Decolourisation of a pigment plant effluent by Pycnoporus cinnabarinus in a packed-bed bioreactor

Summary The decolourisation of wastewater from a pigment plant by the white-rot fungus Pycnoporus cinnabarinus was studied in a packed-bed bioreactor. Decolourisation was first observed 48 to 72 h after inoculation and was followed using UV/VIS spectrophotometry. An assessment of the inhibitory properties of the effluent on the growth of Pycnoporus cinnabarinus showed that this fungus can tolerate high levels of potentially toxic waste.     

Production of penicillin in a fluidized-bed bioreactor using a carrier-supported mycelial growth

A carrier-supported mycelial growth of Penicillium chrysogenum was applied to penicillin fermentation system using celite as a support material. Hyphal growth through the pore matrices of the material showed strong anchorages and provided highly stable biofilm growth. With bioparticles developed in such a manner, both cell growth and penicillin production were observed to increase significantly compared to the conventional dispersed filamentous cultures. Maximum values of specific penicillin production rate were found to be constant regardless of the growth form. A three-phase fluidized-bed fermentor was designed and tested for penicillin production using the bioparticles. Two modes of operation, semicontinuous and repeated fed batch, of the fermentor were tried. It was noted that the overgrowth of free mycelia and the development of fluffy loose bioparticles caused poor mixing and made the fermentor operation quite difficult. Control of the bioparticle size and the extension of production phase were therefore considered important to maintain the reactor productivity at a desired level. From the results of repeated fed-batch operation it was found that the control of bioparticle size could be successfully achieved by phosphate-limiting culture condition. Penicillin production under this condition was also observed to be maintained at a high level (about 80% of the maximum) for at least 1 month.     

Glucoamylases of a fungus isolated from a rotting cassava tuber

Summary Aspergillus niger H-9 is a fungal strain isolated from a rotting cassava tuber in Thailand. In the present study, the production of the enzymes was carried out as solid state ricebran-soybean fermentation. Two types of glucoamylases were isolated and purified. The purified glucoamylases were found to be homogenous on 7.5% polyacrylamide gel disc electrophoresis. The molecular weights of glucoamylase I and II were 59,400–72,600 and 43,000–52,600 respectively. The Km values of glucoamylase I and glucoamylase II were 12.5 and 6.25 mg glucose/ml when soluble starch was used as substrate. The optimal pH of both enzymes was 4.0–5.0. The optimum temperatures for the activities of glucoamylase I and glucoamylase II were 60 and 70°C respectively. Both enzymes were stable in the pH range 3.0–6.0 and temperature stable below 50°C. Both glucoamylases were active on various kinds of starch and dextrin including raw starch. Glucoamylase II was, however, found to hydrolyse raw starch better than glucoamylase I.

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Resumen Aspergillus niger H-9 es una cepa aislada en Tailandia a partir de tuberculos de cassava afectados de podredumbre. En este trabajo la producción de enzimas tuvo lugar mediante fermentación en un medio sólido compuesto por fibra de arroz y soja. Se aislaron y purificaron dos tipos de glucoamilasas. Al realizar una electroforesis en disco de polyacrilamida al 7.5% se observó que las glucoamilasa purificadas eran homogeneas. Los pesos de las glucoamilasas I y II eran respectivamente 59,400–72,600 y 43,000–52,600. Las Km respectivas fueron 12.5 y 6.25 mg ml^–1 cuando se utilizó almidón soluble como substrato. El pH optimo para ambos enzimas fue 4.0–5.0. Las temperaturas óptimas para la glucoamilasa I y la glucoamilasa II fueron respectivamente de 60 y 70°C respectivamente. Ambos enzimas eran estables en el intérvalo de pH 3.0–6.0 y a temperaturas por debajo de 50°C. Los dos enzimas eran activos fiente a distintos tipos de almidón y dextrina incluyendo almidón bruto. La glucoamilasa II hidrolizó mejor el almidón bruto que la glucoamilasa I.

