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  • 1. Basic, Amina
    et al.
    Blomqvist, Madeleine
    Malmö högskola, Faculty of Odontology (OD). Malmö högskola, Biofilms Research Center for Biointerfaces.
    Dahlen, Gunnar
    Svensäter, Gunnel
    Malmö högskola, Faculty of Odontology (OD). Malmö högskola, Biofilms Research Center for Biointerfaces.
    The proteins of Fusobacterium spp. involved in hydrogen sulfide production from L-cysteine2017In: BMC Microbiology, E-ISSN 1471-2180, Vol. 17, no 61Article in journal (Refereed)
    Abstract [en]

    Background: Hydrogen sulfide (H2S) is a toxic foul-smelling gas produced by subgingival biofilms in patients with periodontal disease and is suggested to be part of the pathogenesis of the disease. We studied the H2S-producing protein expression of bacterial strains associated with periodontal disease. Further, we examined the effect of a cysteine-rich growth environment on the synthesis of intracellular enzymes in F. nucleatum polymorphum ATCC 10953. The proteins were subjected to one-dimensional (1DE) and two-dimensional (2DE) gel electrophoresis An in-gel activity assay was used to detect the H2S-producing enzymes; Sulfide from H2S, produced by the enzymes in the gel, reacted with bismuth forming bismuth sulfide, illustrated as brown bands (1D) or spots (2D) in the gel. The discovered proteins were identified with liquid chromatography - tandem mass spectrometry (LC-MS/MS). Results: Cysteine synthase and proteins involved in the production of the coenzyme pyridoxal 5'phosphate (that catalyzes the production of H2S) were frequently found among the discovered enzymes. Interestingly, a higher expression of H2S-producing enzymes was detected from bacteria incubated without cysteine prior to the experiment. Conclusions: Numerous enzymes, identified as cysteine synthase, were involved in the production of H2S from cysteine and the expression varied among Fusobacterium spp. and strains. No enzymes were detected with the in-gel activity assay among the other periodontitis-associated bacteria tested. The expression of the H2S-producing enzymes was dependent on environmental conditions such as cysteine concentration and pH but less dependent on the presence of serum and hemin.

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  • 2.
    Boisen, Gabriella
    et al.
    Malmö University, Faculty of Odontology (OD). Malmö University, Biofilms Research Center for Biointerfaces.
    Davies, Julia R
    Malmö University, Faculty of Odontology (OD). Malmö University, Biofilms Research Center for Biointerfaces.
    Neilands, Jessica
    Malmö University, Faculty of Odontology (OD). Malmö University, Biofilms Research Center for Biointerfaces.
    Acid tolerance in early colonizers of oral biofilms2021In: BMC Microbiology, E-ISSN 1471-2180, Vol. 21, no 1, article id 45Article in journal (Refereed)
    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.

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  • 3.
    Robertsson, Carolina
    et al.
    Malmö University, Faculty of Odontology (OD). Malmö University, Biofilms Research Center for Biointerfaces.
    Svensäter, Gunnel
    Malmö University, Faculty of Odontology (OD). Malmö University, Biofilms Research Center for Biointerfaces.
    Blum, Zoltan
    Malmö University, Faculty of Health and Society (HS), Department of Biomedical Science (BMV).
    Wickström, Claes
    Malmö University, Faculty of Odontology (OD). Malmö University, Biofilms Research Center for Biointerfaces.
    Intracellular Ser/Thr/Tyr phosphoproteome of the oral commensal Streptococcus gordonii DL12020In: BMC Microbiology, E-ISSN 1471-2180, Vol. 20, no 1, article id 280Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: To respond and adapt to environmental challenges, prokaryotes regulate cellular processes rapidly and reversibly through protein phosphorylation and dephosphorylation. This study investigates the intracellular proteome and Ser/Thr/Tyr phosphoproteome of the oral commensal Streptococcus gordonii. Intracellular proteins from planktonic cells of S. gordonii DL1 were extracted and subjected to 2D-gel electrophoresis. Proteins in general were visualized using Coomassie Brilliant Blue and T-Rex staining. Phosphorylated proteins were visualized with Pro-Q Diamond Phosphoprotein Gel Stain. Proteins were identified by LC-MS/MS and sequence analysis.

    RESULTS: In total, sixty-one intracellular proteins were identified in S. gordonii DL1, many of which occurred at multiple isoelectric points. Nineteen of these proteins were present as one or more Ser/Thr/Tyr phosphorylated form. The identified phosphoproteins turned out to be involved in a variety of cellular processes.

    CONCLUSION: Nineteen phosphoproteins involved in various cellular functions were identified in S. gordonii. This is the first time the global intracellular Ser/Thr/Tyr phosphorylation profile has been analysed in an oral streptococcus. Comparison with phosphoproteomes of other species from previous studies showed many similarities. Proteins that are consistently found in a phosphorylated state across several species and growth conditions may represent a core phosphoproteome profile shared by many bacteria.

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  • 4.
    Senneby, Anna
    et al.
    Malmö högskola, Faculty of Odontology (OD). Malmö högskola, Biofilms Research Center for Biointerfaces.
    Davies, Julia
    Malmö högskola, Faculty of Odontology (OD). Malmö högskola, Biofilms Research Center for Biointerfaces.
    Svensäter, Gunnel
    Malmö högskola, Faculty of Odontology (OD). Malmö högskola, Biofilms Research Center for Biointerfaces.
    Neilands, Jessica
    Malmö högskola, Faculty of Odontology (OD). Malmö högskola, Biofilms Research Center for Biointerfaces.
    Acid tolerance properties of dental biofilms in vivo2017In: BMC Microbiology, E-ISSN 1471-2180, Vol. 17Article in journal (Refereed)
    Abstract [en]

    Background: The ecological plaque hypothesis explains caries development as the result of the enrichment of acid tolerant bacteria in dental biofilms in response to prolonged periods of low pH. Acid production by an acid tolerant microflora causes demineralisation of tooth enamel and thus, individuals with a greater proportion of acid tolerant bacteria would be expected to be more prone to caries development. Biofilm acid tolerance could therefore be a possible biomarker for caries prediction. However, little is known about the stability of biofilm acid tolerance over time in vivo or the distribution throughout the oral cavity. Therefore the aim of this study was to assess intra-individual differences in biofilm acid-tolerance between different tooth surfaces and inter-individual variation as well as stability of acid tolerance over time. Results: The majority of the adolescents showed low scores for biofilm acid tolerance. In 14 of 20 individuals no differences were seen between the three tooth sites examined. In the remaining six, acid-tolerance at the premolar site differed from one of the other sites. At 51 of 60 tooth sites, acid-tolerance at baseline was unchanged after 1 month. However, acid tolerance values changed over a 1-year period in 50% of the individuals. Conclusions: Biofilm acid tolerance showed short-term stability and low variation between different sites in the same individual suggesting that the acid tolerance could be a promising biological biomarker candidate for caries prediction. Further evaluation is however needed and prospective clinical trials are called for to evaluate the diagnostic accuracy.

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