Doses of 100 million and 1 billion colony forming units (CFUs) per lozenge resulted in over 80% and 90%, respectively, of healthy young adults having detectable levels of the probiotic one week after the end of the intervention period, according to findings published in PLOS ONE.
Earlier research had indicated that two daily doses of 3.6 billion CFUs/lozenge of BLIS M18 for three months resulted in 22% of school children had detectable salivary levels of BLIS M18. Despite these comparatively lower levels of probiotic persistence in the earlier placebo-controlled trial, a significant reduction in plaque formation was observed over the three months of the trial.
“This study has shown that the persistence of a probiotic S. salivarius strain in the mouth was dose dependent,” wrote the researchers. “This ability to persist could allow the probiotic the opportunity to more effectively counter pathogens as well as inducing host gene expression pathways of homeostasis and cytoskeletal repair in the epithelial lining.”
BLIS is one of the best known probiotics for oral health, and was developed by scientists at the University of Otago in New Zealand. It is a specific strain of Streptococcus salivarius (S. salivarius), which secretes powerful antimicrobial molecules called BLIS: Bacteriocin-Like-Inhibitory Substances.
There are different BLIS ingredients available, including K12 and M18. A spokesperson for Stratum Nutrition, which distributes the probiotics in the US, explained that the primary difference between K12 and M18 are the health function or indications. “While both BLIS probiotic strains start to work in the mouth – K12 supports ENT/immune health and M18 supports dental health,” said the spokesperson.
The researchers recruited 75 people and randomly assigned to one of four dosage groups: 1 million, 10 million, 100 million, or 1 billion CFUs per lozenge for 28 days.
Results indicated that, while 60% of the subjects had measurable levels of S. salivarius in their saliva at the start of the study, the M18 strain almost entirely replaced the indigenous S. salivarius in some people. In addition, “strain M18’s persistence was dependent upon the dose, but not the period of administration”.
The results also indicated that there were no significant ecological shifts in the microbiota following the probiotic dosing, supporting that BLIS M18 colonization does not contribute to a non-specific disruption of indigenous microbiota in the oral cavity of healthy adults.
“Since no widespread perturbation of the existing indigenous microbiota was associated with oral instillation and given its antimicrobial activity against potentially pathogenic streptococci, it appears that application of probiotic strain M18 offers potential low impact alternative to classical antibiotic prophylaxis,” wrote the researchers.
In vitro work also showed that there was a transfer of small DNA molecules (plasmids) that coded for bacteriocin production into the indigenous oral S. salivarius strains. This is the first in vitro evidence of this kind of transfer.
“This opens up the possibility of creating tailor-made probiotic strains through the transmission of megaplasmids from poorly-persisting, antimicrobial producing S. salivarius strains into poor bacteriocin-producing but strongly persisting indigenous S. salivarius, strains potentially conferring better protection to the host.”
Source: PLOS ONE
Published online ahead of print, doi: 10.1371/journal.pone.0065991
“Persistence of the Oral Probiotic Streptococcus salivarius M18 Is Dose Dependent and Megaplasmid Transfer Can Augment Their Bacteriocin Production and Adhesion Characteristics”
Authors: J.P. Burton, P.A. Wescombe, J.M. Macklaim,