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John D Coates - One of the best experts on this subject based on the ideXlab platform.
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An uncharacterized clade in the DMSO reductase family of molybdenum oxidoreductases is a new type of Chlorate reductase.
Environmental microbiology reports, 2020Co-Authors: Tyler P. Barnum, John D CoatesAbstract:The dimethyl sulfoxide (DMSO) reductase family of enzymes has many subfamilies catalyzing unique biogeochemical reactions. It also has many uncharacterized subfamilies. Comparative genomics predicted one such subfamily to participate in a key step of the chlorine cycle because of a conserved genetic association with chlorite dismutase, implying they produce chlorite through Chlorate or perChlorate reduction. We determined the activity of the uncharacterized enzyme by comparing strains in the phototrophic genus Rhodoplanes that encode either a typical perChlorate reductase or the uncharacterized enzyme. Rpl. piscinae and Rpl. elegans, which encode perChlorate reductase, grew by using perChlorate as an electron acceptor. In contrast, Rpl. roseus, which encodes the uncharacterized enzyme, grew by Chlorate reduction but not by perChlorate reduction. This is the first report of perChlorate and Chlorate being used as respiratory electron acceptors by phototrophs. When both Chlorate and perChlorate were present, Rpl. roseus consumed only Chlorate. Highly concentrated Rpl. roseus cells showed some perChlorate consumption, but Chlorate consumption occurred at a ten-fold higher rate. Together, these genomic and physiological data define a new group of Chlorate reductases. Some organisms encode both this Chlorate reductase and a perChlorate reductase, raising new questions about the physiology and evolution of chlorine oxyanion respiration. This article is protected by copyright. All rights reserved.
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Genetic dissection of Chlorate respiration in Pseudomonas stutzeri PDA reveals syntrophic (per)Chlorate reduction.
Environmental microbiology, 2015Co-Authors: Iain C. Clark, Matthew D. Youngblut, Gillian Jacobsen, Kelly M. Wetmore, Adam M. Deutschbauer, Lauren Sudeall Lucas, John D CoatesAbstract:Genes important for growth of Pseudomonas stutzeri PDA on Chlorate were identified using a randomly DNA bar-coded transposon mutant library. During Chlorate reduction, mutations in genes encoding the Chlorate reductase clrABC, predicted molybdopterin cofactor chaperon clrD, molybdopterin biosynthesis and two genes of unknown function (clrE, clrF) had fitness defects in pooled mutant assays (Bar-seq). Markerless in-frame deletions confirmed that clrA, clrB and clrC were essential for Chlorate reduction, while clrD, clrE and clrF had less severe growth defects. Interestingly, the key detoxification gene cld was essential for Chlorate reduction in isogenic pure culture experiments, but showed only minor fitness defects in Bar-seq experiments. We hypothesized this was enabled through chlorite dismutation by the community, as most strains in the Bar-seq library contained an intact cld. In support of this, Δcld grew with wild-type PDA or ΔclrA, and purified Cld also restored growth to the Δcld mutant. Expanding on this, wild-type PDA and a Δcld mutant of the perChlorate reducer Azospira suillum PS grew on perChlorate in co-culture, but not individually. These results demonstrate that co-occurrence of cld and a chloroxyanion reductase within a single organism is not necessary and raises the possibility of syntrophic (per)Chlorate respiration in the environment.
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per Chlorate reducing bacteria can utilize aerobic and anaerobic pathways of aromatic degradation with per Chlorate as an electron acceptor
Mbio, 2015Co-Authors: Charlotte I Carlstrom, Iain C. Clark, Stefan Bauer, Dana Loutey, R A Rohde, Anthony T Iavarone, Lauren N Lucas, John D CoatesAbstract:ABSTRACT The pathways involved in aromatic compound oxidation under perChlorate and Chlorate [collectively known as (per)Chlorate]-reducing conditions are poorly understood. Previous studies suggest that these are oxygenase-dependent pathways involving O 2 biogenically produced during (per)Chlorate respiration. Recently, we described Sedimenticola selenatireducens CUZ and Dechloromarinus chlorophilus NSS, which oxidized phenylacetate and benzoate, two key intermediates in aromatic compound catabolism, coupled to the reduction of perChlorate or Chlorate, respectively, and nitrate. While strain CUZ also oxidized benzoate and phenylacetate with oxygen as an electron acceptor, strain NSS oxidized only the latter, even at a very low oxygen concentration (1%, vol/vol). Strains CUZ and NSS contain similar genes for both the anaerobic and aerobic-hybrid pathways of benzoate and phenylacetate degradation; however, the key genes ( paaABCD ) encoding the epoxidase of the aerobic-hybrid phenylacetate pathway were not found in either genome. By using transcriptomics and proteomics, as well as by monitoring metabolic intermediates, we investigated the utilization of the anaerobic and aerobic-hybrid pathways on different electron acceptors. For strain CUZ, the results indicated utilization of the anaerobic pathways with perChlorate and nitrate as electron acceptors and of the aerobic-hybrid pathways in the presence of oxygen. In contrast, proteomic results suggest that strain NSS may use a combination of the anaerobic and aerobic-hybrid pathways when growing on phenylacetate with Chlorate. Though microbial (per)Chlorate reduction produces molecular oxygen through the dismutation of chlorite (ClO 2 − ), this study demonstrates that anaerobic pathways for the degradation of aromatics can still be utilized by these novel organisms. IMPORTANCE S. selenatireducens CUZ and D. chlorophilus NSS are (per)Chlorate- and Chlorate-reducing bacteria, respectively, whose genomes encode both anaerobic and aerobic-hybrid pathways for the degradation of phenylacetate and benzoate. Previous studies have shown that (per)Chlorate-reducing bacteria and Chlorate-reducing bacteria (CRB) can use aerobic pathways to oxidize aromatic compounds in otherwise anoxic environments by capturing the oxygen produced from chlorite dismutation. In contrast, we demonstrate that S. selenatireducens CUZ is the first perChlorate reducer known to utilize anaerobic aromatic degradation pathways with perChlorate as an electron acceptor and that it does so in preference over the aerobic-hybrid pathways, regardless of any oxygen produced from chlorite dismutation. D. chlorophilus NSS, on the other hand, may be carrying out anaerobic and aerobic-hybrid processes simultaneously. Concurrent use of anaerobic and aerobic pathways has not been previously reported for other CRB or any microorganisms that encode similar pathways of phenylacetate or benzoate degradation and may be advantageous in low-oxygen environments.
