• Applied Biological Chemistry
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• v.40 no.6
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• pp.561-566
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• 1997

Screening, Identification and some cultural characteristics of ALA$({\delta}-aminolevulinic\;acid)$-producing photosynthetic bacteria were carried out for the optimal production of ALA, one of the bioherbicides. Among photosynthetic bacteria isolated from soil, marsh, pond, etc., KK-10 was the best producer of ALA and identified to be Rhodobacter capsulatus belonging to a typical group of nonsulfur purple bacteria. By addition of 15 mM LA (levulinic acid), an inhibitor of ALA dehydrase in cyclic tetrapyrrole biosynthesis, into culture broth at middle log phase of cell growths, ALA production was considerably increased to about 20-fold (28 mg/l). The combined supplementation of glycine and succinate, each with a concentration of 30 mM also enhanced production of ALA and activity of ALA synthase to about 50-fold (73 mg/l) and 2-fold, respectively. The isolated strain was able to produce upto 80 mg/l under the cultural condition optimized by addition 15 mM LA into the synthetic medium at four different points starting middle log phase.

• Korean Journal of Veterinary Research
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• v.46 no.3
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• pp.255-261
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• 2006

Experimental animals have been used to biological and medical purposes and the animals must be, for these purposes, healthy and clean to microbial infection. However, the animals can be easily exposed to pathogenic microorganism via several routes. Of the routes, environmental conditions are the most important factors to keep the animals healthy and clean, especially air condition. Monitoring of air-condition has been required to keep the animal healthy and clean. However, any guideline is not available for experimental conditions with pigs. Therefore, the sampling times and points were compared in different conditions to establish an optimal protocol for monitoring of air borne bacteria. Tryptic soy agar(TSA), blood agar containing 5% defibrinated sheep blood and Sabraud dextrose agar(SDA) were used as media to capture total bacteria, pathogenic bacteria and fungi, respectively. Two methods, compulsive capture using an air-sampler and capturing fall-down bacteria were used to capture the microorganisms in the air. The points and time of capturing were different at each experiment. Air borne microorganisms were captured at three and five points in the open and closed equipments, respectively. Air was collected using an air-sampler for 1 min and 5 min and the agar plates as open status were left from 30 min to 2hr. At first, we monitored an experimental laboratory which dealt with several pathogenic bacteria and then, a protocol obtained from the investigation was applied to open or close experimental conditions with pigs. Number of bacteria was high from 10:00 to 15:00, especially on 13:30-15:30 but sharply decreased after 17:00. The tendency of the number of bacteria was similar between two methods even though the absolute number was higher with air sampler. Critical difference in the number of cells was observed at 5 min with air sampler and 2 hr with fall-down capturing method. However, 1 min with air sampler and 1 hr with fall-down capturing were the best condition to identify bacterial species collected from the air. Number of bacteria were different depending on the sampling points in closed condition but not in opened condition. Based on our results, a guide-line was suggested for screening air-borne microorganism in the experimental conditions with pigs.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1746-1750
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• 2004

The PBM ${BioSign}^{TM}$ Salmonella (PBMS) test kit based on an mmunochromatographic method was evaluated for the screening of Salmonella spp. in pure cultures, and 80, 15, and 10 artificially and naturally contaminated, and negative controlled food samples, respectively. The PBMS test involves presumptive qualitative procedures, detecting the presence of Salmonella spp. in foods within 26 h total testing period and allowing the user to release negative products 70 h earlier than the conventional methods. The PBMS test using Buffered Peptone Water and Rappaport-Vassiliadis broth was evaluated for 10 different food types for various Salmonella spp. It showed detection limits of 1 to 25 colony forming units (CFU)/25 g. No cross-reaction was observed, particularly to other gramnegative bacteria. These results indicate the PBMS test is a rapid and inexpensive procedure for the screening of Salmonella spp. present at low concentrations (1 to 25 CFU/25 g) in foods.

