• Journal of Life Science
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• v.25 no.2
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• pp.180-188
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• 2015

The bacterial strain isolated from Kimchi showed antibacterial activity against Micrococcus luteus IAM 1056. The selected strain was identified as Lactococcus lactis by 16S rRNA nucleotide sequence analysis and named as Lactococcus sp. KD 28. The treatment of culture supernatant with proteinase K removed antibacterial activity, indicating its proteinaceous nature, a bacteriocin. This bacteriocin was sensitive to hydrolytic enzymes such as ${\alpha}$-chymotrypsion, trypsin, proteinase K, lipase, ${\alpha}$-amylase and subtilisin A. The bacteriocin was highly thermostable and resistant to heating at $80^{\circ}C$ for up to an hour but 50 % of the total activity was remained at $100^{\circ}C$ for 30 min. The pH range from 2.0 to 8.0 had no effect on bacteriocin activity and it was not affected by solvents such as acetonitrile, isopropanol, methanol, chloroform and acetone up to 50% concentration. The bacteriocin showed antibacterial activity against M. luteus IAM 1056, Lactobacillus delbrueckii subsp. lactis KCTC 1058, Enterococcus faecium KCTC 3095, Bacillus cereus KCTC 1013, B. subtilis KCTC 1023, Listeria ivanovii subsp. ivanovii KCTC 3444, Staphylococcus aureus subsp. aureus KCTC 1916, B. megaterium KCTC 1098 and B. sphaericus KCTC 1184. The bacteriocin was purified through ammonium sulfate concentration, SP-Sepharose chromatography and RP-HPLC. The molecular weight was estimated to be about 3.4 kDa by tricine-SDS-PAGE analysis.

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.4
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• pp.276-285
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• 2022

This study evaluated the effect of lactic acid bacteria (LAB, a mixture of Enterococcus faecium and Lactobacillus plantarum) supplementation, the storage temperature, and storage period on the fermentation characteristics and in vitro ruminal digestibility of a total mixed ration (TMR). The TMR was prepared into two groups, namely, CON (control TMR without the LAB) and ML (supplementing a mixture of E. faecium and L. plantarum in the ratio of 1% and 2% (v/w), respectively). Both groups were divided and stored at 4℃ or 25℃ for 3, 7, and 14 d fermentation periods. Supplementing LAB to the TMR did not affect the chemical composition of TMR except for the lactate and acetate concentration. Storage temperatures affected (p<0.05) the chemical composition of the TMR, including pH, lactate, and acetate contents. The chemical composition of TMR was also affected (p<0.05) by the storage period. During in vitro rumen fermentation study, the ML treatment showed lower (p<0.05) dry matter digestibility at 24 h incubation with a higher pH compared to the CON. There was no difference in the in vitro dry matter digestibility (IVDMD) of TMR between the CON and ML treatment however, at 24 h, ML treatment showed lower (p<0.05) IVDMD with a higher pH compared to the CON. The effects of storage temperature and period on IVDMD were not apparent at 24 h incubation. In an in vivo study using Holstein steers, supplementing LAB to the basal TMR for 60 d did not differ in the final body weight and average daily gain. Likewise, the fecal microbiota did not differ between CON and ML. However, the TMR used for the present study did include a commercial yeast in CON, whereas ML did not; therefore, results were, to some extent, compromised in examining the effect of LAB. In conclusion, storage temperature and period significantly affected the TMR quality, increasing acetate and lactate concentration. However, the actual effects of LAB supplementation were equivocal.

• Journal of Environmental Health Sciences
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• v.45 no.3
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• pp.222-230
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• 2019

