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Abstract
In all ecosystems bacteria predominantly live on surfaces, encapsulated within an extracellular matrix, and readily establish a multicellular and most often a multispecies organisation known as a biofilm. Microbial biofilm formation is sequential, involving multiple developmental stages and resulting in dynamic communities with cooperative traits resembling those of multicellular organisms. Such traits enable biofilms to survive in harsh environments and increase bacterial tolerance to antimicrobials, leading to a range of negative impacts such as fouling on industrial surfaces and bacterial infections.
This study investigates the impact of micro-fabricated poly-dimethyl siloxane (PDMS) surfaces on initial biofilm formation as well as subsequent development, to explore the utility of surface modification and patterning for biofilm control. Bacterial populations establishing biofilms on different micro-fabricated PDMS surfaces, with micro-scale trenches from 1 to 10 μm, and smooth control surfaces, were first studied using the model biofilm forming bacterium Pseudomonas aeruginosa. Surface micro-fabrication had significant effects on several important biofilm traits, such as reduced microcolony formation, biofilm height, and biovolumes. Similar outcomes were observed for P. aeruginosa grown in other culture conditions, including the use of different culture media such as Luria Broth (LB), Vaatanen Nine Salt Solution (VNSS) and M9 Minimal Media (M9), which displayed broader impacts of different physiological conditions for biofilm development, as well as in studies using two model marine surface colonising organisms, Phaeobacter gallaeciensis and Pseudoalteromonas tunicata. Altered biofilm formation of P. aeruginosa biofilms on micro-fabricated PDMS surfaces also showed decreased chemical resistance of their biofilm populations, compared to biofilms established on control surfaces. Marine field experiments allowing diverse biofilm community formation similarly showed a marked impact on biofilm development by the modified surfaces. In addition to altered biofilm traits similar to those observed for biofilm populations, the biofilm community composition analysed using terminal restriction fragments (T-RF) for phylogenetic fingerprinting, was significantly changed at different times during the long term exposure, as revealed by the changes in T-RF profiles, and hence biofilm development.
The effects of micro-fabricated PDMS surfaces on microbial biofilm formation and development are pronounced, both in laboratory settings and in marine field trials. The findings contribute to ongoing and future research for the delivery of novel biofilm control tools.