Food borne yeasts as DNA-bioprotective agents against model genotoxins.

Yeasts isolated from Italian beverages and foods (wine and cheeses) were identified as Saccharomyces cerevisiae and Debaryomyces hansenii by sequencing the D1/D2 domain of the 26S rRNA gene and differentiated, at strain level, by microsatellite PCR fingerprinting and RAPD-PCR. All the strains showed antioxidant activity, as demonstrated by their ability to scavenge the free radical diphenyl-1-picrylhydrazyl (DPPH). Furthermore, tested strains revealed high in vitro inhibitory activity against two model genotoxins, 4-nitroquinoline-1-oxide (4-NQO) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), as showed by short-term methods with different target cells: SOS-Chromotest with Escherichia coli PQ37 and Comet assay with HT-29 enterocytes.

Raw milk traditional Italian ewe cheeses as a source of Lactobacillus casei strains with acid-bile resistance and antigenotoxic properties.

Twenty-five Lactobacillus casei group strains isolated from ewe cheeses from Abruzzo region, central Italy, were identified by 16S rRNA gene sequencing, differentiated by RAPD-PCR analysis and characterized as in vitro for acid-bile tolerance and antigenotoxic properties. All the strains were very susceptible to simulated gastric fluid (pH 2.0) but most of them recovered viability (ca.

Integrating monitoring networks to obtain estimates of ground-level ozone concentrations --a proof of concept in Tuscany (central Italy).

Prior to 2000 a network of conventional ozone (O3) analysers existed in the Province of Firenze (Tuscany, central Italy). Between 2000 and 2004 the network was extended to incorporate a newly designed bioindicator network of tobacco plants (Nicotiana tabacum Bel W3). The objective was to set-up an integrated monitoring system to obtain estimates of ground-level O3 concentrations over the whole study area (3513 km2) in order to fill data gaps and cover reporting requirements.

Modulatory activity of a Lactobacillus casei strain on 1,2-dimethylhydrazine-induced genotoxicity in rats.

The present study was designed to investigate the putative antigenotoxic effects of supplementing the diet of rats treated with the colon carcinogen 1,2-dimethylhydrazine hydrochloride (DMH) with a Lactobacillus casei strain using an in vivo approach. The antigenotoxic response was evaluated in colon and liver cells using the alkaline comet assay. Since the balance between the bioactivation and detoxification metabolic pathways is crucial for the formation of toxic and genotoxic metabolites, alterations in the level of some xenobiotic metabolizing enzymes (XME) were studied in liver preparations.

In vitro inhibitory activity of probiotic spore-forming bacilli against genotoxins.

Aims: To investigate the ability of bacilli of various species (Bacillus clausii, Bacillus subtilis, Bacillus lentus, Bacillus pumilus. Bacillus megaterium, Bacillus firmus, Bacillus sp.) and origins (probiotic and collection strains) to counteract the activity of some representative DNA-reactive agents.

Evidence for in vitro anti-genotoxicity of cheese non-starter lactobacilli.

The inhibition of direct acting DNA reactive agents by 63 non-starter lactobacilli isolated from raw ewes milk cheeses was examined by short-term assay (SOS-Chromotest) and compared with already characterized starter lactobacilli. The screening revealed strains active against the nitroarene 4-nitroquinoline-1-oxide (NQO) and the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in different species of the genus Lactobacillus (L. rhamnosus, L.

Tolerance to challenges miming gastrointestinal transit by spores and vegetative cells of Bacillus clausii.

Aims: To study Bacillus clausii from a pharmaceutical product (Enterogermina O/C, N/R, SIN, T) and reference strains (B. clausii and Bacillus subtilis) for eco-physiological aspects regarding the gut environment.

Methods And Results: Spores and vegetative cells were challenged in vitro miming the injury of gastrointestinal transit: pH variations, exposure to conjugated and free bile salts, microaerophilic and anaerobic growth.