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Chlorate reduction in shewanella algae acdc is a recently acquired metabolism characterized by gene loss suboptimal regulation and oxidative stress
Molecular Microbiology, 2014Co-Authors: Iain C. Clark, Ryan A Melnyk, Anthony T Iavarone, Pavel S Novichkov, John D CoatesAbstract:Previous work on respiratory Chlorate reduction has biochemically identified the terminal reductase ClrABC and the chlorite detoxifying enzyme Cld. In Shewanella algae ACDC, genes encoding these enzymes reside on composite transposons whose core we refer to as the Chlorate reduction composite transposon interior (CRI). To better understand this metabolism in ACDC, we used RNA-seq and proteomics to predict carbon and electron flow during Chlorate reduction and posit that formate is an important electron carrier with lactate as the electron donor, but that NADH predominates on acetate. Chlorate-specific transcription of electron transport chain components or the CRI was not observed, but clr and cld transcription was attenuated by oxygen. The major Chlorate-specific response related to oxidative stress and was indicative of reactive chlorine species production. A genetic system based on rpsL-streptomycin counter selection was developed to further dissect the metabolism, but ACDC readily lost the CRI via homologous recombination of the composite transposon's flanking insertion sequences. An engineered strain containing a single chromosomal CRI did not grow on Chlorate, but overexpression of cld and its neighbouring cytochrome c restored growth. We postulate that the recently acquired CRI underwent copy-number expansion to circumvent insufficient expression of key genes in the pathway.
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structure and evolution of Chlorate reduction composite transposons
Mbio, 2013Co-Authors: Iain C. Clark, Ryan A Melnyk, Anna Engelbrektson, John D CoatesAbstract:The genes for Chlorate reduction in six bacterial strains were analyzed in order to gain insight into the metabolism. A newly isolated Chlorate-reducing bacterium (Shewanella algae ACDC) and three previously isolated strains (Ideonella dechlora- tans, Pseudomonas sp. strain PK, and Dechloromarinus chlorophilus NSS) were genome sequenced and compared to published sequences (Alicycliphilus denitrificans BC plasmid pALIDE01 and Pseudomonas chloritidismutans AW-1). De novo assembly of genomes failed to join regions adjacent to genes involved in Chlorate reduction, suggesting the presence of repeat regions. Using a bioinformatics approach andfinishing PCRs to connect fragmented contigs, we discovered that Chlorate reduction genes are flanked by insertion sequences, forming composite transposons in all four newly sequenced strains. These insertion sequences delineate regions with the potential to move horizontally and define a set of genes that may be important for Chlorate reduction. In addition to core metabolic components, we have highlighted several such genes through comparative analysis and visualiza- tion. Phylogenetic analysis places Chlorate reductase within a functionally diverse clade of type II dimethyl sulfoxide (DMSO) reductases, part of a larger family of enzymes with reactivity toward Chlorate. Nucleotide-level forensics of regions surrounding chlorite dismutase (cld), as well as its phylogenetic clustering in a betaproteobacterial Cld clade, indicate that cldhas been mobi- lized at least once from a perChlorate reducer to build Chlorate respiration. IMPORTANCE Genome sequencing has identified, for thefirst time, Chlorate reduction composite transposons. These transposons are constructed withflanking insertion sequences that differ in type and orientation between organisms, indicating that this mo- bile element has formed multiple times and is important for dissemination. Apart from core metabolic enzymes, very little is known about the genetic factors involved in Chlorate reduction. Comparative analysis has identified several genes that may also be important, but the relative absence of accessory genes suggests that this mobile metabolism relies on host systems for electron transport, regulation, and cofactor synthesis. Phylogenetic analysis of Cld and ClrA provides support for the hypothesis that Chlorate reduction was built multiple times from type II dimethyl sulfoxide (DMSO) reductases and cld. In at least one case,cld has been coopted from a perChlorate reduction island for this purpose. This work is a significant step toward understanding the genetics and evolution of Chlorate reduction.
David J Nisbet - One of the best experts on this subject based on the ideXlab platform.
