Lactose-reversible coaggregation between oral actinomycetes and Streptococcus sanguis

Area of Science:

• Microbiology
• Oral Biology
• Bacteriology

Background:

• Oral actinomycetes are key members of the human dental plaque microbiome.
• Understanding interspecies interactions, like coaggregation, is crucial for deciphering oral biofilm formation.
• Streptococcus sanguis is a common inhabitant of healthy oral flora.

Purpose of the Study:

• To investigate the coaggregation abilities of freshly isolated oral actinomycetes with Streptococcus sanguis.
• To characterize the nature of these interactions, particularly focusing on lactose-reversible mechanisms.
• To classify oral actinomycetes based on their coaggregation properties.

Main Methods:

• Isolation of oral actinomycetes from human dental plaque.
• Coaggregation assays using fresh isolates and laboratory strains of Streptococcus sanguis.
• Analysis of lactose-reversible interactions and heat treatment effects on coaggregation.
• Delineation of coaggregation groups based on observed interaction patterns.

Main Results:

• Only Actinomyces species coaggregated with Streptococcus sanguis.
• Actinomyces viscosus and Actinomyces naeslundii exhibited significant lactose-reversible coaggregation.
• Four distinct coaggregation groups were identified among the isolates.
• Over 80% of fresh isolates showed coaggregation properties similar to stock strains.

Conclusions:

• Coaggregation between oral actinomycetes and Streptococcus sanguis is largely mediated by lactose-reversible interactions.
• These interactions likely involve lectin-carbohydrate binding on complementary cell surfaces.
• The findings highlight the importance of specific cell-surface interactions in oral microbial ecology.