The pursuit of good microbiological conditions in domestic softeners: a new improvement.

Effective resin disinfection is mandatory to ensure the microbiological quality of water treated by domestic softeners. The wet and sometimes warm environment inside the softener is ideal for bacteria growth. Our research was focused on the evaluation of the microbial quality of water from softeners sanitized by chlorine solutions or by electrolytic systems. We employed the heterotrophic plate count and specific tests to monitor the presence of opportunistic and pathogenic bacteria (Pseudomonas aeruginosa, Escherichia coli, enterococci, and coliforms). Completely new devices were equipped with a commercially available electrolytic system or with a newly patented one or sanitized by automatic or manual addition of chlorine solutions. In all cases, the contamination was reduced, not completely avoided. In particular, the patented electrolytic system significantly reduced bacterial proliferation in strongly contaminated devices. Our data confirm the difficulties encountered to solve the problem of microbiological quality of softened water and offer encouraging information on new possible solutions.

The management and exploitation of naturally light-emitting bacteria as a flexible analytical tool: A tutorial.

Conventional detection of toxic contaminants on surfaces, in food, and in the environment takes time. Current analytical approaches to chemical detection can be of limited utility due to long detection times, high costs, and the need for a laboratory and trained personnel. A non-specific but easy, rapid, and inexpensive screening test can be useful to quickly classify a specimen as toxic or non toxic, so prompt appropriate measures can be taken, exactly where required. The bioluminescent bacteria-based tests meet all these characteristics. Bioluminescence methods are extremely attractive because of their high sensitivity, speed, ease of implementation, and statistical significance. They are usually sensitive enough to detect the majority of pollutants toxic to humans and mammals. This tutorial provides practical guidelines for isolating, cultivating, and exploiting marine bioluminescent bacteria as a simple and versatile analytical tool. Although mostly applied for aqueous phase sample and organic extracts, the test can also be conducted directly on soil and sediment samples so as to reflect the true toxicity due to the bioavailability fraction. Because tests can be performed with freeze-dried cell preparations, they could make a major contribution to field screening activity. They can be easily conducted in a mobile environmental laboratory and may be adaptable to miniaturized field instruments and field test kits.

Trace analysis of pollutants by use of honeybees, immunoassays, and chemiluminescence detection.

Specific and sensitive analysis to reveal and monitor the wide variety of chemical contaminants polluting all environment compartments, feed, and food is urgently required because of the increasing attention devoted to the environment and health protection. Our research group has been involved in monitoring the presence and distribution of agrochemicals by monitoring beehives distributed throughout the area studied. Honeybees have been used both as biosensors, because the pesticides affect their viability, and as "contaminant collectors" for all environmental pollutants. We focused our research on the development of analytical procedures able to reveal and quantify pesticides in different samples but with a special attention to the complex honeybee matrix. Specific extraction and purification procedures have been developed and some are still under optimization. The analytes of interest were determined by gas or liquid chromatographic methods and by compound-specific or group-specific immunoassays in the ELISA format, the analytical performance of which was improved by introducing luminescence detection. The range of chemiluminescent immunoassays developed was extended to include the determination of completely different pollutants, for example explosives, volatile organic compounds (including benzene, toluene, ethylbenzene, xylenes), and components of plastics, for example bisphenol A. An easier and portable format, a lateral flow immunoassay (LFIA) was added to the ELISA format to increase application flexibility in these assays. Aspects of the novelty, the specific characteristics, the analytical performance, and possible future development of the different chromatographic and immunological methods are described and discussed.

A quantitative chemiluminescent assay for analysis of peroxide-based explosives.

A quantitative chemiluminescent method, enabling indirect identification of the peroxide-based explosives TATP (triacetone triperoxide) and HMTD (hexamethylene triperoxide diamine) has been developed. Treatment of these compounds with acidic solutions produced peroxides, which were transformed into radical derivatives by horseradish peroxidase (HRP) and then quantified by measuring the light emitted during their oxidation of luminol. The method was first developed in the microplate format and later optimized for a portable luminometer, to enable rapid application of the assay directly on site. When the portable luminometer was used each analysis took only 5-10 min. The method had good selectivity, sensitivity, and reproducibility; in the microplate format the limits of detection (LOD) and quantification (LOQ) were 40 and 50 ng mL(-1), respectively, for both TATP and HMTD. When the portable luminometer was used the LOD and LOQ were 50 and 100 ng mL(-1), respectively, for both compounds. Introduction of light emission-enhancing compounds did not improve the analytical performance of the assay. Imprecision (CV values) was always below 10%. Recovery varied rapidly with time, with an average value of 78% after 5 min. No false-positive result was detected on measurement of a variety of samples; this is an important feature for analysis on site. The method was applied both to contaminated materials and to fortified soil samples, simulating operational conditions.

Trace metals in arcid clam Scapharca inaequivalvis: effects of molluscan extracts on bioluminescent bacteria.

The relationship between a supposed effect of molluscan extracts on bioluminescent bacteria and metal concentrations in the extracts was investigated. For this purpose a biotoxicological assay based on bioluminescent bacteria (BLB) and extracts from metal exposed molluscs, Scapharca inaequivalvis, was optimized to monitor Cd and Cu marine pollution. Cu and Cd concentrations increased in tissues of experimentally exposed molluscs. Molluscan extracts inhibited the bacterial luminescence, the inhibition decreasing as the time of mollusc exposure to metals increased, suggesting a reduction of the "bioactive" metals. In regard to the use of BLB test in environmental monitoring, the analysis of Cu, Cd, and metallothionein (MT) was first performed in tissues from molluscs collected in three different areas of Northern Adriatic Sea. Metal concentrations reached maximum values in the gills, while Cd was mostly bound to MT in the kidney. Significant differences in metals and MT concentrations were found depending on the sampling sites. The biotoxicological assay resulted slightly correlated with the biochemical parameters.

Bioluminescent bacteria assay of veterinary drugs in excreta of food-producing animals.

The residues of pharmacological treatments on food-producing animals, present in the manure dispersed on agricultural land, can impact environmental and human health through toxic, genotoxic, and drug-resistance development effects. Biotoxicity assays can easily reveal the presence of noxious substances and those based on bioluminescent bacteria (BLB) are particularly simple and rapid. A BLB assay was developed as microplate format by using various strains of Vibrio sp. and was employed to evaluate their response to pure antibiotic solutions and to residues extracted from excreta of antibiotic treated pigs and turkeys. The residues were quantified by HPLC analysis. The BLB assay can be proposed as an easy-to-perform screening tool to assess the presence of residues due to undeclared current, or recently ended, pharmacological treatments, as well as to evaluate their permanence in manure.

Automated and manual luminescent assay of antioxidant capacity: analytical features by comparison.

The analytical performances of a manual and a partially automated chemiluminescent (CL) assay, of total antioxidant capacity (TAC) were assessed. In both cases the light emitting reaction involved luminol, horseradish peroxidase and hydrogen peroxyde, but the emission kinetics and the parameters taken into account to calculate TAC values were completely different. The major characteristics expressing the quality of the two analytical methods, i.e. inaccuracy, repeteability and reproducibility, sensitivity, time required for the analysis and detection limit, were estimated by using standard solutions of Trolox. The reliability of the automated method, in comparison with the more validated manual one, was demonstrated testing food samples such as honey, wine and dietary supplements and performing a statistical analysis of the results. The comparison of the two series of data by t-test resulted in p values in the range 0.1-0.01. The time required for the analysis of each sample was reduced to one third using the automated method.