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reduction of e coli o157 h7 populations in sheep by supplementation of an experimental sodium Chlorate product
Small Ruminant Research, 2003Co-Authors: T S Edrington, Robin C Anderson, Todd R Callaway, Kenneth J Genovese, Y S Jung, J L Mcreynolds, K M Bischoff, David J NisbetAbstract:Ruminant animals are naturally infected with the pathogen Escherichia coli O157:H7, annually responsible for numerous meat recalls, foodborne illnesses and deaths. E. coli are equipped with the enzyme nitrate reductase, which not only enables this bacteria to respire anaerobically, but also converts Chlorate to the toxic metabolite chlorite. This enzyme system is particular to only a few intestinal bacteria, therefore the vast majority are not affected by Chlorate. Sodium Chlorate has been shown to effectively decrease foodborne pathogens in several livestock species, including ruminants. However, because infection and proliferation of E. coli occurs primarily in the lower intestine, there is interest in “by-passing” the rumen, thereby, delivering Chlorate directly to the largest population of pathogens. The objective of the current study was to evaluate the ability of an experimental sodium Chlorate product (ECP II), designed to by-pass the rumen, in reducing fecal shedding and gut concentrations of E. coli O157:H7. Twenty crossbred mature ewes were adapted to a high grain ration and experimentally inoculated with E. coli O157:H7. Thirty-six hours following inoculation, sheep received in their feed one of the following ECP treatments: (1) control (CON), no Chlorate; (2) 1X (LOW); (3) 2X (MED); and (4) 4X (HIGH) where X=1.1 g Chlorate ion equivalents/kg BW (five sheep per treatment). Fecal samples were collected every 12 h following inoculation and 24 h following the feeding of Chlorate, all animals were euthanized and tissue samples and their respective contents collected from the rumen, cecum and rectum. The MED and HIGH Chlorate treatments significantly reduced fecal shedding of E. coli O157:H7 compared to the CON treatment [1.53, 1.11, and 3.89 CFU/g feces (log10), respectively]. Ruminal contents were similar among treatments, while Chlorate tended to decrease (P=0.08) and reduced (P<0.05) E. coli O157:H7 populations in the cecum and rectum, respectively. Populations of generic E. coli in the cecal contents were numerically lower (P=0.11) in the LOW treatment and tended to decrease (P=0.06) in the MED and HIGH Chlorate treatments, respectively. Fermentation profiles through the gastrointestinal tract were unaffected as indicated by slight, but not significant, changes in volatile fatty acids (VFA) profiles in sheep fed Chlorate. Results from this study indicate that this experimental Chlorate product, administered in the feed, was effective in reducing E. coli O157:H7 from the lower gut of sheep as evidenced by the lower cecal and rectal but not ruminal concentrations. Feeding Chlorate may be an effective method to decrease E. coli O157:H7 populations in ruminant animals prior to slaughter.
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sodium Chlorate supplementation reduces e coli o157 h7 populations in cattle
Journal of Animal Science, 2002Co-Authors: Todd R Callaway, Robin C Anderson, Timothy J Anderson, Kenneth J Genovese, L F Kubena, T L Poole, J A Byrd, David J NisbetAbstract:Cattle are a natural reservoir of the food-borne pathogen Escherichia coli 0157:H7. Therefore, strategies that reduce E. coli 0157:H7 prior to slaughter will reduce human exposures to this virulent pathogen. When bacteria that can anaerobically respire on nitrate (e.g., E. coli) are exposed to Chlorate, they die because the intracellular enzyme nitrate reductase converts nitrate to nitrite, but also co-metabolically reduces Chlorate to cytotoxic chlorite. Because Chlorate is bactericidal only against nitrate reductase-positive bacteria, it has been suggested that Chlorate supplementation be used as a strategy to reduce E. coli 0157:H7 populations in cattle prior to harvest. Cattle (n = 8) were fed a feedlot-style high-grain diet experimentally infected with three strains of E. coli O157:H7. Cattle were given access to drinking water supplemented with 2.5 mM KNO 3 and 100 mM NaCl (controls; n = 4) or 2.5 mM KNO 3 and 100 mM NaClO 3 (Chlorate-treated; n = 4). Sodium Chlorate treatment for 24 h reduced the population of all E. coli 0157:H7 strains approximately two logs (10 4 to 10 2 ) in the rumen and three logs (10 6 to 10 3 ) in the feces. Chlorate treatment reduced total coliforms and generic E. coli from 10 6 to 10 4 in the rumen and by two logs throughout the rest of the gastrointestinal tract (ileum, cecum, colon, and rectum). Chlorate treatment reduced E. coli O157:H7 counts throughout the intestinal tract but did not alter total culturable anaerobic bacterial counts or the ruminal fermentation pattern. Therefore, it appears that Chlorate supplementation is a viable potential strategy to reduce E. coli O157:H7 populations in cattle prior to harvest.
