THE CONTROL OF DELETERIOUS BIOFILM ON ABIOTIC SURFACES: FROM A MORE SUSTAINABLE USE OF BIOCIDES TO A NEW ENVIRONMENTALLY-FRIENDLY APPROACH
Tesi di Dottorato
Data di Pubblicazione:
2010
Citazione:
THE CONTROL OF DELETERIOUS BIOFILM ON ABIOTIC SURFACES: FROM A MORE SUSTAINABLE USE OF BIOCIDES TO A NEW ENVIRONMENTALLY-FRIENDLY APPROACH / A. Polo ; supervisor: Francesca Cappitelli ; coordinator: Claudia Sorlini. DIPARTIMENTO DI SCIENZE E TECNOLOGIE ALIMENTARI E MICROBIOLOGICHE, 2010 Dec 20. 23. ciclo, Anno Accademico 2010. [10.13130/polo-andrea_phd2010-12-20].
Abstract:
It is well established that bacteria are the first organisms to adhere and colonize both abiotic and biotic surfaces. Their subsequent multiplication and production of exopolymeric substances (EPS) bring to biofilm formation which is believed to influence the settlement of following colonisers starting biofouling process on surfaces. Biofilm and fouling often have a deleterious effect on colonized surfaces and materials. They explicate a complex and various range of processes on abitic surfaces that cause physical damages, chemical alterations, loss of functionality and discolouration of surfaces, generating tremendous environmental and economical harm for human society. The control of the deleterious biofilm and the following fouling is today a great challenge. Currently, we have two choices: to remove biofilm by traditional methods or to research new effective antifouling approaches.
Traditional techniques consist mainly in the application of biocides, however this practice has several disadvantages. In fact, traditional biocides are not generally specifically target against detrimental microorganisms and they are often potentially toxic both for humans and the environment. In addition, biological matter released by their use can offer a favourable substratum for subsequent colonisations. Others problems concern the development of resistance in target pest populations and the low biodegradability of these chemicals. Moreover, biocides are not always effective at low concentrations because life inside the biofilm leads to increased resistance to antimicrobial products up to 1000-fold compared to planktonic cells. Finally, current legislation in UE and USA regulates the use of biocides and lately several products have been withdrawn from the market. New antifouling strategies need to be effective, economic, safe for the public and to pose negligible risk to human health and the environment. In the last years new strategies able to control biofilm growth have been proposed as alternative to traditional active substances. However, several years will be required to set up and test satisfactory methods, so, these novel strategies can be only a long term solution. In the meantime, as short term solution, it is vital to study methods for a more sustainable use of traditional antimicrobial agents. Therefore, the aims of the PhD project here presented were:
1) to use biocides for the removal of deleterious biofilm from relevant abiotic surfaces in the most sustainable way;
2) to exploit the ability of a new promising inorganic compound, the photocatalytic titanium dioxide, as an innovative non-toxic antifouling system to control biofilm formation on abiotic surfaces.
The study reported in the chapter 3 addresses the first aim. Generally, broad-range biocides are used to remove alterative biofilms from historical and artistic surfaces. In order to obtain a use as sustainable as possible of antimicrobial agents, the strategy has been to identify alterative microorganisms so as to use a suitable biocidal product which targets specifically the biodeteriogen agents.
In this work, for the first time, an integrated biotechnological system that enables the cleaning of cultural heritage stone affected by both biological and chemical alteration process was used.
The study was conducted on alterations found on two stone sculptures decorating the courtyard of the Buonconsiglio Castle in Trento (Italy). Stone, especially if exposed to the weather, is subject to chemical, physical and aesthetical deterioration. In this regard, pollution and environmental parameters play an important role since they are most responsible of deterioration process. Samples from altered and unaltered areas were characterized using stereomicroscope, cross-section
Tipologia IRIS:
Tesi di dottorato
Keywords:
biofilm ; control ; biocide ; safe ; TiO2 ; photocatalysis ; antifouling ; bioremediation
Elenco autori:
A. Polo
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