Enrichment of subgingival microflora on human serum leading to accumulation of Bacteroides species, Peptostreptococci and Fusobacteria

Abstract

This study was undertaken to identify ecological factors that favour opportunistic pathogenic species in the subgingival microflora. In a first approach, human serum as a substitute for gingival exudate, was used for batch-wise enrichment of subgingival plaque. The microflora resulting after 5-6 enrichment steps consisted of black-pigmented and non-black-pigmented Bacteroides species, Peptostreptococcus micros and Fusobacterium nucleatum as the main organisms. It is noted that the same group of species was found to be enriched independent upon the origin of the subgingival plaque sample. It was suggested that these organisms are favoured by the increased flow of gingival exudate during inflammation. The consortium of organisms was capable of selective degradation of serum (glyco-)proteins. Four different types of degradation occurred. After a prolonged period of growth complete degradation of immunoglobulins, haptoglobin, transferrin and complement C3c was observed. Partial degradation of immunoglobulins, haptoglobin, transferrin, albumin, alpha 1-antitrypsin and complement C3c and C4 was generally observed after 48 h of growth. Besides, immunoglobulin protease activity yielding Fc and Fab fragments was found. The consortium was also capable of consuming carbohydrate side-chains as indicated by an altered electrophoretic mobility of the serum glycoproteins.

Are dental diseases examples of ecological catastrophes?

“…Serum has been used as a surrogate for GCF in experiments modelling how the balance of the oral microflora is affected by changes in nutrient status that might occur in the gingival crevice during inflammation. Human serum was used for batch-wise enrichments of samples of subgingival plaque (ter Steeg et al, 1987). After 5-6 enrichment steps, the composition of the microflora showed few similarities with the original plaque sample, and consisted mainly of black-pigmented and non-pigmented Gram-negative anaerobes together with anaerobic streptococci.…”

Physiological Approaches to the Control of Oral Biofilms

“…For example, black-pigmented anaerobes require hemin for growth, and they probably obtain this key cofactor by degrading heme-containing host molecules (hemoglobin, hemopexin, haptoglobin) present in GCF, the flow of which is increased during inflammation. The detection and levels of periodontal pathogens were enhanced when enrichment cultures of subgingival plaque were carried out on human serum, which was used to simulate growth on GCF (ter Steeg et al, 1987Steeg et al, , 1988. There are also (contradictory) data implying that the rise in subgingival levels of Prevotella intermedia seen sometimes during pregnancy is due to the metabolism of the hormones estradiol and progesterone (Kornman, 1982), which can be detected in GCF, while increases in Prevotella spp.…”

“…A similar shift in pH dramatically altered the balance of a community of three black-pigmented anaerobes, with the proportions of P. gingivalis increasing from < 1% at pH 7.0 to > 99% of the cultivable microflora at pH 7.5 (McDermid et al, 1990). Similarly, growth of subgingival plaque on human serum (used as a substrate to mimic GCF) resulted in the enrichment of periodontal pathogens (ter Steeg et al, 1987(ter Steeg et al, , 1988. GCF and serum would provide peptides and heme-containing molecules which are essential for the growth of many periodontopathogens.…”

Use of Quantitative PCR and Culture Methods To Characterize Ecological Flux in Bacterial Biofilms

“…Serum is a constituent of gingival crevicular fluid (GCF) and has been shown to enhance the growth of Prevotella spp. and P. gingivalis (27). Prevotella spp.…”