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Braathen, Gabriella
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Publications (3 of 3) Show all publications
Boisen, G., Prgomet, Z., Enggren, G., Dahl, H., Mkadmi, C. & Davies, J. R. (2023). Limosilactobacillus reuteri inhibits the acid tolerance response in oral bacteria. Biofilm, 6, Article ID 100136.
Open this publication in new window or tab >>Limosilactobacillus reuteri inhibits the acid tolerance response in oral bacteria
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2023 (English)In: Biofilm, E-ISSN 2590-2075, Vol. 6, article id 100136Article in journal (Refereed) Published
Abstract [en]

Probiotic bacteria show promising results in prevention of the biofilm-mediated disease caries, but the mechanisms are not fully understood. The acid tolerance response (ATR) allows biofilm bacteria to survive and metabolize at low pH resulting from microbial carbohydrate fermentation. We have studied the effect of probiotic strains: Limosilactobacillus reuteri and Lacticaseibacillus rhamnosus on ATR induction in common oral bacteria. Communities of L. reuteri ATCC PTA5289 and Streptoccus gordonii, Streptococcus oralis, Streptococcus mutans or Actinomyces naeslundii in the initial stages of biofilm formation were exposed to pH 5.5 to allow ATR induction, followed by a low pH challenge. Acid tolerance was evaluated as viable cells after staining with LIVE/ DEAD & REG;BacLightTM. The presence of L. reuteri ATCC PTA5289 caused a significant reduction in acid tolerance in all strains except S. oralis. When S. mutans was used as a model organism to study the effects of additional probiotic strains (L. reuteri SD2112, L. reuteri DSM17938 or L. rhamnosus GG) as well as L. reuteri ATCC PTA5289 supernatant on ATR development, neither the other probiotic strains nor supernatants showed any effect. The presence of L. reuteri ATCC PTA5289 during ATR induction led to down-regulation of three key genes involved in tolerance of acid stress (luxS, brpA and ldh) in Streptococci. These data suggest that live cells of probiotic L. reuteri ATCC PTA5289 can interfere with ATR development in common oral bacteria and specific strains of L. reuteri may thus have a role in caries prevention by inhibiting development of an acid-tolerant biofilm microbiota.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Probiotics, Acid tolerance, Caries, Early oral biofilms, Pioneer species
National Category
Dentistry
Identifiers
urn:nbn:se:mau:diva-61921 (URN)10.1016/j.bioflm.2023.100136 (DOI)001038416000001 ()37408693 (PubMedID)2-s2.0-85163191080 (Scopus ID)
Available from: 2023-08-16 Created: 2023-08-16 Last updated: 2023-12-07Bibliographically approved
Boisen, G., Davies, J. R. & Neilands, J. (2021). Acid tolerance in early colonizers of oral biofilms. BMC Microbiology, 21(1), Article ID 45.
Open this publication in new window or tab >>Acid tolerance in early colonizers of oral biofilms
2021 (English)In: BMC Microbiology, E-ISSN 1471-2180, Vol. 21, no 1, article id 45Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: In caries, low pH drives selection and enrichment of acidogenic and aciduric bacteria in oral biofilms, and development of acid tolerance in early colonizers is thought to play a key role in this shift. Since previous studies have focussed on planktonic cells, the effect of biofilm growth as well as the role of a salivary pellicle on this process is largely unknown. We explored acid tolerance and acid tolerance response (ATR) induction in biofilm cells of both clinical and laboratory strains of three oral streptococcal species (Streptococcus gordonii, Streptococcus oralis and Streptococcus mutans) as well as two oral species of Actinomyces (A. naeslundii and A. odontolyticus) and examined the role of salivary proteins in acid tolerance development.

METHODS: Biofilms were formed on surfaces in Ibidi® mini flow cells with or without a coating of salivary proteins and acid tolerance assessed by exposing them to a challenge known to kill non-acid tolerant cells (pH 3.5 for 30 min) followed by staining with LIVE/DEAD BacLight and confocal scanning laser microscopy. The ability to induce an ATR was assessed by exposing the biofilms to an adaptation pH (pH 5.5) for 2 hours prior to the low pH challenge.

