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Ralf Rabus - One of the best experts on this subject based on the ideXlab platform.
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Physiological response to temperature changes of the marine, Sulfate‐Reducing Bacterium DesulfoBacterium autotrophicum
FEMS microbiology ecology, 2002Co-Authors: Ralf Rabus, Volker Brüchert, Judith Amann, Martin KönnekeAbstract:The physiological response of bacteria to temperature is critical for the regulation of biogeochemical processes on daily, seasonal, and inter-annual time scales. We investigated the temperature response of the marine Sulfate-Reducing Bacterium DesulfoBacterium autotrophicum strain HRM2. Growth experiments in a temperature gradient block demonstrated that D. autotrophicum is psychrotolerant and grows between 0 and 31°C. The normal range of temperature for growth is between 4 and 29°C. The physiological response to temperature changes was studied with three sets of cells that were acclimated at 4, 10, and 28°C, respectively. Sulfate reduction rates were determined in the temperature gradient block with short-term incubations to minimize growth. The rates were similar at the 4 and 10°C acclimation temperature, and exhibited an enhanced response at 28°C. At every acclimation temperature, Sulfate reduction rates increased 20-fold from −1.7 to 41°C. The relative proportion of cellular unsaturated fatty acids (e.g. cis16:1) and short-chain fatty acids increased when cells were grown at 4°C compared to 28°C. The proteome of D. autotrophicum strain HRM2 was studied by two-dimensional gel electrophoresis with soluble extracts of cells grown at the three respective acclimation temperatures. Protein patterns were similar with the exception of two proteins showing 5–10-fold lower abundance in the 4°C culture compared to the 28°C culture. In general, D. autotrophicum strain HRM2 responded to low temperatures by reduced metabolic activity rather than by pronounced de novo synthesis of specifically adapted enzymes. Such a strategy agrees well with in situ activities measured in field studies and may reflect a common physiological principle of psychrotolerant marine Sulfate-Reducing bacteria.
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physiological response to temperature changes of the marine Sulfate Reducing Bacterium desulfoBacterium autotrophicum
FEMS Microbiology Ecology, 2002Co-Authors: Ralf Rabus, Volker Brüchert, Judith Amann, Martin KönnekeAbstract:The physiological response of bacteria to temperature is critical for the regulation of biogeochemical processes on daily, seasonal, and inter-annual time scales. We investigated the temperature response of the marine Sulfate-Reducing Bacterium DesulfoBacterium autotrophicum strain HRM2. Growth experiments in a temperature gradient block demonstrated that D. autotrophicum is psychrotolerant and grows between 0 and 31°C. The normal range of temperature for growth is between 4 and 29°C. The physiological response to temperature changes was studied with three sets of cells that were acclimated at 4, 10, and 28°C, respectively. Sulfate reduction rates were determined in the temperature gradient block with short-term incubations to minimize growth. The rates were similar at the 4 and 10°C acclimation temperature, and exhibited an enhanced response at 28°C. At every acclimation temperature, Sulfate reduction rates increased 20-fold from −1.7 to 41°C. The relative proportion of cellular unsaturated fatty acids (e.g. cis16:1) and short-chain fatty acids increased when cells were grown at 4°C compared to 28°C. The proteome of D. autotrophicum strain HRM2 was studied by two-dimensional gel electrophoresis with soluble extracts of cells grown at the three respective acclimation temperatures. Protein patterns were similar with the exception of two proteins showing 5–10-fold lower abundance in the 4°C culture compared to the 28°C culture. In general, D. autotrophicum strain HRM2 responded to low temperatures by reduced metabolic activity rather than by pronounced de novo synthesis of specifically adapted enzymes. Such a strategy agrees well with in situ activities measured in field studies and may reflect a common physiological principle of psychrotolerant marine Sulfate-Reducing bacteria.
