The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Satu Pyorala - One of the best experts on this subject based on the ideXlab platform.
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field comparison of real time polymerase chain reaction and Bacterial Culture for identification of bovine mastitis bacteria
Journal of Dairy Science, 2010Co-Authors: M T Koskinen, G J Wellenberg, O C Sampimon, Jani Holopainen, A Rothkamp, L Salmikivi, W A Van Haeringen, Satu PyoralaAbstract:Fast and reliable identification of the microorganisms causing mastitis is important for management of the disease and for targeting antimicrobial treatment. Methods based on PCR are being used increasingly in mastitis diagnostics. Comprehensive field comparisons of PCR and traditional milk bacteriology have not been available. The results of a PCR kit capable of detecting 11 important etiological agents of mastitis directly from milk in 4 h were compared with those of conventional Bacterial Culture (48 h). In total, 1,000 quarter milk samples were taken from cows with clinical or subclinical mastitis, or from clinically healthy quarters with low somatic cell count (SCC). Bacterial Culture identified udder pathogens in 600/780 (77%) of the clinical samples, whereas PCR identified bacteria in 691/780 (89%) of the clinical samples. The PCR analysis detected major pathogens in a large number of clinical samples that were negative for the species in Culture. These included 53 samples positive for Staphylococcus aureus by PCR, but negative by Culture. A total of 137 samples from clinical mastitis, 5 samples from subclinical mastitis, and 1 sample from a healthy quarter were positive for 3 or more Bacterial species in PCR, whereas Culture identified 3 or more species in 60 samples from clinical mastitis. Culture identified a species not targeted by the PCR test in 44 samples from clinical mastitis and in 9 samples from subclinical mastitis. Low SCC samples provided a small number of positive results both in Culture (4/93; 4.3%) and by PCR (7/93; 7.5%). In conclusion, the PCR kit provided several benefits over conventional Culture, including speed, automated interpretation of results, and increased sensitivity. This kit holds much promise as a tool to complement traditional methods in identification of pathogens. In conventional mastitis bacteriology, a sample with 3 or more species is considered contaminated, and resampling of the cow is recommended. Further study is required to investigate how high sensitivity of PCR and its quantitative features can be applied to improve separation of relevant udder pathogens from likely contaminants in samples where multiple species are detected. Furthermore, increasing the number of species targeted by the PCR test would be advantageous.
M T Koskinen - One of the best experts on this subject based on the ideXlab platform.
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field comparison of real time polymerase chain reaction and Bacterial Culture for identification of bovine mastitis bacteria
Journal of Dairy Science, 2010Co-Authors: M T Koskinen, G J Wellenberg, O C Sampimon, Jani Holopainen, A Rothkamp, L Salmikivi, W A Van Haeringen, Satu PyoralaAbstract:Fast and reliable identification of the microorganisms causing mastitis is important for management of the disease and for targeting antimicrobial treatment. Methods based on PCR are being used increasingly in mastitis diagnostics. Comprehensive field comparisons of PCR and traditional milk bacteriology have not been available. The results of a PCR kit capable of detecting 11 important etiological agents of mastitis directly from milk in 4 h were compared with those of conventional Bacterial Culture (48 h). In total, 1,000 quarter milk samples were taken from cows with clinical or subclinical mastitis, or from clinically healthy quarters with low somatic cell count (SCC). Bacterial Culture identified udder pathogens in 600/780 (77%) of the clinical samples, whereas PCR identified bacteria in 691/780 (89%) of the clinical samples. The PCR analysis detected major pathogens in a large number of clinical samples that were negative for the species in Culture. These included 53 samples positive for Staphylococcus aureus by PCR, but negative by Culture. A total of 137 samples from clinical mastitis, 5 samples from subclinical mastitis, and 1 sample from a healthy quarter were positive for 3 or more Bacterial species in PCR, whereas Culture identified 3 or more species in 60 samples from clinical mastitis. Culture identified a species not targeted by the PCR test in 44 samples from clinical mastitis and in 9 samples from subclinical mastitis. Low SCC samples provided a small number of positive results both in Culture (4/93; 4.3%) and by PCR (7/93; 7.5%). In conclusion, the PCR kit provided several benefits over conventional Culture, including speed, automated interpretation of results, and increased sensitivity. This kit holds much promise as a tool to complement traditional methods in identification of pathogens. In conventional mastitis bacteriology, a sample with 3 or more species is considered contaminated, and resampling of the cow is recommended. Further study is required to investigate how high sensitivity of PCR and its quantitative features can be applied to improve separation of relevant udder pathogens from likely contaminants in samples where multiple species are detected. Furthermore, increasing the number of species targeted by the PCR test would be advantageous.
