Biosorption of copper by yeasts.

The ability to accumulate copper from aqueous solutions was determined with different yeast species. Yeast cells did not show any significant differences in process kinetics. The uptake was very fast and was influenced by environmental factors. The metal-accumulating capacity differed among the tested strains. The yeast Candida tropicalis and Pichia guilliermondii were chosen for extensive research. Cells of the stationary growth phase were able to adsorb a high amount of copper. The uptake capacity decreased with increasing biomass concentration. Copper adsorption obeyed the Freundlich isotherm. Optimal pH range was between 5 and 7. The biomass could be used repeatedly for biosorption after desorption by mineral acids.

Microbial transformation of hexachlorocyclohexane.

Some microorganisms are able to accumulate and to metabolize the pesticide lindane (gamma-hexachlorocyclohexane, gamma-HCH) and other HCH-isomers. Microbial activities, detected metabolites, transformation rates, concentrating factors are reviewed. The results are discussed in respect to use microbiological processes for purification of contaminated water and soil and for recycling of waste HCH-isomers.

Kinetic studies of phenol degradation by Rhodococcus sp. P1. I. Batch cultivation.

Rhodococcus sp. P1 utilizes phenol as the sole carbon and energy source via the beta-ketoadipate pathway. In batch cultivation, concentrations up to 2.8 g.l-1 phenol were degraded. The highest values for the specific growth rate of 0.32 h-1 were obtained at concentrations near 0.25 g.l-1. At higher concentrations, substrate inhibition was observed, characterized by increases in lag phase and decreasing growth rates. A mathematical expression was proposed to fit the kinetic pattern of phenol inhibition on the specific growth rate mu: [formula: see text] Nomenclature: K- Exponent of the inhibition function, Ks- Monod saturation constant, g.l-1, KI- Inhibition constant, g.l-1, S- Substrate concentration in culture broth, g.l-1, So- Initial substrate concentration, g.l-1, Y- Yield constant, g cell dry mass.g substrate-1, mu- Specific growth rate, h-1, mu max- Maximum growth rate, h-1.

Kinetic studies of phenol degradation by Rhodococcus sp. P1. II. Continuous cultivation.

The degradation of phenol by Rhodococcus sp. P1 was studied in continuous culture systems. The organism could be adapted by slowly increasing concentration, step by step, up to 30.0 g.l-1 phenol in the influent. The degradation rate reached values of about 0.3 g.g dry mass-1.h-1. Large step increases in phenol concentration and addition of further substrates (e.g., catechol) were tolerated up to a certain concentration. With increasing dilution rate and increasing inlet phenol concentration the stability of the system decreased. Nomenclature: D--Dilution rate, h-1, Dc--Critical dilution rate, h-1, Dx--Yield, g dry mass.l-1.h-1, Ks--Monod saturation constant, g.l-1, S--Growth-limiting substrate concentration in culture broth, g.l-1, SR--Growth-limiting substrate concentration in feed, g.l-1, mean--Biomass concentration in culture broth, g.l-1, YS--Yield constant, g cell dry mass.g substrate-1, mu--Specific growth rate, h-1, mu max--Maximum growth rate, h-1.

Degradation of 3-aminophenol by Arthrobacter spec. mA3.

The bacterial strain mA3 capable of utilizing 3-aminophenol as the sole source of carbon, energy and nitrogen for growth was isolated from an enrichment culture and identified as an Arthrobacter species. Utilization of 0.68 mg/ml 3-aminophenol by batch cultures of this organism was characterized by a specific growth rate (mu) of 0.18 h-1 and a yield coefficient (Y) of 0.60. In chemostat cultures of strain mA3 we determined a critical dilution rate (Dc) of 0.175 h-1 by continuous addition of mineral salt medium with 0.5 mg/ml 3-aminophenol. Evidence was obtained that the degradation of catechol by 3-aminophenol induced as well as non-induced cells follows the beta-ketoadipate pathway. The excess ammonium ions, originating from 3-aminophenol degradation and not needed for assimilation were released into the medium. Cells adapted to 3-aminophenol exhibited a high substrate specificity. Among different aromatic substances tested, only catechol and 3,4-dihydroxybenzoate could serve as a carbon source for growth. The importance of the meta position of the amino group for the first step of hydroxylation is discussed in connection with the substrate specificity of whole mA3 cells.