Screening of potential lactobacilli antigenotoxicity by microbial and mammalian cell-based tests.

Antigenotoxicity is considered an important property for probiotic lactobacilli. The ability of non probiotic lactobacilli from dairy products and starters to inhibit two reference genotoxins: 4-nitroquinoline-1-oxide and N-methyl-N'-nitro-N-nitrosoguanidine was evaluated. The study was carried out using short-term assays with different targets, such as procaryotic cells (SOS-Chromotest for genotoxicity in Escherichia coli and Ames test for mutagenicity in Salmonella typhimurium) and eucaryotic cells (Comet assay for genotoxicity in Caco-2 enterocytes).

Lactic acid bacteria isolated from dairy products inhibit genotoxic effect of 4-nitroquinoline-1-oxide in SOS-chromotest.

Antigenotoxic activity against 4-nitroquinoline-1-oxide (4-NQO) of lactic acid bacteria isolated from commercial dairy products was studied using SOS-Chromotest. The supernatants from bacteria-genotoxin co-incubations in general exhibited a strong suppression on SOS-induction produced by 4-NQO on the tester organism Escherichia coli PQ37 (sfiA::lacZ). High genotoxicity inhibition (>75%) was found for 31/67 of the examined bacteria and the maximum values of some strains within the species were as follows: Lactobacillus casei, 99.

Inhibition of 4-nitroquinoline-1-oxide genotoxicity by Bacillus strains.

The effect of 16 Bacillus strains from pharmaceutical probiotic preparations (Bacillus spp.) and collection (B. subtilis, B.

[A new conservative approach in the treatment of postoperative digestive-tract fistulas. Mechanical closure by a balloon-catheter].

Background: Digestive fistulas represent troublesome complication in patients operated in modern surgical wards where the improved surgical procedures and better intensive care enhance the surgeon to perform more aggressive approaches with a high surgical risk index. The management of a patient presenting a digestive-tract fistula is never easy, being its approach either conservative (TPN) or surgical. We applied an alternative surgical procedure consisting in a mechanical closure of the fistula using a balloon-catheter so as to improve outcome in those patients in whom medical tratment did not show satisfactory RESULTS.

Bacterial amylolytic activity enhances beta-glucuronidase expression of amylase-negative Escherichia coli strain in starch-medium.

The possibility of associating starch degradation with bacterial beta-glucuronidase expression was examined. We proved that starving, in starch medium, amylase-negative Escherichia coli (M94) which has constitutive beta-glucuronidase greatly reduces (p < 0.01) its background activity, but the addition of both cell-free supernatants or cells of Bacillus subtilis (B10) producing amylase greatly increases (p < 0.

Implications of alpha-amylase production and beta-glucuronidase expression in Escherichia coli strains.

Two Escherichia coli strains in which alpha-amylase production differed were used to study in depth some characteristics related to beta-glucuronidase induction by starch. The beta-glucuronidase background activity in Luria broth medium was comparable for the two isolates, but only amylase positive S1 was able to grow on starch molecules supplied as the sole carbon source. In this case growth resulted at higher beta-glucuronidase levels (p < 0.

Effect of different starches on Escherichia coli (S1) beta-glucuronidase expression.

Studies with pure cultures growing in laboratory media indicated that beta-glucuronidase expression of Escherichia coli S1 was considerably affected by starch added to the medium as the only carbon source. This result, which may be an aspecific modulation of enzyme expression, was independent of the starch molecular structure and effects were analogous for maize, rice, wheat or potato starches. It was observed that enzyme expression was little affected by the growth rate.

High Prevalence of Vibrio cholerae Non-O1 Carrying Heat-Stable-Enterotoxin-Encoding Genes among Vibrio Isolates from a Temperate-Climate River Basin of Central Italy.

Vibrio spp. of clinical interest from the Arno River basin (Tuscany, Italy) were investigated in this study. Vibrios were isolated from 70% of water samples.

Carbohydrate enriched diets and bacterial glycosidases in rat faeces.