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Conversion studies with substrate analogues of toluene in a Sulfate-Reducing Bacterium, strain Tol2
Archives of microbiology, 1995Co-Authors: Ralf Rabus, Friedrich WiddelAbstract:Anaerobic toluene oxidation by the Sulfate-Reducing Bacterium, strain Tol2 (proposed nameDesulfobacula toluolica) was specifically inhibited by benzyl alcohol when added at concentrations around 500 μM. Benzyl alcohol added at lower, non-inhibitory concentrations (around 5 μM) was not oxidized by active cells pregrown on toluene, indicating that the alcohol is not a free intermediate of toluene metabolism in the Sulfate reducer. Conversion ofp-xylene in toluene-metabolizing cells top-methylbenzoate as dead-end product suggests that the Sulfate reducer, like denitrifiers, initiates toluene oxidation at the methyl group.
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Complete oxidation of toluene under strictly anoxic conditions by a new Sulfate-Reducing Bacterium.
Applied and Environmental Microbiology, 1993Co-Authors: Ralf Rabus, R. Nordhaus, Wolfgang Ludwig, Friedrich WiddelAbstract:A toluene-degrading Sulfate-Reducing Bacterium, strain Tol2, was isolated from marine sediment under strictly anoxic conditions. Toluene was toxic if applied directly to the medium at concentrations higher than 0.5 mM. To provide toluene continuously at a nontoxic concentration, it was supplied in an inert hydrophobic carrier phase. The isolate had oval, sometimes motile cells (1.2 to 1.4 by 1.2 to 2.0 microns). The doubling time was 27 h. Toluene was completely oxidized to CO2, as demonstrated by measurement of the degradation balance. The presence of carbon monoxide dehydrogenase and formate dehydrogenase indicated a terminal oxidation of acetyl coenzyme A via the CO dehydrogenase pathway. The use of hypothetical intermediates of toluene degradation was tested in growth experiments and adaptation studies with dense cell suspensions. Results do not support a degradation of toluene via one of the cresols or methylbenzoates, benzyl alcohol, or phenylacetate as free intermediate. Benzyl alcohol did not serve as growth substrate; moreover, it was a strong, specific inhibitor of toluene degradation, whereas benzoate utilization was not affected by benzyl alcohol. Sequencing of 16S rRNA revealed a relationship to the metabolically dissimilar genus Desulfobacter and on a deeper level to the genus DesulfoBacterium. The new genus and species Desulfobacula toluolica is proposed. Images
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Complete oxidation of toluene under strictly anoxic conditions by a new Sulfate-Reducing Bacterium.
Applied and environmental microbiology, 1993Co-Authors: Ralf Rabus, R. Nordhaus, Wolfgang Ludwig, Friedrich WiddelAbstract:A toluene-degrading Sulfate-Reducing Bacterium, strain Tol2, was isolated from marine sediment under strictly anoxic conditions. Toluene was toxic if applied directly to the medium at concentrations higher than 0.5 mM. To provide toluene continuously at a nontoxic concentration, it was supplied in an inert hydrophobic carrier phase. The isolate had oval, sometimes motile cells (1.2 to 1.4 by 1.2 to 2.0 microns). The doubling time was 27 h. Toluene was completely oxidized to CO2, as demonstrated by measurement of the degradation balance. The presence of carbon monoxide dehydrogenase and formate dehydrogenase indicated a terminal oxidation of acetyl coenzyme A via the CO dehydrogenase pathway. The use of hypothetical intermediates of toluene degradation was tested in growth experiments and adaptation studies with dense cell suspensions. Results do not support a degradation of toluene via one of the cresols or methylbenzoates, benzyl alcohol, or phenylacetate as free intermediate. Benzyl alcohol did not serve as growth substrate; moreover, it was a strong, specific inhibitor of toluene degradation, whereas benzoate utilization was not affected by benzyl alcohol. Sequencing of 16S rRNA revealed a relationship to the metabolically dissimilar genus Desulfobacter and on a deeper level to the genus DesulfoBacterium. The new genus and species Desulfobacula toluolica is proposed.
Friedrich Widdel - One of the best experts on this subject based on the ideXlab platform.
