E. Zanardini

Comparison of Different Primer Sets for Use in Automated Ribosomal Intergenic Spacer Analysis of Complex Bacterial Communities

ABSTRACT ITSF and ITSReub, constituting a new primer set designed for the amplification of the 16S-23S rRNA intergenic transcribed spacers, have been compared with primer sets consisting of 1406F and 23Sr (M. M. Fisher and E. W. Triplett, Appl. Environ. Microbiol. 65:4630-4636, 1999) and S-D-Bact-1522-b-S-20 and L-D-Bact-132-a-A-18 (L. Ranjard et al., Appl. Environ. Microbiol. 67:4479-4487, 2001), previously proposed for automated ribosomal intergenic spacer analysis (ARISA) of complex bacterial communities. An agricultural soil and a polluted soil, maize silage, goat milk, a small marble sample from the façade of the Certosa of Pavia (Pavia, Italy), and brine from a deep hypersaline anoxic basin in the Mediterranean Sea were analyzed with the three primer sets. The number of peaks in the ARISA profiles, the range of peak size (width of the profile), and the reproducibility of results were used as indices to evaluate the efficiency of the three primer sets. The overall data showed that ITSF and ITSReub generated the most informative (in term of peak number) and reproducible profiles and yielded a wider range of spacer sizes (134 to 1,387) than the other primer sets, which were limited in detecting long fragments. The minimum amount of DNA template and sensitivity in detection of minor DNA populations were evaluated with artificial mixtures of defined bacterial species. ITSF and ITSReub amplified all the bacteria at DNA template concentrations from 280 to 0.14 ng μl−1, while the other primer sets failed to detect the spacers of one or more bacterial strains. Although the primer set consisting of ITSF and ITSReub and that of S-D-Bact-1522-b-S-20 and L-D-Bact-132-a-A-18 showed similar sensitivities for the DNA of Allorhizobium undicula mixed with the DNA of other species, the S-D-Bact-1522-b-S-20 and L-D-Bact-132-a-A-18 primer set failed to detect the DNA of Pseudomonas stutzeri.

Biotechnology applied to cultural heritage: biorestoration of frescoes using viable bacterial cells and enzymes

Aims:  To set up and employ, for the biorestoration of cultural heritage (altered frescoes), an advanced and innovative biotechnology method based on the sequential use of whole viable bacterial cells and specific enzymes.

Advantages of Using Microbial Technology over Traditional Chemical Technology in Removal of Black Crusts from Stone Surfaces of Historical Monuments

ABSTRACT This study compares two cleaning methods, one involving an ammonium carbonate-EDTA mixture and the other involving the sulfate-reducing bacterium Desulfovibrio vulgaris subsp. vulgaris ATCC 29579, for the removal of black crust (containing gypsum) on marble of the Milan Cathedral (Italy). In contrast to the chemical cleaning method, the biological procedure resulted in more homogeneous removal of the surface deposits and preserved the patina noble under the black crust. Whereas both of the treatments converted gypsum to calcite, allowing consolidation, the chemical treatment also formed undesirable sodium sulfate.

Improved Methodology for Bioremoval of Black Crusts on Historical Stone Artworks by Use of Sulfate-Reducing Bacteria

ABSTRACT An improved methodology to remove black crusts from stone by using Desulfovibrio vulgaris subsp. vulgaris ATCC 29579, a sulfate-reducing bacterium, is presented. The strain removed 98% of the sulfates of the crust in a 45-h treatment. Precipitation of black iron sulfide was avoided using filtration of a medium devoid of iron. Among three cell carriers, Carbogel proved to be superior to both sepiolite and Hydrobiogel-97, as it allowed an easy application of the bacteria, kept the system in a state where microbial activity was maintained, and allowed easy removal of the cells after the treatment.

