Mixed Continuous Cultures of Streptococcus mutans with Streptococcus sanguis or with Streptococcus oralis as a Model to Study the Ecological Effects of the Lactoperoxidase System

Abstract

Mixed continuous cultures of Streptococcus species were obtained, using complex carbohydrate (mucin) as a source of nutrients, to study the ecological effects of oxygen and the lactoperoxidase system. S. mutans NCTC10449 was unable to grow as a pure culture on mucin, but attained a significant population size in the presence of S. oralis and S. sanguis strains. The cell densities of the anaerobic mixed cultures decreased when oxygen was supplied, and S. mutans was more suppressed by oxygen than were S. sanguis and S. oralis. However, the concentrations of hydrogen peroxide (30 μmol/l in the mixed culture of S. mutans with S. sanguis and 640 μmol/l in the culture with S. oralis) indicated a certain resistance of the organisms to hydrogen peroxide. Addition of lactoperoxidase and thiocyanate to the oxygen-supplied cultures had a differential effect on the streptococcal populations. While S. mutans was inhibited, and even disappeared in the culture with S. oralis, the growth of S. sanguis and S. oralis was unaffected. This latter observation was in accordance with the OSCN^–– reductase activities of these organisms. When hydrogen peroxide was also added together with lactoperoxidase and thiocyanate, a further inhibition of S. mutans in the culture with S. sanguis was observed. Under these conditions, S. oralis was also inhibited, perhaps by the strong accumulation of OSCN^––, exceeding the capacity of the OSCN^–– reductase. The effects of lactoperoxidase on mixed cultures may reflect the situation in the mouth. Depending on the production of hydrogen peroxide in the environment, mutans streptococci would be inhibited by OSCN^––, while populations of other streptococci would be much less affected by peroxidases in saliva.

Do probiotics offer opportunities to manipulate the periodontal oral microbiota?

“…In this aspect, Hillman & Shivers (1988) showed in a gnotobiotic rat model that the level of A. actinomycetemcomitans colonization in these rats was 45‐fold lower in animals infected with a hydrogen peroxide‐producing S. sanguinis strain when compared with rats infected with a hydrogen peroxide‐deficient mutant of this S. sanguinis strain. Vanderhoeven & Camp (1993) also showed that S. mutans , in co‐culture with S. sanguinis , was more inhibited when hydrogen peroxide was added to the mixture.…”

Influence of Environmental Conditions on Hydrogen Peroxide Formation by Streptococcus gordonii

“…We have examined how certain conditions which emulate those in the oral environment influence hydrogen peroxide synthesis by S. gordonii. Maximal peroxidogenesis is desirable since it seems to be one of the factors in the oral cavity that suppresses the growth of cohabiting cariogenic and periodontal pathogens (16,17,35). Numerous clinical studies have shown that the presence of peroxidogenic streptococci is correlated with the absence of tooth decay and periodontal disease (1,8,9,16,25,32,33).…”

“…pathogens listed above are also susceptible to hypothiocyanite ion (OSCN Ϫ ) (7,35). This antimicrobial agent is generated by salivary peroxidase using streptococcal hydrogen peroxide and thiocyanate ion (SCN Ϫ ), a common component of saliva (27).…”

Effect of cigarette smoke exposure on the growth of Streptococcus mutans and Streptococcus sanguis: An in vitro study

“…S. mutans is the main micro-organism causing dental caries. S. sanguis indirectly affects the caries process through its competition with S. mutans for the inhabitation of extant oral niches during dental plaque formation (Carlsson, Soderholm, & Almfeldt, 1969;Carlsson, Grahnen, Jonsson, & Wikner, 1970) and also the direct biochemical antagonism in situ (van der Hoeven & Camp, 1993). It has been suggested that the higher the ratio of cariogenic bacteria (such as S. mutans) to non-cariogenic bacteria (such as S. sanguis), the higher the risk of developing dental caries and vice versa (de Stoppelaar, van Houte, & Backer-Dirks, 1969;Loesche, Rowan, Straffon, & Loos, 1975).…”