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Conversion studies with substrate analogues of toluene in a Sulfate-Reducing Bacterium, strain Tol2
Archives of microbiology, 1995Co-Authors: Ralf Rabus, Friedrich WiddelAbstract:Anaerobic toluene oxidation by the Sulfate-Reducing Bacterium, strain Tol2 (proposed nameDesulfobacula toluolica) was specifically inhibited by benzyl alcohol when added at concentrations around 500 μM. Benzyl alcohol added at lower, non-inhibitory concentrations (around 5 μM) was not oxidized by active cells pregrown on toluene, indicating that the alcohol is not a free intermediate of toluene metabolism in the Sulfate reducer. Conversion ofp-xylene in toluene-metabolizing cells top-methylbenzoate as dead-end product suggests that the Sulfate reducer, like denitrifiers, initiates toluene oxidation at the methyl group.
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Complete oxidation of toluene under strictly anoxic conditions by a new Sulfate-Reducing Bacterium.
Applied and Environmental Microbiology, 1993Co-Authors: Ralf Rabus, R. Nordhaus, Wolfgang Ludwig, Friedrich WiddelAbstract:A toluene-degrading Sulfate-Reducing Bacterium, strain Tol2, was isolated from marine sediment under strictly anoxic conditions. Toluene was toxic if applied directly to the medium at concentrations higher than 0.5 mM. To provide toluene continuously at a nontoxic concentration, it was supplied in an inert hydrophobic carrier phase. The isolate had oval, sometimes motile cells (1.2 to 1.4 by 1.2 to 2.0 microns). The doubling time was 27 h. Toluene was completely oxidized to CO2, as demonstrated by measurement of the degradation balance. The presence of carbon monoxide dehydrogenase and formate dehydrogenase indicated a terminal oxidation of acetyl coenzyme A via the CO dehydrogenase pathway. The use of hypothetical intermediates of toluene degradation was tested in growth experiments and adaptation studies with dense cell suspensions. Results do not support a degradation of toluene via one of the cresols or methylbenzoates, benzyl alcohol, or phenylacetate as free intermediate. Benzyl alcohol did not serve as growth substrate; moreover, it was a strong, specific inhibitor of toluene degradation, whereas benzoate utilization was not affected by benzyl alcohol. Sequencing of 16S rRNA revealed a relationship to the metabolically dissimilar genus Desulfobacter and on a deeper level to the genus DesulfoBacterium. The new genus and species Desulfobacula toluolica is proposed. Images
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Complete oxidation of toluene under strictly anoxic conditions by a new Sulfate-Reducing Bacterium.
Applied and environmental microbiology, 1993Co-Authors: Ralf Rabus, R. Nordhaus, Wolfgang Ludwig, Friedrich WiddelAbstract:A toluene-degrading Sulfate-Reducing Bacterium, strain Tol2, was isolated from marine sediment under strictly anoxic conditions. Toluene was toxic if applied directly to the medium at concentrations higher than 0.5 mM. To provide toluene continuously at a nontoxic concentration, it was supplied in an inert hydrophobic carrier phase. The isolate had oval, sometimes motile cells (1.2 to 1.4 by 1.2 to 2.0 microns). The doubling time was 27 h. Toluene was completely oxidized to CO2, as demonstrated by measurement of the degradation balance. The presence of carbon monoxide dehydrogenase and formate dehydrogenase indicated a terminal oxidation of acetyl coenzyme A via the CO dehydrogenase pathway. The use of hypothetical intermediates of toluene degradation was tested in growth experiments and adaptation studies with dense cell suspensions. Results do not support a degradation of toluene via one of the cresols or methylbenzoates, benzyl alcohol, or phenylacetate as free intermediate. Benzyl alcohol did not serve as growth substrate; moreover, it was a strong, specific inhibitor of toluene degradation, whereas benzoate utilization was not affected by benzyl alcohol. Sequencing of 16S rRNA revealed a relationship to the metabolically dissimilar genus Desulfobacter and on a deeper level to the genus DesulfoBacterium. The new genus and species Desulfobacula toluolica is proposed.
T.a Hansen - One of the best experts on this subject based on the ideXlab platform.
