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Eleven isolates of sulphate-reducing bacteria (SRB) were isolated from soil contaminated with crude oil derivatives and petroleum-refining wastewaters and used to investigate the effectiveness of carbon reduction and biotransformation of phosphogypsum. One of the isolates (culture no. 10) was found to be very effective with 90% carbon reduction (measured as COD) and the simultaneous biotransformation of approximately 2.65g phosphogypsum/L in industrial petroleum-refining wastewaters.
The paper presents the activity of anaerobic bacterial communities isolated from soil polluted by aircraft fuel on distillery decoctions with phosphogypsum. The microorganisms were selected using the microcosms method, and then enriched on Postgate medium with ethanol. The isolated communities became the inoculum to establish a culture on potato and rye distillery decoctions. The obtained results show that a simultaneous removal of two industrial wastes such as phosphogypsum and distillery decoctions is possible. The introduction of a inoculation comprising a selected anaerobic bacterial community into the culture does not influence the increase of the biotransformation process efficiency.
The activity of photosynthesizing sulfur bacteria in a continuous culture was studied. The bacteria were isolated from the natural environment with the use of the Winogradski column. Isolated bacteria were cultured in synthetic medium and in the effluent from the column containig HS-. Sulphides, the main product of reduction of sulfates in phosphogypsum, were used by green sulfur bacteria in the photosynthetic column. Almost 70% reduction of the concentration of sulfides was observed. After the experiment, diffractometric methods where employed to analyze the sediment from the column.
The possibility of using mineral oils as a carbon source by bacteria adapted to high oil concentrations was tested in liquid media with different pH values (pH = 5,7 and 9). Two types of inocula were tested: inoculum I consisted of selected strains used in the bioremediation of oil-contaminated soils and inoculum II contained bacteria isolated from soil samples previously bioremediated at pH = 5, 7 and 9. Biodegradation was observed in all the investigated media independently of initial pH value and type of inoculum used. After 21 days of cultivation the reduction of oil content reached 60-70% in medium with pH = 5 and 80-90% in medium with pH = 7 and 9, respectively. Inoculum I consisted of strains of Arthrobacter, Pseudomonas, Agrobacter, Xanthomonas spp. After 21 days of incubation the elimination of some strains was observed. In cultures conducted at pH = 5 Agrobacter strain was no longer found, at pH 9 - the Pseudomonas strain was lost. In cultures maintained at pH = 7 all the introduced strains survived. Prolonged incubation in liquid medium at pH = 5 of strains isolated from bioremediated soils (type II inoculum) leads to the elimination of Bacillus from initial consortium of Arthrobacter, Bacillus and Pseudomonas. In cultures containing bacteria of type II inoculum (Arthrobacter, Bacillus, Achromobacter, Agrobacter, Alcaligenes, Pseudomonas, Xanthomonas, Micrococcus) conducted in liquid media at pH = 9 the Micrococcus strain was no longer present. In liquid cultures incubated at pH = 7 all introduced strains were recovered (Arthrobacter, Bacillus, Achromobacter).
The biotransformation of phosphogypsum in cultures of sulfate-reducing bacteria (SRB) isolated from crude petroleum-refining wastewaters or purified using activated sludge method was studied. Selection was with the microcosms method on Postgate and minimal medium with different carbon sources, Emerson medium and petroleum-refining wastewaters. Highest hydrogen sulfide production, in excess of 500 mg/L, was observed in culture of microorganisms isolated from purified petroleum-refining wastewaters in Postgate medium with phenol as sole carbon source. 76% phenol reduction with simultaneous biotransformation of 2.7g phosphogypsum/L (1350 mg SO₄/L) was obtained. The results regarding post-culture sediment indicated 66% utilization of phosphogypsum introduced into the culture (5 g/L), which reflects the active biotransformation of phosphogypsum by the community selected from the wastewaters.
We determined sulphate-reducing activities in media inoculated with soils and with kettle lake sediments in order to investigate their potential in geomicrobiological processes in low-temperature, terrestrial maritime Antarctic habitats. Soil and sediment samples were collected in a glacier valley abandoned by Ecology Glacier during the last 30 years: from a new formed kettle lake sediment and forefield soil derived from ground moraine. Inoculated with these samples, liquid Postgate C and minimal media supplemented with various carbon sources as electron donors were incubated for 8 weeks at 4°C. High rates of sulphate reduction were observed only in media inoculated with soil. No sulphate reduction was detected in media inoculated with kettle lake sediments. In soil samples culture media calcite and elemental sulphur deposits were observed, demonstrating that sulphate-reducing activity is associated with a potential to mineral formation in cold environments. Cells observed on scanning microscopy (SEM) micrographs of post-culture-soil deposits could be responsible for sulphate-reducing activity.
Sulfate-reducing microbial communities were enriched from soils collected in areas with crude-oil exploitation. Cultures were grown in modified Postgate C medium and minimal medium, with ethanol or lactate as an electron donor. The batch cultures were grown with addition of zinc in concentrations of 100–700 mg/l. A lack of increased protein concentration in the solutions compared with the control batch, was noted in cultures containing over 200 mg Zn²⁺/l. The 16S rRNA method was applied to determine the specific composition of the selected microorganism communities. The analysis indicated the presence of Desulfovibrio spp., Desulfobulbus spp. and Desulfotomaculum spp. in the communities. Diffractometric analysis indicated the presence of biogenic sphalerite in cultures with 100 and 200 mg Zn²⁺/l and elemental sulfur in cultures with 200 mg Zn²⁺/l. Other post culture sediments (300−700 mg Zn²⁺/l) contained only hopeite [Zn₃(PO₄)₂‧4H₂O] formed abiotically during the experiment, which was confirmed by studies of the activity of sulfate-reducing microbial communities.
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