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Title: Investigation into compound(s) exhibiting Streptococcus mutans anti-biofilm activity
Author: Sucharit, Supanan
ISNI:       0000 0004 9352 8348
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2020
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Streptococcus mutans is one of the main oral bacteria causing caries through biofilm formation. Bioactive compounds, derived from microorganisms, that disrupt S. mutans biofilms are a potential treatment for dental caries. A high throughput microtitre plate biofilm assay was developed to screen an oral metagenomic library and an environmental isolate library for S. mutans clones that produced anti-biofilm compounds. Anti-biofilm activity was not found in 6,624 screened metagenomic clones. Two different kinds of anti-biofilm activity, biofilm detaching activity and biofilm inhibitory activity, were found to be produced by seven isolates from the environmental library. The biofilm detaching activity was produced by all seven isolates, which were identified as Bacillus velezensis based on whole genome sequencing results. Isolate 6E produced the compound with the biofilm detaching activity in M9 minimal medium supplemented with sucrose. The activity disappeared after boiling and treatment with proteinase K, suggesting that the compound(s) responsible for the biofilm detaching activity was a protein. It was hypothesized that the activity might be due to levansucrase, which produce levan, however commercial levan had no effect on S. mutans biofilm formation. The biofilm detaching activity was not effective when S. mutans biofilms were allowed to form on saliva-coated surfaces. This suggests that the biofilm detaching activity might not be applicable for dental caries protection. The biofilm inhibitory activity was produced by three isolates: 6E, 10G, and 11E. The biofilm inhibitory activity was not detected when the supernatant was boiled. Many purification methods were used to separate the biofilm inhibitory however the compound has not yet been purified The compound derived from B. velezensis 6E, 10G, 11E. with S. mutans biofilm inhibitory activity in this study may have potential to be applied as an anti-dental caries agent and should be investigated further in the future.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available