• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8281-8285
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• 2016

Background: Helicobacter pylori is a cause of chronic gastritis, peptic ulcer disease, and gastric malignancy, infection being a serious health problem in Thailand. Recently, clarithromycin resistant H. pylori strains represent the main cause of treatment failure. Therefore this study aimed to determine the prevalence and pattern of H. pylori resistance to clarithromycin in Suranaree University of Technology Hospital, Suranree University of Technology, Nakhon Ratchasima, Northeastern Thailand, Nakhon Ratchasima province, northeast of Thailand. Materials and Methods: This hospital-based cross-sectional study was carried out between June 2014 and February 2015 with 300 infected patients interviewed and from whom gastric mucosa specimens were collected and proven positive by histology. The gastric mucosa specimens were tested for H. pylori and clarithromycin resistance by 23S ribosomal RNA point mutations analysis using real-time polymerase chain reactions. Correlation of eradication rates with patterns of mutation were analyzed by chi-square test. Results: Of 300 infected patients, the majority were aged between 47-61 years (31.6%), female (52.3%), with monthly income between 10,000-15,000 Baht (57%), and had a history of alcohol drinking (59.3%). Patient symptoms were abdominal pain (48.6%), followed by iron deficiency anemia (35.3%). Papaya salad consumption (40.3%) was a possible risk factor for H. pylori infection. The prevalence of H. pylori strains resistant to clarithromycin was 76.2%. Among clarithromycin-resistant strains tested, all were due to the A2144G point mutation in the 23S rRNA gene. Among mutations group, wild type genotype, mutant strain mixed wild type and mutant genotype were 23.8%, 35.7% and 40.5% respectively. With the clarithromycin-based triple therapy regimen, the efficacy decreased by 70% for H. pylori eradication (P<0.01). Conclusions: Recent results indicate a high rate of H. pylori resistance to clarithromycin. Mixed of wild type and mutant genotype is the most common mutant genotype in Nakhon Ratchasima province, therefore the use of clarithromycin-based triple therapy an not advisable as an empiric first-line regimen for H. pylori eradication in northeast region of Thailand.

• Korean Journal of Microbiology
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• v.26 no.4
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• pp.283-290
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• 1988

A spontaneous revertant of mutation rbsB103 that is ribose taxis-positive was characterized. This revertant was found to be export-competent in the export of ribose-binding protein shown by the disappearance of accumulated mutant precursor protein and the export of mature ribose-binding protein to the periplasm. The reversional change was shown to be in the region of risB gene that codes for the amino terminal portion of ribose-binding protein. Analysis by high-performance liquid chromatography of peptide patterns of ribose-binding proteins confirmed the relationship between the wild-type and the revertant proteins as shown for the mutant previously (Iida et al., 1985). When the processing rate of presursor proteins from the wild type and the revertant strain in vivo was compared by pulse-chase experiment, it was found that processing is less efficient than normal in the revertant. Purified mature proteins from both wild-type and revertant were subjected to amino acid sequencing. The results confirmed the amino acid changes deduced from the DNA sequencing and showed that processing of the revertant precursor occured in the correct position even though there are two different amino acids present in the signal sequence.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.343-353
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• 2018

Our previous research demonstrated the essential role of the xenB gene in stress response to RDX by using Pseudomonas sp. HK-6 xenB knockout. We have extended this work to examine the cellular responses and altered proteomic profiles of the HK-6 xenA knockout mutant under RDX stress. The xenA mutant degraded RDX about 2-fold more slowly and its growth and survival rates were several-fold lower than the wild-type HK-6 strain. SEM revealed more severe morphological damages on the surface of the xenA mutant cells under RDX stress. The wild-type cells expressed proportionally-increased two stress shock proteins, DnaK and GroEL from the initial incubation time point or the relatively low RDX concentrations, but slightly less expressed at prolonged incubation period or higher RDX. However the xenA mutant did not produced DnaK and GroEL as RDX concentrations were gradually increased. The wild-type cells well maintained transcription levels of dnaA and groEL under increased RDX stress while those in the xenA mutant were decreased and eventually disappeared. The altered proteome profiles of xenA mutant cells under RDX stress also observed so that the 27 down-regulated plus the 3 up-regulated expression proteins were detected in 2-DE PAGE. These all results indicated that the intact xenA gene is necessary for maintaining cell integrity under the xenobiotic stress as well as performing an efficient RDX degradation process.

• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.349-354
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• 2000

Abstract A facultative alkalophilic gram-negative Vibrio metschnikovii strain RH530, isolated from the wastewater, produced several alkaline proteases (VAP) including six alkaline serine proteases and a metalloprotease. From this strain, high yielding YAP mutants were isolated by NTG treatment. The isolated mutant KS1 showed nine times more activity than the wild-type after optimization of the culture media. The production was regulated by catabolite repression when glucose was added to the medium. The effects of several organic nitrogen sources on the production of the YAP were investigated to avoid catabolite repression. The combination of 4% wheat gluten meal (WGM), 1.5% cotton seed flour (eSF), and 5% soybean meal (SBM) resulted in the best production when supplemented with 1% NaCl. The YAP showed a resistance to surfactants such as $sodium-{\alpha}-olefin$ sulfonate (AOS), polyoxy ethylene oxide (POE), and sodium dodecyl sulfate (SDS), yet not to linear alkylbenzene sulfonate (LAS). However, the activity of the YAP was restored completely when incubated with LAS in the presence of POE or $Na_2SO_4$. The YAP was stable in a liquid laundry detergent containing 6.6% SLES (sodium lauryl ether sulfate), 6.6% LAS, 19.8% POE, and stabilizing agents for more than two weeks at $40^{\circ}C$, but the stability was sharply decreased even after 1 day when incubated at $60^{\circ}C$. A washing performance test with the YAP exhibited it to be a good washing power by showing 51 % and 60% activity at $25^{\circ}C{\;}and{\;}40^{\circ}C$, respectively, thereby indicating that the YAP also has a good detergency at a low temperature. All the results suggest that the YAP produced from the mutant strain KSI has suitable properties for use in laundry detergents.rgents.

• Korean journal of applied entomology
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• v.16 no.1 s.30
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• pp.21-31
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• 1977

The study has been carried out to compare the pathogenicity, physiological characteristics and genetic reliability between rough colony type strain and smooth colony type strains of Pseudomonas mori (Boyer et Lambert) Stevens which were isolated from diseased plant parts in 5 different areas throughout country. The results are summarized as follow. 1. The rough colony type strain showed more agressive reactions to tested host plant varieties than smooth colony type strains though there was no differences in the appearence of lesion types caused by both strains. 2. Both colony types were differentiated morphologically in that the rough colony type strain was having more than 200r long filamentous body without flagella where as the smooth colony type strains have short rods with one or several polar flagella. 3. The colony of smooth type strains was circular, entire, smooth and opaque, while the rough type strain shelved endulated, irregular margin, rough and wrinkled colony on nutrient agar media. 4. There were no differences between both colony types in the physiological and serological test. 5. Both of smooth and rough colony type strains showed genetic reliability through more than 100 succeeding cultures on the media, and were stable to various chemicals such as 1 to 3 percent of NaCl, 5 kinds of organic acid and 4 kinds of antibiotics.

• Journal of the Korean Society of Food Science and Nutrition
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• v.16 no.4
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• pp.251-261
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• 1987

This study was attempted to increase the production of L-Threonine by Brevibacterium Flavum ATCC 14067, To select the strain which produce the highest threonine, mutants ere induced by N-methyl-N'-nitro-N-nitrosoguanidine treatment. The composition of media and cultural condition for its overproduction of threonine were also studied. In a threonine producer, strain B-13(Met-) was the strain producing the highest amount of threonige among methionine, lysine and isoleucine auxotrophs. The following results were obtained. 1. The wild strain and B-13(Met-) produced threonine 1.4mg/ml and 4.86mg/ml , respectively. 2. The optimum composition of medium for producing threonine by Brevibacterium Flavum B-13 was glucose 10%, ammonium sulfate 4%, potassium phosphate monobasic 0.2%, magnesium sulfate 0.05%, biotin $200{\mu}l$, thiamine $300{\mu}l$. Addition of nicotinic acid also led to increase L-threonine production. 3. In addition of organic nutrients to the fermentation medium, peptone n'ere effective and addition of methionine $100{\mu}g/ml$ produced the highest amount of L-Threonine. Aspartic acid and homoserine were also effective when these amino acid were added to the fermentstion medium. 4. Cultural conditon on threonine production by B-16 were investigated. The optimum pH was 7.0-8.0. The highest amount of threnine was produced after 4 days of cultural period.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.771-781
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• 2015

