Študija razgradnje poliamida z bakterijami

Tahiri, Aleina (author), Rozman, Ula (mentor)

Plastika in zlasti mikroplastika predstavljata enega največjih okoljskih problemov sodobnega časa, saj se zaradi svoje obstojnosti in množične uporabe kopičita v naravi ter povzročata dolgoročne posledice za ekosistem in zdravje ljudi. Zaradi slabe bioragradljivosti in posledično njene obstojnosti se v zadnjih letih vse več raziskav osredotoča na biološke pristope razgradnje plastičnih materialov, ki temeljijo na uporabi organizmov. Namen diplomskega dela je bil preučiti možnost biološke razgradnje poliamida (PA) s pomočjo bakterije Pseudomonas putida in oceniti njen potencial za zmanjševanje plastičnih odpadkov v okolju. Eksperimenti so bili izvedeni v dveh različnih gojiščih, osiromašenem mediju M9, kjer je PA predstavljal edini vir ogljika in s hranili bogatem mediju nutrient broth (NB). Rast bakterij smo spremljali spektrofotometrično, prav tako pa smo ob koncu pettedenskega poskusa kvantificirali delež biofilma, ki je nastal na površini. Analize sprememb materiala so bile izvedene z infrardečo spektroskopijo s Fourierovo transformacijo (FTIR) in z vrstičnim elektronskim mikroskopom (SEM). Rezultati so pokazali, da je bila rast bakterij v mediju M9 omejena, vendar je bakterija kljub pomanjkanju hranil tvorila tanek, a postopno naraščajoč biofilm. V mediju NB je bila rast bakterije v mediju izrazitejša, delež biofilma pa je dosegel največjo količino med 21. in 28. dnem, nato pa se je zmanjšal zaradi izčrpanja hranil in delne razgradnje biomase. Masa PA se je v primeru M9 medija zmanjšala do maksimalno 15 % (po 35 dneh), medtem ko se je masa PA pri eksperimentu v NB zmanjšala le za 5 %, kar lahko pripišemo eksperimentalni napaki. FTIR in SEM analizi nista pokazali sprememb v morfologiji in kemijski sestavi površine PA. Ugotovitve prispevajo k razumevanju interakcije med mikroorganizmi in PA materiali ter nakazujejo, da bakterije, kot je Pseudomonas putida, lahko tvorijo biofilm na površini PA, vendar bi bilo za učinkovitejšo biorazgradnjo potrebno optimizirati pogoje ali podaljšati čas biorazgradnje.

• Language: Slovenian
• Keywords: bakterije, biološka razgradnja, bioremediacija, mikroplastika, plastika, poliamid, Pseudomonas putida
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2026
• PID: 20.500.12556/RUL-181100
• COBISS.SI-ID: 274132483
• Publication date in RUL: 25.03.2026

Secondary language

• Language: English
• Title: Study of the degradation of polyamide by bacteria

Abstract

Plastics, particularly microplastics, have become one of the most significant environmental pollutants of the modern era. Their durability and extensive use lead to persistent accumulation in the environment, posing serious risks to ecosystem and human health. Due to low biodegradability of plastics and their resulting persistence in the environment, recent studies have focused on biological degradation methods that employ organisms. The aim of thesis was to explore the potential biodegradation of polyamide (PA) by the bacterium Pseudomonas putida and to evaluate its capacity to reduce plastic pollution in a sustainable way. Experiments were carried out in two different media, a nutrient deficient M9 medium using PA as the sole carbon source, and a nutrient rich nutrient broth (NB) medium. Bacterial growth was monitored spectrophotometrically, and the amount of biofilm on PA was assessed over a five-week incubation period. Changes in the moprhology and chemical composition were analyzed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results showed that Pseudomonas putida was able to survive and form a thin biofilm on the surface even under nutrient-limited conditions (M9 medium). In the nutrient rich medium, bacterial growth in the medium was significantly higher, while the amount biofilm was lower than in the case of M9 medium peaking between the third and fourth week, followed by a decline due to nutrient depletion and partial biofilm degradation. The mass of PA in the M9 medium decreased by up to 15% (after 35 days), whereas in the experiment with NB, the mass of PA decreased by only 5%, which can be attributed to experimental error. FTIR and SEM analyses did not reveal any changes in the surface morphology or chemical composition of PA. These findings contribute to the understanding of microbial interactions between bacteria and PA and suggest that bacteria such as Pseudomonas putida can form biofilms on the surface of PA. However, more efficient biodegradation would require optimization of conditions or a longer biodegradation period.

• Keywords: bacteria, biodegradation, bioremediation, microplastic, plastic, polyamide, Pseudomonas putida