Effects of anoxic conditions on the enzymatic conversion of D,L‐2‐amino‐thiazoline‐4‐carboxylic acid to L‐cystine
Authors: Nam K. H. , Ryu O. H. , Park J. , Shin C. S. 
Published: December 2004

AbstractThe effects of anoxic conditions on product inhibition and the stability of L‐ATC hydrolase were investigated in the conversion of D,L‐2‐amino‐Δ2‐thiazoline‐4‐carboxylic acid (D,L‐ATC) to L‐cystine using the cell free extract enzyme of Pseudomonas sp. in the presence of hydroxylamine. At L‐cysteine equivalent levels, where one mole of L‐cystine was counted as two moles of L‐cysteine, L‐cystine inhibited the L‐ATC hydrolase reaction to a greater extent than L‐cysteine. In air, the product occurred predominantly as L‐cystine (94.9%), whereas in a nitrogen atmosphere the product occured as a mixture of L‐cysteine (39.3%) and L‐cystine (40.7%). As a result, less product inhibition took place in nitrogen. The activity of L‐ATC hydrolase was almost fully lost after 20 h of incubation by shaking at 30 °C in air, but considerable activity remained under the anoxic conditions of nitrogen. A kinetic analysis of the reactions confirmed that reduced product inhibition and enhanced enzyme stability in nitrogen result in a more efficient enzyme reaction. The inactivation rate constant (k1) was estimated to be 0.11 h−1 in nitrogen and 0.22−1 in air, indicating that the stability of L‐ATC hydrolase in nitrogen was greater than in air. The values of the Kp1 and Kp2 constants related to product inhibition were 43.36 mM and 30.48 mM for L‐cysteine and L‐cystine, respectively, where higher values were an indication of less product inhibition. The value of the rate constant (k2) for the oxidation of L‐cysteine to L‐cystine was 0.09 h−1 in nitrogen and 1.01 h−1 in air, suggesting that the oxidation of L‐cysteine to L‐cystine proceeds faster in air than in nitrogen.
Coconut cake – a potent substrate for the production of lipase by Candida rugosa in solid‐state fermentation
Authors: Benjamin S. , Pandey A. 
Published: December 2004

AbstractInvestigations were conducted with the aim of producing extracellular lipase from Candida rugosa by solid‐state fermentation (SSF), using coconut oil cake (COC) as a solid substrate. To optimize production, various modifications were made to enrich the substrate by supplementing it with mineral solution, different carbon sources and several inorganic as well as organic nitrogen sources. Among them, urea (1%), peptone (3%) and maltose (5%) were found to be most suitable. Addition of olive oil (10%) encouraged lipase synthesis. The maximum lipase activity in the enriched substrate was 87.76 units per gram of dry fermented substrate [U/gds] compared to 25.81 U/gds in the raw cake at 96 h of fermentation, and growth was as high as 14.44 mg/gds of glucosamine. This was reached at 72 h in the enriched substrate. C. rugosa growth was calculated indirectly by estimating the glucosamine content in the cell wall after its hydrolysis. The enzyme yield was far better than any values reported as yet.
Growth and formation of poly (hydroxybutyric acid) by Methylobacterium rhodesianum at methanol concentrations of above 25 g/I
Authors: Bormann E.‐J. , Leissner M. , Beer B. 
Published: December 2004