RESULTS: Biofilm formation significantly increased acid tolerance in all the clinical streptococcal strains (P < 0.05) whereas the laboratory strains varied in their response. In biofilms, S. oralis was much more acid tolerant than S. gordonii or S. mutans. A. naeslundii showed a significant increase in acid tolerance in biofilms compared to planktonic cells (P < 0.001) which was not seen for A. odontolyticus. All strains except S. oralis induced an ATR after pre-exposure to pH 5.5 (P < 0.05). The presence of a salivary pellicle enhanced both acid tolerance development and ATR induction in S. gordonii biofilms (P < 0.05) but did not affect the other bacteria to the same extent.

CONCLUSIONS: These findings suggest that factors such as surface contact, the presence of a salivary pellicle and sensing of environmental pH can contribute to the development of high levels of acid tolerance amongst early colonizers in oral biofilms which may be important in the initiation of caries.

Place, publisher, year, edition, pages
BioMed Central, 2021
Keywords
Acid tolerance response, Actinomyces, Pellicle, Salivary proteins, Streptococci
National Category
Dentistry
Identifiers
urn:nbn:se:mau:diva-41154 (URN)10.1186/s12866-021-02089-2 (DOI)000617808500001 ()33583397 (PubMedID)2-s2.0-85101037383 (Scopus ID)
Available from: 2021-03-10 Created: 2021-03-10 Last updated: 2024-02-05Bibliographically approved
Braathen, G., Ingildsen, V., Twetman, S., Ericson, D. & Jørgensen, M. (2017). Presence of Lactobacillus reuteri in saliva coincide with higher salivary IgA in young adults after intake of probiotic lozenges (ed.). Beneficial Microbes, 8(1), 17-22
Open this publication in new window or tab >>Presence of Lactobacillus reuteri in saliva coincide with higher salivary IgA in young adults after intake of probiotic lozenges
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2017 (English)In: Beneficial Microbes, ISSN 1876-2883, E-ISSN 1876-2891, Vol. 8, no 1, p. 17-22Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to compare the concentration of salivary immunoglobulin A (IgA) and the selected interleukins (IL)-1β, IL-6, IL-8 and IL-10 in young individuals with presence and non-presence of Lactobacillus reuteri in saliva after a three-week intervention with probiotic lozenges. The study group consisted of 47 healthy individuals aged 18-32 years with no clinical signs of oral inflammation. In a randomised, double-blind, placebo-controlled, cross-over trial participants ingested two lozenges per day containing two strains of the probiotic bacterium L. reuteri or placebo lozenges. The intervention and wash-out periods were three weeks. Stimulated and unstimulated whole saliva was collected at baseline and immediately after termination of the intervention periods. The samples were analysed for total protein, salivary IgA and selected cytokines. In this extended analysis, data were collected by analysing baseline and follow-up saliva samples related to ingestion of the probiotic lozenges for the presence of L. reuteri through DNA-extraction, PCR-amplification and gel-electrophoresis. At baseline, 27% of the individuals displayed presence of L. reuteri and 42% were positive immediately after the three-week probiotic intervention. Individuals with presence of L. reuteri in saliva had significantly higher (P<0.05) concentrations of salivary IgA and %IgA/protein at the termination of the probiotic intake compared with non-presence. No differences in the cytokine levels were observed. In conclusion, detectable levels of L. reuteri in saliva coincided with higher concentrations of salivary IgA and %IgA/protein in stimulated whole saliva after the three-week daily intake of probiotic lozenges. Our findings suggest that monitoring the presence of probiotic candidates in the oral environment is important to interpret and understand their possible immune-modulating role in maintaining oral health.

Place, publisher, year, edition, pages
Wageningen Academic Publishers, 2017
Keywords
lactobacilli, immunology, immunoglobulin, cytokine
National Category
Dentistry
Identifiers
urn:nbn:se:mau:diva-15433 (URN)10.3920/BM2016.0081 (DOI)000395551200003 ()27873545 (PubMedID)2-s2.0-85013200707 (Scopus ID)21849 (Local ID)21849 (Archive number)21849 (OAI)
Available from: 2020-03-30 Created: 2020-03-30 Last updated: 2024-04-04Bibliographically approved
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