• Korean Journal of Microbiology
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• v.51 no.2
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• pp.169-176
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• 2015

The malolactic fermentation (MLF), which is widely used in winemaking, is the conversion of malic acid to lactic acid conducted by the malolactic enzyme (Mle) of lactic acid bacteria. In order to select the strains with MLF among 54 lactic acid bacteria isolated from the traditionally fermented foods, we designed a primer set that specifically targets the conserved regions of the mle gene and then selected four strains that harbor the mle gene of Lactobacillus plantarum. All strains were identified as L. plantarum by analyzing the 16S rRNA sequences, biochemical properties, and the PCR products of the recA gene. From comparison of the mle gene sequences consisting of 1,644 bp, the nucleotide and amino acid sequence of strain JBE60 correspond to 96.7% and 99.5% with those of other three strains, respectively. The strain JBE60 showed the highest resistant against 10% (v/v) ethanol among the strains. The strains lowered the concentration of malic acid to average 43%. Considering the ethanol resistance and conversion of malic acid, the strain JBE60 is considered as a potential starter for the malolactic fermentation.

• Microbiology and Biotechnology Letters
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• v.43 no.3
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• pp.219-226
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• 2015

Acetic acid bacteria (AAB) were isolated from vinegar fermented through traditional methods in Namhae county, Gyeongnam, the Republic of Korea. The isolated strains were Gram negative, non-motile, and short-rods. Three selected strains were identified as either Acetobacter pasteurianus or Acetobacter aceti by 16S rRNA gene sequencing. A. pasteurianus NH2 and A. pasteurianus NH6 utilized ethanol, glycerol, D-fructose, D-glucose, D-mannitol, D-sorbitol, L-glutamic acid and Na-acetate. A. aceti NH12 utilized ethanol, n-propanol, glycerol, D-mannitol and Na-acetate. These strains grew best at 30℃ and an initial pH of 3.4. They were tolerant against acetic acid at up to 3% of initial concentration (v/v). The optimum conditions for acetic acid production were 30℃ and pH 3.4, with an initial ethanol concentration of 5%, resulting in an acetic acid concentration of 7.3−7.7%.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.225-230
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• 2011

A bacterium producing the extracellular mannanase and xylanase was isolated from Korean farm soil by successive subcultures in a minimal medium supplemented with palm kernel meal (PKM) and rice bran. The isolate YB-1106 showed 98% similarity with Microbacterium arabinogalactanolyticum on the basis of 16S rRNA gene sequences. The additional carbohydrates including locust bean gum (LBG) and PKM increased the mannanase productivity of the YB-1106, while the xylanase productivity of the isolate was increased by wheat bran, oat spelt xylan, rice bran and xylose. Particularly, maximum mannanase and xylanase activities were obtained in the culture filtrate of tryptic soy broth supplemented with 1% LBG or 2% wheat bran, respectively. Both enzyme activities were produced at stationary growth phase. The mannanase of culture supernatant was the most active at $50^{\circ}C$ and pH 6.0, while xylanase of culture supernatant was the most active at $55^{\circ}C$ and pH 6.5. The predominant products resulting from the mannanase or xylanase hydrolysis were oligosaccharides for LBG or xylan, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3517-3522
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• 2011

Contamination of public bath water by waterborne pathogens can cause disease outbreaks and contribute to background rates of disease. The aim of this study is to determine the prevalence of waterborne pathogens in public baths. A total of 30 water samples were collected from 30 different public baths in seoul, Korea. Pathogens in water samples were concentrated by 0.45 ${\mu}m$ nitrocellulose membrane filter, analyzed by both cultivation and polymerase chain reaction-reverse blot hybridization (PCR-REBA) of partial 16S rRNA gene. Various microorganisms including Escherichia coli and Shigella spp. were identified by microbiological cultivation. E. coli, Shigella spp., Salmonella spp., Pseudomonas spp. and Mycobacterium spp. were identified by PCR-REBA. Our results suggest that appropriate hygiene practice and continuous monitoring is needed for reducing health risk associated with public bath houses.

• Korean Journal of Microbiology
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• v.46 no.4
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• pp.389-396
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• 2010

Insecticidal crystalline toxin producing Bacillus thuringiensis BT17 strain was isolated and identified as B. thuringiensis serovar colmeri by 16S rRNA analysis. BT17 strain produced crystalline ${\delta}$-endotoxin against to Lepidopteran larvae effectively on the culture broth of soybean meal and skim milk, $30^{\circ}C$ and 36 h shaking culture of 280 rpm. The maximum colony forming unit achieved when the culture was continued for 24 h, but the number of crystals increased until 36 h in the 200 L fermentor. Liquid type of biological insecticide product was made, and after 3 months storage in $20^{\circ}C$ the number of crystals was increased up to twice than beginning. Biocontrol effect of BT17 insecticide product was better in Plutella xylostella than in Spodoptera exigua, and the toxicity to animals was negligible.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.5
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• pp.314-324
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• 2011

