Roger A. Korus

Winter rape oil fuel for diesel engines: recovery and utilization.

Although vegetable oil cannot yet be recommended as a fuel for general use, considerable progress in recovery and use of rapeseed oil (Brassica napus L.) for diesel operation has been made. Operation of a small-scale screwpress plant (40 kg/hr) was demonstrated. Maintenance of screw and end rings was a major problem. The plant has operated with a recovery efficiency of 77% and has processed 10,100 kg of seed in 230 hr. High viscosity of the rapeseed oil and its tendency to polymerize within the cylinder were major chemical and physical problems encountered. Attempts to reduce the viscosity of the vegetable oil by preheating the fuel were not successful in sufficiently increasing the temperature of the fuel at the injector to be of value. Short-term engine performance with vegetable oils as a fuel in any proportion show power output and fuel consumption to be equivalent to the diesel-fueled engines. Severe engine damage occurred in a very short time period in tests of maximum power with varying engine rpm. Additional torque tests with all blends need to be conducted. A blend of 70/30 winter rape and No. 1 diesel has been used successfully to power a small single-cylinder diesel engine for 850 hr. No adverse wear, effect on lubricating oil or effect on power output were noted.

Adsorption and biodegradation of pentachlorophenol by polyurethane-immobilized flavobacterium

Flavobacterium cells immobilized in polyurethane foam were used to degrade pentachlorophenol (PCP). Adsorption of PCP by the polyurethane immobilization matrix played an important role in reducing the toxicity of PCP. The adsorption followed the Langmuir model with q m =21.3 mg of PCP/g of dry foam and K d =28.7 mg/L for cell-free foams. Cell growth contributed significantly to PCP removal rates especially when the degradation medium was supplemented with a utilizable carbon source. A substrate inhibition growth model described PCP consumption by Flauvbacterium with model parameters μ m =0.005 min -1 , K g =25 mg/L, K i =1.5 mg/L, Y X/S =0.12 g of cell/g of PCP, and k d =3.33×10 -5 min -1

A rapid engine test to measure injector fouling in diesel engines using vegetable oil fuels

Short engine tests were used to determine the rate of carbon deposition on direct injection diesel nozzles. Winter rape, high-oleic and high-linoleic safflower blends with 50% diesel were tested for carbon deposit and compared to that with D-2 Diesel Control Fuel. Deposits were greatest with the most unsaturated fuel, high-linoleic safflower, and least with winter rape. All vegetable oil blends developed power similar to diesel fueled engines with a 6 to 8% greater fuel consumption.

Kinetics of the amylase system of Saccharomycopsis fibuliger

The extracellular amylases produced by Saccharomycopsis fibuliger have been studied with the intent of identifying the kinetic mechanism and product distribution, and modelling the production of d-glucose during starch hydrolysis. High performance liquid chromatography was effectively used to separate and quantify the product oligomers released. α-Amylase rapidly hydrolysed the long substrate chains into smaller oligomers which became the substrate for glucoamylase in the production of d-glucose. The formation of a rate limiting substrate occurred late in the reaction. Glucoamylase and α-amylase rates were fitted to Michaelis-Menten models with d-glucose inhibition included.

Metal binding by pyridine-2,6-bis(monothiocarboxylic acid), a biochelator produced by Pseudomonas stutzeri and Pseudomonas putida

Pyridine-2,6-bis(monothiocarboxylic acid) (pdtc),a natural metal chelator produced by Pseudomonas stutzeri and Pseudomonas putidathat promotes the degradation of carbon tetrachloride, was synthesized and studiedby potentiometric and spectrophotometric techniques. The first two stepwise protonationconstants (pK) for successive proton addition to pdtc were found to be 5.48 and2.58. The third stepwise protonation constant was estimated to be 1.3. The stability (affinity)constants for iron(III), nickel(II), and cobalt(III) were determined by potentiometric orspectrophotometric titration. The results show that pdtc has strong affinity for Fe(III)and comparable affinities for various other metals. The stability constants (log K) are 33.93 for Co(pdtc)21-; 33.36 for Fe(pdtc)21-; and 33.28 for Ni(pdtc)22-. These protonationconstants and high affinity constants show that over a physiological pH range theferric pdtc complex has one of the highest effective stability constants for ironbinding among known bacterial chelators.

Synthesis and properties of lignin peroxidase from Streptomyces viridosporus T7A

The production of lignin peroxidase byStreptomyces viridosporus T7A was studied in shake flasks and under aerobic conditions in a 7.5-L batch fermentor. Lignin peroxidase synthesis was found to be strongly affected by catabolite repression. Lignin peroxidase was a non-growth-associated, secondary metabolite. The maximum lignin peroxidase activity was 0.064 U/mL at 36 h.In order to maximize lignin peroxidase activity, optimal conditions were determined. The optimal incubation temperature, pH, and substrate (2,4-dichlorophenol) concentration for the enzyme assays were 45°C, 6, and 3 mM, respectively. Stability of lignin peroxidase was determined at 37, 45, and 60°C, and over the pH range 4–9.

