Writing in the Journal of Periodontal Research, scientists from São Paulo State University report that both live L. reuteri or its cell‐free supernatant displayed activity against Porphyromonas gingivalis, which they describe as a “keystone periodontal pathogen”.
However, only the live probiotic increased hemocyte levels in the Galleria mellonella invertebrate model after infection by P. gingivalis, said the researchers.
“We have demonstrated that live Lactobacillus reuteri and its cell‐free supernatant have an antimicrobial effect against P. gingivalis and that the antimicrobial and immunomodulatory effects of L. reuteri in vivo do not depend on cell viability. This allows the development of products without live bacteria while maintaining similar effects,” they wrote.
Periodontitis is a serious gum infection that destroys the soft tissue and bone supporting the teeth. It is reportedly the second most common disease worldwide, with 30–50% of the US population suffering from it.
Previous studies have reported that Lactobacillus reuteri may be effective against Porphyromonas gingivalis, but nobody had evaluated if heat-killed L. reuteri or its cell-free culture supernatant also had activity.
Data from the new in vitro study indicated that both live L reuteri and its supernatant reduced the colony forming units of P. gingivalis by up to 86%.
In addition, live and heat-killed L. reuteri had similar effects on the survival of Galleria mellonella, an described by the researchers as an “alternative experimental in vivo infection model to traditional mammals”. Both live and dead L. reuteri increased survival by up to 46%, said the researchers.
“L. reuteri metabolites are present in different concentrations in live bacterial suspension and in the supernatant, since special conditions of time and substrate addition (glycerol) were offered to the culture to prepare the supernatant,” they explained.
“Once we have evaluated the antimicrobial effect of the whole cell‐free supernatant, further studies are necessary to identify and characterize each bioactive substance of the supernatant and its effects on the inhibition of P. gingivalis growth.”
Source: Journal of Periodontal Research
Published online ahead of print, doi: 10.1111/jre.12704
“Heat‐killed Lactobacillus reuteri and cell‐free culture supernatant have similar effects to viable probiotics during interaction with Porphyromonas gingivalis”
Authors: B.M.C. Geraldo et al.