• Asian-Australasian Journal of Animal Sciences
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• v.29 no.10
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• pp.1490-1499
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• 2016

In this study, 69 lactobacilli isolated from Tibetan Qula, a raw yak milk cheese, were screened for their potential use as probiotics. The isolates were tested in terms of: Their ability to survive at pH 2.0, pH 3.0, and in the presence of 0.3% bile salts; tolerance of simulated gastric and intestinal juices; antimicrobial activity; sensitivity against 11 specific antibiotics; and their cell surface hydrophobicity. The results show that out of the 69 strains, 29 strains (42%) had survival rates above 90% after 2 h of incubation at pH values of 2.0 or 3.0. Of these 29 strains, 21 strains showed a tolerance for 0.3% bile salt. Incubation of these 21 isolates in simulated gastrointestinal fluid for 3 h revealed survival rates above 90%; the survival rate for 20 of these isolates remained above 90% after 4 h of incubation in simulated intestinal fluid. The viable counts of bacteria after incubation in simulated gastric fluid for 3 h and simulated intestinal fluid for 4 h were both significantly different compared with the counts at 0 h (p<0.001). Further screening performed on the above 20 isolates indicated that all 20 lactobacilli strains exhibited inhibitory activity against Micrococcus luteus ATCC 4698, Bacillus subtilis ATCC 6633, Listeria monocytogenes ATCC 19115, and Salmonella enterica ATCC 43971. Moreover, all of the strains were resistant to vancomycin and streptomycin. Of the 20 strains, three were resistant to all 11 elected antibiotics (ciprofloxacin, erythromycin, tetracycline, penicillin G, ampicillin, streptomycin, polymyxin B, vancomycin, chloramphenicol, rifampicin, and gentamicin) in this study, and five were sensitive to more than half of the antibiotics. Additionally, the cell surface hydrophobicity of seven of the 20 lactobacilli strains was above 70%, including strains Lactobacillus casei 1,133 (92%), Lactobacillus plantarum 1086-1 (82%), Lactobacillus casei 1089 (81%), Lactobacillus casei 1138 (79%), Lactobacillus buchneri 1059 (78%), Lactobacillus plantarum 1141 (75%), and Lactobacillus plantarum 1197 (71%). Together, these results suggest that these seven strains are good probiotic candidates, and that tolerance against bile acid, simulated gastric and intestinal juices, antimicrobial activity, antibiotic resistance, and cell surface hydrophobicity could be adopted for preliminary screening of potentially probiotic lactobacilli.

• Journal of Food Hygiene and Safety
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• v.35 no.6
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• pp.618-629
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• 2020

The purpose of this study was to optimize the fermentation condition of black bean by lactic acid bacteria (LAB) and to evaluate the quality characteristics of fermented black bean. Lactobacillus plantarum SU22 isolated from kimchi was selected as a starter for the fermentation of black bean because the strain exhibited strong antimicrobial activity against pathogenic bacteria and did not produce biogenic amines or a carcinogenic enzyme, β-glucuronidase. Fermentation was performed with broth containing puffed black bean (PBB) inoculated with 1% (v/v) of L. plantarum SU22 at 37℃ for 48h. The viable cell count of LAB was over 9 Log CFU/mL in PBB (20%) broth fermented with L. plantarum SU22. Fermentation of alcalase-treated PBB (20%) broth with L. plantarum SU22 was found to be the optimal condition, increasing viable cell count of LAB up to 10.30 Log CFU/mL. Under the optimal condition, the total polyphenol content (94.02 mg GAE/g) and DPPH radical scavenging activity (92.50%) were significantly increased, compared to non-fermented control (87.74 mg GAE/g, 83.14%).