Ethanol fermentation with a flocculating yeast

Abstract A 100 cm × 5.7 cm internal diameter tower fermentor was fabricated and operated continuously for 11 months using the flocforming yeast, Saccharomyces cerevisiae (American Type Culture Collection 4097). Steady state operation of the system was characterized at 32 °C and pH 4.0 for glucose concentrations ranging from 105 to 215 g l−1. The height of the yeast bed in the tower was maintained at 80 cm. The high yeast density, ethanol concentration and low pH prevented bacterial contamination in the reactor. The concentration profiles of glucose and ethanol within the bed were described by a dispersion model. Modeling parameters were determined for the yeast by batch kinetics and tracer experiments. The kinetic model included ethanol inhibition and substrate limitation. A tracer study with step input of d -xylose (a non-metabolizable sugar for S. cerevisiae) determined the dispersion number (D/uL = 0.16) and liquid voidage (ϵ l = 0.25). Measurements taken after 6 months of continuous operation indicated that there was no significant change in fermentor performance.

The effects of various nutrients on extracellular peroxidases and acid-precipitable polymeric lignin production byStreptomyces chromofuscus A2 andS. viridosporus T7A

SummaryThe relationships between growth, medium pH, assimilation of glucose and amino acids, presence or absence of lignocellulose in the medium, lignin solubilization, and the appearance of extracellular peroxidase activity were compared for two lignin-solubilizing actinomycetes, Streptomyces chromofuscus A2 and S. viridosporus T7A. In a mineral salt medium containing yeast extract and three amino acids S. chromofuscus A2 grew faster than S. viridosporus T7A. When d-glucose was added to this medium, it was used in preference to the amino acids, the assimilation of which was delayed. Extracellular peroxidase activity peaked during the stationary phase, and glucose supplementation delayed peroxidase production. The eventual peak in peroxidase activity was higher in glucose-containing medium than in medium without glucose. Supplementation of the medium with lignocellulose did not affect either the level or time of appearance of extracellular peroxidase. However, lignin solubilization in lignocellulose-supplemented medium correlated positively with peroxidase activity: both increased after the cells entered the stationary phase. Supplementation of lignocellulose-containing medium with glucose delayed peroxidase production and lignin solubilization until the glucose had been assimilated. With S. viridosporus T7A, addition of d-glucose to the standard medium affected amino acid assimilation differently from S. chromofuscus A2. Glucose was consumed concomitantly with the amino acids. In the medium supplemented with lignocellulose, peroxidase activity and lignin solubilization correlated as they did for S. chromofuscus A2. A correlation of unknown significance was observed between the peroxidase activities of both strains and increasing medium pH. S. chromofuscus A2 produced more peroxidase and solubilized more lignin from lignocellulose than did S. viridosporus T7A. Overall, these findings show that extracellular peroxidases of both Streptomyces ssp. appear extracellularly primarily after cells cease growing and nutrients have been depleted from the medium. Also, increasing extracellular peroxidase activity and rates of lignin solubilization in both organisms are correlated and subject to glucose repression. These results point to the involvement of stationary-phase active peroxidases in the Streptomyces-catalyzed solubilization of lignin.

Deactivation kinetics of lignin peroxidase from Phanerochaete chrysosporium

Abstract Crude extracellular enzyme from Phanerochaete chrysosporium BKM-F-1767 (ATCC 24725) was used for kinetics and deactivation studies. The kinetics of lignin peroxidase in the crude enzyme was fitted to a ping-pong-bi-bi model with competitive substrate (hydrogen peroxide) inhibition. Several divalent metal salts (MnCl 2 , MnSO 4 , MgCl 2 , and CaCl 2 ) enhanced LiP activity at low concentrations ( m m ) but inhibited at high concentrations ( >2.5 m m ). Deactivation kinetic models from series-type deactivation mechanisms correlated well with the experimental data for peroxide-dependent and pH-dependent deactivation. UV/visible spectral changes during crude enzyme deactivation in the presence of peroxide supported the series deactivation mechanism. Strategies to enhance lignin peroxidase stability are suggested.

Characterization of immobilized enzymes in polyurethane foams in a dynamic bed reactor

Abstractβ-d-Galactosidase (E 3.2.1.23) from Aspergillus oryzae was immobilized with polyurethane foam (PUF). Among several immobilization methods attempted in this work, the immobilized enzyme preparation by in-situ co-polymerization between enzyme and prepolymer HYPOL 3000 showed the highest activity. The intrinsic kinetics of PUF-immobilized enzyme was determined in a dynamic bed reactor, used to increase transport rates. The immobilization mechanism in PUF was studied by measurements of immobilized enzyme kinetics and by using scanning electron microscopy combined with immuno-gold labeling techniques. The results showed that immobilization was predominantly by covalent bonding between primary amino groups of β-d-galactosidase and isocyanate groups of the prepolymers. Entrapment in the PUF micropores assisted the immobilization of enzymes, and adsorption on the surface of macropores was not important for immobilization. The bicinchoninic acid method was applied for the determination of PUF loading capacity and specific enzyme activity and used to determine enzyme deactivation during immobilization.