bluuebunny/crossref_metadata_2025_split huggingface dataset:
Capacities and limits of three different technologies for the biological treatment of leachate from solid waste landfill sites
Authors: Martienssen M. , Schulze R. , Simon J. 
Published: December 2004

AbstractLeachate from a municipal waste landfill site was treated using an activated sludge bioreactor, a fluidized bed biofilm reactor and a packed‐bed column reactor (trickling filter).The leachate contained high organic matter (2.0–2.6 g/l of COD), high ammonium (300–700 mg/l) and sulphide (200–800 mg/l) concentrations, as well as low metal concentrations.The continuously operating reactors were employed to study the effects of TOC loading on the removal of TOC as well as on the nitrification and denitrification processes.Among the three biological treatment technologies investigated, the fluidized bed biofilm reactor was best with respect to removing ammonia and TOC. More than 90% of TOC and 99% of ammonia were removed when TOC loading was less than 0.5 kg/m3 × d. At a TOC loading of 4 kg/m3 × d, the removal of TOC and ammonia was 80% and 99%, respectively.In contrast, the treatment of leachate with the packed‐bed reactor was successful in TOC removing only at TOC loading less than 0.3 kg/m3 × d (TOC elimination decreased from 86% at 0.06 kg/m3 × d to 60% at 0.3 kg/m3 × d). However, the reactor was active in nitrification even at a higher TOC loading (more than a 98% ammonia elimination at a TOC loading of 0.5 kg/m3 × d).Leachate was processed in the activated sludge reactor when TOC loading was less than 0.5 kg/m3 × d (with a removal of TOC and ammonia up to 83% and 99%, respectively). The activated sludge reactor was also effective in TOC removal at a higher TOC loading (e.g. a 74% TOC removal at a TOC loading of 1 kg/m3 × d), but for ammonia elimination, the activity continuously decreased (less than 60% ammonia removal at a TOC loading of 1 kg/m3 × d).Overloading in the activated sludge system was indicated by a high concentration of ammonia and nitrite in the effluent. In the packed bed reactor, overloading was characterized by a progressively incomplete TOC removal. No significant overloading was found in the fluidized bed reactor up to a TOC loading of 4 kg/m3 × d.
The molecular cloning and sequencing of the nitrilase gene of Rhodococcus rhodochrous PA‐34
Authors: Bhalla T. C. , Aoshima M. , Misawa S. , Muramatsu R. , Furuhashi K. 
Published: December 2004

AbstractThe nitrilase of Rhodococcus rhodochrous PA‐34 catalyzes the production of optically active amino acids from aminonitriles. The amino acid sequence of the NH2 terminus of the purified nitrilase was determined for the preparation of a synthetic oligonucleotide as a southern hybridization probe. A 9.5‐kbp Pst I‐fragement, which hybridized with the oligonucleotide probe, was isolated from R. rhodochrous PA‐34 genomic libraries constructed in pUC 19. Nucleotide sequence analysis revealed that the nitrilase gene codes for a putative polypeptide of 380 amino acids which correspond to a relative molecular weight of 41, 723.
Studies of the mixing character and flow distribution in mycelial fermentation broths
Authors: Vanags J. J. , Viesturs U. E. , Priede M. A. 
Published: December 2004

AbstractThe influence of two mixing systems on the principal parameters of mycelial fermentations of Aspergillus niger, Fusicoccum amygdali Del. and Fusarium moniliforme Sheld. as well as their metabolite citric acid, fusicoccin and gibberellic acid production was analyzed from the viewpoint of flow energy distribution in a bioreactor.The growth and metabolite synthesis during fermentation was compared under different mixing conditions in the fermenter FU‐8 with a turbine mixing system (TMS) and a counterflow mixing system (CMS). It was found that the growth, productivity and respiration characteristics as well as the morphology of these cultures varied dependent on the mixing system and agitation regime used. The counterflow mixing system was more favourable for large agglomerates (F. amygdali) or soft pellets (A. niger) forming fungi, while the turbine mixing system was more effective for F. moniliforme growing in the form of small clumps and freely dispersed hyphae. Flow characteristics under different mixing conditions were analyzed in a model fermenter.The kinetic energy of flow fluctuations was measured in gassed and ungassed water and different fermentation broth systems by using a Stirring Intensity Measuring Device (SIMD‐F1). The difference of the energy values at different points was better expressed in the fermenter with a turbine mixing system in comparison with that having a counterflow mixing system. High viscous F. amygdali and A. niger broth provided higher energy values compared to water and low viscous F. moniliforme broth. It was observed that the intensity of growth and the intensity of the synthesis decreased at very high energy values, which was obviously connected to the influence of the irreversible shear stress on the mycelial morphology.
Kinetic study of the anaerobic degradation of toluene by a mixed culture
Authors: Chaduhri B. K. , Wiesmann U. 
Published: December 2004

