Natsaran Saichana - Academia.edu (original) (raw)

Papers by Natsaran Saichana

Phytotaxa

Lophiostomataceae species commonly occur as saprobes on twigs, stems or bark on diverse woody and... more Lophiostomataceae species commonly occur as saprobes on twigs, stems or bark on diverse woody and herbaceous plants in aquatic and terrestrial habitats. In the present study, we introduce Lophiostoma khanzada-kirgizbaeva sp. nov. and Paucispora xishanensis sp. nov. as new species isolated from woody substrates from Uzbekistan and China, respectively. Species delimitation was conducted using morphological and molecular phylogenetic approaches. Maximum likelihood and Bayesian inference analyses of a combined SSU, ITS, LSU, tef1-α and rpb2 sequence matrix revealed that L. khanzada-kirgizbaev and P. xishanensis are distinct from other Lophiostoma and Paucispora species in Lophiostomataceae, respectively.

Phytotaxa, Mar 25, 2022

Grasses are agriculturally, economically and ecologically dominant among plants. Their fungal div... more Grasses are agriculturally, economically and ecologically dominant among plants. Their fungal diversity is fascinating but has been relatively poorly studied or restricted to a few important hosts or pathogens. Therefore, numerous grass-inhabiting fungal species are awaiting discovery or re-study based on morphology and molecular phylogeny. In an ongoing study of grass-inhabiting fungi in Thailand, two interesting saprobic members of Sodariomycetes were collected. Based on morphology, coupled with combined gene analyses of LSU and ITS sequence data, they were identified as Dinemasporium pseudostrigosum and Robillarda africana belonging to Chaetosphaeriaceae and Sporocadaceae, respectively. This is the first report of the two species for Thailand as well as the first record of R. africana occurring on grasses. The newly collected species are compared to other related species and comprehensive descriptions and photo-micrographs are provided.

Bioscience, Biotechnology, and Biochemistry, 2022

We identified a novel flavoprotein–cytochrome c complex d-gluconate dehydrogenase (GADH) encoded ... more We identified a novel flavoprotein–cytochrome c complex d-gluconate dehydrogenase (GADH) encoded by gndXYZ of Gluconobacter oxydans NBRC 3293, which is phylogenetically distinct from previously reported GADHs encoded by gndFGH and gndSLC of Gluconobacter spp. To analyze the biochemical properties of respective GADHs, Gluconobacter japonicus NBRC 3271 mutant strain lacking membranous d-gluconate dehydrogenase activity was constructed. All GADHs (GndFGH, GndSLC, and GndXYZ) were successfully overexpressed in the constructed strain. The optimal pH and KM value at that pH of GndFGH, GndSLC, and GndXYZ were 5, 6, and 4, and 8.82 ± 1.15, 22.9 ± 5.0, and 11.3 ± 1.5 m m, respectively. When the mutants overexpressing respective GADHs were cultured in d-glucose-containing medium, all of them produced 2-keto-d-gluconate, revealing that GndXYZ converts d-gluconate to 2-keto-d-gluconate as well as other GADHs. Among the recombinants, the gndXYZ-overexpressing strain accumulated the highest level...

Key Engineering Materials, 2019

Ability of poly (styrene-alt-maleic anhydride) (PSMA) to undergo a conformational transition into... more Ability of poly (styrene-alt-maleic anhydride) (PSMA) to undergo a conformational transition into an amphipathic α-helix coil offers one possible mechanism by which PSMA surface activity can be switched on or off in response to the pH change. This behaviour allows it to be useful in membrane solubilization for extraction technology. Bioactive compounds are recovered from plant tissues for different reasons. One of the most important reasons is due to the increased demand in nutraceuticals market and modern therapeutics. Despite this, aqueous-based extraction of these compounds has been reported to give low extraction yield. A development of new green extraction protocol is still a challenging task for all researchers nowadays. This study demonstrated, for the first time, possible use of PSMA as a lysis agent for plant bioactive compound extraction. To enhance its membrane affinity at physiological pH, the polymer was esterified with methanol. Both PSMA and its derivative (ePSMA) wer...

Phytotaxa, 2018

A Truncatella-like coelomycete fungus was isolated from dead branches of Cytisus and Helichrysum ... more A Truncatella-like coelomycete fungus was isolated from dead branches of Cytisus and Helichrysum species from Arezzo Province, Italy. DNA sequence analyses of a combined LSU, ITS and SSU dataset indicated a close phylogenetic affinity of our isolate to Hyponectria buxi (Hyponectriaceae). Herein we describe it as a new genus with Pseudotruncatella arezzoensis sp. nov. However it cannot be referred to an appropriate familial position and therefore we refer it to Amphisphaeriales genera incertae sedis. Pseudotruncatella is characterized by holoblastic, annellidic, conidiogenous cells; 3-septate, fusiform to clavate conidia with 3 apical appendages, dark brown median cells and hyaline apical and basal cells. Neotruncatella is relegated to synonymy of Monochaetinula.

