Three species of thermophilic archaebacteria of the genera Sulfolobus (Sulfolobus acidocaldarius and S. solfataricus) and Acidianus (Acidianus brierleyi) were tested for their ability to oxidize pyrite and to grow autotrophically on pyrite, to explore their potential for use in coal desulfurization. Only A. brierleyi was able to oxidize and grow autotrophically on pyrite. Jarosite was formed during the pyrite oxidation, resulting in the precipitation of sulfate and iron. The medium composition affected the extent of jarosite formation.

Demonstration of increased vascular cold reactivity in patients with Raynaud's syndrome is difficult. For medico-legal reasons, it is important to get objective measures of vasospasm in these patients. Evaluation of the degree of vasospasm also provides prognostic information which is useful for patient management. In this study, we compare two methods of arterial circulation measurement. The laser Doppler scanning is a new method, which uses the recently developed laser Doppler perfusion imaging (LDPI) instrument. The aim of the present study was to compare the effect on finger skin blood flow measured with LDPI with changes in finger systolic blood pressure during local cold provocation. The effect of such provocation, skin blood flow and systolic blood pressure, were studied in 15 healthy controls. Six patients with known traumatic vasospastic disease (TVD) were also tested with both methods. Finger skin blood flow was measured with LDPI on the distal phalanx of the index finger of the left hand, every minutes during 6 min of local heating at 40 degrees C followed by local cooling for 3 min at 15 degrees C and then for 3 min at 10 degrees C. Finger systolic blood pressure was measured with strain-gauge method before and after local cooling to 10 degrees C with a cuff perfused with water of desired temperature. The test was performed in the same finger within a week of the laser Doppler scanning. Local finger cooling to 15 degrees C and 10 degrees C caused a significant decrease in blood flow, most marked at 10 degrees C. There was, however, no correlation between the decrease in blood flow and blood pressure. In the TVD-patients decreases in skin blood flow were similar compared with the healthy controls. In contrast, the changes in systolic blood pressure, were outside normal range (systolic quotient <0.65) in five of the six patients (83%), and also in 11 of the 15 healthy controls (73%). In conclusion, there is no correlation between the decrease in finger skin blood flow and systolic blood pressure during local cold provocation. For diagnosis of traumatic vasospastic disease (TVD), local cold-induced changes in finger systolic blood pressure seems superior to changes in skin blood flow, but the ideal clinical method for demonstrating increased cold-induced vasospasm is, however, still lacking.

Experiments were done in order to study the thermophilic archaebacterium Acidianus brierkyi during oxidation of pyrite (FeS$. The microorganisms were grown both separated from the pyrite by a membrane and in close contact with the pyrite. From the results it can be concluded that direct contact is needed for good growth of the strain studied. The obtained results indicate that the direct contact mechanism may be applied to oxidation of sulfidic minerals by A. brierleyi. IntroductionThere is a large degree of interest in biohydrometallurgy in order to use bioleaching to recover metals from low-grade ores where conventional methods are not economical. For exampel, gold is often trapped in a matrix of pyrite and arsenopyrite. The pyrite and the arsenopyrite can be dissolved by microorganisms thereby releasing the gold under mild conditions. Copper mining is another example where biohydrometallurgy has become an important process. Microorganisms capable of oxidizing pyrite and other sulfidic minerals have a potential for desulfurization of coal. The major part of the inorganic sulfur in coal consists of pyrite. The mechanism of microbial oxidation of sulfide minerals has been studied for many years. Two types of mechanisms have been proposed for the oxidation of the mineral pyrite (FeS2), a direct mechanism and an indirect mechanism (Eligwe, 1988). In the direct mechanism the microorganisms oxidize the pyrite directly and physical contact between the pyrite and the microorganisms is thought to be essential for the reaction. In the indirect mechanism the pyrite is oxidized chemically by ferric iron and the ferric iron is then regenerated by the microorganisms. The two mechanisms can be described by the following reactions where reactions 1) and 3) are biological.

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Acidianus brierleyi was demonstrated to remove pyritic sulphur from coal. A. brierfeyi was also found capable of catalyzing the removal of what is normally reported as organic sulphur from coal 171US34. A kinetic analysis was performed by assuming a first order reaction. The first order kinetics allowed a comparison with literature data for Thiobacillus ferrooxidans. Also, formation of jarosite was taken into account in the analysis. The simple first order kinetics was observed to fit the data on removal of sulphur satisfactorily.