Vichien Kitpreechavanich

Microbispora corallina sp. nov., a new species of the genus Microbispora isolated from Thai soil

Two actinomycete strains, DF-28 and DF-32T, were isolated from soil samples collected in a deciduous dipterocarp forest in Thailand. They produced longitudinally paired spores on the tips of short sporophores alternately branched from aerial hyphae, and the chemotaxonomic properties of the isolates were the same as those of members of the family Streptosporangiaceae. These phenotypic properties, together with the results of a phylogenetic analysis based on 16S rRNA gene sequences, indicated that these isolates should be assigned to the genus Microbispora. The two isolates showed more than 93% DNA relatedness to each other, but their relatedness to any previously described species of the genus Microbispora was only 45% or less. They were distinguishable from previously described Microbispora spp. by a combination of physiological and biochemical properties. Therefore, a new species is proposed for these strains, under the name Microbispora corallina sp. nov. The type strain is strain DF-32T (= JCM 10267T).

Comparative Characterization of L-Lactic Acid-Producing Thermotolerant Rhizopus Fungi

Acid-producing Rhizopus fungi from loog-pang, a traditional Thai fermented food, was screened to investigate its potential for use in industrial lactic acid production from starch. A thermotolerant strain, TISTR 3518, was isolated and characterized by its morphological, physiological, genetic and fermentation properties, and compared with its mesophilic isolates, TISTR 3514 and TISTR 3523. TISTR 3518 was characterized by shorter sporangiophores and smaller sporangia than the other isolates; however, apparent differences between the mesophilic isolates and the strain could not be clarified. Moreover, TISTR 3518 grew at 45 degrees C, whereas the others did not. The three isolates showed different profiles of oligosaccharide assimilation and organic acid production. Their rDNA ITS sequences indicated that TISTR 3518 is a strain of Rhizopus microsporus, and TISTR 3514 and TISTR 3523 are strains of Rhizopus oryzae. TISTR 3523 and TISTR 3518 mainly formed L-lactic acid from glucose, while TISTR 3514 primarily formed fumaric acid. Under thermotolerant conditions, R. microsporus TISTR 3518 showed higher glucoamylase activity than the others, suggesting this enzyme from TISTR 3518 is more thermostable than that from TISTR 3523. The strain formed higher amounts of L-lactic acid from starch at 40 degrees C compared to R. oryzae TISTR 3523. This is the first report on the production of optically active L-lactic acid from starch by a thermotolerant fungus and could potentially provide a good tool for transforming biomass resources to chemical materials.

Regeneration and retention of NADP (H) for xylitol production in an ionized membrane reactor

SummaryA sulfonated polysulfone membrane reactor was used forin situ regeneration and retention of coenzymes NADP (H) using the xylose reductase ofCandida pelliculosa coupled with oxidoreductase system ofMethanobacterium sp. in the reduction of xylose to xylitol with hydrogen gas. The membrane could almost completely reject the permeation of NADP (H) (92 and 97%), F420 (97%) and the required enzymes (100%), but not reject for the permeation of xylitol (product). After 4-h reaction for the production of xylitol from xylose (93% yield), although 25% NADP (H) initially added was lost its activity due to unavoidable degradation, the membrane could reject the permeation of the remaining NADP (H) and F420 at the level of 90 and 95%, respectively.

Microbispora siamensis sp. nov., a thermotolerant actinomycete isolated from soil

An actinomycete, strain DMKUA 245(T), isolated from soil, was investigated using a polyphasic approach. The isolate formed longitudinally paired spores on the tips of short sporophores that branched alternately from aerial hyphae. The morphological and chemotaxonomic properties clearly demonstrated that the new isolate belonged to the genus Microbispora. 16S rRNA gene sequence analysis supported the assignment of the novel strain to the genus Microbispora. The gene sequence similarity values between the novel strain and the closely related species Microbispora corallina, Microbispora rosea subsp. rosea, Microbispora rosea subsp. aerata and Microbispora amethystogenes were 98.4 %, 97.4 %, 97.0 % and 96.9 %, respectively. The DNA-DNA hybridization values and some physiological and biochemical properties indicated that strain DMKUA 245(T) could be distinguished from its phylogenetically closest relatives. Based on these genotypic and phenotypic data, strain DMKUA 245(T) represents a novel species in the genus Microbispora for which the name Microbispora siamensis sp. nov. is proposed. The type strain is strain DMKUA 245(T) (=BCC 14407(T)=NBRC 104113(T)). In addition, DNA-DNA relatedness values in reciprocal hybridization experiments showed that M. amethystogenes was a separate genomic species from M. rosea subsp. rosea. A combination of genotypic and phenotypic data supported the classification of M. amethystogenes as a separate species.

