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Cyanobacteria are distributed worldwide, and many new cyanobacterial species are discovered in tropical region. The Nostoc-like genus Amazonocrinis has been separated from the genus Nostoc based on polyphasic methods. However, species diversity within this genus remains poorly understood systematically because only one species (Amazonocrinis nigriterrae) has been described. In this study, two novel strains (NUACC02 and NUACC03) were isolated from moist rice field soil in Thailand. These two strains were characterized using a polyphasic approach, based on morphology, 16S rRNA phylogenetic analysis, internal transcribed spacer secondary structure and ecology. Phylogenetic analyses based on 16S rRNA gene sequences confirmed that the two novel strains formed a monophyletic clade related to the genus Amazonocrinis and were distant from the type species A. nigriterrae. The 16S rRNA gene sequence similarity (<98.1%) between novel strains and all other closely related taxa including the Amazonocrinis members exceeded the cutoff for species delimitation in bacteriology, reinforcing the presence of a new Amazonocrinis species. Furthermore, the novel strains possessed unique phenotypic characteristics such as the presence of the sheath, necridia-like cells, larger cell dimension and akinete cell arrangement in long-chains and the singularity of D1-D1', Box-B, V2, and V3 secondary structures that distinguished them from other Amazonocrinis members. Considering all the results, we described our two strains as Amazonocrinis thailandica sp. nov. in accordance with the International Code of Nomenclature for Algae, Fungi and Plants. [ABSTRACT FROM AUTHOR]

New industrial microorganisms are required to improve biofuel production with a key factor being ethanol fermentation at a high temperature. In this study, 222 yeast isolates from sugarcane field soil from lower Northern Thailand were isolated using yeast extract peptone dextrose medium supplemented with 4% (v/v) ethanol. The isolates were characterized for growth performance under stress conditions and for fermentation activity at high temperatures. A phylogenetic analysis of 25 thermotolerant yeasts grouped the isolates into clusters of Candida blankii, Saccharomyces cerevisiae and Pichia kudriavzevii. Two isolates, P. kudriavzevii NUPHS33 and NUPHS34, exhibited high temperature and ethanol tolerance levels of up to 45 °C and 15 (v/v), respectively. Ethanol production upon utilization of glucose as a carbon source was determined by gas chromatography. The highest ethanol concentration of P. kudriavzevii NUPHS33 and NUPHS34 reached 61.51-1.01 g/l at 45 °C and 69.79-1.54 g/l at 40 °C, respectively, which is significantly greater than the amount of ethanol produced by the industrial strain S. cerevisiae TISTR5606 (p < 0.01). Therefore, the newly isolated thermo- and ethanol-tolerant P. kudriavzevii NUPHS33 and NUPHS34 are highly competent yeasts for high-temperature ethanol fermentation. Our results might be useful to further improve commercial-scale bioethanol production. [ABSTRACT FROM AUTHOR]

Raphidiopsis (previously Cylindrospermopsis) raciborskii is considered as a cylindrospermopsin (CYN) producer in Thailand. There are no reports including molecular information on the genes associated with CYN production of cyanobacteria from Thailand. In the present study, 27 new R. raciborskii strains from Thailand were isolated. Their morphological features and phylogenetic positions based on the partial sequences of 16S rDNA and rbcLX were analyzed for identification. Morphological characteristics of all the strains tested, and the natural samples, were found to be similar to the original description of R. raciborskii. The rbcLX phylogenetic trees revealed that the clade of R. raciborskii is independent from those of R. mediterranea and R. curvata, whereas the 16S rDNA phylogenetic trees failed to discriminate these species. Thus, all the strains tested in the present study were identified as R. raciborskii. Furthermore, the LC/MS/MS analysis confirmed that some of the strains tested produced CYN and 7-deoxy-CYN. The presence of genes associated with CYN biosynthesis (cyrA, cyrB, cyrC, and cyrJ) in Thai Raphidiopsis strains was investigated by PCR and phylogenetic analyses. Results of PCR showed that the PCR amplicons of cyrB and cyrJ were obtained from all toxic strains, while the amplicons of cyrA and cyrC were not obtained in some toxic Thai strains. Our findings supported the observation that cyrB and cyrJ, especially the latter, may be useful for the detection of CYNproducing cyanobacteria in water resources for water supplies and fisheries. [ABSTRACT FROM AUTHOR]

Species of the benthic dinoflagellate genus Gambierdiscus are the putative producer of the toxins causing ciguatera fish poisoning (CFP) in tropical and subtropical areas. Although CFP events and distribution of G. caribaeus have been reported in Thailand, little is known about the conditions that enhance the growth of Gambierdiscus in Thailand. Flence, this study was aimed at determining the effects of temperature and salinity and their interactions on the growth of Thai G. caribaeus. The strain tested showed the highest cell yield in IMK/2 medium. Based on growth rate (p), Thai G. caribaeus grew in the temperature range of 20°C-35°C and the salinity range of 20M0. The suboptimal condition (> 80% of the maximal growth rate) for the strain tested was 20.5°C-30.5°C and salinity of 25.0-37.5. The optimal condition was 25°C and salinity of 30. Furthermore, the Thai G. caribaeus revealed high toxicity to mice. Our results suggest that tolerance of up to 35°C may allow these organisms to be distributed in tropical areas, including Thailand, where the water temperature often exceeds 30°C. [ABSTRACT FROM AUTHOR]

The toxic benthic dinoflagellate genus Ostreopsis has been connected to the production of palytoxin and its analogs in many tropical and temperate areas. Although the type species, O. siamensis, was originally described from the Gulf of Thailand in 1901, little is known about the species composition and distribution of the genus Ostreopsis in Thailand. In this study, a total of 64 Ostreopsis strains isolated from the Andaman Sea as well as the Gulf of Thailand were investigated by analyzing the nucleotide sequences of the LSU rDNA D1/D2, D8/D10 and ITS-5.8S rDNA regions. Phylogenetic analyses (BI and ML) resulted in some of the strains being assigned to previously described clades, O. cf. ovata and Ostreopsis sp. 6, and revealed the existence of a novel clade named Ostreopsis sp. 7, which exhibited large genetic distances from the other clades. Among O. cf. ovata, several strains from Thailand were formed into a new subclade, the Thailand subclade, whereas a few strains belonged to the South China Sea subclade. Morphometric characteristics such as the cell sizes of the two O. cf. ovata subclades and those of Ostreopsis sp. 7 were not significantly different from each other (p > 0.05). Their characteristics were similar but slightly different from those of O. ovata and were significantly different from those of Ostreopsis sp. 6 (p < 0.05). Toxicities of Ostreopsis from Thailand were evaluated using mouse bioassay. Strains of Ostreopsis sp. 6 and Ostreopsis sp. 7 tested were highly toxic, while the two subclades of O. cf. ovata strains seemed to be nontoxic. This study suggests that toxic Ostreopsis sp. 7 is distributed in the Andaman Sea, whereas the two subclades of O. cf. ovata and toxic Ostreopsis sp. 6 are distributed in the Gulf of Thailand. [ABSTRACT FROM AUTHOR]