Phenol hydroxylase from Rhodococcus sp. P 1.

The enzyme phenol hydroxylase (EC 1.14.13.7) was determined and characterized in crude extracts of Rhodococcus sp. P 1. This enzyme catalyzed the first step of phenol degradation. It was inducible, had a pH optimum of 7.9 and a temperature optimum at 20 degrees C and catalyzed also the hydroxylation of some other phenolic compounds.

Degradation of phenolic compounds by the yeast Candida tropicalis HP 15. II. Some properties of the first two enzymes of the degradation pathway.

The first two enzymes of the phenol degradation pathway were determined and characterized in crude extracts from Candida tropicalis HP 15. The phenol hydroxylase (EC 1.14.13.7) was a stable NADPH2- and FAD-dependent enzyme with a pH-optimum of 7.6 to 8.0 and a broad substrate specificity. Influence of ultrasound rapidly reduced the enzyme activity. The catechol 1,2-oxygenase (EC 1.13.1.1) had a broad pH-optimum between 7.5 and 9.6 and a limited substrate specificity. Two active protein bands indicating the presence of two isofunctional enzymes were detectable after electrophoretic separation of crude and partially purified extracts on polyacrylamide gels and specific staining for catechol 1,2-oxygenase activity.

Degradation of phenolic compounds by the yeast Candida tropicalis HP 15. I. Physiology of growth and substrate utilization.

The yeast Candida tropicalis HP 15 was able to utilize phenol up to concentrations of 2.5 g/l as a sole carbon and energy source. Phenol was metabolized via the beta-ketoadipate pathway by an inducible enzyme system. Besides phenol, resorcinol, quinol, hydroxyquinol, catechol, and to a lesser extend 4-chlorocatechol, protocatechuate, p-cresol, m-chlorophenol, and p-chlorophenol were metabolized by the yeast. A total of 30 aromatic compounds were tested as substrates.

[Microbial side chain splitting of phenylurea and carbonic acid anilides]. / Mikrobielle Seitenkettenabspaltung von Phenylharnstoffen und Carbonsäureaniliden.

A Gram- negative rod-shaped bacterium 28/1 isolated by enrichment cultures is able to hydrolyze the amide bond of some phenylurea herbicides and acid anilide herbicides by an inducible amidase. 7.5% of 0.3 mumol.ml-1 linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea) are hydrolyzed after 16 hours. 1,1-Dimethylphenylureas are not degraded. Acid anilides are hydrolyzed at a higher rate, 80% of 0.5 mumol.ml-1 N-(4-chlorophenyl)-propionamide and N-(4-nitrophenyl)-propionamide are transformed after 6 hours. The 1-methoxy-1-methyl phenylureas are effective inducers. Linuron-induced cells have a specific activity of 3-4 nmol per mg dry weight per min on the substrate N-(3,4-dichlorophenyl)-propionamide (Propanil). The rate of hydrolysis is influenced by substituents of the aniline ring and by the structure of the side chain of the acid anilides.

[On the physiology of growth and riboflavin overproduction of Eremothecium ashbyii. III. Investigations on the incorporation of radioactive labeled substrates in cell material and riboflavin (author's transl)]. / Zur Physiologie des Wachstums und der Riboflavin-Uberproduktion von Eremothecium ashbyii. III. Untersuchungen über den Einbau von radioaktiven Substraten in Zellsubstanz und Riboflavin.

The incorporation of glycine-2-14C and adenine-U-14C in cell material and riboflavin was investigated in order to determine the proportions metabolites were channeled in growth processes and product synthesis of Eremothecium ashbyii. Extraction- and measurement methods were developed to compare the incorporation of radioactive metabolites into different cell fractions. Young cells incorporate the labeled compounds in a high rate into the cell material. With increasing age of the culture the incorporation of radioactivity is more directed to riboflavin. 96 hours old cells incorporate about seven times more 14C-adenine into riboflavin than into the cell material.