• Journal of Microbiology and Biotechnology
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• v.31 no.7
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• pp.949-955
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• 2021

Previously, our research group isolated Bifidobacterium breve IDCC4401 from infant feces as a potential probiotic. For this study, we evaluated the safety of B. breve IDCC4401 using genomic and phenotypic analyses. Whole genome sequencing was performed to identify genomic characteristics and investigate the potential presence of genes encoding virulence, antibiotic resistance, and mobile genetic elements. Phenotypic analyses including antibiotic susceptibility, enzyme activity, production of biogenic amines (BAs), and proportion of D-/L-lactate were evaluated using E-test, API ZYM test, high-performance liquid chromatography (HPLC), and D-/L-lactic acid assay respectively. The genome of B. breve IDCC4401 consists of 2,426,499 bp with a GC content of 58.70% and 2,016 coding regions. Confirmation of the genome as B. breve was provided by its 98.93% similarity with B. breve DSM20213. Furthermore, B. breve IDCC4401 genes encoding virulence and antibiotic resistance were not identified. Although B. breve IDCC4401 showed antibiotic resistance against vancomycin, we confirmed that this was an intrinsic feature since the antibiotic resistance gene was not present. B. breve IDCC4401 showed leucine arylamidase, cystine arylamidase, α-galactosidase, β-galactosidase, and α-glucosidase activities, whereas it did not show production of harmful enzymes such as β-glucosidase and β-glucuronidase. In addition, B. breve IDCC4401 did not produce any tyramine, histamine, putrescine, cadaverine, or 2-phenethylamine, which are frequently detected BAs during fermentation. B. breve IDCC4401 produced 95.08% of L-lactate and 4.92% of D-lactate. Therefore, our findings demonstrate the safety of B. breve IDCC 4401 as a potential probiotic for use in the food industry.

• Korean Journal of Community Nutrition
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• v.26 no.4
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• pp.259-269
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• 2021

Objectives: This study aimed to investigate the changes in the eating habits and lifestyle of middle-aged women in Gwangju during the COVID-19 pandemic. Methods: A total of 428 middle-aged women aged between 40 and 60 participated in a survey relating to general information, food and lifestyle, health functional food, and menopausal symptoms. The correlation between the variables was analyzed. Results: In the positive habits, the intake of nutritional supplements for immunity enhancement increased the most, followed by the use of media to learn healthy eating tips, and diets including healthy food. Negative habits increased in the order of frequency of taking delivery orders, levels of stress or anxiety, and time spent sitting or watching movies. In the case of recommended foods, the intake increased the most in the order of eggs, fruits, vegetables, milk/dairy products, and seaweed. Non-recommended foods increased in the order of meat, bread, rice, and noodles. The awareness of health functional foods was in the increasing order of interest, knowledge, consumption experience, and purchase amount. The type of health functional food intake was in the increasing order of probiotics, multivitamin and mineral supplements, vitamin C, collagen, and omega-3. Menopausal symptoms were in the increasing order of bone and joint pain, poor sleep quality, emotional ups and downs, loneliness, and feeling of emptiness. In the correlation of major variables, positive habits showed a significant positive correlation with recommended food intake and the recognition of health functional foods. Negative habits showed a significant positive correlation with non-recommended food intake and a significant positive correlation with menopausal symptoms. Recommended food intake showed a significant positive correlation with health functional food recognition and intake and menopausal symptoms. Conclusions: This study suggests that it is necessary to establish social measures to reduce the negative effects of the COVID-19 pandemic on middle-aged women and to ensure effective self-management through a healthy lifestyle since the pandemic has a long-term impact.

• Journal of Microbiology and Biotechnology
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• v.31 no.5
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• pp.717-725
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• 2021

This study aimed to optimize medium composition and culture conditions for enhancing the biomass of Lactobacillus plantarum 200655 using statistical methods. The one-factor-at-a-time (OFAT) method was used to screen the six carbon sources (glucose, sucrose, maltose, fructose, lactose, and galactose) and six nitrogen sources (peptone, tryptone, soytone, yeast extract, beef extract, and malt extract). Based on the OFAT results, six factors were selected for the Plackett-Burman design (PBD) to evaluate whether the variables had significant effects on the biomass. Maltose, yeast extract, and soytone were assessed as critical factors and therefore applied to response surface methodology (RSM). The optimal medium composition by RSM was composed of 31.29 g/l maltose, 30.27 g/l yeast extract, 39.43 g/l soytone, 5 g/l sodium acetate, 2 g/l K₂HPO₄, 1 g/l Tween 80, 0.1 g/l MgSO₄·7H₂O, and 0.05 g/l MnSO₄·H₂O, and the maximum biomass was predicted to be 3.951 g/l. Under the optimized medium, the biomass of L. plantarum 200655 was 3.845 g/l, which was similar to the predicted value and 1.58-fold higher than that of the unoptimized medium (2.429 g/l). Furthermore, the biomass increased to 4.505 g/l under optimized cultivation conditions. For lab-scale bioreactor validation, batch fermentation was conducted with a 5-L bioreactor containing 3.5 L of optimized medium. As a result, the highest yield of biomass (5.866 g/l) was obtained after 18 h of incubation at 30℃, pH 6.5, and 200 rpm. In conclusion, mass production by L. plantarum 200655 could be enhanced to obtain higher yields than that in MRS medium

