The inhibitory effect of dextranases from Bacillus velezensis and Pseudomonas stutzeri on Streptococcus mutans biofilm

Abstract

Background and Objectives: Dental caries is a breakdown of the teeth enamel due to harmful bacteria, lack of oral hygiene, and sugar consumption. The acid-producing bacterium Streptococcus mutans is the leading cause of dental caries. Dextra- nase is an enzyme that can degrade dextran to low molecular weight fractions, which have many therapeutic and industrial applications. The purpose of the present study was to isolate a novel dextranase-producing bacteria from asource (molasses). The cell-free extracts containing dextranases were tested as antibiofilm agents.
 Materials and Methods: Dextranase-producing bacteria were identified using phenotypic and genotypic methods such as 16S rRNA gene sequencing and enzymatic characterization.
 Results: The highest six dextranase-producing bacterial isolates were Bacillus species. The best conditions for dextranase productivity were obtained after 72hours of culture time at pH 7. The addition of glucose to the medium enhanced the pro- duction of the enzymes. The cell-free extract of the six most activeisolates showed remarkable activity against biofilm for- mation by Streptococcus mutans ATCC 25175. The highest inhibition activities reached 60% and 80%for Bacillus velezensis and Pseudomonas stutzeri, respectively.
 Conclusion: Therefore, our study added to the current dextranase-producing bacteria with potential as a source of dextra- nases.

Effect of mutanase and dextranase on biofilms of cariogenic bacteria: A systematic review of in vitro studies

“…The studies were published from 2004 to 2023, and evaluated the effect of dextranase (23 studies) [ [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] ], mutanase (ten studies) [ 25 , 39 , 44 , [48] , [49] , [50] , [51] , [52] , [53] , [54] ], or combined mutanase and dextranase treatment (seven studies) [ 25 , 39 , 44 , [55] , [56] , [57] , [58] ] on biofilm formation. Mutanase was obtained from fungi in six studies [ 44 , 48 , 53 , 55 , 57 , 58 ] and from bacteria in six studies [ 25 , 49 , [50] , [51] , [52] , [56] ], while fungal and bacterial dextranase were used in 12 [ 31 , 32 , 37 , 38 , 40 , 44 , 46 , 47 , [55] , [56] , [57] , ...…”

“… Mutanase: 20 U (volume: NR); Dextranase: 100 U (volume: NR) Biofilm removal Pre-formed 19 h-old biofilms treated with mutanase + dextranase for up to 1 h Enzyme buffer S. mutans ; TYEB with 1 % sucrose (w/v) Saliva-coated HA (disk) CLSM, CFU NA No significant differences in cell viability and CFU counts between enzyme group and control (values: NR). Liu, 2021 [ 34 ] Dextranase Bacterium Streptococcus mutans 1–500 nM Biofilm inhibition; Biofilm removal Biofilms grown in the presence of dextranase for 12 h; Pre-formed 12 h-old biofilms enzyme-treated for 30 min No treatment S. mutans ; BHI with 1 % sucrose (w/v) NR (96-well plate); glass (tube) Crystal violet staining; biofilm mass (dry weight); CLSM MBIC 50 : 1 nM; 50 nM: 92.0 %; Biofilm mass: 90.0 % (5.9 % SD); Viable cells: 86.7 % (6.3 % SD); Biofilm thickness: significant reduction (values: NR) 50 nM: 43 % (2 % SD); 500 nM: 77 % (2 % SD) Mahmoud, 2022 [ 35 ] Dextranase Bacterium Bacillus velezensis ; Bacterium Pseudomonas stutzeri 28.5 and 30.19 mU/mL Biofilm inhibition Biofilms grown in the presence of dextranase for 24 h No treatment S. mutans ; TSB NR (96-well microtiter plate) Crystal violet staining B. velezensis dextranase: 82.5 %; P. stutzeri dextranase: 84.5 % NA Ning, 2021 [ 36 ] Dextranase Bacterium Cellulosimicrobium sp. PX02 3–15 U/mL Biofilm inhibition; Biofilm removal Biofilms grown in the presence of dextranase for 24 h. Pre-formed 24 h-old biofilms enzyme-...…”

“…Biofilm inhibition (i.e. the prevention of biofilm formation) was the outcome of six studies [ [31] , [32] , [33] , 35 , 38 , 42 ], while biofilm removal was investigated by 16 studies [ [27] , [28] , [29] , 37 , [39] , [40] , [41] , 48 , 49 , [51] , [52] , [53] , [55] , [56] , [57] , [58] ]. Twelve reports compared the effect of enzymes on both outcomes [ 25 , 26 , 30 , 34 , 36 , [43] , [44] , [45] , [46] , [47] , 50 , 54 ].…”

“…Fusobacterium nucleatum , Veillonella parvula ). Eight studies did not supplement the biofilm growth media with sucrose [ 28 , 31 , 32 , 35 , 40 , 48 , 58 ] or did not specify the type of sugar added [ 41 ]. Many reports did not specify the surface the biofilms were grown on, only the type of device used for biofilm formation (e.g.…”

“…Different biofilm quantification methods were reported in the included articles. Crystal violet staining was the most common method and was used in 18 studies [ [25] , [26] , [27] , [28] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , 38 , 40 , 43 , [45] , [46] , [47] , 54 ]. Some studies employed other colorimetric analyses like alcian blue [ 50 ] or erythrosine staining [ 44 , 53 , 57 , 58 ].…”