Purification and characterization of three β-glycosidases exhibiting high glucose tolerance from Aspergillus niger ASKU28

Production and utilization of cellulosic ethanol has been limited, partly due to the difficulty in degradation of cellulosic feedstock. β-Glucosidases convert cellobiose to glucose in the final step of cellulose degradation, but they are inhibited by high concentrations of glucose. Thus, in this study, we have screened, isolated, and characterized three β-glycosidases exhibiting highly glucose-tolerant property from Aspergillus niger ASKU28, namely β-xylosidase (P1.1), β-glucosidase (P1.2), and glucan 1,3-β-glucosidase (P2). Results from kinetic analysis, inhibition study, and hydrolysis of oligosaccharide substrates supported the identification of these enzymes by both LC/MS/MS analysis and nucleotide sequences. Moreover, the highly efficient P1.2 performed better than the commercial β-glucosidase preparation in cellulose saccharification, suggesting its potential applications in the cellulosic ethanol industry. These results shed light on the nature of highly glucose-tolerant β-glucosidase activities in A. niger, whose kinetic properties and identities have not been completely determined in any prior investigations. Graphical Abstract This study presents the identities and kinetic properties of three glucose-tolerant β-glycosidases from A. niger, and their applications in cellulose hydrolysis.

New Insight into Biodegradation of Poly (L-Lactide), Enzyme Production and Characterization

Owing to the global utillization of plastics in large quantities, their disposals as solid waste causes deleterious effect on the environment and global warming occurrence. The development of biodegradable plastics is considered to be a product innovation that can help to resolve the problems of plastic waste. The use of biodegradable plastic is one of method to resolve these problems. Biodegradable polymers were classified into four groups depend on the resources of monomers production such as agro-polymer (cellulose, chitin or starch), produced through fermentation by microorganisms (Polyhydroxyalkanoates, PHA), obtained by petrochemical products (Polycaprolactone, PCL) and conventional synthesis from bio-derived monomer (polylactic acid, PLA). In 2002, Cagill Dow was the global leader in commercialization of PLA production, launched a 300 million-USD effort to begin mass production of plastic based on PLA under the trade name Nature workTM. The branded PLA is a compostable polymer used in a wide range of applications. Thus, PLA is expected to replace presently used plastic material synthesized from petrochemicals. Recently, the plastic compost by microbes has become a method of interest for plastic waste treatment. After worldwide use of PLA and disposal of PLA plastic waste, recycling of the PLA waste is necessary for utilizing materials efficiently. Biological processes by both microbial and enzymatic activities are currently considered to be sustainable recycling methods for PLA. Recently, several actinomycetes and thermophilic bacteria have been reported to exhibit PLA-degrading ability such as Brevibacillus, Bacillus smithii, Geobacillus, and Bacillus licheniformis (Tomita et al., 1999; Sakai et al., 2001; Tomita et al., 2004; Kim et al., 2007). Various reports on PLA-degrading enzyme were investigated such as protease, lipase or hydrolase. Proteinase K, a fungal serine protease of Tritirachium album has received attention since the early study by Williams (1981). At present study, a new incident on the production of enzyme by using statistical method was reported by Sukkhum et al. (2009b). The improvement of PLA-degrading enzyme production was successful and could be scale-up in 3L airlift fermenter. At this time, the available information on PLA-degrading microorganisms and enzymes are still less than that available other biodegradable plastics such as PCL or PHB. Thus, the study on PLA degradability and application of the enzyme for recycling of commercial PLA are very interesting in recent year. This article summarized

Herbidospora sakaeratensis sp. nov., isolated from soil, and reclassification of Streptosporangium claviforme as a later synonym of Herbidospora cretacea

An actinomycete strain, DMKUA 205(T), was isolated from a soil sample collected from the Sakaerat Biosphere Reserve in Nakhonratchasima Province, Thailand. The novel strain produced short chains of non-motile spores on the tips of long sporophores branching from the vegetative hyphae. The morphological and chemotaxonomic properties of this new isolate corresponded to those of members of the genus Herbidospora. Furthermore, 16S rRNA gene sequence analysis showed that the strain was closely related to members of the genus Herbidospora. Phenotypic properties and DNA-DNA relatedness values differentiated the new strain from its closest phylogenetic relatives Herbidospora yilanensis 0351M-12(T) (35-54 % DNA-DNA relatedness) and Herbidospora daliensis 0385M-1(T) (58-65 % relatedness). On the basis of phenotypic, genotypic and phylogenetic data, strain DMKUA 205(T) could be clearly distinguished from the type strains of H. yilanensis and H. daliensis. Therefore, strain DMKUA 205(T) represents a novel species, for which the name Herbidospora sakaeratensis sp. nov. is proposed. The type strain is strain DMKUA 205(T) ( = BCC 11662(T) = NBRC 102641(T)). In addition, the DNA-DNA hybridization results from this study revealed that Streptosporangium claviforme is a later synonym of Herbidospora cretacea.

