Abstract
Adherence of the microorganism to submerged solid surfaces leads to biofilm formation. Biofilm formation modifies the surfaces in favor of bacteria facilitating the survival of the bacteria under different stressed conditions. On the other hand, the formation of biofilm has a direct adverse economic impact in various industries and more importantly in medical practices. This adherence is the reason for the failure of many indwelling medical devices. Surface biofilm adhesion is the key to biofilm growth and stability. Hence this adhesion needs to be substantially lowered to inhibit biofilm stability. Both chemical and physical properties of the surface influence biofilm formation and modulating these properties can control this formation. In this study, we have investigated the effect of Hydrofluoric acid (HF), at a specific concentration as an etchant, on the surface morphology of substrates and the growth of biofilms of Pseudomonas aeruginosa. and Staphylococcus aureus. We find that the bacterial counts on the etched surfaces undergo a periodic increase and decrease. This, on one hand, shows the close correlation between the biofilm growth and the particular roughness scale, and on the other hand, explains the existing contradictory results regarding the effects of etching on substrate roughness and biofilm growth. We propose a simple model of a sequence of hole formation, hole expansion and etching away of the hole walls to form a new, comparatively smooth surface, coupled with the preferential accumulation of bacteria at the hole edges, to explain these periodicities.
Highlights
Biofilms consist of consortia of sessile microbial populations where heterogeneous populations of microbes remain embedded in a matrix
(1) What is the relation between the etching time and the roughness for Hydrofluoric acid (HF) of a particular concentration on glass? (2) What is the consequent relation between the etching time/roughness and the biofilm coverage, again for the same etchant and substrate and for specific bacteria? We have shown that both these follow a periodic nature for Staphylococcus aureus a gram positive and for Pseudomonas aeruginosa a gram negative bacteria
The surface roughness of each of the glass pieces, starting from the unetched to those exposed to HF for different time periods, was measured using a Contact Profilometer (Dektak 150 profiler, Veeco Instruments Inc)
Summary
Biofilms consist of consortia of sessile microbial populations where heterogeneous populations of microbes remain embedded in a matrix. The influence of the chemical composition of substrate surfaces on bacterial attachment and biofilm formation has been investigated by different research groups [5, 6]. This hydrophilicity of glass may be destroyed if they are kept immersed in HF solution, as the reaction of HF with the silica forms hydrophobic Hexafluorosilicate [17] and Silicon Tetrafluoride Besides this chemical change, HF etches the glass surface and makes it rough. While some studies reported enhancement of biofilm growth with enhanced surface roughness [22, 23], others reported just the opposite [24, 25] This question, in all probability, is related to the type and especially the length scale of roughness induced by etching as only roughness at the length scale of micrometres will be able to affect the bacteria. This provides answers to both the questions and the possibility of finding a roughness for minimum coverage
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