Algal biomass cultivated by wastewater is potentially useful resource for biodiesel production. However, little is known about algal nutrient metabolism and microbial interaction with bacteria under real municipal wastewater condition. In this work, we characterized nitrogen and phosphorus removals of municipal wastewater by a representative wastewater-growing algal population. Ankistrodesmus gracilis SAG 278-2, and analyzed its ecological interaction with wastewater bacterial communities. Compared to wastewater sludge itself, algal-bacterial co-culture improved nutrient removal. According to bacterial community analysis with 16S rRNA genes, a selective and dominant growth of a Unclassified Alcaligenaceae population resulted from algal growth in the algal-bacterial co-culture. The selectively stimulated bacterial population is phylogenetically close to Alcaligenes faecalis subsp. 5659-H, which is known to be co-present interact with algae in aquatic environment. These findings suggest that algal growth/metabolism may have effects on selection of a specific bacterial population in algal-bacterial co-cultures that can efficiently remove nutrients from municipal wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.678-683
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• 2007

We isolated a toluene-degrading bacterium, TDB-4, from a bioreactor which designed to remove volatile organic compounds (VOCs) from the contaminated air. Based on the results of 16S rRNA gene analysis, it was classified as Pseudomonas sp. The toluene degradability was estimated in the variable toluene and bacterial concentrations. The bacterial growth and degradation rate was higher in the samples supplied with 50 ${\mu}mole/vial$ of toluene than with 10 ${\mu}mole/vial$. It was decreased, however, in the samples with 100 ${\mu}mole/vial$, indicating that toluene inhibit the growth or degradation activity of TDB-4 at high concentration. When the degradation ability of other compounds was examined, TDB-4 can degrade other VOCs such as styrene, benzene, and xylene. These results will be helpful to optimize the operating conditions to improve the efficiency of a bioreactor in detoxification of VOCs.

• Journal of Life Science
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• v.17 no.11
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• pp.1582-1586
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• 2007

Previous study (J. of Chem. Technol. Biotechnol. 2004, 79, 79-84) showed that bacterial cellulose (BC) produced by a bacterial strain JH232 has potential as a source for environmentally friendly ion exchange membranes. In this study, strain JH232 was investigated for phylogenetic classified and characterized for BC production. Comparative analysis of 16S rRNA gene revealed that the strain belongs to the genus Gluconacetobacter. Maximum production of BC was observed when JH232 was cultured in CSL medium (pH 5.5) at $30^{\circ}C$ as determined by flask experiment. When batch and fed-batch cultures of JH232 were performed in the fermenter experiment to compare BC productivity of the strain, BC productivity of fed-batch culture was 1.56 times higher than that of batch culture.

• Journal of Life Science
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• v.28 no.12
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• pp.1529-1535
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• 2018

The number of antibiotic-resistant bacteria is increasing rapidly while the discovery rate of new antibiotics is in decline. A systematic study is therefore necessary to investigate which bacteria are resistant to medically important antibiotics and how high that resistance is. To that end, this study aimed to analyze which bacteria demonstrated resistance to ampicillin, one of the currently most-widely used medical antibiotics. Water samples were collected from the Changwon-Cheon that runs through Changwon City and from the pond in front of the dormitory building at Changwon University. Hundreds of ampicillin-resistant colonies were obtained and 22 morphologically distinct examples were chosen for further study. These bacteria were identified by amplifying their 16S rRNA genes and comparing those sequences with data in GenBank. The bacteria was identified as belonging to 10 families, 12 genera, and 17 species, and all were able to grow in the presence of $50{\mu}g/ml$ ampicillin while seven showed growth at ampicillin concentrations as high as 1.5 mg/ml.

• Journal of Life Science
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• v.34 no.2
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• pp.86-93
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• 2024

Since replication of plasmids must be strictly controlled, plasmids that generally perform rolling circle replication generally maintain a constant copy number by strictly controlling the replication initiator Rep at the transcriptional and translational levels. Plasmid pJB01 contains three orfs (copA, repB, repC or repABC) consisting of a single operon. From analysis of amino acid sequence, pJB01 CopA was homologous to the Cops, as a copy number control protein, of other plasmids. When compared with a CopG of pMV158, CopA seems to form the RHH (ribbon-helix-helix) known as a motif of generalized repressor of plasmids. The result of gel mobility shift assay (EMSA) revealed that the purified fusion CopA protein binds to the operator region of the repABC operon. To examine the functional role of CopA on transcriptional level, 3 point mutants were constructed in coding frame of copA such as CopA R16M, K26R and E50V. The repABC mRNA levels of CopA R16M, K26R and E50V mutants increased 1.84, 1.78 and 2.86 folds more than that of CopA wt, respectively. Furthermore, copy numbers owing to mutations in three copA genes also increased 1.86, 1.68 and 2.89 folds more than that of copA wt, respectively. These results suggest that CopA is the transcriptional repressor, and lowers the copy number of pJB01 by reducing repABC mRNA and then RepB, as a replication initiator.