Stability of an infectious pancreatic necrosis virus (IPNV) isolate stored under different laboratory conditions.

An infectious pancreatic necrosis virus (IPNV) belonging to the Sp serotype, isolated from scallops Pecten maximus, was propagated and suspended in sterile water and cell culture medium with different salinities and incubated at temperatures ranging from -80 to 40 degrees C. Virus stability was examined by measuring virus titers under different storage conditions. Virus titers were also measured after repeated freezing and thawing, and in incubated sterile filtered scallop hepatopancreas, haemolymph and crystalline style samples, and salmon Salmo salar kidney homogenate. The virus was stable under most storage conditions. Temperatures ranging from -80 to +20 degrees C, as well as salinities from 0 to 40/1000, did not seem to influence the stability of the virus. A reduction was observed above 20 degrees C. Each freezing and thawing procedure resulted in a reduction of the virus titer. This reduction was larger at -80 than at -20 degrees C. The IPNV persisted for a long period in sterile filtered scallop haemolymph, dissolved crystalline style and hepatopancreas. In kidney homogenate from IPNV-infected salmon the virus titers were reduced at least 10-fold during the first day of incubation at all temperatures tested. When virus was propagated in cell culture and subsequently mixed with non-infected salmon kidney homogenate, the virus proved more persistent. Our results illustrate the importance of rapid and standardised laboratory processing of potentially virus-containing tissue samples, and are relevant when considering laboratory storage of samples containing IPNV.

Penetration of Sulfate Reducers through a Porous North Sea Oil Reservoir.

The presence of mesophilic benzoate-degrading sulfate-reducing bacteria in the water systems of three Norwegian oil platforms was investigated. Strain 4502 was isolated from the injection water system, and specific antibodies were produced against this isolate. It was present in the injection water system during a period of 3 years, but not in the in situ reservoir water. Later it was found in water samples collected from the oil field production system. This showed that strain 4502 had penetrated the reservoir together with the injection water and eventually reached the production well.

Distribution of thermophilic marine sulfate reducers in north sea oil field waters and oil reservoirs.

The distribution of thermophilic marine sulfate reducers in produced oil reservoir waters from the Gullfaks oil field in the Norwegian sector of the North Sea was investigated by using enrichment cultures and genus-specific fluorescent antibodies produced against the genera Archaeoglobus, Desulfotomaculum, and Thermodesulforhabdus. The thermophilic marine sulfate reducers in this environment could mainly be classified as species belonging to the genera Archaeoglobus and Thermodesulforhabdus. In addition, some unidentified sulfate reducers were present. Culturable thermophilic Desulfotomaculum strains were not detected. Specific strains of thermophilic sulfate reducers inhabited different parts of the oil reservoir. No correlation between the duration of seawater injection and the numbers of thermophilic sulfate reducers in the produced waters was observed. Neither was there any correlation between the concentration of hydrogen sulfide and the numbers of thermophilic sulfate reducers. The results indicate that thermophilic and hyperthermophilic sulfate reducers are indigenous to North Sea oil field reservoirs and that they belong to a deep subterranean biosphere.

Methanococcus thermolithotrophicus Isolated from North Sea Oil Field Reservoir Water.

Methanococcus thermolithotrophicus ST22 was isolated from produced water of a North Sea oil field, on mineral medium with H(inf2)-CO(inf2) as the sole source of carbon and energy. The isolate grew at 17 to 62(deg)C, with an optimum at 60(deg)C. The pH range was 4.9 to 9.8, with optimal growth at pH 5.1 to 5.9; these characteristics reflected its habitat. Strain ST22 was quickly identified and distinguished from the type strain by immunoblotting.

Archaeoglobus fulgidus Isolated from Hot North Sea Oil Field Waters.

A hyperthermophilic sulfate reducer, strain 7324, was isolated from hot (75 degrees C) oil field waters from an oil production platform in the Norwegian sector of the North Sea. It was enriched on a complex medium and isolated on lactate with sulfate. The cells were nonmotile, irregular coccoid to disc shaped, and 0.3 to 1.0 mum wide. The temperature for growth was between 60 and 85 degrees C with an optimum of 76 degrees C. Lactate, pyruvate, and valerate plus H(2) were utilized as carbon and energy sources with sulfate as electron acceptor. Lactate was completely oxidized to CO(2). The cells contained an active carbon monoxide dehydrogenase but no 2-oxoglutarate dehydrogenase activity, indicating that lactate was oxidized to CO(2) via the acetyl coenzyme A/carbon monoxide dehydrogenase pathway. The cells produced small amounts of methane simultaneously with sulfate reduction. F(420) was detected in the cells which showed a blue-green fluorescence at 420 nm. On the basis of morphological, physiological, and serological features, the isolate was classified as an Archaeoglobus sp. Strain 7324 showed 100% DNA-DNA homology with A. fulgidus Z, indicating that it belongs to the species A. fulgidus. Archaeoglobus sp. has been selectively enriched and immunomagnetically captured from oil field waters from three different platforms in the North Sea. Our results show that strain 7324 may grow in oil reservoirs at 70 to 85 degrees C and contribute to hydrogen sulfide formation in this environment.