University of Zagreb. Faculty of Science. Department of Biology.
Abstract
Mnoge bakterije mogu postojati kao zajednice vezane na površinu poznate kao biofilmovi. Bakterijski biofilm je sesilna zajednica čije su stanice ireverzibilno povezane sa supstratom i međusobno, te uronjene u matriks izvanstanične polimerne tvari (eng. extracellular polymeric substance, EPS) koji su same stvorile. Istraživanje je bilo usmjereno na statičke sustave biofilma koji su posebno korisni za ispitivanje ranijih stadija formiranja biofilma. Za istraživanje su korištene bakterije Bacillus cereus i Acinetobacter junii. Cilj istraživanja bio je odrediti model rasta biofilma kojeg tvore te vrste bakterija u stacionarnim uvjetima, kao i vizualizirati biofilm, usporediti količine nastalog EPS-a, te usporediti rast planktonskih i imobiliziranih bakterija kroz vrijeme u stacionarnim uvjetima (batch culture) te uvjetima kontinuiranog rasta (continuous culture). Budući da se pratila biomasa bakterija kroz vrijeme i količina nastalog EPS-a, bakterije su se bojale bojilom Alcian blue i Karbol-fuksinom. Zaključeno je da u stacionarnim uvjetima model rasta bakterijskog biofilma koji se odvija u pet faza nije primjenjiv za bakteriju B. cereus, dok je primjenjiv za bakteriju A. junii. Također je zaključeno da stacionarni uvjeti pogoduju vrsti B. cereus, dok kod bakterije A. junii nema značajne razlike u uvjetima kontinuiranog rasta i u stacionarnim uvjetima.Many bacteria may exist as surfaces-related communities known as biofilms. Bacterial biofilm is a sessile community whose cells are irreversibly linked to the substrate and mutually, and immersed in the matrix of extracellular polymeric substances (EPS) that they have created. The research was focused on static biofilm systems that are particularly useful for the early stages of biofilm formation. Bacteria Bacillus cereus and Acinetobacter junii were used for the study. The goal was to determine a model of biofilm created by these bacteria species in stationary conditions. Also, visualize the biofilm, compare the amount of produced EPS and compare the growth of planktonic and immobilized bacteria over time in batch culture and continuous culture. Given that we monitored bacterial biomass through the time and the amount of produced EPS, bacteria were stained with Alcian-blue which dye the EPS and Carbol-fuchsin which dye the cells. It was concluded that in stationary conditions the five stage model of biofilm development is not applicable to B. cereus, but is applicable to A. junii. It was also concluded that stationary conditions were beneficial for the growth of B. cereus, whereas in comparison with A. junii there was no significant difference in the stationary assay relative to the continuous growth assay