AbstractMethylobacterium rhodesianum MB 126 was cultivated using extended cultures without outflow. The feeding regime was based on the pH‐regulated synchronous dosages of ammonia, methanol, phosphatc and trace elements according to supposed stoichiometric relations. The acidity of the culture medium was kept constant at pH 6.8, whereas the dissolved oxygen concentration was adjusted at 80% of saturation by autoregulation of the stirrer speed. However, besides testing technical conditions, two types of fermentations were discovered which are described in this paper. Firstly, although at the beginning of the bioprocesses the impeller speed increased up to 2,000 rpm, a decrease of dissolved oxygen down to zero was unavoidable. Secondly, methanol was accumulated temporarily up to 44 g/l and 26 g/l at 23 h of fermentation time and without inhibition of growth at least up to 30 g/l or PHB production. During this accumulation of the carbon substrate, exponential growth phases were detected showing growth rates of μ = 0.20/h and 0.21/h. But then, phases of retarded growth followed, whereas the methanol disappeared either continuously or after a steady level. In the course of a 54‐h fermentation period, the synthesized PHB amounted to a content of above 50% of cell dry mass. From this data, a volumetric productivity of 0.4 g PHB/lxh was estimated. Moreover, the growth related yield coefficients were calculated to YX/MeOH = 0.21 and YX/MeOH = 0.14, whereas the product related yield coefficients amounted to YPHB/MeOH = 0.12 and YPHB/MeOH = 0,09. Since the shift down of growth rates as well as the production of PHB agreed in time with partial oxygen limitation (40% oxygen saturation), the competition observed between the tricarboxylic acid cycle and PHB synthesis was discussed. Summarizing the results, it was concluded that the frequently described inhibitory effect of methanol of above 2 g/l seems to be rather an effect of experimentally chosen conditions than of a general physiological phenomenon. Therefore, it could be demonstrated that the toxicity of methanol could be overcome if it was not dosed at different times but simultaneously with other medium components.
Cell reuse in submerged lactic acid batch fermentation
Authors: Richter K. , Beyer F. 
Published: December 2004

AbstractThe reusability of biomass in lactic acid batch fermentation with free cells of Lactobacillus paracasei was studied in a 2–1 fermenter and in a 50‐1 fermenter. In lab‐scale fermentation experiments, 33 to 100% of the cell mass formed was reused in the subsequent batch in each case. In a series of seven consecutive batches, maximum values of lactate formation productivity of 6.32 to 11.54 g/l × h were observed at initial cell concentrations of 2.1 to 24.6 g/l. In all of the experiments, the initial cell viability was 78% or greater than 78%, and the final cell viability did not fall below 70%. At cell concentrations above 20 g/l, the productivity of lactic acid formation did not increase further, but remained constant. Because its level could be influenced by varying the proportions between the content of yeast extract, peptone and initial cell mass (1:1:2, 1:1:1 and 3.3.1) in the medium and no inhibitory effects were observed, this finding can be attributed to nutrient limitation. A low degree of cell reuse was reached in an analogous series of experiments carried out in a 50‐1 fermenter. In this case, the initial cell concentration varied between 0.5 and 1.1 g/l, and therefore cell growth was not limited by nutrients in the first period of fermentation. Lactate production was still stable after six cell‐reuse operations. The lactic acid yield did not fall below 90%. Temporary storage of the biomass in a refrigerator for a time interval of one to two weeks caused no significant impairment of overall lactate production, but a proportional prolongation of the lag phase occurred with increasing duration of storage.
Purification and immobilization of dextranase
Authors: Rogalski J. , Głowiak G. , Szczodrak J. , Pleszczyńska M. , Szczodrak Z. , Wiater A. 
Published: December 2004

AbstractAn enzymic characteristic of Novo dextranase was presented. In addition to a high dextranolytic activity (7,200 U/ml), the crude enzyme also contained small amounts of protease, glucoamylase, polygalacturonase, carboxymethylcellulase, laminarinase and chitinase. A highly purified dextranase was then simply separated from a commercial preparation by column chromatographies on DEAE‐Sepharose, CM‐Sepharose, and by chromatofocussing on Polybuffer Exchanger PBE‐94. The enzyme was recovered with an over 200‐fold increase in specific activity and a yield of 84%. The final preparation was homogeneous, as observed during high performance liquid chromatography (HPLC). Size‐exclusion HPLC indicated that dextranase had a molecular mass of 35 kDa and its isoelectric point, established by chromatofocussing, was 4.85. Analysis of the dextran break‐down products indicated that purified dextranase represents an endolytic mode of action, and isomaltose and isomaltotriose were identified as the main reducing sugars of dextran hydrolysis. The enzyme was then covalently coupled to the silanized porous glass beads modified by glutaraldehyde (Carrier I) or carbodiimide (Carrier II). It was shown that immobilization of dextranase gave optimum pH and temperature ranges from 5.4 to 5.7 and from 50°C to 60°C, respectively. The affinity of the enzyme to the substrate decreased by a factor of more than 13 for dextranase immobilized on Carrier I and increased slightly (about 1.4‐times) for the enzyme bound to Carrier II.