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bactericidal effect of sodium Chlorate on escherichia coli concentrations in bovine ruminal and fecal contents in vivo
Microbial Ecology in Health and Disease, 2002Co-Authors: Robin C Anderson, Todd R Callaway, Timothy J Anderson, L F Kubena, Nancy K Keith, David J NisbetAbstract:Enterohemorrhagic Escherichia coli causes a potentially fatal disease in humans. Since human infections often occur following consumption of contaminated meat, strategies are sought to rid these pathogens from food-producing animals. E. coli , like most members of the family Enterobacteriaceae , possess respiratory nitrate reductase, an enzyme that coincidentally reduces Chlorate to toxic chlorite. Consequently, a study was performed to assess the effect of intraruminal Chlorate administration on E. coli in the gut of fed and fasted cattle, the latter having been reported to harbor increased concentrations of enteric pathogens. As hypothesized, E. coli concentrations were lower (p<0.05) 10 and 24 h post Chlorate administration, respectively, in rumen contents and feces of Chlorate-treated cows than in untreated cows. Fasting had little effect on gut E. coli concentrations and did not effect the bactericidal effect of Chlorate against E. coli . Chlorate treatment had little or no effect on fermentation efficiency, as evidenced by pH, volatile fatty acid production and concentration of total culturable anaerobes, and had no observable adverse effects on any of the cows. These results suggest that Chlorate may be useful in the pre-harvest control of E. coli . Keywords: Escherichia coli , Chlorate, food safety, ruminant.
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effect of oral sodium Chlorate administration on escherichia coli o157 h7 in the gut of experimentally infected pigs
International Journal of Food Microbiology, 2001Co-Authors: Robin C Anderson, Todd R Callaway, Sandra A Buckley, Timothy J Anderson, Kenneth J Genovese, Cynthia L Sheffield, David J NisbetAbstract:Abstract Strategies are sought to reduce pathogenic Escherichia coli concentrations in food animals. Because E. coli possess respiratory nitrate reductase activity, which also reduces Chlorate to cytotoxic chlorite, we tested and found that oral sodium Chlorate administration reduced gut concentrations of E. coli O157:H7 in experimentally infected pigs and wildtype E. coli concentrations in nonchallenged pigs. Mean±S.E. concentrations (log10 CFU/g) of E. coli O157:H7 in ileal, cecal, colonic and rectal contents from placebo-treated pigs were 4.03±0.66, 3.82±0.24, 4.42±0.25 and 4.03±0.16, respectively. In contrast, E. coli O157:H7 concentrations were reduced (P
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effect of sodium Chlorate on salmonella typhimurium concentrations in the weaned pig gut
Journal of Food Protection, 2001Co-Authors: Robin C Anderson, Todd R Callaway, Sandra A Buckley, Kenneth J Genovese, L F Kubena, R B Harvey, David J NisbetAbstract:Salmonella cause economic losses to the swine industry due to disease and compromised food safety. Since the gut is a major reservoir for Salmonella, strategies are sought to reduce their concentration in pigs immediately before processing. Respiratory nitrate reductase activity possessed by Salmonella also catalyzes the intracellular reduction of Chlorate (an analog of nitrate) to chlorite, which is lethal to the microbe. Since most gastrointestinal anaerobes lack respiratory nitrate reductase, we conducted a study to determine if Chlorate may selectively kill Salmonella within the pig gut. Weaned pigs orally infected with 8 x 10(7) CFU of a novobiocin- and nalidixic acid-resistant strain of Salmonella Typhimurium were treated 8 and 16 h later via oral gavage (10 ml) with 0 or 100 mM sodium Chlorate. Pigs were euthanized at 8-h intervals after receiving the last treatment. Samples collected by necropsy were cultured qualitatively and quantitatively for Salmonella and for most probable numbers of total culturable anaerobes. A significant (P < 0.05) Chlorate treatment effect was observed on cecal concentrations of Salmonella, with the largest reductions occurring 16 h after receiving the last Chlorate treatment. An observed treatment by time after treatment interaction suggests the Chlorate effect was concentration dependent. Chlorate treatment may provide a means to reduce foodborne pathogens immediately before harvest.
Robin C Anderson - One of the best experts on this subject based on the ideXlab platform.
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effect of sodium 36cl Chlorate dose on total radioactive residues and residues of parent Chlorate in growing swine
Journal of Agricultural and Food Chemistry, 2005Co-Authors: David J Smith, C E Oliver, J S Caton, Robin C AndersonAbstract:An experimental Chlorate-based product has been shown to be efficacious in eliminating economically important, Gram-negative human pathogens in the gastrointestinal tracts of food animals. Prior to the commercial marketing of such a product, the magnitude and chemical nature of residues remaining in edible tissues must be determined. Thus, the objective of this study was to determine the tissue distribution and elimination of sodium [36Cl]Chlorate in orally dosed swine. Three sets of pigs, each consisting of a barrow and a gilt, were orally dosed with a total of 20, 40, or 60 mg of sodium [36Cl]Chlorate per kg body weight via the drinking water. Urine and feces were collected throughout the 30 h study. Twenty-four hours after the last exposure to [36Cl]Chlorate, each pig was harvested and both edible and inedible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for Chlorate metabolites. Elimination of radioactivity in urine averaged 81.6, 83.7, and 83.9% of the total dose for the low, medium, and high doses, respectively. Fecal elimination of radioactivity averaged 1.1% of the dosed radiochlorine across all doses. Parent Chlorate always represented greater than 97.4% of the urinary radiochlorine with the remaining radiochlorine being excreted as chloride ion. Chlorate represented 39-77% of fecal radioactivity, depending upon dose. Chlorate concentrations in edible tissues ranged from 0.01 to 0.49 ppm, with residues in liver and skeletal muscle generally lower than those in kidney and adipose tissue. Chlorate residues were concentrated in thyroid tissues (7.7-25.4 ppm) relative to edible tissues. No evidence for the presence of chlorite was observed in excreta or in tissues. Results of this study suggest that further development of Chlorate as a preharvest food safety tool in swine merits consideration.
