Michael Beyer

Degradation of phenanthrene, fluorene and fluoranthene by pure bacterial cultures

SummaryBacterial mixed cultures able to degrade the polycyclic aromatic hydrocarbons (PAH) phenanthrene, fluorene and fluoranthene, were obtained from soil using conventional enrichment techniques. From these mixed cultures three pure strains were isolated:Pseudomonas paucimobilis degrading phenanthrene;P. vesicularis degrading fluorene andAlcaligenes denitrificans degrading fluoranthene. The maximum rates of PAH degradation ranged from 1.0 mg phenanthrene/ml per day to 0.3 mg fluoranthene/ml per day at doubling times of 12 h to 35 h for growth on PAH as sole carbon source. The protein yield during PAH degradation was about 0.25 mg/mg C for all strains. Maximum PAH oxidation rates and optimum specific bacterial growth were obtained near pH 7.0 and 30°C. After growth entered the stationary phase, no dead end-products of PAH degradation could be detected in the culture fluid.

MICROBIAL METABOLISM OF FLUORANTHENE: ISOLATION AND IDENTIFICATION OF RING FISSION PRODUCTS

SummaryThe degradation of fluoranthene by pure cultures of Alcaligenes denitrificanss WW1, isolated from contaminated soil samples, was investigated. The strain showed maximum degradation rates of 0.3 mg fluoranthene/ml per day. A denitrificans was able to utilize also naphthalene, 1- and 2-methylnaphthalene, phenanthrene, and anthracene as sole carbon sources and to co-metabolize fuuorence, pyrene, and benzo(a)anthracene. During growth on fluoranthene in batch culture two metabolic products that were completely degraded before growth entered the stationary phase were detected in the culture fluid. Anslyses by UV, mass and NMR spectroscopy identified the products as acenaphthenone and 3-hydroxymethyl-4,5-benzocoumarine. Fluoranthene-grown resting cells of A. denitrificans showed degradative activity towards 2,3-dihydroxybenzoic acid, pyrogallol, salicylic acid, and catechol. The enzymatic activities in extracts of fluoranthene-induced cells indicate a meta ring fission involved in the degradation of fluoranthene. From these data new aspects of the biodegradative pathway of fluoranthene have been predicted.

Glucoamylase production in batch, chemostat and fed-batch cultivations by an industrial strain of Aspergillus niger

Abstract The Aspergillus niger strain BO-1 was grown in batch, continuous (chemostat) and fed-batch cultivations in order to study the production of the extracellular enzyme glucoamylase under different growth conditions. In the pH range 2.5–6.0, the specific glucoamylase productivity and the specific growth rate of the fungus were independent of pH when grown in batch cultivations. The specific glucoamylase producivity increased linearly with the specific growth rate in the range 0–0.1 h−1 and was constant in the range 0.1–0.2 h−1. Maltose and maltodextrin were non-inducing carbon sources compared to glucose, and the maximum specific growth rate was 0.19 ± 0.02 h−1 irrespective of whether glucose or maltose was the carbon source. In fed-batch cultivations, glucoamylase titres of up to 6.5 g l−1 were obtained even though the strain contained only one copy of the glaA gene.

Influence of pulp density and bioreactor design on microbial desulphurization of coal

SummaryPyrite was microbiologically removed by Thiobacillus ferrooxidans in pure and mixed cultures from German bituminous coal at 10% pulp density with maximum pyrite oxidation rate of 350 mg pyritic S/l per day. However, at pulp densities above 20% bacterial growth and consequently pyrite oxidation were completely prevented both in a conventional airlift reactor and in a stirred-tank reactor. Modifying the airlift reactor by adapting a conical bottom part, bacterial growth and pyrite oxidation could be achieved even at 30% pulp density, resulting in a pyrite removal of more than 90% at a pyrite oxidation rate of 230 mg pyritic S/l per day.

Elemental sulphur in microbiologically desulphurized coals

Abstract Aerobic, acidophilic mixed cultures containing predominantly chemolithoautotrophic Thiobacillus ferrooxidans oxidized 90% of pyritic sulphur from a German bituminous coal when incubated in an airlift reactor at pH values from 2.6 to 1.8 for 12–28 days with pulp densities from 2–30%. The complete sulphur balance measured by elemental analysis of the coal indicates that the total amount of sulphur removed (35–40%) does not correspond to the amount of pyrite oxidized. This is due to an increase in the amount of insoluble sulphate sulphur, analysed as the basic mineral jarosite. At pH values below 1.9 the formation of jarosite was prevented, but the difference between sulphate plus pyrite and the total amount of sulphur, usually claimed to be ‘organic’ sulphur, increased under these conditions. This previously indirectly determined sulphur fraction proved to consist of elemental sulphur and unchanged organic sulphur. The elemental sulphur accumulates during the chemical oxidation of pyrite by ferric ions. The formation of considerable amounts of elemental sulphur was observed with only one out of four coals analysed.