To examine if the molecular chaperone DnaK operon proteins of Streptococcus suis type 2 (SS2) are involved in adhesion to host cells, the abundance values of these proteins from the surface of two SS2 strains of different adhesion capability were compared. Their roles in growth and adhesion to human laryngeal epithelial cell line HEp-2 cells were investigated on SS2 strain HA9801 and its mutants with DnaK operon genes partially knocked-out (PKO mutant) under heat stress. The major difference was that DnaJ was more abundant in strain HA9801 than in strain JX0811. Pretreatment of the bacteria with hyperimmune sera to DnaJ, but not with those to other proteins, could significantly reduce SS2 adhesion to HEp-2 cells. PKO of dnaJ g ene resulted in decreased SS2 growth at 37℃ and 42℃, and reduced its adhesion to HEp-2 cells. The wild-type strain stressed at 42℃ had increased expression of DnaJ on its surface and elevated adhesion to HEp-2 cells, which was also inhibitable by DnaJ specific antiserum. These results indicate that the DnaJ of S. suis type 2 is important not only for thermotolerance but also for adhesion to host cells. Because DnaJ expression is increased upon temperature upshift with increased exposure on the bacterial surface, the febrile conditions of the cases with systemic infections might help facilitate bacterial adhesion to host cells. DnaJ could be one of the potential candidates as a subunit vaccine because of its good immunogenicity.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.173-177
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• 1977

These experiments were conducted to investigate the formation of organic acid and ethanol during fermentation by three yeast strains. One of these was industrial strain (No.7) from Japan, and the others were wild types (No. 47, No. 239) isolated from Takju-mash and Strawbery, respectively. Conditions of fermentation were varied by differing the supply of oxygen (air), and by using different fermentation media The results obtained were as follows: 1) All the yeast strains produced higher amount of total organic acid and ethanol under the conditions which were aerobic, i.e. the flasks were opened during fermentation, than in case of using the flasks with fermentation bung. 2) Organic acid and ethanol were produced rapidly in the mash medium than in the semi-synthetic medium, i.e. total amount of organic acid and ethanol was maximized in a short time in the mash medium. 3) On the mash medium, the highest amount of organic acid was obtained by the strain No. 239, the next by No. 7 and the lowest by No. 47. Ethanol was produced on this medium with decreacing order of No. 47, No. 239, and No. 7. 4) The strain No. 239 was proved to be a powerful organic acid producer, yielding higher amount of organic acid especially under the aerobic conditions. 5) Above results suggests that the strain No. 239 could be of useful in alcoholic drink industry, due to its powerful ethanol-producing characteristic accompaning with high yielding of organic acids.

• Journal of Korean Society of Forest Science
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• v.77 no.2
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• pp.199-207
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• 1988

Three clones of Populus alba ${\times}$ P. grandidentata have been tested for susceptibility to Agrobacterium tumefaciens strains A281 and A348. We determined the optimum concentration of kanamycin sulfate for effective selection of leaf disc-derived, transgenic tissues transformed using Agrobacterium binary vector pGA472 containing a neomycin phosphotransferase gene (NPT-II) which confers kanamycin resistance. Of the wild type Ti plasmids contained by the two Agrobacterium strains, pTiBo542 of strain A281 appears to be best suited to serve as a helper plasmid for binary vector systems. A relatively low concentration (10mg/l) of kanamycin sulfate inhibited adventitious shoot initiation from leaf discs on regeneration medium. Transformed kanamycin-resistant calli were obtained by culturing Agrobacterium inoculated leaf discs on selective regeneration medium. The transformed kanamycin-resistant calli continued to grow on regeneration media supplemented with kanamycin sulfate to levels of 50 and 200mg/l. The growth of non-co-cultivated control calli was severely inhibited on regeneration medium containing 50mg/l kanamycin sulfate.

• Korean Journal of Microbiology
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• v.46 no.4
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• pp.383-388
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• 2010

Alkaline protease-overproducing strains of Vibrio metschnikovii were developed by using the molecular evolution from the classical mutants V. metschnikovii L12-23, N4-8, and KS1. Each vapK (Vibrio alkaline protease K) was obtained from the genomic DNAs of mutants by PCR to carry out the DNA shuffling. The modified vapK-1 obtained by DNA shuffling was used again as a template for the error-prone PCR to make the vapK-2. Both genes were cloned in the plasmid pKF3 to construct the recombinant plasmids which have one or two copies of the modified genes. The recombinant plasmids were back-transformed to V. metschnikovii KS1 to construct recombinant V. metschnikovii that expresses the alkaline protease. About 3.9-fold more protease activity was measured in the strain which has the plasmid containing two copies of vapK-2 when compared to strain KS1. When compared to wild type V. metschnikovii RH530, 43-fold more activity was achieved. Comparison of amino acids among vapK, vapK-1, and vapK-2 revealed that the active sites was highly conserved and not changed. However, many amino acids except the active sites were changed. These results suggested that the changes in amino acids might play an important role in the increase of protease activity by allowing the easy access of substrate to active sites of the protease. The fermentation of alkaline protease from the V. metschnikovii KS1 harboring the plasmid that contains two copies of vapK-1 showed the possibility of this strain to be used as industrial producer.