Confocal Raman microscopy to identify bacteria in oral subgingival biofilm models

PLoS One. 2020 May 11;15(5):e0232912. doi: 10.1371/journal.pone.0232912. eCollection 2020.

Abstract

The study of oral disease progression, in relation to the accumulation of subgingival biofilm in gingivitis and periodontitis is limited, due to either the ability to monitor plaque in vitro. When compared, optical spectroscopic techniques offer advantages over traditional destructive or biofilm staining approaches, making it a suitable alternative for the analysis and continued development of three-dimensional structures. In this work, we have developed a confocal Raman spectroscopy analysis approach towards in vitro subgingival plaque models. The main objective of this study was to develop a method for differentiating multiple oral subgingival bacterial species in planktonic and biofilm conditions, using confocal Raman microscopy. Five common subgingival bacteria (Fusobacterium nucleatum, Streptococcus mutans, Veillonella dispar, Actinomyces naeslundii and Prevotella nigrescens) were used and differentiated using a 2-way orthogonal Partial Least Square with Discriminant Analysis (O2PLS-DA) for the collected spectral data. In addition to planktonic growth, mono-species biofilms cultured using the 'Zürich Model' were also analyzed. The developed method was successfully used to predict planktonic and mono-species biofilm species in a cross validation setup. The results show differences in the presence and absence of chemical bands within the Raman spectra. The O2PLS-DA model was able to successfully predict 100% of all tested planktonic samples and 90% of all mono-species biofilm samples. Using this approach we have shown that Confocal Raman microscopy can analyse and predict the identity of planktonic and mono-species biofilm species, thus enabling its potential as a technique to map oral multi-species biofilm models.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinomyces
  • Bacteria / isolation & purification*
  • Bacteriological Techniques / methods
  • Biofilms / growth & development
  • Culture Media
  • Fusobacterium nucleatum
  • Gingiva / microbiology
  • Gingivitis / microbiology*
  • Microbial Viability
  • Microbiota
  • Microscopy, Confocal / methods
  • Nonlinear Optical Microscopy / methods*
  • Periodontitis / microbiology*
  • Plankton
  • Prevotella intermedia
  • Streptococcus mutans
  • Veillonella

Substances

  • Culture Media

Supplementary concepts

  • Actinomyces naeslundii
  • Veillonella dispar

Grants and funding

This work is funded by the European Union’s Horizon 2020 research innovation programme under grant agreement No. 722871 in the scope of the Marie Skłodowska-Curie Action ITN BioClean to LSK. P&G and other partners contributed time, industrial supervision, training and technical guidance/expertise, access to equipment, placements in industry and co-authored and reviewed associated papers, including this submission all in line with EU Horizon 2020 funding rules. More details can be found on the Horizon 2020 website (http://www.biocleanh2020.eu/index.php). The funders had no role in study design, data collection and analysis, or decision to publish the manuscript.