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Establishment of a Simple and Rapid Identification Method for Listeria spp. by Using High-Resolution Melting Analysis, and Its Application in Food Industry
Chihiro Ohshima, Hajime Takahashi, Chirapiphat Phraephaisarn, Mongkol Vesaratchavest, Suwimon Keeratipibul, Takashi Kuda, Bon Kimura
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0099223
Abstract: Listeria monocytogenes is the causative bacteria of listeriosis, which has a higher mortality rate than that of other causes of food poisoning. Listeria spp., of which L. monocytogenes is a member, have been isolated from food and manufacturing environments. Several methods have been published for identifying Listeria spp.; however, many of the methods cannot identify newly categorized Listeria spp. Additionally, they are often not suitable for the food industry, owing to their complexity, cost, or time consumption. Recently, high-resolution melting analysis (HRMA), which exploits DNA-sequence differences, has received attention as a simple and quick genomic typing method. In the present study, a new method for the simple, rapid, and low-cost identification of Listeria spp. has been presented using the genes rarA and ldh as targets for HRMA. DNA sequences of 9 Listeria species were first compared, and polymorphisms were identified for each species for primer design. Species specificity of each HRM curve pattern was estimated using type strains of all the species. Among the 9 species, 7 were identified by HRMA using rarA gene, including 3 new species. The remaining 2 species were identified by HRMA of ldh gene. The newly developed HRMA method was then used to assess Listeria isolates from the food industry, and the method efficiency was compared to that of identification by 16S rDNA sequence analysis. The 2 methods were in coherence for 92.6% of the samples, demonstrating the high accuracy of HRMA. The time required for identifying Listeria spp. was substantially low, and the process was considerably simplified, providing a useful and precise method for processing multiple samples per day. Our newly developed method for identifying Listeria spp. is highly valuable; its use is not limited to the food industry, and it can be used for the isolates from the natural environment.
Genetic Diversity and Microevolution of Burkholderia pseudomallei in the Environment
Narisara Chantratita equal contributor,Vanaporn Wuthiekanun equal contributor,Direk Limmathurotsakul,Mongkol Vesaratchavest,Aunchalee Thanwisai,Premjit Amornchai,Sarinna Tumapa,Edward J. Feil,Nicholas P. Day,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2008, DOI: 10.1371/journal.pntd.0000182
Abstract: Background The soil dwelling Gram-negative pathogen Burkholderia pseudomallei is the cause of melioidosis. The diversity and population structure of this organism in the environment is poorly defined. Methods and Findings We undertook a study of B. pseudomallei in soil sampled from 100 equally spaced points within 237.5 m2 of disused land in northeast Thailand. B. pseudomallei was present on direct culture of 77/100 sampling points. Genotyping of 200 primary plate colonies from three independent sampling points was performed using a combination of pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Twelve PFGE types and nine sequence types (STs) were identified, the majority of which were present at only a single sampling point. Two sampling points contained four STs and the third point contained three STs. Although the distance between the three sampling points was low (7.6, 7.9, and 13.3 meters, respectively), only two STs were present in more than one sampling point. Each of the three samples was characterized by the localized expansion of a single B. pseudomallei clone (corresponding to STs 185, 163, and 93). Comparison of PFGE and MLST results demonstrated that two STs contained strains with variable PFGE banding pattern types, indicating geographic structuring even within a single MLST-defined clone. Conclusions We discuss the implications of this extreme structuring of genotype and genotypic frequency in terms of micro-evolutionary dynamics and ecology, and how our results may inform future sampling strategies.
