Povezava med razgradnjo izbranih tipov plastike ter produkcijo esteraz pri ekstremnotolerantnih glivah, izoliranih iz notranjih okolij

Blaznik, Neža (author), Gunde Cimerman, Nina (mentor)

Plastika iz leta v leto postaja večji okolijski problem, saj se z večanjem njene proizvodnje viša tudi njena akumulacija na kopnem in v morju. Ena izmed obetavnih rešitev za zmanjšanje okolijskega bremena odpadne plastike s čim manj negativnih vplivov na okolje, je biološka razgradnja z mikroorganizmi in njihovimi encimi. Biološka razgradnja se začne s kolonizacijo površine plastike. Sledijo razgradnja polimerov na manjše fragmente, absorbcija manjših fragmentov v mikroorganizme ter njihova oksidacija do končnih produktov. Glive lahko razgrajujejo veliko naravnih in nekatere sintetične materiale. Lastnosti, ki jim pri tem pomagajo so sposobnost pritrditve na hidrofobne površine, prodiranje v materiale in izločanje zunajceličnih encimov. Naseljujejo lahko ekstremna okolja v naravi in v naših domovih. V magistrski nalogi smo uporabili 57 sevov gliv, ki so bile izolirane iz plastičnih in gumiranih predelov pomivalnih in pralnih strojev. Želeli smo preveriti, ali izbrane vrste ekstremotolerantnih gliv kot edini vir ogljika uporabijo sledeče tipe plastike: poliamid, polietilen z nizko gostoto, polietilen tereftalat, polipropilen in poliuretan. Sposobnost razgradnje izbranih plastik smo merili s spremljanjem deleža CO2 v plinasti fazi ob inkubaciji seva s plastiko in ugotovili, da je 49 % izbranih sevov med inkubacijo s plastiko proizvedlo več CO2 kot med inkubacijo brez plastike. Identificirali smo sedem sevov, ki v literaturi še niso omenjeni v povezavi z razgradnjo plastike. Z encimskimi testi na tekočem in trdnem gojišču smo določali prisotnost esteraz v izbranih sevih. Pri 43 % sevov, ki so ob inkubaciji s plastiko proizvedli več CO2, smo s kvalitativnim encimskim testom na trdnem ali tekočem gojišču zaznali tudi največjo produkcijo esteraz. S kvalitativnim encimskim testom v prilagojenem gojišču YNB smo encimsko aktivnost zaznali pri dveh od devetih testiranih sevov.

• Language: Slovenian
• Keywords: biološka razgradnja plastike, ekstremotolerantne glive, plinska kromatografija, encimski testi, esteraze
• Work type: Master's thesis/paper
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2024
• PID: 20.500.12556/RUL-162808
• Publication date in RUL: 27.09.2024

Secondary language

• Language: English
• Title: The connection between the degradation of selected types of plastic and the production of esterases in extremotolerant fungi isolated from indoor environments

Abstract

Plastic is becoming a bigger environmental problem every year, because as production increases, so does the accumulation of plastic on land and in the sea. One of the promising solutions to reduce the environmental burden of plastic waste with the least possible negative impact on the environment is biological degradation with microorganisms and their enzymes. Biodegradation begins with the colonization of the plastic surface. This is followed by the decomposition of the polymers into smaller fragments, absorption of the smaller fragments into the microorganisms and their oxidation into end products. Fungi can degrade many natural and some synthetic materials. The enabling properties are the ability to attach to hydrophobic surfaces, to penetrate materials and secrete extracellular enzymes. They can inhabit extreme environments in nature and in our homes. Fifty-seven strains of fungi isolated from plastic and rubber parts of dishwashers and washing machines were used in this experiment. We characterized the selected species of extremotolerant fungi regarding their ability to utilize the following types of plastics as their only source of carbon: polyamide, low-density polyethylene, polyethylene terephthalate, polypropylene and polyurethane. The ability to degrade selected plastics was measured by monitoring the proportion of released CO2 in the gas phase during incubation of the strain with plastic. It was found that 49 % of the selected strains produced more CO2 during incubation with plastic than during incubation without plastic. We identified seven strains that have not yet been mentioned in the literature in connection with the degradation of plastics. The secretion of esterases by the selected strains was determined using an enzyme assay on liquid and solid culture media. In 43 % of the strains that produced more CO2 when incubated with plastic, we also detected the highest production of esterases using a qualitative enzyme assay on a solid or liquid culture medium. Enzyme activity was detected in two of the nine strains tested using a qualitative enzyme assay on the adapted YNB culture medium.

• Keywords: biological degradation of plastics, extremotolerant fungi, gas chromatography, enzyme assays, esterases