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reduction of e coli o157 h7 populations in sheep by supplementation of an experimental sodium Chlorate product
Small Ruminant Research, 2003Co-Authors: T S Edrington, Robin C Anderson, Todd R Callaway, Kenneth J Genovese, Y S Jung, J L Mcreynolds, K M Bischoff, David J NisbetAbstract:Ruminant animals are naturally infected with the pathogen Escherichia coli O157:H7, annually responsible for numerous meat recalls, foodborne illnesses and deaths. E. coli are equipped with the enzyme nitrate reductase, which not only enables this bacteria to respire anaerobically, but also converts Chlorate to the toxic metabolite chlorite. This enzyme system is particular to only a few intestinal bacteria, therefore the vast majority are not affected by Chlorate. Sodium Chlorate has been shown to effectively decrease foodborne pathogens in several livestock species, including ruminants. However, because infection and proliferation of E. coli occurs primarily in the lower intestine, there is interest in “by-passing” the rumen, thereby, delivering Chlorate directly to the largest population of pathogens. The objective of the current study was to evaluate the ability of an experimental sodium Chlorate product (ECP II), designed to by-pass the rumen, in reducing fecal shedding and gut concentrations of E. coli O157:H7. Twenty crossbred mature ewes were adapted to a high grain ration and experimentally inoculated with E. coli O157:H7. Thirty-six hours following inoculation, sheep received in their feed one of the following ECP treatments: (1) control (CON), no Chlorate; (2) 1X (LOW); (3) 2X (MED); and (4) 4X (HIGH) where X=1.1 g Chlorate ion equivalents/kg BW (five sheep per treatment). Fecal samples were collected every 12 h following inoculation and 24 h following the feeding of Chlorate, all animals were euthanized and tissue samples and their respective contents collected from the rumen, cecum and rectum. The MED and HIGH Chlorate treatments significantly reduced fecal shedding of E. coli O157:H7 compared to the CON treatment [1.53, 1.11, and 3.89 CFU/g feces (log10), respectively]. Ruminal contents were similar among treatments, while Chlorate tended to decrease (P=0.08) and reduced (P<0.05) E. coli O157:H7 populations in the cecum and rectum, respectively. Populations of generic E. coli in the cecal contents were numerically lower (P=0.11) in the LOW treatment and tended to decrease (P=0.06) in the MED and HIGH Chlorate treatments, respectively. Fermentation profiles through the gastrointestinal tract were unaffected as indicated by slight, but not significant, changes in volatile fatty acids (VFA) profiles in sheep fed Chlorate. Results from this study indicate that this experimental Chlorate product, administered in the feed, was effective in reducing E. coli O157:H7 from the lower gut of sheep as evidenced by the lower cecal and rectal but not ruminal concentrations. Feeding Chlorate may be an effective method to decrease E. coli O157:H7 populations in ruminant animals prior to slaughter.
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sodium Chlorate supplementation reduces e coli o157 h7 populations in cattle
Journal of Animal Science, 2002Co-Authors: Todd R Callaway, Robin C Anderson, Timothy J Anderson, Kenneth J Genovese, L F Kubena, T L Poole, J A Byrd, David J NisbetAbstract:Cattle are a natural reservoir of the food-borne pathogen Escherichia coli 0157:H7. Therefore, strategies that reduce E. coli 0157:H7 prior to slaughter will reduce human exposures to this virulent pathogen. When bacteria that can anaerobically respire on nitrate (e.g., E. coli) are exposed to Chlorate, they die because the intracellular enzyme nitrate reductase converts nitrate to nitrite, but also co-metabolically reduces Chlorate to cytotoxic chlorite. Because Chlorate is bactericidal only against nitrate reductase-positive bacteria, it has been suggested that Chlorate supplementation be used as a strategy to reduce E. coli 0157:H7 populations in cattle prior to harvest. Cattle (n = 8) were fed a feedlot-style high-grain diet experimentally infected with three strains of E. coli O157:H7. Cattle were given access to drinking water supplemented with 2.5 mM KNO 3 and 100 mM NaCl (controls; n = 4) or 2.5 mM KNO 3 and 100 mM NaClO 3 (Chlorate-treated; n = 4). Sodium Chlorate treatment for 24 h reduced the population of all E. coli 0157:H7 strains approximately two logs (10 4 to 10 2 ) in the rumen and three logs (10 6 to 10 3 ) in the feces. Chlorate treatment reduced total coliforms and generic E. coli from 10 6 to 10 4 in the rumen and by two logs throughout the rest of the gastrointestinal tract (ileum, cecum, colon, and rectum). Chlorate treatment reduced E. coli O157:H7 counts throughout the intestinal tract but did not alter total culturable anaerobic bacterial counts or the ruminal fermentation pattern. Therefore, it appears that Chlorate supplementation is a viable potential strategy to reduce E. coli O157:H7 populations in cattle prior to harvest.