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.280-289
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• 2021

Genetic markers currently used for the discrimination of Lactobacillus delbrueckii subspecies have low efficiency for identification at subspecies level. Therefore, our objective in this study was to select novel genetic markers for accurate identification and discrimination of six L. delbrueckii subspecies based on pangenome analysis. We evaluated L. delbrueckii genomes to avoid making incorrect conclusions in the process of selecting genetic markers due to mislabeled genomes. Genome analysis showed that two genomes of L. delbrueckii subspecies deposited at NCBI were misidentified. Based on these results, subspecies-specific genetic markers were selected by comparing the core and pangenomes. Genetic markers were confirmed to be specific for 59,196,562 genome sequences via in silico analysis. They were found in all strains of the same subspecies, but not in other subspecies or bacterial strains. These genetic markers also could be used to accurately identify genomes at the subspecies level for genomes known at the species level. A real-time PCR method for detecting three main subspecies (L. delbrueckii subsp. delbrueckii, lactis, and bulgaricus) was developed to cost-effectively identify them using genetic markers. Results showed 100% specificity for each subspecies. These genetic markers could differentiate each subspecies from 44 other lactic acid bacteria. This real-time PCR method was then applied to monitor 26 probiotics and dairy products. It was also used to identify 64 unknown strains isolated from raw milk samples and dairy products. Results confirmed that unknown isolates and subspecies contained in the product could be accurately identified using this real-time PCR method.

• Journal of Periodontal and Implant Science
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• v.51 no.3
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• pp.199-212
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• 2021

Purpose: This randomized clinical placebo-controlled trial was conducted to evaluate the effectiveness of Lactobacillus reuteri as a probiotic in guided pocket recolonization (GPR) for the treatment of chronic periodontitis (CP) adjunctive to scaling and root planing (SRP). Methods: Forty-eight CP patients were randomly assigned to 3 treatment groups: group 1 (SRP+placebo), group 2 (SRP+single application of probiotic), and group 3 (SRP+incremental application of probiotic). Clinical parameters were evaluated at baseline and at 8, 12, and 24 weeks, whereas biochemical parameters were measured at baseline and 12 weeks. Results: At 24 weeks, the probing pocket depth and clinical attachment level improved in all 3 groups from baseline with no significant intergroup differences; however, a statistically significant difference was observed in localized plaque and gingival scores between groups 1 and 3 (P<0.05). At 12 weeks, matrix metalloproteinase-8 (MMP-8), nitric oxide (NO), and gingipains-R (Rgps) levels improved in all 3 groups, with statistically significant differences between groups 1 and 3 for MMP-8 and NO (P<0.05), but no difference for Rgps levels. Conclusions: Within its limitations, the results of this study show that incremental 3-time application of L. reuteri as a probiotic led to improvements in clinical and biochemical parameters. This protocol can be a useful adjunct to SRP in the non-surgical management of CP.

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.92-103
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• 2021

Lactobacillus casei, one of the most widely used probiotics, has been reported to alleviate multiple diseases. However, the effects of this species on intestinal diseases are strain-specific. Here, we aimed to screen L. casei strains with inflammatory bowel disease (IBD)-alleviating effects based on in vitro physiological characteristics. Therefore, the physiological characteristics of 29 L. casei strains were determined, including gastrointestinal transit tolerance, oligosaccharide fermentation, HT-29 cell adhesion, generation time, exopolysaccharide production, acetic acid production, and conjugated linoleic acid synthesis. The effects of five candidate strains on mice with induced colitis were also evaluated. The results showed that among all tested L. casei strains, only Lactobacillus casei M2S01 effectively relieved colitis. This strain recovered body weight, restored disease activity index score, and promoted anti-inflammatory cytokine expression. Gut microbiota sequencing showed that L. casei M2S01 restored a healthy gut microbiome composition. The western blotting showed that the alleviating effects of L. casei M2S01 on IBD were related to the inhibition of the NF-κB pathway. A good gastrointestinal tolerance ability may be one of the prerequisites for the IBD-alleviating effects of L. casei. Our results verified the efficacy of L. casei in alleviating IBD and lay the foundation for the rapid screening of L. casei strain with IBD-alleviating effects.