AbstractToluene was anaerobically degraded by an enriched mixed culture under methanogenic conditions. The mixed culture was originally developed from cow‐dung and sludge from a laboratory reactor, in which benzene was anerobically degraded by sulphate‐reducing bacteria. First the mixed culture was enriched on toluene over a year with and without the use of sulphate in the medium. For the evaluation of growth‐kinetic and maintenance parameters, namely μmax, Ks, kd and Y, the anaerobic degradation of toluene was carried out in batch as well as in continous reactors systems. The gas volume and the methane content in the produced gas was somewhat lover than the theoretical value expected, indicating an incomplete degradation of some of the complex intermediates of the toluene degradation pathway. However, the mixed culture was able to transform 41.3% of the toluene carbon into methane.
Extracellular acid phosphatase as a minor enzyme during the production of proteinases by Humicola lutea 120–5
Authors: Tchorbanov B. , Aleksieva P. , Dambadarja N. , Dyulgerova G. 
Published: December 2004

AbstractExtracellular acid phosphatase was studied as a minor enzyme of the fungal strain Humicola lutea 120–5 having a clear relation to the secretion of acid proteinases. A medium lacking in mineral orthophosphates ensured a fivefold higher yield of phosphatase while the proteinase production was reduced. An acid phosphatase fraction free of proteinase activity was isolated demonstrating a maximum hydrolysis of 4‐nitrophenyl‐phosphate at a pH of 4.0 and 50°C. The phosphatase catalyzed a partial dephosphorylation of up to 30% of casein at a pH of 3.0 causing a complete substrate precipitation. Both proteinase and phosphatase biosynthesis increased twofold when natural casein was replaced by partially dephosphorylated casein in the cultivation medium.
Studies on polyphosphate and poly‐β‐hydroxyalkanoate accumulation in Acinetobacter johnsonii 120 and some other bacteria from activated sludge in batch and continuous culture
Authors: Weltin D. , Hoffmeister D. , Dott W. , Kämpfer P. 
Published: December 2004

AbstractTwelve bacterial isolates, four of them assigned to the genus Acinetobacter, were taken from sewage of a treatment plant with Enhanced Biological Phosphorus Removal (EBPR) and screened for phosphorus uptake, polyphosphate (polyP) accumulation and adsorption under limited carbon and nitrogen conditions. In addition, poly‐β‐hydroxyalkanoate (PHA) production was studied under carbon, nitrogen, phosphorus, and oxygen limitation. Under C limitation, the uptake of phosphorus was highest, ranging up to 66 mg P per g dry weight (dw) for the Acinetobacter isolates, whereas the highest amount of polyP was detected under limited N conditions (up to 25 mg PolyP / g dw). Extra‐cellular polyP was detected, however to a minor extent, accounting for a maximum of 10% of the total polyP in one Acinetobacter isolate. The highest PHA concentration (given as 3‐hydroxybutyrate, 3 HB) with 211 mg 3 HB / g dry weight (21% of the dried cell mass) was found for A. johnsonii 120 under nitrogen limitation, but also under P and O2 limitation, PHA, mainly poly‐β‐hydroxybutyrate and poly‐β‐hydroxyvalerate, were produced. Three isolates, assigned to the genus Pseudomonas, showed even higher values (345–427 mg 3 HB / g dw) under N limitation. Studies with Acinetobacter johnsonii 120 in continuous culture, simulating the aerobic/anaerobic periods of a waste‐water treatment plant, resulted in a P elimination of 36% at an anaerobic contact time of 0.6 h. This value increased to 51% at an anaerobic contact time of 3.1 h. No release of phosphate and no uptake of acetate could be detected during the anaerobic period. In addition, Acinetobacter johnsonii 120 was not able to synthesize PHA under anaerobic conditions. By changing the anaerobic conditions to aerobic, a continuous decrease of the polyP content relative to the totalP content from 45% (day 1 of the aerobic process) to 19% (day 17 of the aerobic process) was observed. The amount of PHA increased to 50.4 mg 3 HB/g dw under aerobic conditions. The results indicate again that the EPBR process cannot be defined by simply applying the knowledge of the metabolic processes, observed or assumed in Acinetobacter pure cultures, to the complexity of the process in sewage treatment plants.
Describing microbial degradation processes with the EVOLON model
Authors: Bley Th. , Albrecht K.‐F. , Miethe D. , Riis V. , Babel W. 
Published: December 2004