Journal of biochemistry, Jan 17, 2015

Methylobacterium extorquens AM1 is an aerobic facultative methylotroph known to secrete pyrroloqu... more Methylobacterium extorquens AM1 is an aerobic facultative methylotroph known to secrete pyrroloquinoline quinone (PQQ), a cofactor of a number of bacterial dehydrogenases, into the culture medium. To elucidate the molecular mechanism of PQQ biosynthesis, we are focusing on PqqE which is believed to be the enzyme catalyzing the first reaction of the pathway. PqqE belongs to the radical S-adenosyl-l-methionine (SAM) superfamily, in which most, if not all, enzymes are very sensitive to dissolved oxygen and rapidly inactivated under aerobic conditions. We here report that PqqE from M. extorquens AM1 is markedly oxygen-tolerant; it was efficiently expressed in Escherichia coli cells grown aerobically and affinity-purified to near homogeneity. The purified and reconstituted PqqE contained multiple (likely three) iron-sulfur clusters and showed the reductive SAM cleavage activity that was ascribed to the consensus [4Fe-4S](2+) cluster bound at the N-terminus region. Mössbauer spectrometric...

Biotechnology advances, Jan 5, 2014

Acetic acid bacteria are gram-negative obligate aerobic bacteria assigned to the family Acetobact... more Acetic acid bacteria are gram-negative obligate aerobic bacteria assigned to the family Acetobacteraceae of Alphaproteobacteria. They are members of the genera Acetobacter, Gluconobacter, Gluconacetobacter, Acidomonas, Asaia, Kozakia, Swaminathania, Saccharibacter, Neoasaia, Granulibacter, Tanticharoenia, Ameyamaea, Neokomagataea, and Komagataeibacter. Many strains of Acetobacter and Komagataeibacter have been known to possess high acetic acid fermentation ability as well as the acetic acid and ethanol resistance, which are considered to be useful features for industrial production of acetic acid and vinegar, the commercial product. On the other hand, Gluconobacter strains have the ability to perform oxidative fermentation of various sugars, sugar alcohols, and sugar acids leading to the formation of several valuable products. Thermotolerant strains of acetic acid bacteria were isolated in order to serve as the new strains of choice for industrial fermentations, in which the cooling...

Microbiology, 2011

Acetobacter pasteurianus is a Gram-negative strictly aerobic bacterium that is widely used for th... more Acetobacter pasteurianus is a Gram-negative strictly aerobic bacterium that is widely used for the industrial production of vinegar. Three Acetobacter pasteurianus strains, SKU1108, NBRC 3283 and IFO 3191, have the same 16S rRNA sequence (100 % sequence identity) but show differences in thermotolerance. To clarify the relationships between phylogeny and thermotolerance of these strains, genome-wide analysis of these three strains was performed. Concatenated phylogenetic analysis of a dataset of 1864 orthologues has shown that the more thermotolerant strains, SKU1108 and NBRC 3283, are more closely related to each other than to the more thermosensitive strain, IFO 3191. In addition, we defined a dataset of 2010 unique orthologues among these three strains, and compared the frequency of amino acid mutations among them. Genes involved in translation, transcription and signal transduction are highly conserved among each unique orthologous dataset. The results also showed that there are several genes with increased mutation rates in IFO 3191 compared with the thermotolerant strains, SKU1108 and NBRC 3283. Analysis of the mutational directions of these genes suggested that some of them might be correlated with the thermosensitivity of IFO 3191. Concatenated phylogenetic analysis of these closely related strains revealed that there is a phylogenetic relationship associated with this phenotype among the thermotolerant and thermosensitive strains.

Journal of Molecular Biology, 2011

L-Sorbose reductase from Gluconobacter frateurii (SR) is an NADPHdependent oxidoreductase. SR pre... more L-Sorbose reductase from Gluconobacter frateurii (SR) is an NADPHdependent oxidoreductase. SR preferentially catalyzes the reversible reaction between D-sorbitol and L-sorbose with high substrate specificity. To elucidate the structural basis of the catalytic mechanism and the substrate specificity of SR, we have determined the structures of apo-SR, SR in complex with NADPH, and the inactive mutant (His116Leu) of SR in complex with NADPH and L-sorbose at 2.83 Å, 1.90 Å, and 1.80 Å resolutions, respectively. Our results show that SR belongs to the short-chain dehydrogenase/reductase (SDR) family and forms a tetrameric structure. Although His116 is not conserved among SDR family enzymes, the structures of SR have revealed that His116 is important for the stabilization of the proton relay system and for active-site conformation as a fourth catalytic residue. In the ternary complex structure, L-sorbose is recognized by 11 hydrogen bonds. Site-directed mutagenesis of residues around the L-sorbose-binding site has shown that the loss of almost full enzymatic activity was caused by not only the substitution of putative catalytic residues but also the substitution of the residue used for the recognition of the C4 hydroxyl groups of L-sorbose (Glu154) and of the residues used for the construction of the substrate-binding pocket (Cys146 and Gly188). The recognition of the C4 hydroxyl group of L-sorbose would be indispensable for the substrate specificity of SR, which recognizes only L-sorbose and D-sorbitol but not other sugars. Our results indicated that these residues were crucial for the substrate recognition and specificity of SR.

