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An actinomycete strain RM579 T isolated from roots of Pithecellobium dulce in Thailand was studied using the polyphasic taxonomic approach. The results of comparative 16S rRNA gene sequence and phylogenetic analysis showed that strain RM579 T belonged to the family Pseudonocardiaceae and it was most closely related to members of the genera Amycolatopsis (≤94.5% sequence similarity) and Haloechinothrix (≤93.4% sequence similarity). A phylogenetic tree constructed by neighbor-joining method indicated that strain RM579 T was positioned within the clade of the genus Amycolatopsis and formed a monophyletic cluster with Amycolatopsis taiwanensis 0345M-7 T , Amycolatopsis pigmentata TT00-43 T and Amycolatopsis helveola TT99-32 T . Strain RM579 T formed white aerial mycelium and yellowish-brown substrate mycelium that fragments into rod-shaped elements. Morphological features and chemotaxonomic characteristics of strain RM579 T were consistent with those of the genus Amycolatopsis. The cell wall of strain RM579 T contained meso-diaminopimelic acid. Arabinose, galactose, mannose, and ribose were detected as whole-cell sugars. Mycolic acids were absent. The acyl type of the muramic acid in the cell wall was N-acetyl. Diphosphatidylglycerol, hydroxyl-phosphatidylethanolamine, phosphatidylinositol, and an unidentified phospholipid were detected as polar lipids. The major cellular fatty acids (>10%) were iso-C 16:0 , iso-C 16:0 2-OH, and C 16:1 cis9. The resultant data indicated that strain RM579 T should be classified as representative of a novel species in the genus Amycolatopsis, for which the name Amycolatopsis pithecelloba sp. nov. is proposed. The type strain is RM579 T (=TBRC 1849 T =NBRC 106096 T ).

Four strains representing three novel anamorphic yeast species were isolated from the external surface of sugarcane leaves (DMKU-RK254(T)), corn leaves (DMKU-RK548(T)), bean leaves (K129) in Thailand and hengchun pencilwood leaves (TrB1-1(T)) in Taiwan. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, the sequence analysis of the D1/D2 region of the large subunit (LSU) rRNA gene, the internal transcribed spacer (ITS) region, the actin gene (ACT1) and the elongation factor 2 gene (EF2), the four strains were determined to represent novel Yamadazyma species although formation of ascospores was not observed. Strain DMKU-RK254(T) was determined to be related to Candida diddensiae, Candida naeodendra and Candida kanchanaburiensis but with 1.8, 1.8 and 2.0 % nucleotide substitutions in the D1/D2 region of the LSU rRNA gene, respectively. It was assigned to Yamadazyma siamensis sp. nov. (type strain DMKU-RK254(T) = BCC 50730(T) = NBRC 108901(T) = CBS 12573(T)). The sequences of the D1/D2 region of the LSU rRNA gene, the ITS region, ACT1 gene and EF2 gene of two strains (DMKU-RK548(T) and K129) were identical but differed from that of strain TrB1-1(T) by 0.6, 1.0, 3.3 and 5.9 % nucleotide substitutions, respectively. Therefore, the two strains (DMKU-RK548(T) and K129) and strain TrB1-1(T) were assigned to be two separate species. The closest species in terms of pairwise sequences similarity of the D1/D2 region to the two novel species was Yamadazyma philogaea but with 1.1-1.7 % nucleotide substitutions. The two strains (DMKU-RK548(T) and K129) were assigned to Yamadazyma phyllophila sp. nov. (type strain DMKU-RK548(T) = BCC 50736(T) = NBRC 108906(T) = CBS 12572(T)) and the strain TrB1-1(T) was named Yamadazyma paraphyllophila sp. nov. (type strain TrB1-1(T) = BCRC 23030(T) = CCTCC AY 204005(T) = CBS 9928(T)).