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1191-1196
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• 2008

Staphylococcus aureus is a common etiologic agent for Gram-positive sepsis, and its lipoteichoic acid (LTA) may be important in causing Gram-positive bacterial septic shock. Here, we demonstrate that highly purified LTA (pLTA) isolated from Lactobacillus plantarum inhibited S. aureus LTA (aLTA)-induced TNF-${\alpha}$ production in THP-1 cells. Whereas pLTA scarcely induced TNF-${\alpha}$ production, aLTA induced excessive TNF-${\alpha}$ production. Interestingly, aLTA-induced TNF-${\alpha}$ production was inhibited by pLTA pretreatment. Compared with pLTA, aLTA induced a strong signal transduction through the MyD88, NF-${\kappa}B$, and MAP kinases. This signaling, however, was reduced by a pLTA pretreatment, and resulted in the inhibition of aLTA-induced TNF-${\alpha}$ production. Whereas dealanylated LTAs, as well as native LTAs, contributed to TNF-${\alpha}$ induction or TNF-${\alpha}$ reduction, deacylated LTAs did not, indicating that the acyl chain of LTA played an important role in the LTA-mediated immune regulation. These results suggest that pLTA may act as an antagonist for aLTA, and that an antagonistic pLTA may be a useful agent for suppressing the septic shock caused by Gram-positive bacteria.

• Food Science and Preservation
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• v.23 no.4
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• pp.576-584
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• 2016

In this study, antioxidant activities and physicochemical properties of chocolate fermented with Lactobacillus plantarum CK10 were investigated. The pH level decreased from $5.26{\pm}0.02$ to $3.98{\pm}0.06$ during fermentation while titratable acidity increased from $5.36{\pm}0.19$ to $13.31{\pm}0.34$. The total polyphenol and flavonoid contents slightly increased during fermentation, but it was numerically negligible. Slight increase and decrease in the radical scavenging activities of chocolate, against DPPH-, ABTS-, and alkyl-radical, were observed during 32 hr of fermentation, but the changes were not statistically relevant. Composition ratios (% area by GC analysis) of lactic acid, xanthosine, and theobromine increased with fermentation time while hydroxymethylfurfural (HMF) and caffeine decreased after 32 hr of fermentation, in the order of xanthine (22.7%), theobrome (20.0%), lactic acid (14.9%), HMF (9.1%) and caffeine (9.0%). However, there was no remarkable changes in theobromine and caffeine contents in chocolate during fermentation.

• Korean Journal of Food Science and Technology
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• v.45 no.1
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• pp.77-83
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• 2013

In this study, we observed optimal conditions and suitable bacteria for the fermentation of steam-dried ginseng berry extracts (SGB) and determined antioxidant effects of the fermented extracts. Five bacteria (Lactobacillus fermentarum, L. plantarum, L. brevis, L. casei, Bacillus subtillis) were examined on their growth activities and viabilities in various culture temperatures ($25-35^{\circ}C$) and concentrations (25-100%). L. plantarum was considered to be the most suitable bacteria for the fermentation in both growth activity and viability. Moreover, the extracts fermented with L. plantarum showed more potent antioxidant efficacy in both 1,1-diphenyl-2-picrylhydrazyl radical and hydroxyl radical scavenging assay. High performance liquid chromatography analysis revealed that fermentation with L. plantarum changed the contents and components of ginsenosides. In conclusion, these data suggest that L. plantarum efficiently ferment SGB and the fermented extracts may have therapeutical values against oxidative stress and be a good candidate in adjuvant therapy where ginsenoside would be the main composition.

• Journal of Microbiology and Biotechnology
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• v.24 no.8
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• pp.1051-1058
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• 2014

Platelet-activating factor receptor (PAFR) plays an important role in bacterial infection and inflammation. We examined the effect of the bacterial cell wall components lipopolysaccharide (LPS) and lipoteichoic acid (LTA) from Lactobacillus plantarum (pLTA) and Staphylococcus aureus (aLTA) on PAFR expression in THP-1, a monocyte-like cell line. LPS and aLTA, but not pLTA, significantly increased PAFR expression, whereas priming with pLTA inhibited LPS-mediated or aLTA-mediated PAFR expression. Expression of Toll-like receptor (TLR) 2 and 4, and CD14 increased with LPS and aLTA treatments, but was inhibited by pLTA pretreatment. Neutralizing antibodies against TLR2, TLR4, and CD14 showed that these receptors were important in LPS-mediated or aLTA-mediated PAFR expression. PAFR expression is mainly regulated by the nuclear factor kappa B signaling pathway. Blocking PAF binding to PAFR using a PAFR inhibitor indicated that LPS-mediated or aLTA-mediated PAF expression affected TNF-${\alpha}$ production. In the mouse small intestine, pLTA inhibited PAFR, TLR2, and TLR4 expression that was induced by heat-labile toxin. Our data suggested that pLTA has an anti-inflammatory effect by inhibiting the expression of PAFR that was induced by pathogenic ligands.