Sphaerisporangium krabiense sp. nov., isolated from soil.

A Gram-staining-positive, filamentous bacterial strain, designated A-T 0308(T), was isolated from soil of a tropical mangrove forest in Thailand. Strain A-T 0308(T) developed spherical sporangia containing non-motile spores on aerial mycelium. The novel strain contained meso-diaminopimelic acid, N-acetyl-type peptidoglycan and madurose, mannose, ribose, galactose and glucose as whole-cell sugars. The predominant menaquinones were MK-9(H(4)) and MK-9(H(6)); a small amount of MK-9(H(2)) and MK-9 was also detected. Mycolic acids were not detected. The diagnostic phospholipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and phosphoglycolipid. The predominant cellular fatty acids were iso-C(16:0) and 10-methylated C(17:0). The G+C content of the DNA was 72 mol%. Phenotypic and chemotaxonomic analyses showed that the novel isolate had characteristics typical of members of the genus Sphaerisporangium. 16S rRNA gene sequence analysis also indicated that the strain belongs to the genus Sphaerisporangium and that it represents a clade distinct from other members of the genus with sequence similarities ranging from 96.3 to 97.8% between the novel strain and its closest relatives. Based on the results of phenotypic, chemotaxonomic and phylogenetic studies, strain A-T 0308(T) (=BCC 21702(T) =NBRC 107571(T)) represents a novel species of the genus Sphaerisporangium, for which the name Sphaerisporangium krabiense sp. nov. is proposed.

Antagonistic activity of endo-β-1,3-glucanase from a novel isolate, Streptomyces sp. 9X166, against black rot in orchids.

A total of 123 actinomycetes was isolated from 12 varieties of wild orchids and screened for potential antagonistic activity against Phytophthora, which causes black rot disease in orchids. In vitro and in vivo experimental results revealed that Streptomyces sp. strain 9X166 showed the highest antagonistic activity; its β‐1,3‐glucanase production ability was a key mechanism for growth inhibition of the pathogen. PCR amplification and DNA sequencing of the 16S ribosomal RNA gene allowed the identification of this strain, with high similarity (99.93%) to the novel species Streptomyces similaensis. The glucanase enzyme, purified to homogeneity by anion exchange and gel filtration chromatography, showed a specific activity of 58 U mg−1 (a 3.9‐fold increase) and yield of 6.4%. The molecular weight, as determined by SDS‐PAGE and gel filtration, was approximately 99 and 80 kDa, respectively, suggesting that the enzyme was a monomer. The purified enzyme showed the highest substrate specificity to laminarin, indicating that it was β‐1,3‐glucanase. The hydrolyzed products of cello‐oligosaccharides suggested that this enzyme was endo‐type β‐1,3‐glucanase. Streptomyces sp. 9X166 culture filtrate, possessing β‐1,3‐glucanase activity, could degrade both freeze‐dried and living mycelium. This is the first report on a β‐1,3‐glucanase‐producing Streptomyces sp. that could be an effective biocontrol agent for black rot disease in orchids.

Actinomycetospora endophytica sp. nov., isolated from wild orchid (Podochilus microphyllus Lindl.) in Thailand

A novel endophytic actinomycete, designated strain A-T 8314T, was isolated from a wild orchid, Podochilus microphyllus Lindl., collected from Trat Province, Thailand. The taxonomic position of strain A-T 8314T was established using a combination of genotypic and phenotypic analyses. The isolate was a Gram-positive bacterium that developed bud-like spore chains. Strain A-T 8314T grew aerobically at an optimum temperature of 20-25 °C and an optimal pH 6.0. The cell wall contained meso-diaminopimelic acid, and the whole-cell sugars were ribose, arabinose and galactose. The predominant menaquinone was MK-8 (H4). The polar lipid profile contained phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, phosphatidylmonomethylethanolamine, hydroxy-phosphatidylmonomethylethanolamine and hydroxyl phosphatidylethanolamine. The predominant cellular fatty acid was iso-C16 : 0. The DNA G+C content of the genomic DNA was 73.2±0.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain A-T 8314T belonged to the genus Actinomycetospora, and was most closely related to Actinomycetospora chiangmaiensis YIM 0006T (98.8 %) and Actinomycetosporacorticicola 014-5T (98.6 %). The DNA-DNA relatedness values that distinguished A-T 8314T from its closest species were below 70 %. Following an evaluation of phenotypic, chemotaxonomic and genotypic studies, it was concluded that the new isolate represents as a novel species, for which the name Actinomycetospora endophytica sp. nov is proposed. The type strain is A-T 8314T (=TBRC 5722T=NBRC 113235T).