20.500.12556/RUL-183038 Vloga fiziologije Staphylococcus capitis na namnoževanje in učinkovitost bakteriofaga K Role of Staphylococcus capitis Physiology in Bacteriophage K Multiplication and Efficiency Zaradi vse pogostejše bakterijske odpornosti proti antibiotikom, fagna terapija predstavlja obetavno alternativo za zdravljenje kroničnih bakterijskih okužb, med katerimi so pogoste okužbe z bakterijami rodu Staphylococcus. V naravnih in kliničnih okoljih se bakterije po svojem metabolnem stanju bistveno razlikujejo od tistih, ki jih običajno preučujemo v laboratorijskih pogojih, kjer so razmere za rast praviloma optimalne in ne odražajo realnega okolja. Zato je za zanesljivo napoved učinkovitosti fagne terapije nujno preučiti delovanje bakteriofagov v bakterijah, ki se nahajajo v hranilno revnih okoljih. V tej študiji smo raziskali vpliv fiziološkega stanja bakterije Staphylococcus capitis na fagno okužbo in razmnoževanje litičnega bakteriofaga K. Bakterijo smo gojili v kemostatu pri različnih hitrostih redčenja (D), s katerimi smo uravnavali njeno specifično hitrost rasti (µ) in s tem njeno metabolno stanje. Učinkovitost fagne okužbe smo ovrednotili z določevanjem fagnih rastnih parametrov, ki opisujejo potek litičnega cikla in uspešnost fagnega namnoževanja. Vrednosti fagnih parametrov v bakterijah z upočasnjenim metabolizmom smo primerjali z vrednostmi v bakterijah iz eksponentne stopnje rasti. Ugotovili smo, da je v oslabljenih bakterijskih celicah latentna perioda (LP) daljša, medtem ko se velikost izbruha (BS) linearno zmanjšuje z upadanjem hitrosti rasti bakterije. Konstanta adsorpcije (ka) je dosegla najvišje vrednosti pri izrazito počasi rastočih bakterijah, kar pojasnjujemo z oslabljeno strukturo celične stene. Hkrati je bila visoka tudi pri eksponentno rastočih bakterijah. Iz fagnih parametrov smo izračunali fagni fitnes (FF) kot celovit pokazatelj uspešnosti fagne okužbe. Fagna terapija je bila najučinkovitejša pri eksponentno rastočih bakterijah, kjer aktiven metabolizem gostitelja omogoča visoko stopnjo razmnoževanja bakteriofagov in učinkovito lizo. Nasprotno se fagni fitnes pri nizkih hitrostih rasti bakterije izrazito zmanjša. Pri počasneje rastočih bakterijah je fagna terapija sicer omejena, vendar ni povsem izključena, saj fagni fitnes kljub zmanjšani presnovni aktivnosti gostitelja ostaja pozitiven. Sinteza novih fagov in liza še vedno potekata, vendar z zmanjšano učinkovitostjo. Trende spreminjanja fagnih parametrov in fagnega fitnesa v odvisnosti od fiziološkega stanja gostitelja smo opisali z matematičnimi modeli. Due to the increasing bacterial resistance to antibiotics, phage therapy represents a promising alternative for the treatment of chronic bacterial infections, among which infections caused by bacteria of the genus Staphylococcus are common. Bacteria in natural and clinical environments differ significantly in their metabolic state from those typically studied under laboratory conditions, where growth conditions are generally optimal and do not reflect the real environments. Therefore, to reliably predict the effectiveness of phage therapy, it is essential to study the action of bacteriophages in bacteria found in nutrient-limited environments. In this study, we investigated the influence of the physiological state of Staphylococcus capitis bacteria on phage infection and the replication of the lytic bacteriophage K. The bacterium was cultivated in a chemostat at different dilution rates (D), which allowed precise control of its specific growth rate (µ) and thus its metabolic state. Phage infection efficiency was evaluated by determining phage growth parameters that describe the progression of the lytic cycle and the success of phage multiplication. Phage parameter values obtained for bacteria with reduced metabolic activity were compared with those measured in exponentially growing bacteria. We found that in metabolically weakened bacterial cells, the latent period (LP) was longer, while the burst size (BS) decreased linearly with decreasing bacterial growth rate. The adsorption constant (ka) reached its highest values in extremely slow-growing bacteria, which we attribute to a weakened cell wall structure. At the same time, the adsorption constant was also high in exponentially growing bacteria. Based on the phage parameters, we calculated phage fitness (FF) as an overall indicator of phage infection efficiency. Phage therapy was most effective in exponentially growing bacteria, where active host metabolism supports rapid phage replication and efficient lysis. In contrast, phage fitness markedly decreased at low bacterial growth rates. Although phage therapy is limited in slowly growing bacteria, it is not completely ineffective, as phage fitness remains positive despite reduced host metabolic activity. Phage production and lysis still occur, but with reduced efficiency. The dependence of phage parameters and phage fitness on the host’s physiological state was described using mathematical models. bakterija Staphylococcus capitis bakteriofag K kemostat fagni parametri fagna terapija bacteria Staphylococcus capitis bakteriophage K chemostat phage parameters phage therapy true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2026-06-02 14:30:03 2026-06-02 14:30:20 2026-06-30 11:36:25 0000-00-00 00:00:00 2026 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 25625 283081987 Blaznik_Spela_-_Vloga_fiziologije_Staphylococcus_capitis_na_namnozevanje_in_ucinkovitost_bakteri.pdf Blaznik_Spela_-_Vloga_fiziologije_Staphylococcus_capitis_na_namnozevanje_in_ucinkovitost_bakteri.pdf 1 DEE74AAEF249CF9475A3A8D034749377 3d077c7983466d94c1217a843fd430fe304f1865b15057ab66a1876d40f69678 7529742b-5e7e-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=234849 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0