Safety and toxicity assessment of Lactobacillus salivarius AP-32 with Probiotic potential in vivo and in vitro.

The maximum tolerated dose of L. salivarius AP-32 in a 14-day acute toxicity study was 16 g/kg body weight in rodents with no adverse effects observed.

• Acute toxicity study duration was 14 days
• Maximum tolerated dose was 16 g/kg body weight
• No adverse effects were observed at this dose
• Study was conducted in rodents

The no-observed-adverse-effect level (NOAEL) of L. salivarius AP-32 in a 90-day subchronic toxicity study was 1.88 g/kg body weight.

• Subchronic toxicity study duration was 90 days
• NOAEL was established at 1.88 g/kg body weight
• No adverse effects were observed at this dose level
• Study was conducted in rodents

L. salivarius AP-32 showed no mutagenicity in the Ames test up to a concentration of 5000 μg/mL.

• Ames test was conducted as an in vitro mutagenicity assessment
• No mutagenic response was observed at the highest tested concentration of 5000 μg/mL
• This finding supports the non-mutagenic profile of the strain in vitro

L. salivarius AP-32 showed no genotoxicity in vivo, with no chromosomal aberrations in mouse spermatogonia and no bone marrow cytotoxicity.

• In vivo genotoxicity was assessed via chromosomal aberration assay in mouse spermatogonia
• No chromosomal aberrations were detected
• Bone marrow cytotoxicity was also absent
• These results confirm a lack of in vivo mutagenic activity

L. salivarius AP-32 exhibited γ-hemolysis, bile salt hydrolase activity, was non-toxic to Caco-2 cells, and did not induce cytotoxicity.

• Hemolytic activity was characterized as γ-hemolysis, indicating a non-pathogenic hemolytic profile
• Bile salt hydrolase activity was detected
• No cytotoxicity was observed in Caco-2 cell assays
• These properties are relevant to safety assessment for probiotic use

L. salivarius AP-32 demonstrated strong acid and bile tolerance and intestinal adhesion properties.

• The strain showed strong tolerance to acidic conditions
• Bile tolerance was also characterized as strong
• Intestinal adhesion capacity was demonstrated
• These characteristics support survival and colonization in the gastrointestinal tract

L. salivarius AP-32 exhibited antimicrobial activity against five pathogenic microorganisms.

• Antimicrobial activity was demonstrated against Helicobacter pylori, Salmonella enterica subsp. enterica, Escherichia coli, Listeria monocytogenes, and Vibrio parahaemolyticus
• Activity was observed against both gram-positive and gram-negative pathogens
• This broad-spectrum antimicrobial activity supports its potential as a probiotic

L. salivarius AP-32 induced M2 macrophage polarization, suggesting immunomodulatory activity.

• The strain was found to induce M2 macrophages
• M2 macrophage polarization is associated with anti-inflammatory immune responses
• This immunomodulatory property may contribute to the probiotic potential of the strain

Prior research indicated that milk and soybean fermented L. salivarius AP-32 has potential applications in regulating blood glucose, alleviating neonatal jaundice, and suppressing vaginal and urinary tract pathogens.

• Blood glucose regulation was identified as a potential health benefit
• Alleviation of neonatal jaundice was documented in prior research
• The strain showed activity against vaginal and urinary tract pathogens
• These benefits were associated with milk and soybean fermented forms of L. salivarius AP-32

L. salivarius AP-32 was isolated from the human gut, supporting its relevance as a human-origin probiotic candidate.

• The strain was isolated from the human gut
• Human origin is considered a favorable characteristic for probiotic strains intended for human use
• The strain is also referred to as Ligilactobacillus salivarius AP-32 based on updated taxonomy