Genetic adaptation of Streptococcus mutans during biofilm formation on different types of surfaces.
BACKGROUND
Adhesion and successful colonization of bacteria onto solid surfaces play a key role in biofilm formation. The initial adhesion and the colonization of bacteria may differ between the various types of surfaces found in oral cavity. Therefore, it is conceivable that diverse biofilms are developed on those various surfaces. The aim of the study was to investigate the molecular modifications occurring during in vitro biofilm development of Streptococcus mutans UA159 on several different dental surfaces.


RESULTS
Growth analysis of the immobilized bacterial populations generated on the different surfaces shows that the bacteria constructed a more confluent and thick biofilms on a hydroxyapatite surface compared to the other tested surfaces. Using DNA-microarray technology we identified the differentially expressed genes of S. mutans, reflecting the physiological state of biofilms formed on the different biomaterials tested. Eight selected genes were further analyzed by real time RT-PCR. To further determine the impact of the tested material surfaces on the physiology of the bacteria, we tested the secretion of AI-2 signal by S. mutans embedded on those biofilms. Comparative transcriptome analyses indicated on changes in the S. mutans genome in biofilms formed onto different types of surfaces and enabled us to identify genes most differentially expressed on those surfaces. In addition, the levels of autoinducer-2 in biofilms from the various tested surfaces were different.


CONCLUSIONS
Our results demonstrate that gene expression of S. mutans differs in biofilms formed on tested surfaces, which manifest the physiological state of bacteria influenced by the type of surface material they accumulate onto. Moreover, the stressful circumstances of adjustment to the surface may persist in the bacteria enhancing intercellular signaling and surface dependent biofilm formation.
Shemesh
Moshe
M
Biofilm Research Laboratory, Institute of Dental Sciences, Faculty of Dental Medicine, Hebrew University-Hadassah POB 12272, Jerusalem 91120, Israel.
Tam
Avshalom
A
Aharoni
Reuven
R
Steinberg
Doron
D
D000222:Adaptation, Physiological / Q000235:genetics*; D001499:Bayes Theorem; D018441:Biofilms / Q000254:growth & development*; D018914:Cells, Immobilized / Q000378:metabolism / Q000502:physiology; D003188:Composite Resins; D003793:Dental Restoration, Permanent; D017886:Durapatite; D020869:Gene Expression Profiling; D005798:Genes, Bacterial; D006714:Homoserine / Q000031:analogs & derivatives / Q000235:genetics / Q000378:metabolism; D007783:Lactones / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D011137:Polystyrenes; D012329:RNA, Bacterial / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013295:Streptococcus mutans / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013499:Surface Properties; D014025:Titanium
D003188:Composite Resins; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D011137:Polystyrenes; D012329:RNA, Bacterial; D006714:Homoserine; D017886:Durapatite; D014025:Titanium