Biodegradation of Chlorsulfuron and Metsulfuron‐Methyl by Aspergillus niger in Laboratory Conditions

Two sulfonylurea herbicides, chlorsulfuron and metsulfuron‐methyl, were studied under laboratory conditions, in order to elucidate the biodegradation pathway operated by Aspergillus niger, a common soil fungus, which is often involved in the degradation of xenobiotics. HPLC‐UV was used to study the kinetic of degradation, whereas LC‐MS was used to identify the metabolites structure. In order to avoid the chemical degradation induced by a decrease in pH, due to the production of citric acid by the fungus, the experiments were performed in a buffered neutral medium. No significant degradation for both compounds was observed in mineral medium with 0.2% sodium acetate. On the contrary, in a rich medium, after 28 days the degradations, chemical degradation excluded, were about 30% for chlorsulfuron and 33% for metsulfuron‐methyl. The main microbial metabolites were obtained via cleavage of the sulfonylurea bridge. In addition the fungus seems to be able to hydroxylate the aromatic ring of chlorsulfuron. In the case of metsulfuron‐methyl the only detected metabolite was the triazine derivative, while the aromatic portion was completely degraded. Finally, the demethylation of the methoxy group on the triazine ring, previously observed with a Pseudomonas fluorescens strain, was not observed with A. niger.

THE USE OF MICROORGANISMS FOR THE REMOVAL OF SULPHATES ON ARTISTIC STONEWORKS

Abstract One of the most important causes of decay of calcareous stones is due to the conversion of calcium carbonate into calcium sulphate (gypsum). In order to optimise a strategy for the removal of the sulphates from artistic stoneworks, a procedure based on the use of sulphate-reducing bacteria, has been established. Different strains of Desulfovibrio in pure and mixed cultures were tested in batch to verify their sulphate-reducing potentiality. The biomasses of the selected strains, D. desulfuricans 1 and D. vulgaris, were applied under anaerobic conditions to the sample surfaces directly and after adhesion to sepiolite used as a substratum. Stone samples artificially enriched with sulphates and real fragments of a marble column and a marble statue were treated. The results obtained show that sulphate removal was more effective on real samples than on artificially enriched samples and in the both cases when the treatment was performed using sepiolite as substratum. The best result was obtained on the statue fragment with 81% sulphate removal after 36 h (against 20% for control).

Influence of atmospheric pollutants on the biodeterioration of stone

Abstract Studies have been carried out on specimens of Saltrio stone, Carrara and Candoglia marbles, exposed for some years to the polluted atmosphere of Milan. The test specimens, which were directly exposed to the washing away, showed alterations in the form of grey-black stains which were different in dimensions and quantity according to the stone material, while those sheltered showed only a uniform grey deposit of particulate matter. The decay on the exposed specimens has been tested by gravimetric analyses and scanning electron microscopy (SEM) observations. Microbiological investigations evidenced that microorganisms, either chemoautotrophic or photosynthetic, were not present in any sample. On the washed out test specimens, the presence of heterotrophic bacteria was considerable, while the sheltered specimens showed negligible values. Chemical analysis, carried out through gas chromatography–mass spectrometry (GC/MS), of the particulate deposited on the test specimens, evidenced the presence of a wide range of aromatic and aliphatic hydrocarbons and fatty acids. Cultural tests of mixed cultures and isolated strains were carried out by using a mineral medium added with 14 organic compounds, typical representatives of atmospheric pollution, as a sole source of carbon and energy. The results evidenced that the mixed cultures in particular, as well as some of the isolated strains, are capable of using many of the tested molecules (fatty acid, aliphatic compounds, p-xylene).

Effects of low electric current (LEC) treatment on pure bacterial cultures

Aims: This research focused on the effects of low electric current (LEC) on the cell viability and metabolic activity of Escherichia coli and Bacillus cereus.

The microbial degradation of azimsulfuron and its effect on the soil bacterial community

Aims:  Azimsulfuron is a recently introduced sulfonylurea herbicide useful in controlling weeds in paddy fields. To date very little information is available on the biodegradation of this pesticide and on its effect on the soil microbial community. The aim of this work was to study its biodegradation both in slurry soil microcosms and in batch tests with mixed and pure cultures.

Effects of low electric treatment on yeast microflora

Aims: To contribute to the understanding of phenomena related to different intensity electric current treatments on the growth and metabolism of selected micro‐organisms using laboratory samples of pure and co‐cultures (Saccharomyces cerevisiae strain 404 and Hanseniaspora guilliermondii strain 465).