Jan Gerritse - One of the best experts on this subject based on the ideXlab platform.
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Ethyl tert-butyl ether (EtBE) degradation by an algal-Bacterial Culture obtained from contaminated groundwater
Water Research, 2019Co-Authors: Marcelle J. Van Der Waals, Caroline Plugge, Marion Meima-franke, Pieter De Waard, Paul L.e. Bodelier, Hauke Smidt, Jan GerritseAbstract:EtBE is a fuel oxygenate that is synthesized from (bio)ethanol and fossil-based isobutylene, and replaces the fossil-based MtBE. Biodegradation of EtBE to harmless metabolites or end products can reduce the environmental and human health risks after accidental release. In this study, an algal-Bacterial Culture enriched from contaminated groundwater was used to (i) assess the potential for EtBE degradation, (ii) resolve the EtBE degradation pathway and (iii) characterize the phylogenetic composition of the Bacterial community involved in EtBE degradation in contaminated groundwater. In an unamended microcosm, algal growth was observed after eight weeks when exposed to a day-night light cycle. In the fed-batch reactor, oxygen produced by the algae Scenedesmus and Chlorella was used by bacteria to degrade 50 μM EtBE replenishments with a cumulative total of 1250 μM in a day/night cycle (650 lux), over a period of 913 days. The microbial community in the fed-batch reactor degraded EtBE, using a P450 monooxygenase and 2-hydroxyisobutyryl-CoA mutase, to tert-butyl alcohol (TBA), ethanol and CO2 as determined using 13C nuclear magnetic resonance spectroscopy (NMR) and gas chromatography. Stable isotope probing (SIP) with 13C6 labeled EtBE in a fed-batch vessel showed no significant difference in community profiles of the 13C and 12C enriched DNA fractions, with representatives of the families Halomonadaceae, Shewanellaceae, Rhodocyclaceae, Oxalobacteraceae, Comamonadaceae, Sphingomonadaceae, Hyphomicrobiaceae, Candidatus Moranbacteria, Omnitrophica, Anaerolineaceae, Nocardiaceae, and Blastocatellaceae. This is the first study describing micro-oxic degradation of EtBE by an algal-Bacterial Culture. This algal-Bacterial Culture has advantages compared with conventional aerobic treatments: (i) a lower risk of EtBE evaporation and (ii) no need for external oxygen supply in the presence of light. This study provides novel leads towards future possibilities to implement algal-Bacterial consortia in field-scale groundwater or wastewater treatment.
Robert J Steffan - One of the best experts on this subject based on the ideXlab platform.
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biodegradation of methyl tert butyl ether by a pure Bacterial Culture
Applied and Environmental Microbiology, 2001Co-Authors: Paul B Hatzinger, Kevin Mcclay, Simon Vainberg, Marina Tugusheva, Charles W Condee, Robert J SteffanAbstract:Methyl tert-butyl ether (MTBE) has been used as a gasoline additive since the late 1970s to replace lead and other toxic chemicals and as an oxygenate to meet the vehicle emissions requirements of the 1990 Clean Air Act Amendments (21). Reformulated gasoline presently contains approximately 11% (vol/vol) MTBE. The widespread use of MTBE in gasoline has led to accidental spills and its discharge into soils and groundwater. Because it is highly soluble in water (∼43,000 ppm) and has a low tendency to adsorb to soils, it moves rapidly in groundwater (25) and is now often found in groundwater near service stations, fuel storage facilities, and filling terminals throughout the United States. As little as 4 liters of reformulated gasoline can contaminate >106 liters of groundwater to above its odor and taste threshold of 40 μg/liter. The full extent of MTBE contamination in groundwater in the United States has only recently been under careful assessment. A study performed as part of the U.S. Geological Survey's National Water-Quality Assessment Program revealed that MTBE is the second most commonly detected contaminant in urban groundwater (26). As an example of how widespread this problem has become, Buscheck et al. (5) reviewed groundwater monitoring data from 700 service station sites in the United States and observed that >80% of the active sites and 74% of the inactive sites had MTBE contamination. Approximately 96, 98, and 86% of the service