AbstractThe remediation of polluted soils by microbial communities is a complex process, characterized by many competitive and cooperative mutual relations between the individual organisms. For the overall characteristic of such processes, top‐down systems analyses promise a better description for prognostic aims than bottom‐up approaches.This is demonstrated using the EVOLON model to fit the cumulative O2 consumption data of a microbial ecosystem metabolizing diesel fuel in polluted soil. The EVOLON is a generic top‐down model providing close approximation to the experimental data.The advantage of using this model instead of other similar models is demonstrated by a comparison of the deviations between model values and experimental data (residuals).
Effect of the peptide and vitamin composition of casein hydrolysates on the β‐galactosidase activity of Kluyveromyces bulgaricus cells
Authors: Decleire M. , DeCat W. , Motte J. C. , Van huynh N. , Callebaut A. 
Published: December 2004

AbstractInstead of yeast extracts, casein hydrolysates from several suppliers were added to culture media and analyzed with respect to their ability to stimulate β‐galactosidase activity in Kluyveromyces bulgaricus cells. Four enzymatic casein hydrolysates caused a significantly higher stimulation of enzyme activity, while acid casein hydrolysates clearly reduced the enzyme activity. Enzymatic casein hydrolysates, inducing high and low lactase activity, were analyzed with respect to average peptide length (APL), vitamins (niacin, pathothenate) as well as free and bound amino acids. The molecular weights of these casein hydrolysates were estimated by gel filtration. No correlation was found between the degree of enzyme stimulation and the vitamin contents, the APL values and the free amino acid contents of the casein hydrolysates. Casein hydrolysates stimulating the lactase activity were less soluble in water and, in a gel filtration column, they showed three peaks with slightly lower molecular weights than the three peaks seen in hydrolysates which had no effect on activity. APL values of alcoholic precipitates of casein hydrolysates showed an inverse correlation to lactase activity. The molecular weights of alcoholic precipitates of lactase stimulating digests were also lower compared to non‐stimulating ones. Alcoholic precipitates with lactase‐stimulating activity were more hydrophilic, as was shown by a smaller proportion absorbed in a C18 column and by amino acid analysis. Our results sugest that alcoholic precipitates could probably be important in the lactase stimulation and their composition should be further investigated. The mechanism is nevertheless complex and may be caused by various simultaneous factors.
Analyzing nitrogen and sulphide elimination from leachate by coulometric continuous flow titration
Authors: Becker M. , Martienssen M. , Fuhrmann B. , Spohn U. 
Published: December 2004

AbstractThe process of leachate denitrification by populations of nitrifying and denitrifying bacteria was investigated. Leachate, derived from a local municipal landfill site, was nitrified in a continuously operating packed‐bed biofilm reactor and thereafter denitrified in an activated sludge bioreactor. To follow the progress of nitrogen elimination, ammonium, nitrite and nitrate concentrations were determined at all stages of the process. While the nitrite and nitrate concentrations were measured by conventional colorimetric methods, computer controlled coulometric titration with in situ generated hypobromite was used for ammonium determination, which had previously been selectively separated from the sample matrix by gas dialysis. The detection range of the method was from 1 × 10−6 to 1 × 10−3 M ammonium (relative standard deviation (RSD) = 2%, n = 6). No interference of the complex sample matrix was found in ammonium determination. The average ammonium concentration in the leachate was 409 mg/l (standard deviation (SD) = 142 mg/l, n = 55). The ammonium concentrations decreased to 1–5 mg/l during nitrification under continuous operating conditions. Increased ammonium concentrations after nitrification correlated with a decrease in the efficiency of nitrogen elimination by up to 45% due to the build‐up of high concentrations of nitrite. The concentration of sulphides, another source of pollution of the leachate, was also determined by triangle programmed coulometric titration. The average concentration of sulphides in the leachate was 221 mg/l (SD = 374 mg/l; n = 55). The sulphide concentrations decreased to concentrations below the detection limit of the coulometric titration (2 × 10−6M) during nitrification.
Kinetics of olive oil hydrolysis in an enzyme membrane reactor. Bond graph network model of reactor performance (part 1)
Authors: Ceynowa J. , Adamczak P. , Staniszewski M. 
Published: December 2004

