3-Phenyllactic acid generated in medicinal plant extracts fermented with plant-derived lactic acid bacteria inhibits the biofilm synthesis of Aggregatibacter actinomycetemcomitans

Abstract

In the present study, the effect of PLA on a periodontic pathogen, Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), the biofilm, and virulence-related genes was investigated. We confirmed that two lactic acid bacteria (LAB) strains isolated from plant sources, Lactiplantibacillus plantarum MSC-C2 and Pediococcus pentosaceus K40, secrete PLA into the de Man, Rogosa & Sharpe (MRS) broth when supplemented with phenyl pyruvic acid (PPA) as a precursor to PLA. Moreover, PLA was generated in the fermentation broths of two medicinal plant extracts, Paeonia lactiflora Pall (PR) and Carthamus tinctorius (CT), when used by each LAB strain and each extract supplemented with PPA. We determined that the minimum inhibitory concentration (MIC) of PLA against A. actinomycetemcomitans was 20 mM. PLA significantly decreased biofilm formation and suppressed the transcription of pgA, ltxA, and cdtB genes, which encode the poly-N-acetylglucosamine (PGA) polysaccharide of biofilm matrix and exotoxins leukotoxin and cytolethal distending toxin (CDT), respectively. The PLA produced by the MSC-C2 and K40 strains was increased several times by the addition of PPA to the MRS broth. The anti-biofilm effect of the extracts from the fermentation broth was proportional to the increasing PLA concentration, while a cumulatively higher effect than that of PLA alone suggested a combinational effect of PLA and the other metabolites, such as lactic acid (LA). Among the two medicinal plants, PLA, produced after the addition of PPA, was higher in PR extract in case of both the LAB strains. PLA production by the MSC-C2 strain in the PR extract reached 4.8 ± 0.23 mM, which was obviously higher than that in the MRS broth (3.88 ± 0.12 mM) supplemented with 1 mg/ml PPA. The activity to inhibit biofilm formation in the fermented PR extract was clearly high. PLA formed in the fermented PR extract downregulated the dispersin B encoding the dspB gene together with pgA, ltxA, and cdtB. In conclusion, this study shows a promising activity of PLA against the A. actinomycetemcomitans biofilm and virulence genes. In addition, the combinational effect of PLA and the medicinal plant extract can be achieved by fermentation with a specific plant-derived LAB strain.

Anti-Biofilm Activity of Chlorogenic Acid against Pseudomonas Using Quorum Sensing System

“…In summary, CGA influences biofilm formation by interfering with transcription regulators and signaling molecule synthesis (Figure 4e). Several studies have found that the suppressed effects were all involved in the transcriptional inhibition of genes controlling the syntheses and secretions of exopolysaccharides, extracellular proteins and virulence factors [38,39]. This study further confirms that CGA affects the Las, Rhl and Pqs systems.…”

Postbiotics Derived from L. paracasei ET-22 Inhibit the Formation of S. mutans Biofilms and Bioactive Substances: An Analysis

“…In the common organic acids of the postbiotics and secretions of L. paracasei ET-22, abundant phenyllactic acid was reported to show broad-spectrum inhibition of the biofilm formation of pathogenic bacteria, such as Actinobacillus actinomycetemcomitans , Listeria monocytogenes , Staphylococcus aureus , and Salmonella enteritidis [ 38 ]. Several studies have found that the suppressed effects were all involved in the transcriptional inhibitions of genes controlling the syntheses and secretions of exopolysaccharides, extracellular proteins, and virulence factors [ 39 , 40 , 41 , 42 ]. Another study further confirmed that phenyllactic acid played an inhibitive role on the QS system, including the Rhl and PQS QS systems, to suppress the gene expression of relative virulence-factors and biofilm development [ 43 ].…”

Quorum-quenching enzyme Est816 assisted antibiotics against periodontitis induced by Aggregatibacter actinomycetemcomitans in rats

“…The optical density values of the semi-quantitative analysis of the biofilm were detected at 570 nm using a microplate reader. To determine biofilm reduction ( Shakya et al., 2022 ), the percentages of biofilm was calculated as follows: (Abs Control represented the group without the addition of drugs). For testing biofilm eradication rates, A. actinomycetemcomitans suspension in the 96-well plate was incubated at 37 ◦ C for 48 hours to form a mature biofilm.…”