The diversity of bacteria nodulating Aeschynomene americana L. in Thailand was determined from phenotypic characteristics and multilocus sequence analysis of the 16S rRNA gene and 3 housekeeping genes (dnaK, recA, and glnB). The isolated strains were nonphotosynthetic bacteria and were assigned to the genus Bradyrhizobium, in which B. yuanmingense was the dominant species. Some of the other species, including B. japonicum, B. liaoningense, and B. canariense, were minor species. These isolated strains were divided into 2 groups-nod-containing and divergent nod-containing strains-based on Southern blot hybridization and PCR amplification of nodABC genes. The divergent nod genes could not be PCR amplified and failed to hybridize nod gene probes designed from B. japonicum USDA110, but hybridized to probes from other bradyrhizobial strains under low-stringency conditions. The grouping based on sequence similarity of nod genes was well correlated with the grouping based on that of nifH gene, in which the nod-containing and divergent nod-containing strains were obviously distinguished. The divergent nod-containing strains and photosynthetic bradyrhizobia shared close nifH sequence similarity and an ability to fix nitrogen in the free-living state. Surprisingly, the strains isolated from A. americana could nodulate Aeschynomene plants that belong to different cross-inoculation (CI) groups, including A. afraspera and A. indica. This is the first discovery of bradyrhizobia (nonphotosynthetic and nod-containing strain) originating from CI group 1 nodulating roots of A. indica (CI group 3). An infection process used to establish symbiosis on Aeschynomene different from the classical one is proposed.

Three strains (LM008(T), LM068 and LM078(T)), representing two novel yeast species were isolated from the phylloplane of three plant species by an enrichment technique. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, and the sequence analysis of the D1/D2 domain of the large subunit rRNA gene and the internal spacer region, the three strains were assigned as two novel Candida species. Strain LM008(T) was assigned to be Candida sirachaensis sp. nov. (type strain LM008(T) = BCC 47628(T) = NBRC 108605(T) CBS 12094(T)) in the Starmerella clade. Two strains (LM068 and LM078(T)) represent a single species in the Lodderomyces-Spathaspora clade for which the name Candida sakaeoensis sp. nov. is proposed with the type strain LM078(T) = BCC 47632(T) = NBRC 108895(T) = CBS 12318(T).

A novel actinomycete, designated strain RM287(T), was isolated from surface-sterilized roots of Samanea saman (Jacq.) Merr., collected from Bangkok, Thailand. The status of the novel strain was determined using a polyphasic taxonomic approach. Phylogenetic analyses based on 16S rRNA gene sequences showed that the organism formed a distinct phyletic line within the radiation of the genus Amycolatopsis. The 16S rRNA gene sequence similarity indicated that strain RM287(T) was most closely related to Amycolatopsis mediterranei IMSNU 20056(T) (97.4 %), A. rifamycinica DSM 46095(T) (97.2 %), A. kentuckyensis NRRL B-24129(T) (97.2 %), A. pretoriensis DSM 44654(T) (97 %) and A. australiensis DSM 44671(T) (97 %). The novel organism was found to have chemical properties typical of members of the genus Amycolatopsis such as meso-diaminopimelic acid as the dignostic diamino acid in the cell-wall peptidoglycan and arabinose and galactose as the diagnostic sugars. The major menaquinone was MK-9(H(4)). The major fatty acids were iso-C(16 : 0) iso-C(15 : 0), iso 2-OH-C(16 : 0) and iso-C(17 : 0). The DNA G+C content was 71.7 mol%. Phenotypic data clearly distinguished the novel isolate from its closest relatives. The combined genotypic and phenotypic data indicated that strain RM287(T) represented a novel species of the genus Amycolatopsis. The proposed name for this organism is Amycolatopsis samaneae sp. nov., with the type strain RM287(T) ( = TISTR 1919(T) = BCC 35842(T) = NBRC 106095(T)).