Physiological characterisation of Penicillium chrysogenum strains expressing the expandase gene from Streptomyces clavuligerus during batch cultivations. Growth and adipoyl-7-aminodeacetoxycephalosporanic acid production.

Abstract. The production of adipoyl-7-aminodeacetoxycephalosporanic acid (ad-7-ADCA) was studied, using two recombinant strains of Penicillium chrysogenum carrying the expandase gene from Streptomyces clavuligerus. The adipoyl-side chain of this compound may easily be removed using an amidase; and this process therefore represents a new route for the production of 7-ADCA, which serves as a precursor for the production of many semi-synthetic cephalosporins. In this study, one low- and one high-yielding strains were characterised and the specific productivities of ad-7-ADCA and by-products of the biosynthetic pathway were compared. The fluxes through the biosynthetic pathway were quantified and it was found that there was a 30% higher flux through the expandase in the high-yielding strain. In both strains, there was a significant degradation of adipate. Furthermore, the initial adipate concentration in batch cultures was shown to have a positive effect on the formation of ad-7-ADCA.

Hydrodynamic guiding for addressing subsets of immobilized cells and molecules in microfluidic systems

BackgroundThe interest in microfluidics and surface patterning is increasing as the use of these technologies in diverse biomedical applications is substantiated. Controlled molecular and cellular surface patterning is a costly and time-consuming process. Methods for keeping multiple separate experimental conditions on a patterned area are, therefore, needed to amplify the amount of biological information that can be retrieved from a patterned surface area. We describe, in three examples of biomedical applications, how this can be achieved in an open microfluidic system, by hydrodynamically guiding sample fluid over biological molecules and living cells immobilized on a surface.ResultsA microfluidic format of a standard assay for cell-membrane integrity showed a fast and dose-dependent toxicity of saponin on mammalian cells. A model of the interactions of human mononuclear leukocytes and endothelial cells was established. By contrast to static adhesion assays, cell-cell adhesion in this dynamic model depended on cytokine-mediated activation of both endothelial and blood cells. The microfluidic system allowed the use of unprocessed blood as sample material, and a specific and fast immunoassay for measuring the concentration of C-reactive protein in whole blood was demonstrated.ConclusionThe use of hydrodynamic guiding made multiple and dynamic experimental conditions on a small surface area possible. The ability to change the direction of flow and produce two-dimensional grids can increase the number of reactions per surface area even further. The described microfluidic system is widely applicable, and can take advantage of surfaces produced by current and future techniques for patterning in the micro- and nanometer scale.

Development of Microbiological/Adsorptive Methods for Remediation of PAH-Contaminated Soils

Sites of closed-down coke oven plants and gas works are frequently contaminated with organic harmful compounds and need to be decontaminated. Experience has shown that any decontamination is expensive and time consuming. Besides thermal and physical methods also biotechnical decontamination methods gain more and more importance. For these methods suited microorganisms convert within months, in less favourable cases in several years time, the pollutant contained in the soil, either in-situ or after the soil having been excavated (on site). Experience gained from known pilot decontamination projects have shown that the microbial degradability as well as the bio-availability of the contaminants are the key factors for the success of such decontamination measures. At present insufficient understanding of the phenomena involved, prevents to predict the suitability of biological decontamination methods and their effectiveness.

Entwicklung Mikrobiologisch/Adsorptiver Methoden zur Dekontaminierung von Pak-Belasteten Böden

Fruhere Standorte von Kokereien und Gaswerken sind haufig in einem solchen Umfang mit organischen Schadstoffen kontaminiert, das sie saniert werden mussen. Aller Erfahrung nach ist jede Sanierung teuer und langwierig. Neben thermischen und physikalischen Methoden gewinnen auch biotechnische Sanierungsverfahren zunehmend an Bedeutung, bei denen entweder an Ort unde Stelle (in-situ) oder nach Ausgraben des Bodens (on-site) geeignete Mikroorganismen innerhalb von Monaten, ungunstigenfalls von Jahren, die Schadstoffe zu ungefahrlichen Verbindungen abbauen. Erfahrungen aus bisher bekannt gewordenen Sanierungen bzw. Pilotsanierungen zeigen, das die mikrobielle Abbaubarkeit der Schadstoffe sowie die Zuganglichkeit der Schadstoffe fur die Mikroorganismen wesentlichen Einflus auf den Sanierungserfolg haben. Aufgrund mangelnder Kenntnisse ist es bislang nicht moglich, Vorhersagen uber einzusetzende biologische Sanierungstechniken und den zu erwartenden Erfolg einer Sanierungsmasnahme fur kontaminierte Standorte zu machen.