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DMSP: tetrahydrofolate methyltransferase from the marine Sulfate-Reducing Bacterium strain WN
Journal of Sea Research, 2000Co-Authors: M Jansen, T.a HansenAbstract:Abstract Dimethylsulfoniopropionate (DMSP), an important compatible solute of many marine algae, can be metabolised by bacteria via cleavage to dimethylsulfide and acrylate or via an initial demethylation. This is the first report on the purification of an enzyme that specifically catalyses the demethylation of DMSP. The enzyme was isolated from the Sulfate-Reducing Bacterium strain WN, which grows on DMSP and demethylates it to methylthiopropionate. DMSP:tetrahydrofolate (THF) methyltransferase from strain WN was purified 76-fold [to a specific activity of 40.5 μmol min −1 (mg protein) −1 ]. SDS polyacrylamide gel electrophoresis showed two bands of approximately 10 and 35 kDa; in particular the 35 kDa polypeptide became significantly enriched during the purification. Storage of the purified fraction at −20°C under nitrogen resulted in a 99% loss of activity in two days. The activity could be partially restored by addition of 200 μM cyanocobalamin, hydroxocobalamin or coenzyme B 12 . ATP did not have any positive effect on activity. Reduction of the assay mixture by titanium(III)nitrilotriacetic acid slightly stimulated the activity. Gel filtration chromatography revealed a native molecular mass between 45 and 60 kDa for the DMSP:THF methyltransferase. The enzyme was most active at 35°C and pH 7.8. Glycine betaine, which can be considered an N-containing structural analogue of DMSP, did not serve as a methyl donor for DMSP:THF methyltransferase. Various sulfur-containing DMSP-analogues were tested but only methylethylsulfoniopropionate served as methyl donor. None of these compounds inhibited methyl transfer from DMSP to THF. Strain WN did not grow on any of the sulfur-containing DMSP-analogues.
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DMSP: tetrahydrofolate methyltransferase from the marine Sulfate-Reducing Bacterium strain WN
Journal of Sea Research, 2000Co-Authors: M Jansen, T.a HansenAbstract:Dimethylsulfoniopropionate (DMSP), an important compatible solute of many marine algae, can be metabolised by bacteria via cleavage to dimethylsulfide and acrylate or via an initial demethylation. This is the first report on the purification of an enzyme that specifically catalyses the demethylation of DMSP. The enzyme was isolated from the Sulfate-Reducing Bacterium strain WN, which grows on DMSP and demethylates it to methylthiopropionate. DMSP:tetrahydrofolate (THF) methyltransferase from strain WN was purified 76-fold [to a specific activity of 40.5 mu mol min(-1) (mg protein)(-1)]. SDS polyacrylamide gel electrophoresis showed two bands of approximately 10 and 35 kDa; in particular the 35 kDa polypeptide became significantly enriched during the purification. Storage of the purified fraction at -20 degrees C under nitrogen resulted in a 99% loss of activity in two days. The activity could be partially restored by addition of 200 mu M cyanocobalamin, hydroxocobalamin or coenzyme B-12-ATP did not have any positive effect on activity. Reduction of the assay mixture by titanium(III)nitrilotriacetic acid slightly stimulated the activity. Gel filtration chromatography revealed a native molecular mass between 45 and 60 kDa for the DMSP:THF methyltransferase. The enzyme was most active at 35 degrees C and pH 7.8. Glycine betaine, which can be considered an N-containing structural analogue of DMSP, did not serve as a methyl donor for DMSP:THF methyltransferase. Various sulfur-containing DMSP-analogues were tested but only methylethylsolfoniopropionate served as methyl donor. None of these compounds inhibited methyl transfer from DMSP to THF. Strain WN did not grow on any of the sulfur-containing DMSP-analogues. (C) 2000 Elsevier Science B.V. All rights reserved
M Jansen - One of the best experts on this subject based on the ideXlab platform.