• Journal of Microbiology and Biotechnology
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• v.24 no.11
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• pp.1559-1565
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• 2014

Cellulase and xylanase are main hydrolysis enzymes for the degradation of cellulosic and hemicellulosic biomass, respectively. In this study, our aim was to develop and test the efficacy of a rapid, high-throughput method to screen hydrolytic-enzyme-producing microbes. To accomplish this, we modified the 3,5-dinitrosalicylic acid (DNS) method for microwell plate-based screening. Targeted microbial samples were initially cultured on agar plates with both cellulose and xylan as substrates. Then, isolated colonies were subcultured in broth media containing yeast extract and either cellulose or xylan. The supernatants of the culture broth were tested with our modified DNS screening method in a 96-microwell plate, with a $200{\mu}l$ total reaction volume. In addition, the stability and reliability of glucose and xylose standards, which were used to determine the enzymatic activity, were studied at $100^{\circ}C$ for different time intervals in a dry oven. It was concluded that the minimum incubation time required for stable color development of the standard solution is 20 min. With this technique, we successfully screened 21 and 31 cellulase- and xylanase-producing strains, respectively, in a single experimental trial. Among the identified strains, 19 showed both cellulose and xylan hydrolyzing activities. These microbes can be applied to bioethanol production from cellulosic and hemicellulosic biomass.

• Genomics & Informatics
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• v.14 no.4
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• pp.255-264
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• 2016

The plethora of genome sequence information of bacteria in recent times has ushered in many novel strategies for antibacterial drug discovery and facilitated medical science to take up the challenge of the increasing resistance of pathogenic bacteria to current antibiotics. In this study, we adopted subtractive genomics approach to analyze the whole genome sequence of the Fusobacterium nucleatum, a human oral pathogen having association with colorectal cancer. Our study divulged 1,499 proteins of F. nucleatum, which have no homolog's in human genome. These proteins were subjected to screening further by using the Database of Essential Genes (DEG) that resulted in the identification of 32 vitally important proteins for the bacterium. Subsequent analysis of the identified pivotal proteins, using the Kyoto Encyclopedia of Genes and Genomes (KEGG) Automated Annotation Server (KAAS) resulted in sorting 3 key enzymes of F. nucleatum that may be good candidates as potential drug targets, since they are unique for the bacterium and absent in humans. In addition, we have demonstrated the three dimensional structure of these three proteins. Finally, determination of ligand binding sites of the 2 key proteins as well as screening for functional inhibitors that best fitted with the ligands sites were conducted to discover effective novel therapeutic compounds against F. nucleatum.

• Journal of fish pathology
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• v.5 no.2
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• pp.143-152
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• 1992

Metallothionein is an essential and common protein to regulate the intracellular concentration of heavy metals, which exist in most organisms from bacteria to vertebrates. Although the detailed function of metallothianein has not been fully identified until yet, it may be involoved in the cellular protection against the heavy metal toxicity and in the global regulation of several other genes and the expression of metalloproteins. We have cloned the full cDNA clone of metallothionein gene in Channel Catfish by Reverse Transcriptase-Polymerase Chain Reaction(RT-PCR) starting from poly(A)-containing mRNAs. All PCR fragments have been subcloned into EcoRV site of pBluescript SK+ and dT-tailed at Smal site of pUC19, then PCR products are recovered by the double digestion of recombinant plasmids wiht EcoRI and HindIII, which are adjacent to EcoRV site in multicloning sites or by rapid PCR screening. The nucleotide sequence analysis of pMT150(one of the PCR clones) showed high homology with several other piscine metallothionein cDNA genes.