Objectives: This study aims to evaluate water quality in terms of microorganisms and identify the antibiotic resistance of Enterococci isolated from the recycling water in floor fountains at three parks and one reservoir in the Gwangju area. Methods: Water samples were analyzed for Enterococci using membrane Enterococcus indoxyl ${\beta}$ d glucoside agar (mEI) as described in USEPA Method 1600. The vancomycin-resistant Enterococci with VanA and VanB were identified by PCR. An examination of the antibiotic resistance of isolates against 14 antibiotics was performed by the disk diffusion method. Results: The drinking water quality criterion was exceeded for total colony counts in 68% of all recycling water samples. The average concentration of total califorms and fecal coliforms was 139,325 and 413 CFU/100 mL, respectively. VanA and VanB were not detected from the isolates. We found the antibiotic resistant Enterococci strains to be E. faecalis, E. faecium, E. durans, E. mundtii, E. hirae, and E. thailandicus. The isolates were resistant to Rifampin (50%), Erythromycin (25.8%), Tetracycline (10.2%), Nitrofurantoin (8.1%), Minocycline (3.1%), Erythromycin (1.2%), Penicillin (0.7%), Norfloxacin (0.5%), and Teicoplanin (0.5%) among the 14 antibiotics tested. Antibiotic resistance tests for Enterococci from the recycling water of floor fountains resulted in 30.2% showing resistance to two or more antibiotics. Conclusions: These results showed that the multi-antibiotic resistance of Enterococci, E. coli, and others should be investigated continuously in each environment field.

• Journal of Microbiology and Biotechnology
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• v.18 no.7
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• pp.1266-1273
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• 2008

Lactic acid bacteria (LAB) with antimicrobial activity and high exopolysaccharide (EPS) production ability isolated from sourdough were studied for their fermentation characteristics as potential new starter cultures. The values of pH, titratable acidity, and viable cell counts were $4.06{\pm}0.009-4.50{\pm}0.015,\;0.787{\pm}0.020%-1.172{\pm}0.018%,\;and\;8.78{\pm}0.08-8.98{\pm}0.06$ log CFU/ml, respectively. In order to select probiotics with a high survival rate in the gut, isolates were tested to assess resistance against the artificial gastric acid and bile juice. Viable LAB counts were significantly (p<0.05) affected by the acidity. At pH 2.0, the total declines in the initial bacterial counts were 4.52$\pm$0.07 log for S. thermophilus St-Body-1, >7.98$\pm$0.03 log for E. flavescens DU-10, >7.95$\pm$0.05 log for E. faecium DU-12, and 3.15$\pm$0.06 log for L. amylovorus DU-21. Among the strains, L. amylovorus DU-21 was the only strain that had bile tolerance under simulated gastrointestinal conditions. In order to improve EPS production by L. amylovorus DU-21, the influence of carbon source was studied. When glucose was used as a carbon source, EPS production dramatically increased to 17.19$\pm$0.28 g/l (p<0.05). The maximum cell growth (10.012$\pm$>0.012 log CFU/ml) and EPS production (18.71$\pm$0.19 g/l) were achieved when 15 g/l of glucose was employed as the carbon source.

• Food Science of Animal Resources
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• v.28 no.4
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• pp.457-462
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• 2008

Lactococcus lactis NK34, isolated from jeotgal (Korean traditional fermented fish), produces bacteriocin against bovine mastitis pathogens such as Staphylococcus aureus 7, S. aureus 8, Staphylococcus chromogenes 10, S. chromogenes 19, Staphylococcus hominis 9, Streptococcus uberis E290, Enterococcus faecium E372, Streptococcus agalactiae ATCC 13813, Pseudonocardia autotrophia KCTC 9455, and Staphylococcus simulans 78. Lacticin NK34 was inactivated by protease XIV but not by protease IX, protease XIII, proteinase K, $\acute{a}$-chymotrypsin, trypsin, and pepsin. Also, lacticin NK34 was stable over a pH range of 2 to 9 for 4 hr and withstood exposure to temperatures of 30-$100^{\circ}C$ for 30 min. Lacticin NK34 showed bactericidal effects against S. simulans 78. This bacteriocin was purified using ammonium sulfate precipitation, ion exchange chromatography, ultrafiltration, and hydrophobic chromatography. Tricin-SDS-PAGE of purified bacteriocin gave the same molecular weight (3.5 kDa) as nisin. The gene encoding this bacteriocin was amplified by PCR using nisin gene-specific primers. It showed similar sequences to this nisin Z gene. These results indicate that lacticin NK34 is a nisin-like bacteriocin, and could be used as an antimicrobial alternative for livestock.

