Microtitration plate most-probable-number tests for the enumeration of Escherichia coli in estuarine and marine waters

Utilization of a submersible UV fluorometer for monitoring anthropogenic inputs in the Mediterranean coastal waters

We evaluated the performances of a submersible ultraviolet fluorometer (EnviroFlu-HC, TriOS Optical Sensors) dedicated to the real time measurement of polycyclic aromatic hydrocarbons (PAHs) in the aquatic media. We conducted calibration experiments and in situ measurements in the coastal Mediterranean Sea. We found that the EnviroFlu-HC was not strictly specific to PAHs, even though it exhibited the highest sensitivity for phenanthrene, but could response to tryptophan-like material as well, and in a much less extent, to humic substances. The sensor signal showed great spatial and temporal variations in clean and polluted sites, with likely a high contribution of PAHs in the harbors, and a high contribution of tryptophan-like and humic-like materials in the sewage effluent. We conclude that the EnviroFlu-HC is a good tool for monitoring anthropogenic inputs in the coastal waters, although its utilization should be combined to other fluorescence measurements to improve the information about the nature of the aromatic compounds detected.

Geographical variation in antibiotic resistance profiles of Escherichia coli isolated from swine, poultry, beef and dairy cattle farm water retention ponds in Florida1

AIMS

The aim of this study was to assess geographical variation in multiple antibiotic resistance (MAR) profiles of livestock Escherichia coli as well as to evaluate the ability of MAR profiles to differentiate sources of faecal pollution.

METHODS AND RESULTS

More than 2000 E. coli isolates were collected from water retention ponds and manure of swine, poultry, beef and dairy farms in south, central and north Florida, and analysed for MAR using nine antibiotics. There were significant differences in antibiotic resistance of E. coli by season and livestock type for more than one antibiotic, but regional differences were significant only for ampicillin. Over the three regions, discriminant analysis using MAR profiles correctly classified 27% of swine, 49% of poultry, 56% of beef and 51% of dairy isolates.

CONCLUSIONS

Regional variations in MAR combined with moderate discrimination success suggest that MAR profiles of E. coli may only be marginally successful in identifying sources of faecal pollution.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrates the existence of regional and seasonal differences in MAR profiles as well as the limited ability of MAR profiles to discriminate among livestock sources.

Bioluminescent Most-Probable-Number Method To Enumerate lux -Marked Pseudomonas aeruginosa UG2Lr in Soil

Bioluminescence measured with a luminometer and charge-coupled device was an effective marker in most-probable-number assays for luxAB -marked Pseudomonas aeruginosa UG2Lr in soil. Most-probable-number assays with microtiter plate wells and luminometer tubes gave estimates for UG2Lr that were similar to viable colony counts. Both methods detected five cells per g of soil.