Prevention of oral biofilm formation and degradation of biofilm by recombinant α-1,3-glucanases from Streptomyces thermodiastaticus HF3-3

J Gen Appl Microbiol. 2020 Nov 30;66(5):256-264. doi: 10.2323/jgam.2019.11.003. Epub 2020 Jun 26.


The genes encoding α-1,3-glucanases (Agls; AglST1 and AglST2) from Streptomyces thermodiastaticus HF3-3 were cloned and were then expressed in Escherichia coli Rosetta-gami B (DE3). We purified the resultant histidine (His)-tagged α-1,3-glucanases (recombinant enzymes, rAglST1 and rAglST2). Both the recombinant enzymes were similar to the wild-type enzymes. We examined the effects of rAglST1 and rAglST2 on the formation and degradation of biofilms on glass plates with Streptococcus mutans NRBC 13955 by evaluating the biofilm content (%), release of reducing sugar (mM), release of S. mutans (log CFU/mL), and the biofilm structure using laser scanning microscopy (LSM). The results showed that after incubation for 16 h, rAglST1 and rAglST2 reduced the formation of biofilm to 52% and 49% of the control, respectively. The result may reflect the fact that the concentration of the reducing sugar and the number of S. mutans cells in the rAglATs-added medium were higher than in the control medium. After an 8-h treatment with rAglST1 and rAglST2, biofilms decreased to less than 60% of the control. The number of S. mutans cells in the reaction mixture gradually increased during the incubation period. The enzymes can degrade the biofilms that were pre-formed on the glass plate by more than 50% after a 30-min incubation in the presence of toothpaste ingredients (1% w/v of sodium fluoride, benzethonium chloride, and sodium dodecyl sulfate) at 50°C. Our study showed that rAglST1 and rAglST2 have advantageous properties for dental care applications.

Keywords: Streptomyces thermodiastaticus; biofilm; degradation; prevention; α-1,3-glucanase.

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Bacterial Proteins / pharmacology*
  • Biofilms / drug effects*
  • Biofilms / growth & development
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Glycoside Hydrolases / genetics
  • Glycoside Hydrolases / metabolism
  • Glycoside Hydrolases / pharmacology*
  • Hydrogen-Ion Concentration
  • Recombinant Proteins / metabolism
  • Recombinant Proteins / pharmacology
  • Streptococcus mutans / drug effects
  • Streptococcus mutans / growth & development
  • Streptococcus mutans / metabolism
  • Streptomyces / enzymology*
  • Streptomyces / genetics
  • Temperature
  • Toothpastes / chemistry


  • Bacterial Proteins
  • Recombinant Proteins
  • Toothpastes
  • Glycoside Hydrolases
  • endo-1,3-alpha-glucanase

Supplementary concepts

  • Streptomyces thermodiastaticus