• Food Science of Animal Resources
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• v.39 no.5
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• pp.804-819
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• 2019

Ezine cheese is a non-starter and long-ripened cheese produced in the Mount of Ida region of Canakkale, Turkey, with a protected designation of origin status. Non-starter lactic acid bacteria (NSLAB) have a substantial effect on the quality and final sensorial characteristics of long-ripened cheeses. The dominance of NSLAB can be attributed to their high tolerance to the hostile environment in cheese during ripening relative to many other microbial groups and to its ability to inhibit undesired microorganisms. These qualities promote the microbiological stability of long-ripened cheeses. In this study, 144 samples were collected from three dairies during the ripening period of Ezine cheese. Physicochemical composition and NSLAB identification analyses were performed using both conventional and molecular methods. According to the results of a 16S rRNA gene sequence analysis, 13 different species belonging to seven genera were identified. Enterococcus faecium (38.42%) and E. faecalis (18.94%) were dominant species during the cheese manufacturing process, surviving 12 months of ripening together with Lactobacillus paracasei (13.68%) and Lb. plantarum (11.05%). The results indicate that NSLAB contributes to the microbiological stability of Ezine cheese over 12 months of ripening. The isolation of NSLAB with antimicrobial activity, potential bacteriocin producers, yielded defined collections of natural NSLAB isolates from Ezine cheese that can be used to generate specific starter cultures for the production of Ezine cheese (PDO).

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.10
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• pp.1429-1436
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• 2006

Fermentation characteristics, nutrient retention and aerobic stability of barley silages prepared using 6 commercial inoculants were evaluated using 126 mini-silos (3-L) in a completely randomized design. Whole barley forage was chopped, wilted to 39% DM and treated with water (control, S) or one of six inoculants: A (containing Lactobacillus plantarum); B (L. plantarum and Enterococcus faecium); C (L. plantarum and Pediococcus cerevisiae); D (L. plantarum, Pediococcus pentosaceus and Propionibacterium freudenreichii, plus hydrolytic enzymes); E (Lactobacillus buchneri plus hydrolytic enzymes); F (L. buchneri and P. pentosaceus plus hydrolytic enzymes). Samples of treated forage were collected for analysis at the time of ensiling, and then 18 silos of each treatment were filled, capped and weighed. Triplicate silos were weighed and opened after 1, 3, 5, 7, 33, and 61 d. On d 61, $400{\pm}5g$ of material from each silo was placed in 1-L styrofoam containers, covered with cheesecloth and held at room temperature. Silage temperature was recorded hourly for 14 d via implanted thermocouple probes. Chemical composition of the forage at ensiling was consistent with previously reported values. At d 61, pH was lowest (p<0.01) in silage S. Ammonia-N was lower (p<0.05) in silage A than in silages S, B, E, or F. Compared to pre-ensiling values, water soluble carbohydrate concentrations were elevated in silages S, A, B, C and D, and decreased in E and F. Lactic acid concentrations were similar (p>0.10) across treatments. Acetic acid levels were highest (p<0.01) in silage E and lowest (p<0.01) in silage D. Recovery of DM was lower (p<0.01) in silage F than in silages S, A, B, C, or D. On d 61, yeasts were most numerous (p<0.01) in silage D, which was the only silage in which temperature rose more than $2^{\circ}C$ above ambient during aerobic exposure. Silage D also had the highest (p<0.01) pH and ADIN content after aerobic exposure. Lactic acid and WSC content of silage D decreased dramatically during the 14-d aerobic exposure period. Yeast counts (at d 14 of exposure) were lowest (p<0.01) in silages E and F. In general, the commercial inoculants did not appear to enhance the fermentation of barley silage to any appreciable extent in laboratory silos.

• Biomedical Science Letters
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• v.20 no.2
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• pp.77-84
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• 2014