This glasshouse experiment was carried out in the 2004 at the Department of Agricultural Production, Faculty of Technology, Mahasarakham University, Mahasarakham 4400, Northeast Thailand to compare amounts of infection of Pseudocercospora leaf spot disease in leaves of cowpea cultivars being screened between detached leaf and plastic growth pouches techniques. The experiment was laid in a factorial arranged in a Randomized Complete Block Design (RCBD) with four replications. KVC7, IT81D-1228-14-1 and KKU25 cowpea cultivars were used as factor A, detached leaf and plastic growth pouches techniques were used as factor B and four levels of the concentrations of the spores of the disease, i.e., 0, l x 10(4), 5 x 10(4) and 1 x 10(5) of disease forming units mL(-1) of distilled water were used as factor C. The results showed that KVC7 and IT81D-1228-14-1 cultivars possessed immune and high resistant properties against the disease, respectively, whereas KKU25 cultivar ranked as a susceptible cultivar. Detached leaf technique gave higher amount of infection of the disease than plastic growth pouches technique and the differences were highly significant. A plentiful amount of Infected disease was attained with an inoculation rate of l x 10(5) forming units mL(-1) of distilled water, which was considered too high and the most appropriate concentrations for use lie on both concentrations, i.e., 1 x 10(4) and 5 x 10(4) forming units mL(-1) of distilled water. An interaction among factors AxBxC was severely found with KKU25 cultivar, particularly on day 28 after inoculation, whilst other two cultivars gave a minute amount of disease incidences (%) where detached leaf technique gave much higher disease incidences than plastic growth pouches technique, thus detached leaf technique should be of higher advantages.

This investigation was carried out at the Experimental Farm, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand to evaluate intensity of infection of Pseudocercospora Leaf Spot disease of cowpea cultivars, grown under field conditions with the use of Yasothon soil series (Oxic Paleustults). The experimental design used was a strip split plot design with four replications. The experiment consisted of three factors, i.e., with and without infector rows (Factor A), with and without inoculation and inoculated dates, i.e. none inoculation, inoculated at days 15 and 30 after sowing of seeds in main plots (Factor B) and three cowpea cultivars of KVC7, KKU25 and IT81D-1228-14-1 (Factor C). The results showed that the use of infector rows of cowpea plants (KKU25) being sown at 15 days before sowing seeds of cowpea cultivars in main plots gave a similar intensity of disease as those infector rows being sown at 30 days before sowing seeds of cowpea cultivars in main plots but significantly higher than without infector rows. Pathogenic disease being inoculated to the cowpea plants at 15 days after the sowing of seeds in main plots gave significantly higher intensity of disease than none inoculation. The establishment of infector rows at 15 days ahead of the sowing of seeds in main plots together with an inoculation of the disease at 15 days after the sowing of seeds in main plots gave the best results in evaluating amount of the infected disease. Thus infector rows surrounded the main plots are required whenever trials on disease evaluation are taken place.

The analysis of nod genes and 16S rRNA gene regions, Nod factors, and nodulation abilities of Brady rhizobium strains isolated from tropical Thai Vigna species is reported. A total of 55 Bradyrhizobium strains isolated from two cultivated and six wild Vigna species growing in central and northern Thailand were evaluated. Thai Vigna spp. Bradyrhizobium strains showed higher levels of nod gene RFLP diversity compared with Thai soybean Brady rhizobium strains or temperate strains of Bradyrhizobium japonicum and Bradyrhizobium elkanii. Analysis of the 16S rRNA gene region using selected strains also suggests a high genetic diversity of the Thai Vigna-Bradyrhizobium association. Based on thin-layer chromatography analysis, Nod factors produced by tropical Thai Vigna spp. Brady rhizobium strains are more diverse than temperate Japanese and US strains of B. japonicum and B. elkanii. Thai Vigna spp. Bradyrhizobium strains showed variation in nodulation ability and affinity, estimated by the number of normal nodules versus green nodules in an inoculation study. There are some Bradyrhizobium-host combinations that could not form any nodules, suggesting that some genetic differentiation has evolved in their host range. However, most of the Thai Vigna spp. Bradyrhizobium strains formed nodules on the cultigens soybean (Glycine max), mungbean (Vigna radiata), azuki bean (Vigna angularis), and cowpea (Vigna unguiculata). This is the first study on Bradyrhizobium strains associated with a range of cultivated and wild Vigna and reveals that these Bradyrhizobium strains are diverse and may provide novel sources of useful variation for the improvement of symbiotic systems.