Journal of Biotechnology, 2013

In vitro adaptation is one of the most challenging subjects in biology to understand adaptive evo... more In vitro adaptation is one of the most challenging subjects in biology to understand adaptive evolution. Microbial adaptation to temperature is not only interesting in terms of understanding the adaptation mechanism, but also useful for industrial applications. In this study, we attempted the in vitro adaptation of Acetobacter pasteurianus SKU1108 by repeating its cultivation under high-temperature acetic acid fermentation conditions. As a result, thermo-adapted strains having the higher fermentation ability than the wild-type strain were obtained. Mutations and/or disruptions in several proteins of the adapted strains were detected with NGS sequencing technology. In particular, two different adapted strains had mutations or disruptions in three specific genes in common, suggesting that these genes are essential for thermotolerance or fermentation at higher temperature. In order to clarify their involvement in thermotolerance, two of the three genes were disrupted and their phenotype was examined. The results showed that mutations of the two proteins, MarR and an amino acid transporter, are partly responsible for higher fermentation ability and/or thermotolerance. Thus, it was suggested that these elevated abilities of the adapted strains are acquired by assembling several single gene mutations including the above two mutations.

Bioscience, Biotechnology, and Biochemistry, 2012

Further upstream of sldSLC, genes for FAD-dependent D-sorbitol dehydrogenase in Gluconobacter fra... more Further upstream of sldSLC, genes for FAD-dependent D-sorbitol dehydrogenase in Gluconobacter frateurii, three additional genes (sldR, xdhA, and perA) are found: for a transcriptional regulator, NAD(P)-dependent xylitol dehydrogenase, and a transporter protein, a member of major facilitator superfamily, respectively. xdhA and perA but not sldR were found to be in the same transcriptional unit. Disruption of sldR resulted in a dramatic decrease in sldSLC promoter activity, indicating that it is an activator for sldSLC expression. The recombinant protein of XdhA expressed in Escherichia coli showed NAD-dependent dehydrogenase activities with xylitol and D-sorbitol, but a mutant strain defective in this gene showed similar activities with both substrates as compared to the wild-type strain. Nonetheless, the growth of the xdhA mutant strain on D-sorbitol and xylitol was retarded, and so was that of a mutant strain defective in perA. These results indicate that xdhA and perA are involved in assimilation of D-sorbitol and xylitol.

Analytica Chimica Acta, 2011

In the present work, a rapid method with little sample handling has been developed for determinat... more In the present work, a rapid method with little sample handling has been developed for determination of 23 selected volatile organic compounds in environmental and wastewater samples. The method is based on headspace solid-phase microextraction (SPME) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) determination using triple quadrupole analyzer (QqQ) in electron ionization mode. The best conditions for extraction were optimised with a factorial design taking into account the interaction between different parameters and not only individual effects of variables. In the optimized procedure, 4 mL of water sample were extracted using a 10 mL vial and adding 0.4 g NaCl (final NaCl content of 10%). An SPME extraction with carboxen/polydimethylsiloxane 75 m fiber for 30 min at 50 • C (with 5 min of previous equilibration time) with magnetic stirring was applied. Chromatographic determination was carried out by GC-MS/MS working in Selected Reaction Monitoring (SRM) mode. For most analytes, two MS/MS transitions were acquired, although for a few compounds it was difficult to obtain characteristic abundant fragments. In those cases, a pseudo selected reaction monitoring (pseudo-SRM) with three ions was used instead. The intensity ratio between quantitation (Q) and confirmation (q) signals was used as a confirmatory parameter. The method was validated by means of recovery experiments (n = 6) spiking mineral water samples at three concentration levels (0.1, 5 and 50 g L −1). Recoveries between 70% and 120% were generally obtained with relative standard deviations (RSDs) lower than 20%. The developed method was applied to surface water and wastewater from a wastewater treatment plant and from a municipal solid-waste treatment plant. Several compounds, like chloroform, benzene, trichloroethylene, toluene, tetrachloroethylene, dibromochloromethane, xylenes and bromoform were detected and confirmed in all the samples analyzed.