西班牙的藝術家正採用一項修復古蹟的新技術──利用細菌來修復瓦倫西亞南部教堂中400年歷史的珍貴壁畫，這項新技術最早是為了修復同樣是稀世珍寶的義大利壁畫而開發出來的。
西班牙的藝術品修復者們正打算在瓦倫西亞桑托斯橫斯一座教堂裡，由17世紀安東尼奧帕羅米諾所創作的壁畫上試驗這項新技術。他們展示了一種能清潔藝術品的特殊菌種。不僅能以快速、具有專一性且尊重畫作的方式達到清潔畫作的目的，對修復工作者及周圍環境也不會有任何毒害。這項測試是由瓦倫西亞理工大學文物修復研究所以及先進食品微生物中心組成的團隊所完成的。
這項研究被發佈在最近Polytechnic City of Innovation所舉行的研討會上，與會者包括最早開發出這項技術的義大利科學家。
Gianluigi Colalucci是修復西斯汀教堂的主要成員之一，他和同事將過去的專業經驗分享給正在嘗試修復西班牙桑托斯橫斯教堂的工作團隊。Colalucci及同事Carlo Giantomassi已經將這項由義大利微生物學家Giancarlo Ranalli所開發出來的技術應用在修復Campo Santo di Pisa的畫作上。該教堂位在著名的比薩斜塔旁。
他們採用的微生物是偽單孢菌科(Pseudomonas family)的一種，因為這項工程的關係，該微生物已被轉化成膠體。
Giantomassi告訴研討會與會者說，「我們使用的這些壁畫是在二次世界大戰中被破壞的」。「以前的人使用一種不易被溶解的動物膠將畫作貼附在牆上，因此要將畫作從牆上拿下來，使用傳統的方法根本不可能做到。這種細菌能吃掉膠的部份，保持畫作的完整性。」
過去，修復人員使用一些易起反應的化學品來去除沉積在古老藝術品表面的外來物，但這些化學品不具有選擇性而且有毒。修復人員們也嘗試過利用機械方法將外來物沉積層磨掉，但這非常耗時而且會傷害到畫作本身。
桑托斯橫斯教堂裡的壁畫大約在1936年左右遭到大火破壞，在1960年代曾經以不適當的方法修復過。在文物修復研究所開始針對這些畫作進行修復工作時，瓦倫西亞計畫就啟動了。
研究者們遇到的難題是，如何處理鹽霜（由鹽的結晶堆積成白色似類疥癬的物質）、以及大量殘存在已取下壁畫上的動物膠。
因此，微生物學教授Rosa Maria Montes以及生物學家Pilar Bosch一同前往義大利，向原技術開發人員學習如何利用細菌去除義大利畫作上的外來物。
Bosch表示，「重力及蒸發作用使有機物質分解後產生的鹽類，遷移到畫作上，形成一層白色外殼而掩蓋住畫作，有時候也會造成畫作上顏料層的損失。」
回到瓦倫西亞後，西班牙團隊說他們已經培育出最合適的偽單孢菌菌種，能夠正確地吃掉在鴿巢後方、半月形穹頂上發現的鹽霜。
西班牙科學家還創造出一種使用細菌的新方法，能減少作用時間。
Bosch說，「在義大利，他們使用脫脂棉來操作這些微生物，而我們已經開發出一種塗佈在表面上的膠，能避免因水氣穿透過材料而引發的新問題。」
他解釋說:「我們利用細菌去除動物膠，一個半小時後。畫作表面變得乾淨且乾燥。在缺乏水分的環境下，剩餘的細菌會自動死亡。」
這個新方法已經在桑托斯橫斯教堂中兩個半月形拱頂上試驗過，科學家們打算將這個方法也用在另外兩個拱頂上。
瓦倫西亞研究計畫是由瓦倫西亞理工大學的研發計畫所贊助支持。Bosch的博士論文獲得西班牙科技與研發部門提供的研究經費，在該論文中完成瓦倫西亞計畫的定論。科學家們正考慮與私人企業開啟合作關係。
Bosch說，「在得到好的試驗結果後，我們將持續研究並改進這項技術，目標是能將這項技術運用到其他表面處理問題上。我們發現，在自然界中存在許多幾乎不挑食的的細菌種類，相信未來我們能利用不同菌種去清除其他物質。」
Bacteria 'Trained' to Clean Ancient Artworks
Spanish art experts are employing bacteria to restore priceless 400-year-old frescoes in a church in the southern city of Valencia using a technique developed to restore equally precious frescoes in Italy.
