Our projects aims on eliminating bioerosion occurred on marbles using a natural way to kill the microorganisms that inhibit the marble.
Compared to other inorganic materials , rock surfaces are easy to be colonized by microorganisms. The mere presence of microorganisms in/on the rock doesn’t necessarily indicate decay. In fact the process of biodeterioration starts when combining the presence of microorganisms with other factors like chemical, physical and or environmental factors that have an impact (positive or negative) on the growth of microbiota.
The classification of microorganisms is based on their localisation and distribution on and/or within the substrate so we have
Epilithobionts
Endolithobionts (Fig.1)
1. Chasmolithic microorganisms
(living in pre-existing fissures or cracks)
2. Euendolithic
(boring actively into the substrate)
3. Cryptoendolithic
(developing beneath the surface)
It was reported that areas that are more exposed to the sun are more susceptible to biocorrosion than other surfaces that are in sheltered areas. The forms of corrosion that are created there have different patterns like channels, pitting and decay at single calcite crystal level. In these cases even if precipitation of mineral phases occurs, incoherent material is easily removed from the surface
Our project aims on using an antimicrobial peptide isolated from horseshoe crab hemocytes, Tachyplesin I aiming on the microbiota living on the marbles
Antimicrobial peptides are an abundant and diverse group of molecules that are produced by many tissues and cell types in a variety of invertebrate, plant and animal species. Their amino acid composition and size allow them to attach and insert into the membrane pores and as a result they damage and kill microorganisms.
Consulting an in situ research that took place in Propylaia (north wing marble stone) the Erechteion (interior of temple Ionian post) and Erechteion (south porch) we noticed that Bacillus subtilis strain acr04 acr11acr05 acr04 acrr17 was found in all 3 locations as well as a wide range of other gram + and gram - bacteria.
After that we began researching for a peptide that will act against these bacteria so we came across a paper by published in J.Biochem in 1989 which suggested that Tachyplesin is an antimicrobial peptide that was found in the acid extract of hemocytes from the Japanese horseshoe crab (tachypleus tridentatus) and is widely effective amongst many Gram positive and Gram negative bacteria. Especially the native tachyplesin is effective against Bacillus subtilis with minimal inhibitory concentration (μg/ml) 3.13.
So after that we pigged into literature and came across a paper by Shemyakin and Ovchinnikov by the Institute of Bioorganic Chemistry in the Russian Academy of Sciences in Moscow, Russia. They were testing an improved strategy for recombinant production and purification of antimicrobial peptide Tachyplesin I and its analogs with high cell selectivity. They managed to demonstrate that highly potent THI could be used as a template to design more selective analogs toward bacterial cells by substitution of the β-turn region Tyr8 or Ile11 residues with serine. Being much more selective and less cytotoxic, the analogs Y8S and I11S of the AMP THI have the significantly enhanced TIs and can be considered as treating infectious diseases caused by both Gram-positive and Gram-negative bacterial pathogens.
Having seen all that we decided to test the action of Y8S and I11S of the AMP THI on bacteria inhibiting the marble.
Our project will consist of inserting the coding area of Y8S and I11S in 2 different plasmids and transforming E.coli bacteria.
When that will have been completed we have arranged with YSMA, the Acropolis restoration service to be sent cultures of microbiota that have been collected on the marbles so we can test the efficacy of our product.
Urzi, Clara, MICROBIAL DETERIORATION OF ROCKS AND MARBLE MONUMENTS OF THE MEDITERRANEAN BASIN: A REVIEW, Microbial Deterioration of Rocks and Marble Monuments, 2004, 441-457
M. Garcia-Valles C. Urzi, F. De Leo, P. Salamone and M. Vendrell- Saz, Biological weathering and mineral deposits of the Belevi marble quarry (Ephesus, Turkey), International Biodeterioration ά Biodegradation, 2000, 221-227
Μ. Garcia-Valles, C. Urzi and M. Vendrell-Saz, Environmental Geology 41, 2002, 889-897
A.Brogden, Kim, ANTIMICROBIAL PEPTIDES: PORE FORMERS OR METABOLIC INHIBITORS IN BACTERIA? www.nature.com/reviews/micro, 2005, 238-250
Toshiyuki Miyata, Fuminori Tokunaga , Takashi Yoneya Katsuhiro Yo, Antimicrobial Peptides Isolated from Horseshoe Crab Hemocytes, Tachyplesin II and PolyphemusinsI and II: Chemical Structures and Biological Activity, J.Biochem, 1989, 663-668
Kanini, Dora Nikolakopoulou Efstathios Katsifas Nikolaos I. Kyratsous Grammatiki, Bacterial Deterioration of Marble Monuments: A Case Study of the Conservations Project of Acropolis, Geomicrobiology, 2014, 726-736