• Microbiology and Biotechnology Letters
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• v.20 no.3
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• pp.335-343
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• 1992

A Streptomyces strain No. 182-27, which produced amino acid antimetabolite, was isolated from soil. During the course of screening for new amino acid antimetabolites from the culture broths of Actinomycetes, we found that the strain produced a substance active against Gram-positive bacteria and its activity was reversed by L-Ieucine on the synthetic minimal agar medium in the culture broth. The morphological and cultural characteristics serve to identify the producing organism strain 182-27 as the Streptomyces, although the species of this strain should be resolved in further studies. Fermentation was carried out in the synthetic medium at $28^{\circ}C$ for 78 hours. The fermentation yield reached about 2 mg per liter of the broth. Purification was done by ion exchange resin, active carbon, silica gel column chromatography and obtained 20 mg of pure active substance from the 20 $\ell$ culture broth. The 182-27 substance was obtained as white powder, mp 18SoC. From the physicochemical characteristics of the substance, it was amino acid like substance but unknown about its chemical structure. It is active against some Gram-positive bacteria and reversed by L-Ieucine.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.8
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• pp.1289-1295
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• 2014

The aim of this study was to select the most suitable starter cultures for production of fermented sausages. A total of 27 strains isolated from Korean fermented foods and natural substances were characterized with respect to their physicochemical properties in a fluid (submerged) model system modified according to the special conditions of fermented sausages. Three of these strains were pre-selected for testing as potential cultures based on their ability to grow fast and initiate rapid acidification. The selected strains were identified by API and partial sequence analysis of 16S rRNA. The results exhibited sequence similarity to known sequences of Staphylococcus warneri, Staphylococcus epidermidis and Lactobacillus plantarum. Among them, relatively good growth properties and nitrite reduction activities were detected for S. epidermidis and L. plantarum and low pH values and high total acidities were observed in the model system fermented with these isolates compared with reference strains.

• Food Science and Biotechnology
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• v.14 no.4
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• pp.503-508
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• 2005

Screening for antilisterial activity was performed in about three thousand isolates of lactic acid bacteria (LAB) from Chinese cabbage kimchi, and finally based on the relatively stronger antilisterial activities eight bacterial strains were selected. The bacteria were further characterized in terms of their tolerance to artificial gastric juice, pH 2.5, bile salts (0.3% oxgall), and to the different NaCl concentrations. Of the isolates, YK005 was especially investigated for its physiological characteristics due to its inhibitory activity against gram-positive Listeria monocytogenes as well as gram-negative Escherichia coli O157:H7, as they have been constantly reported to be resistant against bacteriocins produced by a number of LAB strains. YK005 was found to be rod-shaped, $3.8\;{\mu}m$ long ${\times}\;0.5\;{\mu}m$ wide, non-sporeforming, non-motile, catalase-negative, and produced gas from glucose (heterolactic). Based on the biochemical data obtained by API 50 CHL medium, the isolate was tentatively identified as Lactobacillus brevis. To validate the result obtained by the biochemical identification, rRNA-based PCR experiments using a pair of species-specific primers for L. brevis were conducted and a single band of 1400 bp was observed, which strongly indicated that YK005 belongs to L. brevis. The LAB isolates are potentially exploited as human probiotic organisms and are employed to control some food-borne pathogens like L. monocytogenes.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.311-318
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• 2010

Antimicrobial finishing of textiles has been found to be an economical way to prevent (or treat) skin disorders. Hence, this research effort was aimed at elucidating the relationship between the molecular weight (MW) of chitosan and its antimicrobial activity upon six dermal reference microorganisms, as well as the influence of the interactions with cotton fabrics on said activity. Using 3 chitosans with different MWs, as well as two chitooligosaccharide (COS) mixtures, a relevant antimicrobial effect was observed by 24 h for the six microorganisms tested; it was apparent that the antimicrobial effect is strongly dependent on the type of target microorganism and on the MW of chitosan - being higher for lower MW in the case of E. coli, K. pneumoniae, and P. aeruginosa, and the reverse in the case of both Gram-positive bacteria. Furthermore, a strong antifungal effect was detectable upon C. albicans, resembling the action over Gram-positive bacteria. Interactions with cotton fabric resulted in a loss of COS activity when compared with cultured media, relative to the effect over Gram-negative bacteria. However, no significant differences for the efficacy of all the 5 compounds were observed by 4 h. The three chitosans possessed a higher antimicrobial activity when impregnated onto the fabric, and presented a similar effect on both Gram-positive bacteria and yeast, in either matrix. Pseudomonas aeruginosa showed to be the most resistant microorganism to all five compounds.