Spanish restorers are testing this new technique on the frescoes of Antonio Palomino from the 17th century in the Church of Santos Juanes in Valencia.
They have shown that a special type of bacteria is capable of cleaning works of art in a fast, specific and respectful way as well as being non-toxic to the restorer or the environment.
The team that completed the tests are from the Institute of Heritage Restoration and the Centre for Advanced Food Microbiology, both from the Polytechnic University of Valencia.
These developments were announced at a recent seminar held at the Polytechnic City of Innovation, which was attended by the Italian creators of these techniques using bacteria.
One of Italy's leading restorers, Gianluigi Colalucci, who restored the Sistine Chapel, and his colleagues have shared their expertise with the Spanish restorers working on the murals of the Church of Santos Juanes.
Colalucci and colleague Carlo Giantomassi had applied the technique, developed by Italian microbiologist Giancarlo Ranalli, in their restoration of the wall paintings of Campo Santo di Pisa, next to the city's famous Leaning Tower.
The microrganism selected by the restorers is part of the Pseudomonas family and it has been converted into a gel for the works.
"The frescoes on which we are using it were damaged after the Second World War," Giantomassi told the seminar participants.
"To remove them from the walls they were using animal glues which in time have become insoluble and impossible to remove with traditional methods. The bacteria are able to eat these glues and leave the painted section intact."
In the past, to remove foreign materials encrusted on ancient artworks restorers used reactive chemicals that are non-selective and toxic. Or they tried to wear away the crust by mechanical means, which is time consuming and can damage the paint.
The Valencia project began when the Institute of Heritage Restoration was working with the murals of the Church of Santos Juanes, which were virtually destroyed after a fire in 1936 and were improperly restored in the 1960s.
The researchers had difficulty dealing with salt efflorescence, the white scabs caused by the buildup of crystallized salts and the enormous amount of gelatine glue remaining on the pulled-off murals.
So microbiology professor Rosa Maria Montes and biologist Pilar Bosch travelled to Italy to learn from the originators about their work using bacteria to remove foreign matter from Italian artworks.
"By the action of gravity and evaporation, the salts of organic matter in decomposition migrate to the paintings and produce a white crust hiding the work of art and sometimes can also cause the loss of the painting layer," says Bosch.
Back in Valencia, the Spanish team say they "trained" the most suitable strain of Pseudomonas bacteria to literally eat the saline efflorescence found in the lunettes of the vault behind which pigeons nest.
The Spanish scientists reduced the application time and created a new way of using the bacteria.
Bosch said, "In Italy, they use cotton wool to apply the micro-organisms. We, however, have developed a gel that acts on the surface, which prevents moisture from penetrating deep into the material and causing new problems."
"After an hour and a half, we remove the gel with the bacteria. The surface is then cleaned and dried. Without a wet environment, the remaining bacteria die," he explained.
The new method has been tested on two lunettes of the vault in the Church of Santos Juanes and scientists expect to apply it on another two.
The Valencia research project was funded through the R&D support program of the Polytechnic University of Valencia and concluded with Bosch's doctoral thesis, which received a grant from the Spanish Ministry of Science and Innovation. The scientists are considering partnerships with private businesses.
"After the good results of the tests, we will continue the studies and improve the technique with the aim of transferring it to other surfaces," said Bosch. "As in nature we find different species of bacteria that feed on almost anything, we are convinced that we can eliminate other substances from different types of materials."
全文及圖片詳見：ENS報導
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