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Résumé Aspergillus niger H-9 est une souche de moisissure isolée en Thailande à partir de tubercules pourris de manioc. Dans cette étude, la production d'enzymes a été obtenue par fermentation en milieu solide sur son de riz et soja. Deux types de gluco-amylases ont été isolés et purifiés. Les enzymes purifiés sont homogènes en disque-éléctrophorèse sur gel de polyacrylamide. Les poids moléculaires des gluco-amylases I et II sont respectivement de 59,400–72,600 et 43,000–52,000 et leurs Km pour l'amidon soluble de 12.5 et 6.25 mg de glucose/ml. Le pH optimum des deux enzymes est compris entre 4.0 et 5.0. Leurs températures optimales sont respectivement de 60 et 70°C. Les deux enzymes sont stables de pH 3.0–6.0 et aux températures inférieures à 50°C. Les deux gluco-amylases sont actives sur différents types d'amidon et de dextrines, y compris l'amidon cru. Toutefois, la gluco-amylase II hydrolyse l'amidon cru plus activement que la gluco-amylase I.

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Paper presented at the VII International Conference on the Global Impacts of Applied Microbiology, Helsinki, 12–16 August 1986.     

Decolourisation of synthetic and spentwash melanoidins using the white-rot fungus Phanerochaete chrysosporium JAG-40

Phanerochaete chrysosporium JAG-40 was isolated from the soil samples saturated with spilled molasses collected from a sugar mill. This isolate decolourised synthetic and natural melanoidins present in spentwash in liquid fermentation; up to 80% in 6 days at 30 degrees C under aerobic conditions. A large inoculum size stimulated fungal biomass production, but this gave less decolourisation of pigment; 5% w/v (dry weight) mycelial suspension was found optimum for maximum decolourisation in melanoidin medium supplemented with glucose and peptone. Gel-filtration chromatography showed that larger molecular weight fractions of melanoidin were decolourised more rapidly than small molecular weight fractions.     

Nitrate removal from drinking water in a fluidized-bed biological denitrification bioreactor

In most industrially developed countries an increasing degree of nitrification can be observed in potential water reservoirs. High nitrate content is unacceptable by public health standards. Since contamination seems to be unavoidable, the only realistic solution is purification prior to utilization. One of the potential variations is biological denitrification with a highly intensive facility, a fluidized- or expanded-bed bioreactor. Based on laboratory and pilot plant experiments, a detailed analysis is presented on the problems arising and solutions offered in the construction of a purification system meeting high quality requirements of drinking water purification. The crucial point is selection of the denitrifying microorganisms and organic matter required for denitrification, which simultaneously determines the attachment of bacteria to the support material (autoimmobilization), the intensity of nitrate removal and the character of post-purification.     

Petroleum-contaminated water treatment in a fluidized-bed bioreactor with immobilized Rhodococcus cells

Biotreatment of petroleum-contaminated water in a fluidized-bed bioreactor (FBB) is a relatively new and promising technology, which efficiency is strongly affected by the biocatalyst used. Our laboratory experiments involved biotreatment of the water contaminated with a synthetic petroleum mixture consisting of aliphatic and polyaromatic hydrocarbons (PAHs) using a continuous column bioreactor with recycle. Different type biocatalysts were tested, including Rhodococcus bacteria immobilized in hydrophobized carriers such as sawdust, poly(vinyl alcohol) cryogel (cryoPVA) and poly(acrylamide) cryogel (cryoPAAG). Biocatalyst abilities to oxidize petroleum hydrocarbons were evaluated using the Columbus Micro-Oxymax^® respirometer. The hydrophobized sawdust-supported biocatalyst demonstrated substantially higher metabolic activity than C₁₂-cryoPAAG-based biocatalyst due to larger number of immobilized Rhodococcus cells and, therefore, had benefits for application in FBBs. The obtained results showed that designed FBB process is successful, providing 70–100% removal of n-alkanes (C₁₀–C₁₉) and 66–70% removal of 2–3-ring PAHs from contaminated water after 2–3 weeks.     

Dynamics of a biological fixed film for phenol degradation in a fluidized-bed bioreactor

Experimental and modeling studies were conducted to analyze the dynamic response behavior of a phenol-oxidizing fixed film using a differential, fluidized-bed bioreactor in a recycle loop with a well-mixed reservoir. With the bioreactor at steady state, a pulse of phenol was added to perturb the system, and the phenol concentration was monitored continuously until steady state was again achieved.The experimental dynamics were compared with a dynamic mathematical model based on diffusion and reaction within the biofilm, liquid mixing, and biofilm growth. Constant-pH experiments could be adequately described using an unstructured, double-Monod kinetic expression with substrate inhibition by phenol.However, in dynamic experiments without pH control, the pH of the liquid phase dropped, and damped oscillations were observed in the phenol concentration and reaction rate trajectories. Oscillatory solutions could not be induced in the model, even when product inhibition was included, and a linear stability analysis did not reveal tendencies toward instability. The cause of the experimental oscillations remains unknown.     