• Journal of Microbiology and Biotechnology
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• v.31 no.11
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• pp.1545-1551
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• 2021

Exopolysaccharides (EPSs) such as capsular polysaccharide (CPS) are important bioactive carbohydrate compounds and are often used as bioenrichment agents and bioabsorbers to remove environmental pollutants like di-n-butyl phthalate (DBP). Among the EPS-producing bacteria, lactic acid bacteria (LAB) have gained the most attention. As generally recognized as safe (GRAS) microorganisms, LAB can produce EPSs having many different structures and no health risks. However, EPS production by LAB does not meet the needs of large-scale application on an industrial scale. Here, the capA gene (encoding CPS biosynthesis protein) was overexpressed in Lactobacillus plantarum P1 to improve the production of EPSs and further enhance the DBP adsorption capability. Compared with P1, the CPS production in capA overexpressed strain was increased by 11.3 mg/l, and the EPS thickness was increased from 0.0786 ± 0.0224 ㎛ in P1 to 0.1160 ± 0.0480 ㎛ in P1-capA. These increases caused the DBP adsorption ratio of P1-capA to be doubled. Overall, the findings in this study provide a safe method for the adsorption and removal of DBP.

• Journal of Microbiology and Biotechnology
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• v.32 no.1
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• pp.72-80
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• 2022

In this study, the survival capacity (acid and bile salt tolerance, and adhesion to gut epithelial cells) and probiotic properties (enzyme activity-inhibition and anti-inflammatory activities, inhibition of adipogenesis, and stress hormone level reduction) of Lactiplantibacillus plantarum LRCC5314, isolated from kimchi (Korean traditional fermented cabbage), were investigated. LRCC5314 exhibited very stable survival at ph 2.0 and in 0.2% bile acid with 89.9% adhesion to Caco-2 intestinal epithelial cells after treatment for 2 h. LRCC5314 also inhibited the activities of α-amylase and α-glucosidase, which are involved in elevating postprandial blood glucose levels, by approximately 72.9% and 51.2%, respectively. Treatment of lipopolysaccharide (LPS)-stimulated RAW 264.7 cells with the LRCC5314 lysate decreased the levels of the inflammatory factors nitric oxide, tumor necrosis factor (TNF-α), interleukin (IL)-1β, and interferon-γ by 88.5%, 49.3%, 97.2%, and 99.8%, respectively, relative to those of the cells treated with LPS alone. LRCC5314 also inhibited adipogenesis in differentiating preadipocytes (3T3-L1 cells), showing a 14.7% decrease in lipid droplet levels and a 74.0% decrease in triglyceride levels, as well as distinct reductions in the mRNA expression levels of adiponectin, FAS, PPAR/γ, C/EBPα, TNF-α, and IL-6. Moreover, LRCC5314 reduced the level of cortisol, a hormone with important effect on stress, by approximately 35.6% in H295R cells. L. plantarum LRCC5314 is identified as a new probiotic with excellent in vitro multifunctional properties. Subsequent in vivo studies may further demonstrate its potential as a functional food or pharmabiotic.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.244-250
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• 2021

Purpose: The purpose of this study was to examine effects of culture conditions on the growth and antibacterial activity of Streptococcus salivarius K12. Materials and Methods: S. salivarius K12 was cultivated in medium containing animal and plant protein or in medium of neutral and acidic conditions. The growth of S. salivarius K12 was measured every 2 hours by a spectrophotometer. The antimicrobial activity of S. salivarius K12 against Streptococcus mutans and Porphyromonas gingivalis was investigated by the susceptibility assay using the spent culture medium. Results: the growth of S. salivarius K12 showed faster in medium containing plant protein and neutral pH condition. The antimicrobial and antifungal activity of S. salivarius K12 appeared stronger in medium containing plant protein than animal proteins. Conclusion: For application of S. salivarius K12 to bacterial oral disease, co-substances may be needed for S. salivarius K12 to colonize in the oral cavity and enhance the antimicrobial activity.

• Journal of Microbiology and Biotechnology
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• v.32 no.5
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• pp.612-620
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• 2022

Recent studies have revealed that probiotics and their metabolites are present under various conditions; however, the role of probiotic metabolites (i.e., postbiotics in pathological states) is controversial. Natural killer (NK) cells play a key role in innate and adaptive immunity. In this study, we examined NK cell activation influenced by a postbiotics mixture in response to gut microbiome modulation in stress-induced mice. In vivo activation of NK cells increased in the postbiotics mixture treatment group in accordance with Th1/Th2 expression level. Meanwhile, the Red Ginseng treatment group, a reference group, showed very little expression of NK cell activation. Moreover, the postbiotics mixture treatment group in particular changed the gut microbiome composition. Although the exact role of the postbiotics mixture in regulating the immune system of stress-induced mice remains unclear, the postbiotics mixture-induced NK cell activation might have affected gut microbiome modulation.