The expression of some faecal hydrolytic enzymes in rats fed for 4 months on sucrose or starch enriched diets was compared with a standard diet. The assay reliability was confirmed for animal and experimental variability. The beta-D-glucuronidase and beta-D-glucosidase activities were always higher in rats fed on starch than on other diets.

Comparison of fluorogenic and conventional membrane filter media for enumerating coliform bacteria.

4-Methylumbelliferyl-beta-D-galactoside and 4-methylumbelliferyl-beta-D-glucuronide were added to MacConkey broth and their diagnostic powers for total coliforms (TC) and Escherichia coli, respectively, were tested by membrane filtration at primary isolation. Examining water samples from different sources proved the usefulness of fluorogenic rather than reference media both as regards recovery efficiency and rapidity (possible within 12 h) of analyses. The recoveries obtained by fluorogenic and conventional tests for both TC and E.

beta-N-acetylhexosaminidases from Serratia marcescens.

Two forms of beta-N-acetylhexosaminidase from Serratia marcescens with an optimum pH of 5.0 and 6.5, respectively, to 4-methylumbelliferyl-2-acetamido-2-deoxy-beta-D-glucopyranoside were separated by DEAE-cellulose chromatography and Sephacryl S-200 chromatography.

Fluorogenic detection of atypical coliforms from water samples.

We examined the effectiveness of fluorogen in detecting bacterial enzymes in atypical or injured coliform strains in environmental water samples. 4-methylumbelliferyl-beta-D-galactoside and 4-methylumbelliferyl-beta-D-glucuronide, substrates for beta-galactosidase and beta-glucuronidase respectively, were used as markers for total and faecal coliform bacteria and it was confirmed that fluorogenic assays have a greater sensitivity than reference methods. It was also observed that adding MU-conjugates (50 micrograms/ml) to low selective media for membrane filtration, besides shortening test times, reduces false negative results when detecting sanitary microbial indicators of water pollution.

[Development of antibiotic resistance in purified sewage effluents subjected to chlorination].

Antibiotic-resistance is widely spread phenomenon in the environment because of uncontrolled discharge of urban and animal wastewaters. Sewage treatment can significantly reduce the number of both sensitive and resistant bacteria. A reduction of about 1.

The effect of anaerobic and aerobic wastewater treatment on faecal coliforms and antibiotic-resistant faecal coliforms.

The efficiency of anaerobic treatment of animal wastes and aerobic treatment of urban sewage in removing faecal coliforms and their effect on the antibiotic-resistant coliforms was evaluated in this study. A two reactor anaerobic digester and six activated sludge plants were studied. The concentrations of both faecal coliforms in sampling from influents and treated effluents were calculated to determine efficiency of plants during depuration treatments.

[Submerged-phase gel electrophoresis in the analysis of plasmids for epidemiologic purposes].

The validity of the submarine agarose gel electrophoresis as routine method for plasmidic epidemiology was considered. Using standard plasmids, the efficiency of a performed protocol conditions (5 V/cm for 3 hours, 0.8% agarose) in screening plasmids of different size was studied.

Resistotype heterogeneity of Escherichia coli strains isolated from humans, animals and sewage waters.

The tests commonly used for bacterial identification, especially in the field of microbial environmental analyses frequently do not provide a sufficient strain differentiation. Considering the importance that accurate characterization of bacterial pollution indicators could have as epidemiological tools, this study used a resistogram subtyping method for Escherichia coli as a tentative method of effecting a good monitoring of the environmental spread of this microorganism. The resistance of 313 E.

Relationship between environment spread and presence in hosts of Escherichia coli strains resistant to antibiotics and metals.

The antibiotic and metal resistance percentages of 315 E. coli strains, isolated from: a sample population not-exposed to antibiotics, hospitalized inpatients and from bred animals, were compared with the resistance percentages of 217 environmental isolates (sewage and river isolates). The highest levels of resistance and multiresistance were found for clinical and river isolates.