Giancarlo Ranalli

COMPOSTING OF SOLID AND SLUDGE RESIDUES FROM AGRICULTURAL AND FOOD INDUSTRIES. BIOINDICATORS OF MONITORING AND COMPOST MATURITY

A study to monitor the composting process, to evaluate the effectiveness of bioindicators for the quality and maturity of cured compost obtained by a mixture of winery residues, sludges from dairies and solid residues from food processing (grape-stalks, grape-dregs, rice husks), was conducted. Composting process lasting five months was monitored by chemico-physical, spectroscopic (FTIR, DTG and DSC), microbiological and enzymatic analyses. Biological activities (ATP, DHA contents and several enzymatic activities), impedance variations (DT) of mixed cultures during growth and potential pathogens (E. coli and Salmonella sp.), were determined. The phytotoxicity tests gave a germination index higher than 90% and no significant genotoxic differences between controls and the compost samples were evidenced. Pathogens were not found on the cured compost that can therefore be satisfactorily used as amendment for agricultural crops. However, no single measurement of a composting process factor, biological, chemical or physical, gave a comprehensive view of the quality of a specific composting. We proposed a tool of bioindicators of potential activity and markers in combination for integrated evaluation of monitoring of composting process and compost quality. The responses of several enzymatic activities were positive and indicative of their favorable use capable to reveal even very small changes within microbial population and activity in test and monitoring of compost programmes.

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.

Feasibility of Removing Surface Deposits on Stone Using Biological and Chemical Remediation Methods

The study was conducted on alterations found on stone artwork and integrates microbial control and a biotechnological method for the removal of undesirable chemical substances. The Demetra and Cronos sculptures are two of 12 stone statues decorating the courtyard of the Buonconsiglio Castle in Trento (Italy). An initial inspection of the statues revealed putative black crusts and highlighted the microbial contamination causing discoloration. In 2006, the Cultural Heritage Superintendence of Trento commissioned us to study and remove these chemical and biological stains. Stereomicroscopy characterised the stone of the sculptures as oolitic limestone, and infrared analyses confirmed the presence of black crusts. To remove the black crusts, we applied a remediation treatment of sulphate-reducing bacteria, which removes the chemical alteration but preserves the original stone and the patina noble. Using traditional and biomolecular methods, we studied the putative microbial contamination and confirmed the presence of biodeteriogens and chose biocide Biotin N for the removal of the agents causing the discolouration. Denaturing gradient gel electrophoresis fluorescent in situ hybridisation established that Cyanobacteria and green algae genera were responsible for the green staining whereas the black microbial contamination was due to dematiaceous fungi. After the biocide Biotin N treatment, we applied molecular methods and demonstrated that the Cyanobacteria, and most of the green algae and dematiaceous fungi, had been efficiently removed. The reported case study reveals that conservators can benefit from an integrated biotechnological approach aimed at the biocleaning of chemical alterations and the abatement of biodeteriogens.

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).

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.

Bacterial aerosol emission from wastewater treatment plants:Culture methods and bio-molecular tools

In this report we describe the results of a studyconducted in order to better estimate airbornemicroorganisms. A method based on a bio-moleculartechnique, Polymerase Chain Reaction (PCR) wascompared with the culture methods based on the viablecounts of total and fecal bacteria. Microbial aerosolemission from the surfaces of aeration tanks of anindustrial and municipal wastewater treatment plant(Como, Italy), at different seasons, was determined.This study was accomplished by conducting test runs inwhich SAS (Surface Air Systems, PBI) viable sampler,Sartorius MD8 with membrane gelatine filter andgravity method with Petri dishes were used to collectbacterial aerosol samples in situ. Total aerobicheterothropic bacteria, Mycetes, total and fecalcoliforms were determined. The preliminary resultsshow that: no correlation was found between the twodifferent passive and active culture techniques, dueto the different mechanisms of capture of bioaerosolagents on the media; optimal values for the recoveryof E. coli viable bacteria by MD8 samplerwith gelatine membrane, time and temperature ofstorage, were recognised. For the PCR technique, acouple of primers (URL 301–URR 432) to detect E. coli, on definite air samples, was used, operativeconditions were defined, and then, applied inmonitoring on in situ bioaerosol samples. At thewastewater plant, the highest total aerobic bacteriaemission rate during the preliminary mechanicaltreatments and in correspondence of the enclosedactivated sludge phase, as a consequence of theremarkable aeration of the tanks, were registered. Thesensitivity (82 CFU/m3) and rapidity (less than 8hours) of the biomolecular methods to determine thepresence and the fecal coliforms (E. coli) ratein bioaerosols was considered satisfactory.

Composting of effluent from a new two‐phases centrifuge olive mill. microbial characterization of the compost

A study to evaluate the quality of cured compost obtained by a mixture of crude olive husks, oil mill wastewaters and fresh olive tree leaves inoculated with cow manure, after 6 months of composting, has been conducted. Biological activities (ATP, DHA, DNA contents and enzymatic activities), several microbiological groups (including pathogenic bacteria, E.coli and Salmonellae), microflora composition were determined. Phytotoxicity tests were also carried out. The composting process brought about the total disappearance of phytotoxicity encountered in raw materials. The development of enzymatic activities was positive and no pathogen was found. The compost can therefore be satisfactorily used as amendment for agricultural crops.

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).