Colour removal from bagasse-based pulp mill effluent using a white rot fungus

Colour removal of pulp plant effluent was studied using white rot fungus, Trametes (Coriolus) versicolor. The batch experiments were carried out using fungus in the form of mycelial pellets. In the present investigation, the effect of pH, concentrations of glucose (substrate), initial effluent colour and ammonium chloride (nutrient) on colour removal efficiency were studied. It was found that the maximum colour removal efficiency of 82.5% was obtained with an optimal glucose and ammonium chloride concentrations of 15 g/l and 0.5 g/l respectively at a pH of 4.5 without diluting the effluent.     

Concentration multiplicity in a draft tube fluidized-bed bioreactor involving two limiting substrates

Concentration multiplicity in a two-phase or three-phase draft tube fluidized-bed bioreactor containing biofloc particles is studied. The kinetics of biological reactions considered involve two limiting substrates. The necessary and sufficient conditions for concentration multiplicity in both the biofilm and bioreactor are examined in terms of effectiveness factor, inlet and bulk concentration of substrates, and liquid flow rate. Hysteresis behavior in both the biofilm and bioreactor and multiplicity of concentration profiles in the biofilm are also discussed.     

Development of a bioreactor system using an immobilized white rot fungus for decolorization

In this paper the fixed film reactor system containing immobilized Phanerochaete chrysosporium cells was employed for decolorization of Red 533 dispersed dye. The inlet dye concentration and the inlet flow rate were shown to affect the decolorization efficiency. Each decolorization process was conducted continuously for 10–20 days or more and the decolorization efficiency remained higher than 80%. The immobilized cultures possessed good biological activities and the biodegrading system also showed capability for a long term operation.     

Development of a bioreactor system using an immobilized white rot fungus for decolorization

In this research the wood-rotting fungus Phanerochaete chrysosporium culture was shown to be immobilized very well on the porous foam material. The biomass concentration increased to about 2–3 g/l in 4–5 days. Repeated-batch decolorization tests using immobilized Phanerochaete chrysosporium cells were conducted for 16 days with initial concentrations of 50–500 ppm of Red 533 dispersed dye, a decolorization efficiency of 80% or higher was achieved within a period of one or two days. The ability of the immobilized culture to perform a long-term decolorization operation was confirmed. The authors wish to thank I.T.R.I. and the National Science Council of R.O.C. for financial supports.     

漂白废水中关键有毒物质鉴别的实例研揪

以纸张漂白废水为研究对象,采用毒性鉴别评价(TIE, Toxicity Identification     

Contamination of a high-cell-density continuous bioreactor

Continuous fermentations were carried out with a recombinant flocculent Saccharomyces cerevisiae strain in an airlift bioreactor. Once operating under steady state at a dilution rate of 0.45 h(-1), the bioreactor was contaminated with Escherichia coli cells. The faster growing E. coli strain was washed out of the bioreactor and the recombinant, slower growing flocculating S. cerevisiae strain remained as the only species detected in the bioreactor. Flocculation, besides allowing for the realization of high-cell-density systems with corresponding unusual high productivity, may be used as a selective property for controlling some contamination problems associated with prolonged continuous operation.     

Biodegradation of nonylphenol in a continuous packed-bed bioreactor

A packed bed bioreactor, with 170 ml glass bead carriers and 130 ml medium, was tested for the removal of the endocrine disrupter, nonylphenol, with a Sphingomonas sp. The bioreactor was first continuously fed with medium saturated with nonylphenol in an attempt to simulate groundwater pollution. At best, nonylphenol was degraded by 99.5% at a feeding rate of 69 ml h^–1 and a removal rate of 4.3 mg nonylphenol day^–1, resulting in a 7.5-fold decrease in effluent toxicity according to the Microtox. The bioreactor was then fed with soil leachates at 69 ml h^–1 from artificially contaminated soil (1 g nonylphenol kg^–1 soil) and a real contaminated soil (0.19 g nonylphenol kg^–1 soil). Nonylphenol was always completely removed from the leachates of the two soils. It was removed by 99% from the artificial soil but only 62% from real contaminated soil after 18 and 20 d of treatment, respectively, showing limitation due to nonylphenol adsorption.     