station sites in Texas, Maryland, and California, respectively, where groundwater was analyzed for MTBE had significant MTBE contamination. Of these sites, 63, 82, and 47%, respectively, had MTBE concentrations greater than 1 mg/liter. This widespread contamination has led to increased public and regulatory scrutiny and a need to identify cost-effective remediation technologies. Relatively little work has been done to address the biodegradability of MTBE. In an early study, an aerobic consortium isolated from acclimated sludge was maintained on MTBE as a sole source of carbon (23). MTBE was degraded to tert-butyl alcohol (TBA), which was also degraded by the enrichment Culture. This Culture has been the focus of a bioremediation demonstration where it was injected directly into an MTBE-contaminated aquifer at the Port Hueneme Naval Station in California (24). MTBE biodegradation has been reported in sewage sludge (20), soils (33), river sediments (3, 4), and a biofilter inoculated with groundwater (7, 8), although the responsible bacteria were not isolated or characterized. At least partial MTBE degradation has been observed in a few pure Cultures of bacteria (9, 14, 15, 16, 17, 28) and fungi (12), and recent studies demonstrated growth of a pure Culture (strain PM1) on MTBE as the sole carbon source (6, 11). Anaerobic degradation of MTBE has been observed in one aquifer (32), but it was not shown in anaerobic samples from several other sites (18, 30). We previously reported that MTBE is mineralized by propane-oxidizing bacteria and proposed a pathway for MTBE degradation (28). Our initial studies suggested that MTBE is first oxidized to TBA, but more recent studies have demonstrated that the first oxidation product may be tert-butyl formate (16). TBA is subsequently degraded by the strains through the intermediate 2-hydroxy isobutyric acid (HIBA), which accumulates in the Culture media. HIBA is not an effective growth substrate for the propane-oxidizing bacteria studied, but it is eventually metabolized to CO2 by the strains. We recently isolated and described a new MTBE-degrading organism, Hydrogenophaga flava strain ENV735, which grows slowly on MTBE but can be grown rapidly on other substrates for research and bioremediation applications (29). In this report, we evaluate MTBE and TBA degradation by strain ENV735 more closely and attempt to identify factors that could account for the persistence of MTBE in the environment. The results of the study suggest that MTBE and TBA are oxidized by separate enzyme systems in this strain.
H L Wisniewski - One of the best experts on this subject based on the ideXlab platform.
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isolation of a Bacterial Culture that degrades methyl t butyl ether
Applied and Environmental Microbiology, 1994Co-Authors: Joseph P Salanitro, L A Diaz, M P Williams, H L WisniewskiAbstract:We have isolated a mixed Bacterial Culture (BC-1) which is capable of degrading the gasoline oxygenate methyl t-butyl ether (MTBE). BC-1 was developed from seed microorganisms present in a chemical plant biotreater sludge. This enrichment Culture has been maintained in continuous Culture treating high concentrations of MTBE (120 to 200 mg/liter) as the sole carbon source in a simple feed containing NH4+, PO43-, Mg2+, and Ca2+ nutrients. The unit had a stable MTBE removal rate when maintained with a long cell retention time (ca. 80 to 90 days); however, when operated at a ≤50-day cell waste rate, loss of MTBE-degrading activity was observed. The following three noteworthy experimental data show that MTBE is biodegraded extensively by BC-1: (i) the continuous (oxygen-sparged) Culture was able to sustain a population of autotrophic ammonia-oxidizing bacteria which could nitrify influent NH4+ concentrations at high rates and obtain CO2 (sole carbon source for growth) from the metabolism of the alkyl ether, (ii) BC-1 metabolized radiolabeled either (14CH3O-MTBE) to 14CO2 (40%) and 14C-labeled cells (40%), and (iii) cell suspensions of the Culture were capable of degrading (substrate depletion experiments) MTBE to t-butyl alcohol, a primary metabolite of MTBE. BC-1 is a mixed Culture containing several Bacterial species and is the first Culture of its kind which can completely degrade an alkyl ether.
