Heat-treated Pediococcus acidilactici LM1013-mediated inhibition of biofilm formation by Cutibacterium acnes and its application in acne vulgaris: A single-arm clinical trial.

PURPOSE: Acne vulgaris is a common skin disease accompanied by chronic inflammation in the pilosebaceous follicles, resulting from excessive Cutibacterium acnes. This study aimed to investigate the inhibition of biofilm formation by C. acnes ATCC 6919 using heat-treated Pediococcus acidilactici LM1013 (HT-LM1013), previously isolated from the Korean traditional fermented alcoholic beverage-makgeolli, and its application as a leave-on-type product for patients with acne vulgaris. METHODS: HT-LM1013 was prepared by Lactomason and homogenized using a high-pressure homogenizer. The minimum inhibitory concentration (MIC), tricarboxylic acid (TCA) cycle, and lipase activity were evaluated for C. acnes inhibition. Inhibition of biofilm formation was demonstrated using a crystal violet solution. Damaged C. acnes was observed using field-emission scanning electron microscopy (FE-SEM). Clinical trials were performed using a leave-on-type product containing HT-LM1013. RESULTS: HT-LM1013 inhibited the TCA cycle (36.80%) and lipase activity using palmitate (31.89%), stearate (36.91%), and oleate (30.86%) as substrates at 1 × MIC (p < 0.01). After treatment with HT-LM1013, concave and elongated shapes of C. acnes were observed by FE-SEM. In addition, HT-LM1013 inhibited biofilm formation by 71.75% at 1 × MIC (p < 0.001) and removed 73.35% of mature biofilms (p < 0.01). In the clinical trial, the leave-on-type product decreased the number of closed comedones from 14.04 to 10.22, open comedones from 7.22 to 4.39%, and sebum content to 76.23% at week 4 (p < 0.01). The satisfaction score of the participants was recorded 3.83 on a five-point scale. CONCLUSION: HT-LM1013 is potent for the treatment of acne vulgaris.

Characterization of a novel extracellular α-amylase from Ruminococcus bromii ATCC 27255 with neopullulanase-like activity.

Ruminococcus is one of the keystone bacteria of the human colonic microbiota and is highly specific for utilization of resistant starch via formation of amylosomes. Here, we present the characteristics of an extracellular amylase, Rbamy5, in Ruminococcus bromii. In an in silico study, it showed low homology with any other known amylases, but it was evolutionarily classified as a GH13_36 subfamily intermediary amylase. Recombinant Rbamy5 exhibited maximum activity toward amylose (384 ±â€¯26 U·mg-1) over soluble starch (254 ±â€¯3 U·mg-1), amylopectin (46.1 ±â€¯2.6 U·mg-1) and pullulan (72.5 ±â€¯0.41 U·mg-1) at 45 °C and pH 5.0. It was also able to degrade small substrates such as maltotriose (G3), maltotetraose (G4), and maltopentaose (G5) into maltose (G2). Despite lacking a specific N-terminal domain, Rbamy5 opened the cyclodextrin ring, which resembles those of neopullulanase. Moreover, it accumulated short α-(1 → 6)-branched maltooligosaccharides from soluble starch and maltosyl-ß-cyclodextrin (G2-ß-CD), while panose was solely derived from pullulan. These results suggest that Rbamy5 may have a role to provide branched maltooligosaccharides to stimulate the growth of beneficial microorganisms in the human intestine.