Periodic analysis of local epidemiologic data of prevalent pathogens of blood culture can provide clinicians with relevant information to guide empirical antibiotic therapy. In this study, we analyzed a pattern of change of causative microorganisms and antimicrobial resistance at a tertiary medical center in Chungcheong province from 2003 to 2012, retrospectively. Of 70,258 blood specimens cultured, 6,063 (8.6%) were positive. Among the positive isolates, 95.9% were aerobic or facultative anaerobic bacteria, 0.1% were anaerobes, and 3.9% were fungi. Coagulase-negative Staphylococci (CoNS) (32.9%), Escherichia coli (16.7%), Staphylococcus aureus (9.1%), Klebsiella pneumoniae (6.4%), and ${\alpha}$-hemolytic Streptococcus (5.9%) were commonly isolated bacteria, and Candida albicans (1.4%) was the most commonly isolated fungi. Enterococcus faecium progressively increased but Streptococcus pneumoniae, Acinetobacter baumannii and Proteus species gradually decreased over a period of 10 years. The multidrug-resistant microorganisms such as methicillin-resistant S. aureus (MRSA), vancomycin-resistant enterococci (VRE), cefotaxime-resistant E. coli, imipenem-resistant Pseudomonas aeruginosa (IRPA) and imipenem-resistant A. baumannii (IRAB), were significantly increased. Therefore, there is a need for a more strict control of antibiotics and a more updated guideline for the treatment of bloodstream infection.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.3
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• pp.369-378
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• 2011

The effect of a homolactic inoculant containing a blend of Lactobacillus plantarum, Pediococcus acidilactici and Enterococcus faecium or, the anionic surfactant, sodium dodecyl sulphate (SDS), alone or in combination on fermentation characteristics, aerobic stability and in situ DM, OM and NDF degradability of barley silage was investigated. Barley (Hordeum vulgare, L.) was harvested (45% DM), chopped and treated with water at 24 ml/kg forage (Control), inoculant at $1.09{\times}10^5$ cfu/g forage (I), SDS at 0.125% (wt/wt) of forage (S) or with the inoculant ($1.09{\times}10^5$ cfu/g) plus SDS (0.125% wt/wt; I+S). The treated forages were ensiled in triplicate mini silos and opened for chemical and microbiological analyses on d 1, 2, 3, 7, 14, 42 and 77. Silage samples from d 77 were opened and aerobically exposed for 7 d. The in situ rumen degradability characteristics of silage DM, OM and NDF were also determined. The terminal concentration of NDF in S and I+S was lower (p<0.001) than in other treatments. Lactate concentration was higher (p<0.001) and the rate and extent of pH decline were greater (p<0.001) in I and I+S than S and Control silages. A homolactic pathway of fermentation in I and I+S was evidenced by reduced (p<0.001) water-soluble carbohydrates concentration, higher lactate (p<0.01), lower acetate (p<0.01) and lower pH values (p<0.001) than in S and Control silages. All silages remained stable over 7 d of exposure to air as indicated by lower temperatures and moulds, and by non-detectable yeast populations. The treated silages had lower DM and OM degradability than in the Control but NDF degradation characteristics of I+S were improved compared to other treatments. It is concluded that the inoculant alone improved the fermentation characteristics whereas the combination of the inoculant with SDS improved both fermentation and NDF degradability of barley silage.

• Journal of Korean Neurosurgical Society
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• v.46 no.2
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• pp.123-129
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• 2009

Objective: This study was aimed to identify the incidence and risk factors of vancomycin-resistant enterococcus (VRE) colonization in neurosurgical practice of field, with particular attention to intensive care unit (ICU). Methods: This retrospective study was carried out on the Neurosurgical ICU (NICU), during the period from January. 2005 to December. 2007, in 414 consecutive patients who had been admitted to the NICU. Demographics and known risk factors were retrieved and assessed by statistical methods. Results: A total of 52 patients had VRE colonization among 414 patients enrolled, with an overall prevalence rate of 6.1%. E. faecium was the most frequently isolated pathogen, and 92.3% of all VRE were isolated from urine specimen. Active infection was noticed only in 2 patients with bacteremia and meningitis. Relative antibiotic agents were third-generation cephalosporin in 40%, and vancomycin in 23%, and multiple antibiotic usages were also identified in 13% of all cases. Multivariate analyses showed Glasgow coma scale (GCS) score less than 8, placement of Foley catheter longer than 2 weeks, ICU stay over 2 weeks and presence of nearby VRE-positive patients had a significantly independent association with VRE infection. Conclusion: When managing the high-risk patients being prone to be infected VRE in the NICU, extreme caution should be paid upon. Because prevention and outbreak control is of ultimate importance, clinicians should be alert the possibility of impending colonization and infection by all means available. The most crucial interventions are careful hand washing, strict glove handling, meticulous and active screening, and complete segregation.