AbstractHydrolyses of olive oil were performed in a reactor with lipase immobilized on a laboratory ultrafiltration poliamide‐6 membrane. The reactor consisted of two circulating phases of olive oil and buffer solution. For the characterization of the reactor performance, a model of the hydrolysis process was developed. It was created by means of thermodynamic network representation of both the chemical processes and the transport of the reactants. According to an estimated bond graph network, the model is represented quantatively by a set of thirty‐three differential equations representing the time derivatives of the particular species concentration. The parameters of the model were estimated based on experimental data and/or literature notations. Close agreement of numerical estimations of the product concentrations with experimental data was gained. The model enabled an extended analysis of the influence of different reaction parameters, enzyme inhibition and concentration of the reactants on reactor performance.
Urease immobilized on an aminated polysulphone membrane – inhibition by boric acid
Authors: Krajewska B. , Zaborska W. , Leszko M. , Olech A. 
Published: December 2004

AbstractAn enzymatic membrane for application in the processes of decomposition and removal of urea from aqueous solutions was prepared: jack bean urease was immobilized on an aminated polysulphone membrane by adsorption. The inhibition of the system by boric acid was studied using procedures based on the MICHAELIS‐MENTEN integrated equation (non‐linear regression, and the linear transformations of WALKER and SCHMIDT, JENNINGS and NIEMANN, and BOOMAN and NIEMANN). The reaction was carried out in a 100 mM phosphate buffer of pH 7.0, containing 2 mM EDTA, obtained by neutralization of orthophosphoric acid with NaOH, at an initial urea concentration of 10 mM, and a temperature of 25 °C. The reaction was initiated by the addition of the enzyme to the urea solution, and was monitored by removing samples of the reaction mixture for NH3 determinations by the phenol‐hypochlorite method until the urea was exhausted. The results were compared with those obtained earlier under the same reaction conditions for free urease and urease covalently immobilized on chitosan. The inhibition was found to be competitive, similar to that of the free enzyme and urease immobilized on chitosan, with inhibition constants Ki equal to 0.36, 0.19 and 0.60 mM. The results show that adsorption of the enzyme on a polysulphone membrane changed the enzyme to a lesser degree than covalent immobilization of the enzyme on a chitosan membrane.
Growth patterns of yeast colonies depending on nutrient supply
Authors: Boschke E. , Bley Th. 
Published: December 2004

AbstractCommon theories of microbial growth and physiology are formulated exclusively in terms of the isolated microorganisms – especially bacteria. This is, however, an inadmissible simplification because it is obvious that the organization of microbial populations and colonies follows certain general rules.Bacterial colonies are able to generate complex interfacial growth patterns similar to those observed during diffusion‐limited growth processes in non‐living systems. One reason for these patterns is assumed to be the ability of many bacteria to swarm in an active manner on a substrate surface. Therefore the models of bacterial colony growth incorporate “random walkers”, which move actively in response to a gradient in the concentration of nutrients and communicate with each other by means of a chemotactic feedback.A selected number of yeasts were tested with regard to their colony growth patterns depending on the medium parameters such as nutrient concentration. Growth patterns similar to those which were described in literature for bacteria were also found in these experiments. It concerns in particular growth types like compact growth, fractal growth and dense‐branching growth.This result allows a hypothesis to be formulated, that – especially in the case of fractal growth patterns – wandering of cells on a substrate surface may be induced by uncontrolled “swimming” on a thin water film caused by the metabolic activity (e.g. respiration) of the cells on the surface of the agar.Furthermore it was found that an interplay between changes in the individual morphology of yeast cells and the morphology transitions takes place. Such growth patterns are known for Candida sp. which are able to form pseudomycel and blastospores.
Production of extracellular enzymes by two Pleurotus species using banana pseudostem biomass
Authors: Ghosh M. , Mukherjee R. , Nandi B. 
Published: December 2004

