The ability of 135 Staphylococcus strains isolated from Spanish dry-cured hams to produce enterotoxins in culture was investigated by the reversed passive latex agglutination method. A high percentage of enterotoxigenic Staphylococcus aureus strains (85.9%o) was recorded, and 54.3% of these produced enterotoxin A. One of the two Staphylococcus epidermidis strains produced enterotoxin C. The reversed passive latex agglutination method yielded satisfactory results.
The microbiological quality and heterotrophic bacterial populations of 26 thermal mineral water springs in Spain were studied. In most of the springs the number of viable aerobes was less than 10(3) cfu ml-1 and the number of sporulated bacteria less than 10(2) cfu ml-1. No significant differences were found in the counts obtained with Plate Count Agar (PCA) and PCA diluted 1:10 and incubated at 22 degrees, 37 degrees and 45 degrees C. Total coliforms were found in 14 springs, faecal streptococci in three, spores of sulphite-reducing Clostridium and Pseudomonas aeruginosa in seven. Neither Escherichia coli nor Staphylococcus aureus were found. A total of 665 strains were isolated and 85.4% of these identified; 329 were Gram-positive and 239 were Gram-negative. The genera most prevalent present in the springs were Pseudomonas (in 92.3%), Bacillus (65.4%), Enterobacter, Micrococcus and Staphylococcus (50%), Acinetobacter (42.3%), Arthrobacter (38.4%), Clostridium (27%) and Xanthomonas (23%). Gram-negative bacteria predominated in the mesothermal springs and Gram-positive bacteria in the hyper- and hypothermal springs. The most common Gram-negative rod species isolated were Ps. fluorescens, Ps. aeruginosa, Ps. putida, Ent. agglomerans, Ent. sakazakii, Ac. calcoaceticus and Ent. amnigenus.
This work assesses the main sources of uncertainty of the determination of several secondary organic aerosol (SOA) components. The evaluation of the uncertainty associated with analytical methods is essential in order to demonstrate that the results obtained in routine analysis are reliable. The current work has thoroughly evaluated the sources of uncertainties associated with the analytical method employed to quantify the SOA produced from photo-oxidation of complex mixtures of volatile organic compounds (VOCs) in smog chambers. Measurement uncertainties were calculated by applying a bottom-up approach. The combined uncertainty of the analytical method ranged from 8% for glyoxal to 29% for methyl benzoquinone. The results clearly show that the determination of some SOA compounds is associated with a high level of uncertainty, and thus the quantification process for these at lower levels remains challenging.
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