Measurement of metabolic activities of Porphyromonas gingivalis by impedance measurements and fluorescamine labelling technique

• Published in: FEMS immunology and medical microbiology 1993-03, Vol.6 (2‐3), p.179-180
• Main Authors: Gharbia, S.E., Shah, H.N.
• Format: Article
• Language: English
• Subjects: Bacteriology; Biological and medical sciences; Electric Impedance; Fluorescamine; Fluorescamine labelling; Fundamental and applied biological sciences. Psychology; Impedance measurement; Metabolism. Enzymes; Microbiology; Peptides - metabolism; Porphyromonas gingivalis; Porphyromonas gingivalis - metabolism
• ISSN: 0928-8244; 1574-695X
• DOI: 10.1111/j.1574-695X.1993.tb00322.x

Porphyromonas gingivalis colonizes subgingival sites where dietary carbohydrates are unavailable as bacterial growth substrates. Consequently, this species is remarkably adept at utilizing peptides as energy sources. In vivo, these substrates are probably derived from the hydrolysis of both host and bacterial macromolecules. In the present study, we employed impedance measurements and a fluorescamine labelling technique to study the utilization of peptides and amino acids by P. gingivalis strain W83. Initially there was a lag period of 0.5 h after which a linear growth response of 12.26 h was recorded for the peptide source. This was visualized as an increase in mu Siemens due to small changes in bacterial growth and was confirmed by cultural methods. There was a concomitant decrease in peptides present in the cell suspension medium. By contrast, amino acids were rapidly taken from the medium without any observed increase in cell number. This was demonstrated as a decrease in mu Siemens and was due to changes in ionic strength of the medium. A corresponding decrease in amino acid concentration correlated with these changes.