Burkholderia pseudomallei genome plasticity associated with genomic island variation
Sarinna Tumapa, Matthew TG Holden, Mongkol Vesaratchavest, Vanaporn Wuthiekanun, Direk Limmathurotsakul, Wirongrong Chierakul, Edward J Feil, Bart J Currie, Nicholas PJ Day, William C Nierman, Sharon J Peacock
BMC Genomics , 2008, DOI: 10.1186/1471-2164-9-190
Abstract: Five islands from B. pseudomallei strain K96243 were chosen as representatives of different types of genomic islands present in this strain, and their presence investigated in other B. pseudomallei. In silico analysis of 10 B. pseudomallei genome sequences provided evidence for the variable presence of these regions, together with micro-evolutionary changes that generate GI diversity. The diversity of GIs in 186 isolates from NE Thailand (83 environmental and 103 clinical isolates) was investigated using multiplex PCR screening. The proportion of all isolates positive by PCR ranged from 12% for a prophage-like island (GI 9), to 76% for a metabolic island (GI 16). The presence of each of the five GIs did not differ between environmental and disease-associated isolates (p > 0.05 for all five islands). The cumulative number of GIs per isolate for the 186 isolates ranged from 0 to 5 (median 2, IQR 1 to 3). The distribution of cumulative GI number did not differ between environmental and disease-associated isolates (p = 0.27). The presence of GIs was defined for the three largest clones in this collection (each defined as a single sequence type, ST, by multilocus sequence typing); these were ST 70 (n = 15 isolates), ST 54 (n = 11), and ST 167 (n = 9). The rapid loss and/or acquisition of gene islands was observed within individual clones. Comparisons were drawn between isolates obtained from the environment and from patients with melioidosis in order to examine the role of genomic islands in virulence and clinical associations. There was no reproducible association between the individual or cumulative presence of five GIs and a range of clinical features in 103 patients with melioidosis.Horizontal gene transfer of mobile genetic elements can rapidly alter the gene repertoire of B. pseudomallei. This study confirms the utility of a range of approaches in defining the presence and significance of genomic variation in natural populations of B. pseudomallei.Burkholderia pseu
Anti-Aeromonas hydrophila activity and characterisation of novel probiotic strains of Bacillus subtilis isolated from the gastrointestinal tract of giant freshwater prawns
Mongkol Thirabunyanon
Maejo International Journal of Science and Technology , 2009,
Abstract: The antagonistic activity of two Bacillus strains isolated from the gastrointestinal tract of giant freshwater prawns against Aeromonas hydrophila was evaluated in vitro. The characterisation of the novel probiotic strains of these bacilli was also performed. Bacillus subtilis P33 and 72 were found to have high inhibition activities against the growth of A. hydrophila by two assay methods: paper disc and well diffusion. Probiotic properties, namely acid and bile salt tolerance, autoaggregation, coaggregation, hydrophobicity and adhesion to Caco-2 cells, were further analysed. Survival rates in model gastrointestinal tract condition, viz. pH 2.5 for 3 h and 0.3% bile salt for 24 h, were shown to be more than 95% and 90% respectively. The ability of B. subtilis strains of P33 and P72 to adhere to epithelial cells of the host animal was measured by percentage autoaggregation (35.7 and 42.2%), coaggregation (11.1 and 11.6%), hydrophobicity in n-hexadencane (25.6 and 30.0%), xylene (32.2 and 36.1%), toluene (30.3 and 31.6%), and adhesion to Caco-2 cells (4.21 and 3.23 log cfu/ml respectively). These results indicate that both strains of B. subtilis P33 and P72 can be considered to be good novel probiotic candidates for use in the prawn aquaculture industry.
Biotherapy for and protection against gastrointestinal pathogenic infections via action of probiotic bacteria
Mongkol Thirabunyanon
Maejo International Journal of Science and Technology , 2011,
Abstract: The microbiota in the human intestine play an important function in human health and disease. Gastrointestinal infections by foodborne pathogens are a main cause of morbidity and mortality worldwide. Such infections can be caused by contaminated foods or other sources which come in contact with human intestinal epithelial cells. In recent years, probiotics have been recommended as alternative biotherapeutic agents against intestinal pathogenic infections. Two genera of probiotics, Lactobacillus and Bifidobacterium, are commercially valuable applications, several forms of which are available as capsules or in functional food products such as yogurt, fermented juices and sausages. Probiotics protect against gastrointestinal pathogenic infection via several mechanisms. These include production of antimicrobial substances, competition for nutrient substrates, competitive exclusion, enhancement of intestinal barrier function, and immunomodulation. Probiotic bacteria have been documented as being effective in biotherapeutic applications against gastrointestinal pathogens, e.g. Helicobacter pylori, Salmonella, Escherichia coli, Listeria monocytogenes, and rotaviruses. This alternative therapeutic application of probiotics to protect against gastrointestinal pathogenic infections may be of great importance for future medicinal use.
