23 24Viruses are among the most important pathogens present in water contaminated with 25 feces or urine and represent a serious risk to human health. Four procedures for 26 concentrating viruses from sewage have been compared in this work, three of which 27were developed in the present study. Viruses were quantified using PCR techniques. 28According to statistical analysis and the sensitivity to detect human adenoviruses 29 (HAdV), JC polyomaviruses (JCPyV) and noroviruses genogroup II (NoV GGII), (i) a 30 new procedure (elution and skimmed-milk flocculation procedure (ESMP)) based on 31 the elution of the viruses with glycine-alkaline buffer followed by organic flocculation 32 with skimmed-milk was found to be the most efficient method when compared to (ii) 33 ultrafiltration and glycine-alkaline elution, (iii) a lyophilization-based method and (iv) 34 ultracentrifugation and glycine-alkaline elution. Through the analysis of replicate 35 sewage samples, ESMP showed reproducible results with a coefficient of variation 36 (CV) of 16% for HAdV, 12% for JCPyV and 17% for NoV GGII. Using spiked 37 samples, the viral recoveries were estimated at 30%-95% for HAdV, 55%-90% for 38JCPyV and 45%-50% for NoV GGII. ESMP was validated in a field study using 39

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E. SUÑ E N. 1998. Antimicrobial activity of seven commercial smoke preparations (four liquid and three solid) was studied. The minimum inhibitory concentration (MIC) was determined against a selection of food spoilage and pathogenic micro-organisms. The main smoke components were identified and quantified by gas chromatography/mass spectrometry. The most effective condensate was S2. All strains except Salmonella enteritidis were inhibited by S2 with an MIC ³0·5-1·5%. Smoke extract L2 inhibited growth of Vibrio vulnificus, Yersinia enterocolitica, Bacillus subtilis, Staphylococcus aureus, Listeria monocytogenes, L. inocua, Brochothrix thermosphacta and Lactococcus lactis ssp. lactis with an MIC of ³0·2-0·8%. The condensate L3 inhibited effectively V. vulnificus, B. subtilis, L. innocua and Staph. aureus. L1, L4, S1 and S3 had no inhibitory effects at levels tested against most micro-organisms. Vibrio vulnificus was the most susceptible micro-organism to test compounds. The antimicrobial activity of smoke preparations was related to the concentration of phenols.

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