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bactericidal effect of sodium Chlorate on escherichia coli concentrations in bovine ruminal and fecal contents in vivo
Microbial Ecology in Health and Disease, 2002Co-Authors: Robin C Anderson, Todd R Callaway, Timothy J Anderson, L F Kubena, Nancy K Keith, David J NisbetAbstract:Enterohemorrhagic Escherichia coli causes a potentially fatal disease in humans. Since human infections often occur following consumption of contaminated meat, strategies are sought to rid these pathogens from food-producing animals. E. coli , like most members of the family Enterobacteriaceae , possess respiratory nitrate reductase, an enzyme that coincidentally reduces Chlorate to toxic chlorite. Consequently, a study was performed to assess the effect of intraruminal Chlorate administration on E. coli in the gut of fed and fasted cattle, the latter having been reported to harbor increased concentrations of enteric pathogens. As hypothesized, E. coli concentrations were lower (p<0.05) 10 and 24 h post Chlorate administration, respectively, in rumen contents and feces of Chlorate-treated cows than in untreated cows. Fasting had little effect on gut E. coli concentrations and did not effect the bactericidal effect of Chlorate against E. coli . Chlorate treatment had little or no effect on fermentation efficiency, as evidenced by pH, volatile fatty acid production and concentration of total culturable anaerobes, and had no observable adverse effects on any of the cows. These results suggest that Chlorate may be useful in the pre-harvest control of E. coli . Keywords: Escherichia coli , Chlorate, food safety, ruminant.
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effect of oral sodium Chlorate administration on escherichia coli o157 h7 in the gut of experimentally infected pigs
International Journal of Food Microbiology, 2001Co-Authors: Robin C Anderson, Todd R Callaway, Sandra A Buckley, Timothy J Anderson, Kenneth J Genovese, Cynthia L Sheffield, David J NisbetAbstract:Abstract Strategies are sought to reduce pathogenic Escherichia coli concentrations in food animals. Because E. coli possess respiratory nitrate reductase activity, which also reduces Chlorate to cytotoxic chlorite, we tested and found that oral sodium Chlorate administration reduced gut concentrations of E. coli O157:H7 in experimentally infected pigs and wildtype E. coli concentrations in nonchallenged pigs. Mean±S.E. concentrations (log10 CFU/g) of E. coli O157:H7 in ileal, cecal, colonic and rectal contents from placebo-treated pigs were 4.03±0.66, 3.82±0.24, 4.42±0.25 and 4.03±0.16, respectively. In contrast, E. coli O157:H7 concentrations were reduced (P
Alfons J M Stams - One of the best experts on this subject based on the ideXlab platform.
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per Chlorate reduction at high temperature physiological study of archaeoglobus fulgidus and potential implications for novel souring mitigation strategies
International Biodeterioration & Biodegradation, 2014Co-Authors: Martin G Liebensteiner, Alfons J M Stams, Bart P LomansAbstract:The recent finding that Archaeoglobus fulgidus is able to couple (per)Chlorate reduction to growth expanded this trait to the hyperthermophilic range of life. This sulfate-reducing archaeon is considered to be one of the major contributors to souring in hot oil reservoirs. Therefore, it is important to study its physiology in depth, particularly in view of novel souring mitigation strategies. A. fulgidus does not possess the classical (per)Chlorate reduction pathway, as it lacks the key enzyme chlorite dismutase. Rather, the microorganism seems to couple (per)Chlorate reduction to sulfur metabolism. Growth experiments show the strict necessity of sulfur compounds to sustain perChlorate reduction. Furthermore, the chemical formation of elemental sulfur was observed during perChlorate reduction, a compound that is biologically reduced again. Additional experiments showed that tetrathionate, but not elemental sulfur and polysulfide, serves as an electron acceptor for growth by A. fulgidus. Taken together these results provide further evidence for the importance of chemical and biological redox reactions involving sulfur compounds during (per)Chlorate reduction. In non-reduced media also, nitrate could be reduced by A. fulgidus, though not coupled to growth. This observation and the fact that A. fulgidus had prolonged adaptation phases on sulfate after long-lasting growth on perChlorate are of interest in the development of new souring mitigation strategies using nitrate and/or (per)Chlorate.
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archaeal per Chlorate reduction at high temperature an interplay of biotic and abiotic reactions
Science, 2013Co-Authors: Martin G Liebensteiner, Alfons J M Stams, Martijn W H Pinkse, Peter J Schaap, Bart P LomansAbstract:PerChlorate and Chlorate anions [(per)Chlorate] exist in the environment from natural and anthropogenic sources, where they can serve as electron acceptors for bacteria. We performed growth experiments combined with genomic and proteomic analyses of the hyperthermophile Archaeoglobus fulgidus that show (per)Chlorate reduction also extends into the archaeal domain of life. The (per)Chlorate reduction pathway in A. fulgidus relies on molybdo-enzymes that have similarity with bacterial enzymes; however, chlorite is not enzymatically split into chloride and oxygen. Evidence suggests that it is eliminated by an interplay of abiotic and biotic redox reactions involving sulfur compounds. Biological (per)Chlorate reduction by ancient archaea at high temperature may have prevented accumulation of perChlorate in early terrestrial environments and consequently given rise to oxidizing conditions on Earth before the rise of oxygenic photosynthesis.