To determine the taxonomic relationship between Thai soybean bradyrhizobia and soybean bradyrhizobia from other regions, a total of 62 Bradyrhizobium strains were isolated in Thailand. The genetic diversity of the strains was examined with reference to 46 Japanese and 15 USDA strains. The degree of sequence divergence in and around common nod gene regions of the 123 strains was estimated by restriction fragment length polymorphism analysis using the Bradyrhizobium japonicum USDA 110 common nodDYABC gene probe. The phylogenetic grouping of the strains resulted in four major clusters. Cluster 1 comprised the Japanese and USDA strains, which originated in temperate regions, whereas clusters 3 and 4 comprised the tropical Thai strains. Cluster 1 strains comprised the DNA homology groups I and Ia, and hence, were classified as B. japonicum. Cluster 2 strains were in the DNA homology group II, and hence, were classified as Bradyrhizobium elkanii. Clusters 3 and 4 strains, however, did not correspond to any known DNA homology groups. These results indicate that Thai soybean bradyrhizobia are distantly related to B. japonicum and B. elkanii.

Part of a comprehensive study of fungi occurring in commodities in Thailand, this paper reports results from 276 samples of mung beans, rice, sorghum and soybeans as well as other minor crops. Samples for major commodities were taken from farmers' stocks, middlemen and retail outlets, while those for minor crops were mostly from retail. Each sample was divided into two portions, one being examined in Bangkok and the second at North Ryde. Mycological examinations were carried out by direct plating after surface disinfection in chlorine. Media used were dichloran rose bengal chloramphenicol agar, dichloran 18% glycerol agar, Aspergillus flavus and parasiticus agar and dichloran chloramphenicol peptone agar. Fungi were identified to species level and percentage infection of samples calculated. The dominant fungus found in mung beans was Fusarium semitectum, which was present in 40% of samples and at a high level (18% of all seeds) overall. Aspergillus flavus was also found in 40% of samples, but only in 2% of seeds overall. Lasiodiplodia theobromae was the only other fungus exceeding 1% total infection. The major fungi found in soybeans were A. flavus (67% of samples; 6% overall) and Cladosporium cladosporioides (49% of samples; 9% overall). Storage fungi were more common in soybeans than the other commodities, indicating longer or adverse storage. Paddy rice contained high levels of a wide variety of field fungi, notably Fusarium semitectum, Bipolaris oryzae, and Curvularia, Phoma and Colletotrichum species. However, probably due to the heat generated by milling, milled rice contained very few fungi, which were mostly of storage origin. Only 3% of particles examined contained internal fungi. Infection in sorghum was typical of oilseeds, dominated by Aspergillus flavus, which was present in 86% of samples, with an overall infection rate of 12%. Beans other than soybeans were infected by a wide range of field fungi, but at low levels, with less than half of seeds examined being infected internally. With the exception of sorghum, the levels of mycotoxigenic fungi encountered were much lower than observed previously in nuts and oilseeds.

Detection of Salmonella spp. in 344 samples of bean sprouts was attempted by pre-enriched in buffered peptone water (BPW) or lactose broth (LB) at 37 degrees C, followed by selective enrichments, selenite cystein broth (SCB) and Rappaport medium (RV) at 43 degrees C. Four selective media, bismuth sulphite agar (BSA), brilliant green agar (BGA), Salmonella-Shigella agar (SSA) and MacConkey agar (MA) were used for isolation. Salmonellae were isolated from 30 (8.7%) samples. They were serotypes lexington (56.7%), orion (16.7%), senftenberg (16.7%), tennessee (3.3%), poona (3.3%) and weltevreden (3.3%). Pre-enrichment in LB, followed by enrichment in SCB and streaking on to BSA gave the highest recoveries. Fifteen of 30 strains isolated were sensitive to all 14 antibiotics tested. Seven strains were resistant to one, and a strains showed multiple resistance to 2-4 antimicrobial agents.