Piecewise Surface Fitting for 3D Image Extraction
Mongkol Hunkrajok,Wanrudee Skulpakdee
Lecture Notes in Engineering and Computer Science , 2008,
Early fruit setting from tissue culture-derived mangosteen tree
Sompong Te-chato,Mongkol Lim
Songklanakarin Journal of Science and Technology , 2004,
Abstract: Vitro-plantlets of mangosteen derived from culturing young leaves were acclimatized in 1993. Small and large polybag seedlings were carefully raised under controlled environmental conditions until 1994 when they were ready to be transferred to the field. During this stage, morphological abnormalities of the seedlings were recorded. After transferring to the field for 5-6 years (1994-1999) at Yi Ngo District, Narathiwat Province and Klong Hoi Khong District, Songkhla Province, morphological characters of the plants were again observed in comparison with seed-derived plants. The results showed that tissue culture-derived plants were more bushy and started blooming 5 years after planting while the seed-derived plants still had tall canopy (not bushy) and were not bearing fruit in the same period of time. However, the blooming of cultured plants did not give the fruit setting in the first blooming year. All flowers dropped off completely. Heavy fruit setting was observed in the following year (2000). Tissue culture trees had smaller but healthier leaves whereas seed-derived trees had pale yellowish green leaves. Fruit qualities in terms of total soluble solids (TSS) and total acids (TA) were not much different between the two types of these mangosteen trees.
Bis(acetato-κ2O,O′)(4,4′-dimethyl-2,2′-bipyridine-κ2N,N′)copper(II) monohydrate
Aphiwat Kaewthong,Mongkol Sukwattanasinitt,Nongnuj Muangsin
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812020193
Abstract: In the title compound, [Cu(C2H3O2)2(C12H12N2)2]·H2O, the CuII atom exhibits a distorted octahedral coordination geometry, defined by two N atoms from one 4,4′-dimethyl-2,2′-bipyridine ligand and four O atoms from two acetate ligands. In the crystal, O—H...O hydrogen bonds are observed between the coordinated carboxylate O atoms and the solvent water molecule.
Mechanical and Gas Barrier Properties of Nylon 6/Clay Nanocomposite Blown Films
Anongnat Somwangthanaroj,Mongkol Tantiviwattanawongsa,Wiwut Tanthapanichakoon
Engineering Journal , 2012, DOI: 10.4186/ej.2012.16.2.93
Abstract: Nylon 6/clay nanocomposite films were prepared by melt mixing nylon 6 with organoclay using a twin screw extruder attached to a blown film die. The type of surfactant used in the pretreatment of organoclay was expected to affect the degree of clay dispersion, which would in turn affect the degree of crystallinity, crystalline phase and bulk properties of the polymer composite. Two different surfactants used to treat the surface of montmorillonite clay were trimethyl tallow quaternary ammonium chloride (M3T, a single-chain surfactant) and dimethyl bis (hydrogenated-tallow) ammonium chloride (M2(HT)2, a double-chain surfactant). The addition of the resulting organoclay into nylon 6 was found to enhance the formation of γ-phase and increase the degree of crystallinity and crystallization temperature of the nylon 6. In fact nanocomposite films containing the single-chain surfactant showed a higher degree of clay dispersion in nylon 6 matrix, up to 148% higher stiffness and up to 100% lower oxygen permeability than those films containing the corresponding double-chain surfactant at the same inorganic loadings investigated. As expected, the nanocomposite films exhibited 58% higher stiffness in the machine direction than the transverse direction.
Implementation of Auto Monitoring and Short-Message-Service System via GSM Modem
Akilan Thangarajah,Buddhapala Wongkaew,Mongkol Ekpanyapong
Computer Science , 2015,
Abstract: Auto-Monitoring and Short-Messaging-Service System is a real-time monitoring system for any critical operational environments. It detects an undesired event occurring in the environment, generates an alert with detailed message and sends it to the user to prevent hazards. This system employs a Friendly ARM as main controller while, sensors and terminals to interact with the real world. A GSM network is utilized to bridge the communication between monitoring system and user. This paper presents details of prototyping the system.
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