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U ovom radu istraživana je uspješnost primjene metode gama zračenja u svrhu dekontaminacije i očuvanja djela kulturne baštine. Zbog široke rasprostranjenosti gljivica, sva su djela izložena opasnosti degradacije, koja može biti izbjegnuta ukoliko se vodi pravovaljana skrb o artefaktima i tako onemogući rast biokontaminanata. Ispitana je i prirodna kontaminacija samog materijala, te se nakon vizualne identifikacije kolonija mikroskopom, pristupilo zračenju uzoraka. Uzorci su bili podijeljeni u dvije skupine. Jedna skupina je prije zračenja bila inkubirana u vlažnim (Rv=70-80%, t=25°C), a druga u suhim uvjetima (t=25°C). Obje skupine uzoraka zračene su dozama zračenja od 2, 7, 20 i 50 kGy u dvije brzine, 0,1 Gy/s i 9,8 Gy/s. Djelotvornost metode pratili smo porastom kolonija 0.,7.,14. i 28. dana, nakon izlaganja uzorka zračenju. Dobiveni rezultati eksperimenata pokazuju da su prirodni kontaminanti neosjetljivi na primijenjeno zračenje, jer je porast kolonija zabilježen kod uzoraka zračenim visokim dozama, koje su nekoliko puta veće od doza koje se koriste za dekontaminaciju umjetnina. Uočen je porast i drugih vrsta gljivica. Točkasta kontaminacija papira, otežava izvođenje konačnog zaključka o učinkovitosti fungicidnog/fungistatskog djelovanja gama zračenja. This paper analyzes the use and effectiveness of gamma radiation, in order to decontaminate and protect cultural heritage. Fungi are widely spread in the environment, ergo they pose the risk to many works of art, and biodegradation is inevitable, unless the proper care is taken of these artefacts. Also, the natural contamination of the material has been analyzed, colonies were identified microscopically, following gamma radiation of the samples. Samples were divided into two groups. One group was exposed to the conditions of elevated humidity (Rw=70-80%, t=25°C), and the other group did not undergo any treatment, those samples remained in dry conditions. Both groups were irradiated with subsequent radiation doses 2,7,20 and 50 kGy, which were administered with two different velocities of 0,1Gy/s and 9,8 Gy/s. The effectiveness of the method was evaluated in correspondence with colony growth after the certain time, i.e. 0th, 7th, 14th and 28th day after irradiation has taken the place. Natural contaminants have shown radio resistance due to given results, because there has been noticed colony growth in samples, which were treated with a high dose of radiation. The dose of the matter is several times higher than dose, which is usually used for decontamination purpose. Growth of other fungal species has been noticed too. Due to dot contamination, it is very difficult to conclude how effective fungicide gamma radiation actually is.

Veliki dio kulturne baštine čine objekti od papirnatih materijala. Kao takvi izrazito su podložni kontaminaciji gljivicama koje svojim djelovanjem ubrzavaju njegovo propadanje. Jedna od najpogodnijih metoda za zaustavljanje destruktivnog djelovanja gljivica je gama zračenje. U ovom je radu ispitivan utjecaj gama zračenja na prirodnu mikobiotu papira te utjecaj na inokuliranog sekundarnog kolonizatora, vrstu Cladosporium sphaerospermum. Uzorci su tretirani pomoću izvora u Laboratoriju za radijacijsku kemiju i dozimetriju (LRKD) Instituta Ruđer Bošković (IRB). Primijenjene su apsorpcijske doze od 2, 7, 20 i 50 kGy u dvije brzine zračenja 0,1 Gy/s i 8,6 Gy/s. Mikrobiološka analiza ozračenih uzoraka provedena je neposredno nakon zračenja te 14., 28., i 56. dan nakon zračenja. Učinak gama zračenje ovisan je o dozi i o brzini doze. Iz dobivenih rezultata vidljivo je da najniža doza od 2 kGy nije učinkovita u redukciji plijesni ni pri nižoj ni pri višoj brzini doze. Dok su veće doze od 7, 20 i 50 kGy pri višoj brzini učinkovito reducirale i prirodnu mikobiotu i inokuliranu vrstu C. sphaerospermum. To potvrđuje i izračunata vrijednost D10 (decimalna redukcijska doza), odnosno doza potrebna da se inaktivira 90% od početnog broja plijesni u uzorku, koja za C. sphaerospermum i brzinu zračenja 0,1 Gy/s iznosi 11,29 kGy, a za brzinu 8,6 kGy iznosi 4,35 kGy. Potrebno je dakle naći odgovarajuću dozu koja će reducirati mikroorganizme na prihvatljivu razinu, a istovremeno imati minimalni negativni učinak na kemijski sastav papira stoga su u tom području potrebna daljnja ispitivanja. Za učinkovitu je primjenu gama zračenje u konzervaciji papirnatih objekata kulturne baštine potreban interdisciplinarni pristup. Major part of cultural heritage is made up of paper-based materials. As such, they are highly susceptible to fungal contamination, which causes paper to decay. One of the most convenient methods of stopping the destructive action of fungi is gamma irradiation. This paper was aimed to assess the influence of gamma irradiation on the naturally occurring mycobiota as well as artificially inoculated secondary colonizer Cladosporium sphaerospermum. Inoculated samples have been treated by the Laboratory for radiation chemistry and dosimetry of Ruđer Bošković Institute source. Doses of 2, 7, 20 and 50 kGy were applied at two dose rates of 0,1 and 8,6 Gy/s. Microbiological analysis of irradiated samples was conducted immediately after radiation and on 14, 28 and 56 days after radiation. Fungicidal effect of gamma radiation was dose and dose rate-dependent. From the obtained results it is apparent that the lowest dose of 2 kGy is not effective in reducing mold at either lower or higher dose rates. While higher doses of 7, 20 and 50 kGy at higher dose rate effectively reduced the naturally occurring mycobiota as well as artificially inoculated secondary colonizer C. sphaerospermum. This is also confirmed by the calculated value D10 (decimal reduction dose), the dose required to inactivate 90% of the initial number of molds in the sample, which is 11.29 kGy for C. sphaerospermum and the rate of radiation 0.1 Gy/s, and for 8.6 kGy is 4.35 kGy. Thus, it is necessary to find an appropriate dose which will reduce the microorganisms to an acceptable level while at the same time will have a minimal negative effect on the chemical composition of the paper, so further testing in this area is required. To conclude, for the efficient use of gamma irradiation in conservation of paper-based cultural heritage objects, an interdisciplinary approach is needed.