Biocleaning of cultural heritage items is mainly performed using living microorganisms. Approaches utilizing the enzymes of isolated microorganisms have not been frequently investigated. To find an enzymatic alternative for the removal of an oil-based overpainting, we focused on the characterization and use of a yeast Extracellular Enzymatic Mixture (EEM). A historical silk yeast was selected for its lipolytic properties and its EEM was extracted after cultivation on a medium supplemented with linseed oil. The EEM protein content was visualized by SDS-PAGE, its concentration assessed by fluorimeter and the enzymatic activity evaluated by p-NPP spectrophotometric lipase assay. The yeast growth was suppressed by adding diverse metal ions (Cd, Zn, Cr and Cu) in Reasoner's 2A (R2A) broth, while the quantity and activity of EEM were affected by adding Fe and Pb. Various delivery systems (agar-agar, tylose and klucel G) alone or in a combination with EEM were assayed on the historical painting surface. The colorimetric measurements and the ATR-FTIR analysis indicated that the combinations tylose-EEM and klucel G-EEM can be easily and effectively applied as biocleaning procedures to remove oil-based overpainting from fragile and valuable historical painting surfaces.

文化遗产项目的生物清洁主要使用活微生物进行。尚未经常研究利用分离微生物的酶的方法。为了找到去除油基涂层的酶替代方案，我们专注于酵母细胞外酶混合物 (EEM) 的表征和使用。选择了历史悠久的丝酵母，因为它具有脂肪分解特性，并在补充有亚麻籽油的培养基上培养后提取其 EEM。EEM 蛋白含量通过 SDS-PAGE 显示，其浓度通过荧光计评估，酶活性通过 p-NPP 分光光度计脂肪酶测定评估。通过在 Reasoner 的 2A (R2A) 肉汤中添加多种金属离子（Cd、Zn、Cr ​​和 Cu）来抑制酵母生长，而EEM的数量和活性受Fe和Pb的影响。在历史绘画表面上分析了单独或与 EEM 组合的各种传递系统（琼脂、tylose 和 klucel G）。比色测量和 ATR-FTIR 分析表明，tylose-EEM 和 klucel G-EEM 的组合可以轻松有效地用作生物清洁程序，以从易碎和有价值的历史绘画表面去除油基涂层。