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DMSP: tetrahydrofolate methyltransferase from the marine Sulfate-Reducing Bacterium strain WN
Journal of Sea Research, 2000Co-Authors: M Jansen, T.a HansenAbstract:Abstract Dimethylsulfoniopropionate (DMSP), an important compatible solute of many marine algae, can be metabolised by bacteria via cleavage to dimethylsulfide and acrylate or via an initial demethylation. This is the first report on the purification of an enzyme that specifically catalyses the demethylation of DMSP. The enzyme was isolated from the Sulfate-Reducing Bacterium strain WN, which grows on DMSP and demethylates it to methylthiopropionate. DMSP:tetrahydrofolate (THF) methyltransferase from strain WN was purified 76-fold [to a specific activity of 40.5 μmol min −1 (mg protein) −1 ]. SDS polyacrylamide gel electrophoresis showed two bands of approximately 10 and 35 kDa; in particular the 35 kDa polypeptide became significantly enriched during the purification. Storage of the purified fraction at −20°C under nitrogen resulted in a 99% loss of activity in two days. The activity could be partially restored by addition of 200 μM cyanocobalamin, hydroxocobalamin or coenzyme B 12 . ATP did not have any positive effect on activity. Reduction of the assay mixture by titanium(III)nitrilotriacetic acid slightly stimulated the activity. Gel filtration chromatography revealed a native molecular mass between 45 and 60 kDa for the DMSP:THF methyltransferase. The enzyme was most active at 35°C and pH 7.8. Glycine betaine, which can be considered an N-containing structural analogue of DMSP, did not serve as a methyl donor for DMSP:THF methyltransferase. Various sulfur-containing DMSP-analogues were tested but only methylethylsulfoniopropionate served as methyl donor. None of these compounds inhibited methyl transfer from DMSP to THF. Strain WN did not grow on any of the sulfur-containing DMSP-analogues.
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DMSP: tetrahydrofolate methyltransferase from the marine Sulfate-Reducing Bacterium strain WN
Journal of Sea Research, 2000Co-Authors: M Jansen, T.a HansenAbstract:Dimethylsulfoniopropionate (DMSP), an important compatible solute of many marine algae, can be metabolised by bacteria via cleavage to dimethylsulfide and acrylate or via an initial demethylation. This is the first report on the purification of an enzyme that specifically catalyses the demethylation of DMSP. The enzyme was isolated from the Sulfate-Reducing Bacterium strain WN, which grows on DMSP and demethylates it to methylthiopropionate. DMSP:tetrahydrofolate (THF) methyltransferase from strain WN was purified 76-fold [to a specific activity of 40.5 mu mol min(-1) (mg protein)(-1)]. SDS polyacrylamide gel electrophoresis showed two bands of approximately 10 and 35 kDa; in particular the 35 kDa polypeptide became significantly enriched during the purification. Storage of the purified fraction at -20 degrees C under nitrogen resulted in a 99% loss of activity in two days. The activity could be partially restored by addition of 200 mu M cyanocobalamin, hydroxocobalamin or coenzyme B-12-ATP did not have any positive effect on activity. Reduction of the assay mixture by titanium(III)nitrilotriacetic acid slightly stimulated the activity. Gel filtration chromatography revealed a native molecular mass between 45 and 60 kDa for the DMSP:THF methyltransferase. The enzyme was most active at 35 degrees C and pH 7.8. Glycine betaine, which can be considered an N-containing structural analogue of DMSP, did not serve as a methyl donor for DMSP:THF methyltransferase. Various sulfur-containing DMSP-analogues were tested but only methylethylsolfoniopropionate served as methyl donor. None of these compounds inhibited methyl transfer from DMSP to THF. Strain WN did not grow on any of the sulfur-containing DMSP-analogues. (C) 2000 Elsevier Science B.V. All rights reserved
Bharat K. C. Patel - One of the best experts on this subject based on the ideXlab platform.
