Hyemin Kim

In addition to its role as an essential pollinator, the Western honeybee, Apis mellifera, is regarded as a good model insect due to its highly evolved sociality, labor division, and flexibility of colony management. Therefore, to identify the molecular mechanisms involved in various colony compositions and flexibility of worker division, it is essential to investigate the gene expression in various developmental stages of the honeybee. For target gene quantification, quantitative realtime PCR (qRT-PCR) has been widely used. However, a reliable reference gene stably expressing across different samples should be selected. Thus, to identify credible reference genes in honeybee colonies, we evaluated five candidate genes (RPS5, RPS18, GAPDH, ARF1, and RAD1a) in samples collected from seven developmental stages (egg, 1st instar larvae, 3rd instar larvae, 5th instar larvae, pupa, nurse, and forager) using three analysis programs algorithms (geNorm, NormFinder, and BestKeeper). Although the reference gene ranked slightly different in analysis algorithms, our study suggests that RAD1a is the most suitable reference gene for accurate normalization of target gene expression at the developmental stage of the honeybee.

Alcoholic liver fatty disease (ALFD) is caused by excessive and chronic alcohol consumption. Alcohol consumption causes an imbalance in the intestinal microflora, leading to liver disease induced by the excessive release of endotoxins into the hepatic portal vein. Therefore, research on the intestinal microflora to identify treatments for ALFD is increasing. In this study, the protective effects of lactic acid bacteria (LAB) strains, including Levilactobacillus brevis, Limosilactobacillus reuteri, and Limosilactobacillus fermentum, were evaluated in ethanol-induced HepG2 cells. Among the evaluated LAB, nine strains increased aldehyde dehydrogenase (ALDH) levels and downregulated lipid peroxidation and liver transferase in the ethanol-induced HepG2 cells. Moreover, L. brevis MG5280 and MG5311, L. reuteri MG5458, and L. fermentum MG4237 and MG4294 protected against ethanol-induced HepG2 cell damage by regulating CYP2E1, antioxidant enzymes (SOD, CAT, and GPX), lipid synthesis factors (SREBP1C and FAS), and lipid oxidation factors (PPARα, ACO, and CPT-1). Moreover, five LAB were confirmed to be safe probiotics based on antibiotic susceptibility and hemolysis assays; their stability and adhesion ability in the gastrointestinal tract were also established. In conclusion, L. brevis MG5280 and MG5311, L. reuteri MG5458, and L. fermentum MG4237 and MG4294 may be useful as new probiotic candidates for ALFD prevention.

Bacterial vaginosis (BV) is caused by a microbial imbalance of the vaginal ecosystem, causing genital discomfort and potentially even various complications in women. Moreover, research on the treatment or prevention of BV is increasing. In this study, we evaluated the antimicrobial and anti-inflammation effects of the lactic acid bacteria (LAB) Ligilactobacillus salivarius MG242, Limosilactobacillus fermentum MG901, and Lactiplantibacillus plantarum MG989 in a BV-induced mice model. The oral administration of the LAB significantly inhibited the growth of Gardnerella vaginalis up to 43% (p < 0.05). The LAB downregulated the expression of pro-inflammatory cytokines (IL-1β and TNF-α) and myeloperoxidase (p < 0.05). Upon histological examination, the exfoliation of epithelial cells in the vaginal tissues was found to be reduced in the probiotic administration group compared to the infected group. In addition, the LAB tolerated the gastric and/or intestinal simulated conditions and proliferated, showing potential in promoting health based on hemolysis activity, antibiotic susceptibility, enzyme activity, and lactic acid production. Altogether, our results showed that the investigated LAB may be a good food ingredient candidate for ameliorating BV in women.

In this study, lactic acid bacteria (LAB) strains derived from human and fermented food sources were examined to identify their properties related to obesity, as well as establish their safety and stability as probiotics. LAB (Lacticaseibacillus rhamnosus MG4502, Lactobacillus gasseri MG4524, Limosilactobacillus reuteri MG5149, and Weissella cibaria MG5285) exhibited antioxidant activity through DPPH (>26.1%) and ABTS (>40.1%) radical scavenging assays and α-glucosidase inhibitory activities (>60.3%), respectively. The LAB strains promoted anti-adipogenesis by reducing lipid accumulation in 3T3-L1 cells by Oil Red O staining (>70.3%). In addition, we found that these LAB strains were resistant to simulated gastric and intestinal fluids (pH 3, 4, 7, and 8) and showed potential for health promotion, based on hemolysis, cell adhesion, antibiotic susceptibility, and enzyme production. Thus, LAB may be used as probiotic ingredients with beneficial effects.