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per Chlorate reduction by an acetogenic bacterium sporomusa sp isolated from an underground gas storage
Applied Microbiology and Biotechnology, 2010Co-Authors: Melike Balk, Farrakh Mehboob, Antonie H Van Gelder, Irene W C Rijpstra, Jaap Sinninghe S Damste, Alfons J M StamsAbstract:A mesophilic bacterium, strain An4, was isolated from an underground gas storage reservoir with methanol as substrate and perChlorate as electron acceptor. Cells were Gram-negative, spore-forming, straight to curved rods, 0.5–0.8 μm in diameter, and 2–8 μm in length, growing as single cells or in pairs. The cells grew optimally at 37°C, and the pH optimum was around 7. Strain An4 converted various alcohols, organic acids, fructose, acetoin, and H2/CO2 to acetate, usually as the only product. Succinate was decarboxylated to propionate. The isolate was able to respire with (per)Chlorate, nitrate, and CO2. The G+C content of the DNA was 42.6 mol%. Based on the 16S rRNA gene sequence analysis, strain An4 was most closely related to Sporomusa ovata (98% similarity). The bacterium reduced perChlorate and Chlorate completely to chloride. Key enzymes, perChlorate reductase and chlorite dismutase, were detected in cell-free extracts.
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isolation and characterization of alicycliphilus denitrificans strain bc which grows on benzene with Chlorate as the electron acceptor
Applied and Environmental Microbiology, 2008Co-Authors: Sander A B Weelink, N C G Tan, Harm Ten Broeke, Corne H Van Den Kieboom, Wim Van Doesburg, Alette A M Langenhoff, Jan Gerritse, Howard Junca, Alfons J M StamsAbstract:A bacterium, strain BC, was isolated from a benzene-degrading Chlorate-reducing enrichment culture. Strain BC degrades benzene in conjunction with Chlorate reduction. Cells of strain BC are short rods that are 0.6 μm wide and 1 to 2 μm long, are motile, and stain gram negative. Strain BC grows on benzene and some other aromatic compounds with oxygen or in the absence of oxygen with Chlorate as the electron acceptor. Strain BC is a denitrifying bacterium, but it is not able to grow on benzene with nitrate. The closest cultured relative is Alicycliphilus denitrificans type strain K601, a cyclohexanol-degrading nitrate-reducing betaproteobacterium. Chlorate reductase (0.4 U/mg protein) and chlorite dismutase (5.7 U/mg protein) activities in cell extracts of strain BC were determined. Gene sequences encoding a known chlorite dismutase (cld) were not detected in strain BC by using the PCR primers described in previous studies. As physiological and biochemical data indicated that there was oxygenation of benzene during growth with Chlorate, a strategy was developed to detect genes encoding monooxygenase and dioxygenase enzymes potentially involved in benzene degradation in strain BC. Using primer sets designed to amplify members of distinct evolutionary branches in the catabolic families involved in benzene biodegradation, two oxygenase genes putatively encoding the enzymes performing the initial successive monooxygenations (BC-BMOa) and the cleavage of catechol (BC-C23O) were detected. Our findings suggest that oxygen formed by dismutation of chlorite can be used to attack organic molecules by means of oxygenases, as exemplified with benzene. Thus, aerobic pathways can be employed under conditions in which no external oxygen is supplied.
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per Chlorate reduction by the thermophilic bacterium moorella perchloratireducens sp nov isolated from underground gas storage
Applied and Environmental Microbiology, 2008Co-Authors: Melike Balk, Sander A B Weelink, Ton Van Gelder, Alfons J M StamsAbstract:A thermophilic bacterium, strain An10, was isolated from underground gas storage with methanol as a substrate and perChlorate as an electron acceptor. Cells were gram-positive straight rods, 0.4 to 0.6 μm in diameter and 2 to 8 μm in length, growing as single cells or in pairs. Spores were terminal with a bulged sporangium. The temperature range for growth was 40 to 70°C, with an optimum at 55 to 60°C. The pH optimum was around 7. The salinity range for growth was between 0 and 40 g NaCl liter−1 with an optimum at 10 g liter−1. Strain An10 was able to grow on CO, methanol, pyruvate, glucose, fructose, cellobiose, mannose, xylose, and pectin. The isolate was able to respire with (per)Chlorate, nitrate, thiosulfate, neutralized Fe(III) complexes, and anthraquinone-2,6-disulfonate. The G+C content of the DNA was 57.6 mol%. On the basis of 16S rRNA analysis, strain An10 was most closely related to Moorella thermoacetica and Moorella thermoautotrophica. The bacterium reduced perChlorate and Chlorate completely to chloride. Key enzymes, perChlorate reductase and chlorite dismutase, were detected in cell extracts. Strain An10 is the first thermophilic and gram-positive bacterium with the ability to use (per)Chlorate as a terminal electron acceptor.
