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Poolsawat O.,Suranaree University of Technology | Poolsawat O.,Center for Agricultural Biotechnology PERDO CHE | Tharapreuksapong A.,Suranaree University of Technology | Wongkaew S.,Suranaree University of Technology | And 2 more authors.
Journal of Phytopathology | Year: 2010

Anthracnose is one of the major diseases affecting grape (Vitis vinifera L.) cultivars in Thailand. Isolates of Sphaceloma ampelinum, the anamorph stage of Elsinoe ampelina, were collected from various regions of Thailand. Nineteen single-conidial isolates were evaluated for differences in conidial morphology, DNA patterns and pathogenicity. These isolates could not be unambiguously distinguished based on conidial morphology; however, they were genetically differentiated using random amplified polymorphic DNA markers. Cluster analysis by the unweighted paired grouped mean arithmetic average classified these isolates into four groups. Pathogenicity analysis using nine grape genotypes and five S. ampelinum isolates showed that 'Wilcox321' and 'Illinois547-1 were highly resistant to all isolates, suggesting their usefulness as resistant sources in future breeding programmes. © 2010 Blackwell Verlag GmbH.

Wichaphon J.,Mahidol University | Wichaphon J.,Center for Agricultural Biotechnology PERDO CHE | Thongthai C.,Mahidol University | Assavanig A.,Mahidol University | Lertsiri S.,Mahidol University
Flavour and Fragrance Journal | Year: 2012

Numerous investigations on aroma characteristics of fish sauce in particular samples have been conducted extensively; however, the relation of those volatile aroma profiles and aroma characteristics to quality and categorization of the product have never been reported. This study explored the contribution of volatile aroma components on product quality categorization of 52 Thai fish sauce samples. First, odour-active compounds were investigated by dynamic headspace gas chromatography-olfactometry (GC-O) from eight selected samples with four different qualities, including mature-unblended samples, premium-grade samples, first-grade samples and second-grade samples. Eleven odour-active compounds, i.e. acetic acid, propanoic acid, 2-methylpropanoic acid, butanoic acid, 3-methylbutanoic acid, dimethyl trisulfide, 3-(methylthio)propanal, 1-octen-3-ol, 2-butanol, trimethylamine and n-propanol, contributed to the aroma characteristics of Thai fish sauce. A combination score was assigned to express the integration of flavour dilution on dynamic headspace dilution analysis and intensity of odour perceived on GC-O. The combination scores were analysed with principal component analysis to categorize these eight selected samples. Furthermore, these odour-active compounds detected as released volatile compounds from 52 fish sauce samples were applied for categorization of 52 samples. As a result, both combination scores and relative concentrations of these odour-active compounds could discriminate the fish sauce products according to their conventional grading which is based on total nitrogen of the sample. © 2011 John Wiley & Sons, Ltd.

Saktaweewong S.,Mahidol University | Saktaweewong S.,Center for Agricultural Biotechnology PERDO CHE | Phinyocheep P.,Mahidol University | Ulmer C.,Helmholtz Center for Infection Research | And 3 more authors.
Journal of Molecular Catalysis B: Enzymatic | Year: 2011

This work focused on lipase-catalyzed triglyceride hydrolysis in biphasic media. The effect of specific interfacial area of oil-in-water emulsions on the hydrolysis activity of lipase was particularly investigated following a rigorous methodology and using two different oils, tributyrin and olive oil. The specific interfacial area was varied over several orders of magnitude by changing either the amount of emulsified oil or the average diameter of oil droplets. This work particularly focused on the effect of changing droplet size (at given amount of oil) on lipase activity. When the specific interfacial area was varied over several orders of magnitude, the specific activity of the enzyme exhibited a non-monotonic variation with a pronounced maximum. At low specific interfacial area, initial velocity increased with specific interfacial area. Inhibition of enzyme activity at a high interfacial concentration of triglyceride was observed. Experimental results were interpreted on the basis of a theoretical mechanism assuming Michaelis-Menten mechanism for enzyme catalysis, Langmuir-type adsorption isotherm for enzyme and limitation of enzyme-substrate formation by enzyme adsorption process. © 2011 Elsevier B.V.

Narit T.,Prince of Songkla University | Narit T.,Center for Agricultural Biotechnology PERDO CHE | Anuchit C.,National Biological Control Research Center
Philippine Agricultural Scientist | Year: 2011

Factors affecting the attraction of two fruit fly species [Bactrocera cucurbitae (Coquillett) and B. papayae Drew and Hancock] to the odor of the bacterium Enterobacter cloacae were studied. The experimental factors analyzed were sex (S), mating experience (M), feeding status (F) and host fruit provision (H). For B. cucurbitae, all main factors and their interaction did not affect net attractancy to bacterial odor except for the interaction between M and F where protein-deprived virgin flies gave significantly the lowest percentage net attractancy. In B. papayae, the main effects of S, M and H and the interaction effect of (S×M×F) and (M×F×H) significantly influenced net attractancy. Male flies which have mated and those not given host fruit showed high response to bacterial odor. For the interactive factors, mated male and protein-fed flies had higher net attractancy to bacterial odor compared with the virgin female and protein-fed flies. On the other hand, flies which had mated which were protein-deprived and were not provided with host fruit, gave higher net attractancy compared with virgin flies which were fed with protein and host fruit. B. papayae was more attracted to the bacterial odor than B. cucurbitae.

Thaochan N.,Walailak University | Thaochan N.,Center for Agricultural Biotechnology PERDO CHE | Drew R.A.I.,Griffith University | Hughes J.M.,Griffith University | And 2 more authors.
Journal of Insect Science | Year: 2010

Bacteria were isolated from the crop and midgut of field collected Bactrocera cacuminata (Hering) and Bactrocera tryoni (Froggatt) (Diptera: Tephritidae). Two methods were used, firstly isolation onto two types of bacteriological culture media (PYEA and TSA) and identification using the API-20E diagnostic kit, and secondly, analysis of samples using the 16S rRNA gene molecular diagnostic method. Using the API-20E method, 10 genera and 17 species of bacteria in the family Enterobacteriaceae were identified from cultures growing on the nutrient agar. The dominant species in both the crop and midgut were Citrobacter freundii, Enterobacter cloacae and Klebsiella oxytoca. Providencia rettgeri, Klebsiella pneumoniae ssp ozaenae and Serratia marcescens were isolated from B. tryoni only. Using the molecular cloning technique that is based on 16S rRNA gene sequences, five bacteria classes were dignosed Alpha-, Beta-, Gamma- and Delta- Proteobacteria and Firmicutes including five families, Leuconostocaceae, Enterococcaceae, Acetobacteriaceae, Comamonadaceae and Enterobacteriaceae. The bacteria affiliated with Firmicutes were found mainly in the crop while the Gammaproteobacteria, especially the family Enterobacteriaceae, was dominant in the midgut. This paper presents results from the first known application of molecular cloning techniques to study bacteria within tephritid species and the first record of Firmicutes bacteria in these flies.

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