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Isolation and characterization of a thermophilic Sulfate-Reducing Bacterium, Desulfotomaculum thermosapovorans sp. nov
International journal of systematic bacteriology, 1995Co-Authors: Marielaure Fardeau, Bharat K. C. Patel, Bernard Ollivier, Prem P. Dwivedi, Michel Ragot, Jean-louis GarciaAbstract:Strain MLFT(T = type strain), a new thermophilic, spore-forming Sulfate-Reducing Bacterium, was characterized and was found to be phenotypically, genotypically, and phylogenetically related to the genus Desulfotomaculum. This organism was isolated from a butyrate enrichment culture that had been inoculated with a mixed compost containing rice hulls and peanut shells. The optimum temperature for growth was 50°C. The G+C content of the DNA was 51.2 mol%. Strain MLFTincompletely oxidized pyruvate, butyrate, and butanol to acetate and presumably CO2. It used long-chain fatty acids and propanediols. We observed phenotypic and phylogenetic differences between strain MLFTand other thermophilic Desulfotomaculum species that also oxidize long-chain fatty acids. On the basis of our results, we propose that strain MLFTis a member of a new species, Desulfotomaculum thermosapovorans.
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Desulfacinum infernum gen. nov., sp. nov., a thermophilic Sulfate-Reducing Bacterium from a petroleum reservoir
International Journal of Systematic Bacteriology, 1995Co-Authors: Gavin N. Rees, Prem P. Dwivedi, Gino S. Grassia, Alan J. Sheehy, Bharat K. C. PatelAbstract:A thermophilic Sulfate-Reducing Bacterium, Desulfacinum infernum, is described. This Bacterium was isolated from produced formation water from a North Sea petroleum reservoir. In liquid culture, the cells are oval, 1.5 by 2.5 to 3 μm, nonmotile and gram negative. Spore formation has not been observed. Growth occurs at temperatures ranging from 40 to 65°C, with optimum growth occurring at 60°C, and at levels of salinity ranging from 0 to 50 g of NaCl per liter, with optimum growth occurring in the presence of 10 g of NaCl per liter. D. infernum grows on a range of organic acids, including formate, acetate, buryrate, and palmitate, and alcohols. D. infernum can grow autotrophically with H2. A vitamin supplement is required for growth. Sulfite and thioSulfate are used as electron acceptors. Sulfur and nitrate are not reduced. The DNA base composition is 64 mol% G+C. Phylogenetically, D. infernum clusters with members of the delta subdivision of the Proteobacteria. Its closest relatives are Syntrophobacter wolinii (level of similarity, 90.6%) and Desulfomonile tiedjei (level of similarity, 87.1%).
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Desulfovibrio longreachii sp. nov., a Sulfate-Reducing Bacterium isolated from the Great Artesian Basin of Australia
FEMS microbiology letters, 1994Co-Authors: A.c. Redburn, Bharat K. C. PatelAbstract:A new mesophilic, thermotolerant Sulfate-Reducing Bacterium, was isolated from the flowing bore waters of a deep aquifer, the Great Artesian Basin, Australia. The strain, designated isolate AB16910a, is a curved rod and resembled members of the genus Desulfovibrio. However, the isolate can be differentiated from other members of the Desulfovibrio species because of the high G+C content of 69±0.25% the 16S rRNA sequence data and other physiological characteristics. The name Desulfovibrio longreachii is proposed for the new isolate.
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Desulfotomaculum australicum, sp. nov., a Thermophilic Sulfate-Reducing Bacterium Isolated from the Great Artesian Basin of Australia
Systematic and Applied Microbiology, 1993Co-Authors: Christopher Love, Bharat K. C. Patel, Peter D. Nichols, Erko StackebrandtAbstract:Summary A new thermophilic species of spore-forming Sulfate-Reducing Bacterium, Desulfotomaculum australicum is described. D. australicum is physiologically different to all other validated species of Desulfotomaculum. It has a high iso-saturated branched (15:0 and 17:0) phospholipid composition (87%), a feature in common with other true thermophiles. Phylogenetically, D. australicum clusters with the mesophilic D. orientis and D. ruminis. However, a set of signature nucleotides that would support the clustering of these three organisms within the radiation of Gram-positive bacteria could not be detected.