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bromate chlorite Chlorate haloacetic acids and trihalomethanes occurrence in indoor swimming pool waters in italy
Microchemical Journal, 2014Co-Authors: Elena Righi, Guerrino Predieri, Guglielmina Fantuzzi, Gabriella AggazzottiAbstract:Abstract Subjects attending indoor swimming pools are exposed to disinfection by-products (DBPs) by inhalation, dermal contact and/or ingestion, as a consequence of water disinfection treatments with chlorine and related compounds. The occurrence of trihalomethanes (THMs) in pool waters has been well documented, while information about other DBPs, including bromate, chlorite, Chlorate and haloacetic acids (HAAs), is very limited even though some of these substances are potentially dangerous for human health. The aim of this study was to investigate the occurrence of bromate, chlorite, Chlorate, HAAs and THMs both in pool and in source water of 24 public indoor swimming pools in Emilia Romagna Region, Northern Italy. THMs were evaluated with a standardized method involving the head-space gas-chromatographic technique, while HAAs, bromate, chlorite, and Chlorate were detected by Ion Chromatography with Mass Spectrometry. THMs were measured in all the pool water samples (mean value: 36.9 ± 28.2 μg/l), while they were detectable in less than 50% of source waters and always at very low levels (mean value: 2.0 ± 4.1 μg/l), as a consequence of drinking water disinfection with chlorine dioxide, a widespread disinfection method in Italy. Bromate was always absent in source water samples, and it was detected in 3 samples of pool water only (range: 10–48 μg/l). HAAs were scarcely detected in source waters (3 positive samples, maximum level observed: 21 μg/l), while in pool water they were always present at detectable levels and showed high concentrations (range: 11–403 μg/l, mean value of 164 ± 108 μg/l). Chlorite was present in 22 water supply samples (mean value: 149 ± 122 μg/l) but only in one pool water. Chlorate, on the contrary, resulted as the most prevalent DBP both in source (range: 2–499 μg/l) and in pool waters, where it showed the highest levels, with a mean value of 3661 μg/l and a maximum value of 19 537 μg/l. Such environmental levels could result in an important human exposure, mainly by ingestion and/or dermal contact, to non volatile DBPs different than THMs. Exposure to those DBPs, therefore, needs to be further investigated and strategies aimed at minimizing it should be identified and undertaken. Attention should be paid, above all, to Chlorate: this substance appears really widespread in swimming pool water and, according to the most recent toxicological studies, its potential human health effects could be relevant.
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trihalomethanes chlorite Chlorate in drinking water and risk of congenital anomalies a population based case control study in northern italy
Environmental Research, 2012Co-Authors: Elena Righi, Guglielmina Fantuzzi, Petra Bechtold, D Tortorici, Paolo Lauriola, E Calzolari, G Astolfi, Mark J Nieuwenhuijsen, Gabriella AggazzottiAbstract:Abstract Background Epidemiological evidence of an association between disinfection by-products (DBPs) exposure via drinking water and reproductive outcomes is still inconclusive. Objective The aim of this study was to investigate the association between trihalomethanes (THMs), chlorite and Chlorate exposure and congenital anomalies. Methods A case-control study was carried out in Emilia-Romagna Region (Italy). Data on 1917 different congenital anomalies (neural tube, cardiac, diaphragm and abdominal wall, oesophagus, cleft lip and palate, respiratory, urinary tract and chromosomal anomalies) observed in the period 2002–2005 were extracted from the Regional Malformation Registry. Four controls (newborns without anomalies) were randomly selected form the Regional Birth Register and frequency matched to cases according to pregnancy period. The network supplying water during the first trimester of pregnancy was identified on the basis of mother's address: DBPs data, technical and structural information were linked to each subject. Results Overall, THMs exposure was very low (mean: 3.8±3.6 μg/l), and no risk excess was observed. Chlorite and Chlorate values were fairly high (mean: 427±184 μg/l and 283±79 μg/l, respectively). Women exposed to chlorite level >700 μg/l were at higher risk of newborns with renal defects (OR: 3.30; 95% IC: 1.35–8.09), abdominal wall defects (OR: 6.88; 95% IC: 1.67–28.33) and cleft palate (OR: 4.1; 95% IC: 0.98–16.8); women exposed to Chlorate level >200 μg/l were at higher risk of newborns with obstructive urinary defects (OR: 2.88; 95% IC: 1.09–7.63), cleft palate (OR: 9.60; 95% IC:1.04–88.9) and spina bifida (OR: 4.94; 95% IC:1.10–22). Conclusions This was the first study showing an excess risk of different congenital anomalies related to chlorite and Chlorate exposure via drinking water: further research is needed to confirm the observed relationships in large datasets, specifically for Chlorate, an unregulated DBP.
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environmental surveillance of a sample of indoor swimming pools from emilia romagna region microclimate characteristics and chemical parameters particularly disinfection by products in pool waters
Annali di igiene : medicina preventiva e di comunità, 2010Co-Authors: Guglielmina Fantuzzi, Guerrino Predieri, Elena Righi, Pierluigi Giacobazzi, K Mastroianni, Gabriella AggazzottiAbstract:The aim of the present study was to investigate the environmental and healthy aspects from a representative sample of indoor swimming pools located in the Emilia Romagna region. During the sampling sessions, the occupational environment was evaluated in terms of microclimate parameters and thermal comfort/discomfort conditions. Moreover the chemical risk was assessed by analyzing from the pool water the presence of disinfection by-products (DBPs), such as: trihalomethanes (THMs), haloacetic acids (HAAs), chlorite, Chlorate and bromate. The analytical results are in agreement with the Italian legislation (Accordo Stato-Regioni; 2003) even if in some of the sampled indoor swimming pools, the dosed combined chlorine levels, were greater than the Italian limit. With the regard to the microclimate conditions evaluation, the considered thermal indices, Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD%), described a satisfactory occupational environment. Among DBPs, the THMs mean levels (41.4 +/- 30.0 microg/l) resulted close to the values of the current Italian drinking water legislation, and seem to not represent an health issue. The pool waters Chlorate levels (range: 5 - 19537 microg/l) need further investigations as recent epidemiological studies on drinking water hypothesized a potential genotoxicity effect of these compounds which are involved in cellular oxidative processes.