Abstract
The research aim was to optimize the operating parameters of a diode laser irradiation for the effective disinfection of degraded collagenous materials. Historical leather shoes stored at the Auschwitz-Birkenau State Museum in Oświęcim (Poland) were the main study objects. Surfaces of contaminated small spots occurring on the degraded materials were sampled with moistened swabs and microbiologically examined using the molecular techniques MALDI-TOF MS, 16S rRNA, and NGS sequencing. The surfaces were colonized by bacteria with 106 CFU/100 cm2 and 104 CFU/100 cm2 by fungi, on average. Microorganisms of the genera Bacillus and Penicillium were predominant. The effectiveness of the laser treatment was assessed for the new and degraded collagenous materials against isolated environmental strains using four variants of exposure time and number of repetitions. 0.3 W/CW 2 × 2 min variant was the most effective and also did not noticeably change the color of the treated samples. The variant caused a reduction in the numbers of microorganisms by 96–100%. After 1 month, four types of leather were subjected to comprehensive physico-chemical analyses. SEM and FTIR techniques confirmed that laser irradiation in the selected optimal variant did not affect the surface morphology and collagen structure, while XPS technique enabled detection of subtle changes in non-historical protective coatings on the surfaces of tested degraded historical materials.
Highlights
KL Auschwitz-Birkenau, a former German Nazi Concentration and Extermination Camp in Oswiecim, is evidence of one of the greatest crimes ever committed against humanity
Conducting microbiological tests before conservation treatments and application of suitable methods of disinfection are crucial for the preservation of objects against biodeterioration and are necessary to protect the health of employees of the museum
The average concentration of bacteria obtained in this study was lower, and the one of fungi was similar to that of microorganisms inhabiting leather shoes of prisoners from the collection of the State Museum at Majdanek, Poland, which originate from the period of World War II (Perkowski and Gozdziecki, 2002; Falkiewicz-Dulik, 2015)
Summary
KL Auschwitz-Birkenau, a former German Nazi Concentration and Extermination Camp in Oswiecim, is evidence of one of the greatest crimes ever committed against humanity. It served for the annihilation of prisoners of various ethnicities through inhuman conditions such as starvation and slave labor. Later it became the largest extermination center established by the German Nazi regime for the immediate and mass killing of people. The historical collection, which is currently located at the Auschwitz-Birkenau State Museum in Oswiecim, Poland (A-BSM), retains the memory of people who were deliberately murdered in this place and illustrates the way in which it was done. Due to the careful preservation of the original evidence carried out without unnecessary reconstruction, the place and the objects are still authentic and integral
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