Development of a predictive description of an immobilized-cell, three-phase, fluidized-bed bioreactor

A Large bioreactor is an inhomogenous system with concentration gradients which depend on the fluid dynamics and the mass transfer of the reactor, the feeding strategy, the saturation constant, and the cell density. The responses of Escherichia coli cells to short-term oscillations of the carbon/energy substrate in glucose limited fed-batch cultivations were studied in a two-compartment reactor system consisting of a stirred tank reactor (STR) and an aerated plug flow reactor (PFR) as a recycle loop. Short-term glucose excess or starvation in the PFR was simulated by feeding of glucose to the PFR or to the STR alternatively. The cellular response to repeated short-term glucose excess was a transient increase of glucose consumption and acetate formation. But, there was no accumulation of acetate in the culture, because it was consumed in the STR part where the glucose concentration was growth limiting. However, acetate accumulated during the cultivation if the oxygen supply in the PFR was insufficient, causing higher acetate formation. The biomass yield was then negatively influenced, which was also the case if the PFR was used to simulate a glucose starvation zone. The results suggest that short-term heterogeneities influence the cellular physiology and growth, and can be of major importance for the process performance. (c) 1995 John Wiley & Sons, Inc.     

The generation of high biomass from chlororespiring bacteria using a continuous fed-batch bioreactor

A continuous fed-batch reactor system was developed to rapidly obtain dense chlororespiring cultures of Anaeromyxobacter dehalogenans strain 2CP-C. A syringe pump continuously delivered concentrated 2,6-dichlorophenol (50–150 mM) to an anaerobic reactor vessel at a rate that sustained linear growth but prevented the substrate toxicity of chlorophenol. Dechlorination was not significantly inhibited by end product phenol up to 8 mM. A cell density of 76.8 mg protein l^–1 was obtained in 24 h. Specific growth rates averaged 0.033 h^–1at 50% substrate limitation, which was in agreement with the maximum specific growth rate of 0.068 h^–1. This reactor system provides an efficient, cost-effective, and convenient method to rapidly obtain dense dechlorinating biomass and is promising to accelerate investigations of enzymes involved in chlororespiration.     

Gas phase acetaldehyde production in a continuous bioreactor

The gas phase continuous production of acetaldehyde was studied with particular emphasis on the development of biocatalyst (alcohol oxidase on solid phase support materials) for a fixed bed reactor. Based on the experimental results in a batch bioreactor, the biocatalysts were prepared by immobilization of alcohol oxidase on Amberlite IRA-400, packed into a column, and the continuous acetaldehyde production in the gas phase by alcohol oxidase was performed. The effects of the reaction temperature, flow rates of gaseous stream, and ethanol vapor concentration on the performance of the continuous bioreactor were investigated. (c) 1993 John Wiley & Sons, Inc.     

Simultaneous filtration and immobilization of cells from a flowing suspension using a bioreactor containing polyethylenimine coated cotton threads: Application in the continuous inversion of concentrated sucrose syrups

Polyethylenimine(PEI)-coated cotton threads were shown to have potential for reducing microbial load from a flowing suspension. Turbid cell suspensions perfused through the PEI column appeared as totally clear in the effluent. The adhesion efficiency of the matrix was found to depend on the concentration of PEI used to treat the threads. Threads coated with 2.5% PEI were found to show optimal retention of cells. A considerable amount of binding was seen over a broad range of ionic concentration (0–0.3 M) and pH (3.6–10.3). Under similar conditions control threads did not show any filtration capacity. Saccharomyces cerevisiae, Saccharomyces fragilis, Escherichia coli and an Acetobacter species could be effectively filtered using PEI-coated threads. This technique can find potential for the simultaneous filtration and immobilization of cells in a bioreactor to be used in continuous bioprocessing as exemplified for the inversion of sucrose syrups using baker's yeast. The bioreactor could continuously hydrolyse 60% (w/v) sucrose syrups with a productivity of 2.25 kg/day for over a month without loss in efficiency.