AbstractThe degradation of lignocellulosic biomass of banana pseudoste was investigated during solid state fermentation (SSF) by P. ostreatus and P. sajor‐caju. Both organisms proved to be efficient degraders of banana pseudostem biomass. P.ostreatus degraded hemicellulose (40% of dry weight, d.w.) better than cellulose (17.5% of d.w.) and lignin (10% of d.w.). P. sajor‐caju also degraded hemicellulose (31% of d.w.) better than cellulose (12.4% of d.w.) and lignin (6% of d.w.). In both cases, a preferential removal of hemicellulose during the initial growth period and a delayed degradation of lignin were observed. The kinetics of cellulolytic, hemicellulolytic and lignolytic enzyme production in liquid culture were also examined. The activities of CMCase and β‐glucosidase were highest at 16 days of growth and avicelase activity was at its maximum after 24 days (CMCase ‐ 1.1 IU/ml, β‐glucosidase ‐ 0.09 IU/ml in the case of P. ostreatus; CMCase ‐ 1.0 IU/ml, β‐glucosidase ‐ 0.087 ‐ IU/ml in the case of P. sajor‐caju.). Xylanase and laccase activity reached their maximum after day 16 and day 24 of incubation, respectively. (Xylanase ‐ 1.1 IU/ml and laccase 3.0 IU/ml in the case of P. ostreatus; xylanase ‐ 1.0 IU/ml and laccase ‐ 3.6 IU/ml in the case of P. sajor‐caju.). The efficient degrading capacity of test fungi demonstrated their potential use in the conversion of banana pseudostem biomass into mycelial protein‐rich fermented animal feed.
Fusion of yeast protoplasts and isolated nuclei of Fusarium moniliforme
Authors: Heluane H. , Defigueroa L. I. C. , Vázquez F. 
Published: December 2004

AbstractProtoplasts of a xylose‐fermenting yeast strain (a fusion product of Pachysolen tannophilus and Saccharomyces cerevisiae) were fused with isolated nuclei of the xylan degrading filamentous fungus Fusarium moniliforme. Polyethyleneglycol 4000 was used as the fusogenic agent. Fourteen stable hybrids showing xylanase activity were obtained. It can be assumed that this ability was acquired from the nuclear genome of the fungus, since the parental yeast strain did not show any xylanase activity. The enzymatic activity was determined quantitatively. The parental strain of the fungus reached its maximum xylanase activity of 796 nkat/ml at 96 h of growth. Four of the hybrids had a xylanase activity of between 211 and 297 nkat/l at 24 h of growth. Zymograms of these hybrids showed the presence of xylanases when grown on xylan as the sole carbon source. Using pulse field electrophoresis gels, no difference between the chromosome pattern of the fusion products and the parental yeast strain was observed.
Microbial degradation of poly‐β‐hydroxybutyrate using landfill soils
Authors: Tansengco M. , Dogma I. 
Published: December 2004

AbstractThe population of poly‐β‐hydroxybutyrate‐degrading microorganisms and the biodegradation of PHB in local landfill soils were examined in vitro and in vivo. Forty‐two PHB‐degraders consisting of 12 bacteria, 25 actinomycetes and 5 moulds were isolated. The total PHB‐degraders averaged 4.7 × 107 and 20 × 104 colony forming units (cfu)/g for San Mateo wet and dry soils, respectively, and 2.3 × 107 and 8.5 × 104 cfu/g for Carmona wet and dry samples, respectively. The PHB‐degraders formed 0–59% of the total microbial population in San Mateo and 8–42% in Carmona. Complete (100%) degradation of PHB powder was observed for Chryseomonas‐27 and Aspergillus‐39 on day 5 in shake flask culture and for Streptomyces‐4 on day 7. Burial test in landfill soils showed a 90–91% weight loss of PHB film strips within four weeks; the weight loss of polypropylene film strips was up to 0.12% only. Scanning electron micrographs of degraded films revealed the attachment of microbial cells and fungal mycelium and spores on the surfaces. Holes and cavities were also noted due to the microbial degradation processes.