• Preventive Nutrition and Food Science
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• v.15 no.2
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• pp.159-166
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• 2010

The aim of this study was to develop species-specific primer sets for kimchi Lactobacillus. Known gene sequences of Lactobacillus 16S rRNA were collected from the NCBI Gene bank, and 69 primer sets were designed using the homologous gene sequence. Six species of kimchi Lactobacilli were used as reference strains: Lactobacillus brevis KCTC3102, Lactobacillus farciminis KCTC3681, Lactobacillus fermentum KCTC3112, Lactobacillus hilgardii KCTC3500, Lactobacillus plantarum KCTC3099, and Lactobacillus sanfranciscensis KCTC3205. PCR amplification and gel electrophoresis were performed to identify the accuracy and specificity of the developed primer set. The results show that the primer set of 5'-aagcctgcgaaggcaag-3' & 5'-aggccaccggctttg-3', 5'-acatactatgcaaatctaagagattagacg-3' & 5'-actgagaatggctttaagagattagcttac-3' resulted in a specific PCR band on L. hilgardii, and primer set of 5'-ctaataccgcataacaactactttcacat-3' & 5'-aacttaataaaccgcctacattctctttac-3' on L. farciminis. The results indicate that the developed primer sets can provide a useful tool for the identification and differentiation of L. hilgardii and L. farciminis from other Lactobacillus species of kimchi.

• Molecules and Cells
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• v.38 no.2
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• pp.163-170
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• 2015

Lipoteichoic acid (LTA) is a major component of the cell wall of Gram-positive bacteria. Its effects on living organisms are different from those of lipopolysaccharide (LPS) found in Gram-negative bacteria. LTA contributes to immune regulatory effects including anti-aging. In this study, we showed that LTA isolated from Lactobacillus plantarum (pLTA) inhibited melanogenesis in B16F10 mouse melanoma cells. pLTA reduced the cellular activity of tyrosinase and the expression of tyrosinase family members in a dose-dependent manner. The expression of microphthalmia- associated transcription factor (MITF), a key factor in the synthesis of melanin, was also decreased by pLTA. Further, we showed that pLTA activated melanogenesis signaling, such as extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3-kinse (PI3K)/AKT. In addition, the expression of heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) and HuR, which are important RNA-binding proteins (RBPs), was reduced. pLTA likely degrades MITF via regulation of melanogenic signaling and RNA stability of melanogenic proteins, resulting in the reduction of melanin. Thus, our data suggest that pLTA has therapeutic potential for treating hyperpigmentation disorders and can also be used as a cosmetic whitening agent.

• Food Science of Animal Resources
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• v.34 no.6
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• pp.836-843
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• 2014

Obesity, a condition in which an abnormally large amount of fat is stored in adipose tissue, causing an increase in body weight, has become a major public health concern worldwide. The purpose of this study was to optimize the process for fermented milk for the production of a functional product with an anti-obesity effect by using Lactobacillus plantarum Q180 isolated from human feces. We used a 3-factor, 3-level central composite design (CCD) combined with the response surface methodology (RSM). Concentration of skim milk powder (%, $X_1$), incubation temperature ($^{\circ}C$, $X_2$), and incubation time (h, $X_3$) were used as the independent factors, whereas pH (pH, $Y_1$), anti-lipase activity (%, $Y_2$) and anti-adipogenetic activity (%, $Y_3$) were used as the dependent factors. The optimal conditions of fermented milk for the highest anti-lipase and anti-adipogenetic activity with pH 4.4 were the 9.5% of skim milk powder, $37^{\circ}C$ of incubation temperature, 28 h of incubation time. In the fermentation condition, the predicted values of pH, anti-lipase activity and anti-adipogenetic activity were 4.47, 55.55, and 20.48%, respectively. However, the actual values of pH, anti-lipase activity and anti-adipogenetic activity were 4.50, 52.86, and 19.25%, respectively. These results demonstrate that 9.5% of skim milk powder and incubation at $37^{\circ}C$ for 28 h were the optimum conditions for producing functional fermented milk with an anti-obesity effect.

• 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.