Nuttha Thongchul
Chulalongkorn University
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Publication
Featured researches published by Nuttha Thongchul.
Journal of Bioscience and Bioengineering | 2009
Songsri Kulpreecha; Atipol Boonruangthavorn; Boonyarit Meksiriporn; Nuttha Thongchul
This research aimed at increasing the cell density and production of the homopolymer polyhydroxybutyrate (PHB) by Bacillus megaterium BA-019, using renewable and inexpensive bioresources as a substrate. A higher cell density and a greater PHB production level were obtained by using sugarcane molasses and urea as carbon and nitrogen sources, respectively. The limitation of nitrogen at a C/N molar ratio of 25 resulted in enhanced cell growth and PHB production in batch cultures. Fed-batch cultivation with the feeding nutrient composed of MSM with sugarcane molasses, urea and trace elements, and controlled by a pH-stat feeding control, lead to a significantly enhanced cell concentration and PHB production. The optimal feeding medium in this system required a higher total sugar concentration (400 g/l) and a C/N molar ratio of 10 mol/mol. Under these conditions the highest attained cell mass (72.6 g/l DW) and PHB content (42% of cell dry wt.) were achieved in a short cultivation time (24 h), leading to improved PHB productivity (1.27 g/l/h). However, dissolved oxygen was limiting and thus the system is likely to be suboptimal and capable of even further improvements to the PHB production rate.
Colloids and Surfaces B: Biointerfaces | 2012
Oraphan Wiarachai; Nuttha Thongchul; Suda Kiatkamjornwong; Voravee P. Hoven
Taking advantage of the large surface area that is covered with permanent positive charges of quaternary ammonium entities, this research aimed to develop environmentally friendly, organic antibacterial material from quaternized chitosan particles that may be applicable for biomedical devices, health and textile industries. The particles were formulated by ionic crosslinking of chitosan with tripolyphosphate followed by quaternization under heterogeneous conditions, via either direct methylation or reductive N-alkylation with a selected aldehyde followed by methylation. Sub-micron, spherical and positively charged quaternized chitosan particles were formed, as determined by (1)H NMR, FT-IR, PCS and TEM analysis. Antibacterial activity tests, performed by viable cell (colony) counts, suggested that all quaternized chitosan particles exhibited superior antibacterial activity against the model Gram-positive bacteria, Staphylococcus aureus, as compared to the native chitosan particles at neutral pH. Only some quaternized chitosan particles, especially those having a high charge density and bearing large alkyl substituent groups, were capable of suppressing the growth of the model Gram-negative bacteria, Escherichia coli. The inhibitory efficiency of the quaternized chitosan particles was quantified in terms of the minimum inhibitory concentration (MIC). Damaging impact of the quaternized chitosan particles on the bacteria was also qualitatively determined by microscopic observation of the bacterial morphology.
Applied Biochemistry and Biotechnology | 2011
Sarintip Sooksai; Nuttha Thongchul
Rhizopus oryzae is becoming more important due to its ability to produce an optically pure l-lactic acid. However, fermentation by Rhizopus usually suffers from low yield because of production of ethanol as a byproduct. Limiting ethanol production in living immobilized R. oryzae by inhibition of alcohol dehydrogenase (ADH) was observed in shake flask fermentation. The effects of ADH inhibitors added into the medium on the regulation of ADH and lactate dehydrogenase (LDH) as well as the production of cell biomass, lactic acid, and ethanol were elucidated. 1,2-diazole and 2,2,2-trifluroethanol were found to be the effective inhibitors used in this study. The highest lactic acid yield of 0.47 g/g glucose was obtained when 0.01 mM 2,2,2-trifluoroethanol was present during the production phase of the pregrown R. oryzae. This represents about 38% increase in yield as compared with that from the simple glucose fermentation. Fungal metabolism was suppressed when iodoacetic acid, N-ethylmaleimide, 4,4′-dithiodipyridine, or 4-hydroxymercury benzoic acid were present. Dramatic increase in ADH and LDH activities but slight change in product yields might be explained by the inhibitors controlling enzyme activities at the pyruvate branch point. This showed that in living R. oryzae, the inhibitors regulated the flux through the related pathways.
Journal of The Chinese Institute of Chemical Engineers | 2006
Nuttha Thongchul; Shang-Tian Yang
Oxygen was found to be the critical factor affecting lactic acid production by Rhizopus oryzae in a rotating fibrous bed bioreactor (RFBB), which was used to immobilize fungal mycelia and control fungal morphology during fermentation. A lack of oxygen resulted in low lactic acid production because the pathway becomes shunted to ethanol production, and it eventually leads to a loss in fungal activity and cell death. However, simply maintaining a high level of dissolved oxygen (DO) in the RFBB did not significantly improve lactic acid production, whereas increasing oxygen transfer rate led to a slight increase in lactic acid productivity. Ethanol production occurred even though a high oxygen transfer rate in the fermentation medium was maintained, indicating an anoxic condition occurring in the biofilm due to diffusion limitation. The effective diffusivities of oxygen and glucose in the biofilm were determined experimentally and then used in a diffusion model to estimate the critical biofilm thickness, which was found to be much smaller than the actual thickness of the biofilm attached on the fibrous matrix, suggesting the occurrence of oxygen starvation in the overgrown biofilm. Controlling the biofilm thickness to prevent oxygen diffusion limitation could be achieved by shaving off the fungal hyphae at the outer region or limiting cell growth by reducing the nitrogen concentration in the medium. Shaving occurs when the shear stress is higher than the hyphae tensile strength, and the shaving rate is proportional to the specific energy dissipation rate, which in turn is affected by the rotational speed of the fibrous matrix. However, increasing the rotational speed did not improve lactic acid production because the shear stress generated from the fluid motion was not high enough to shave off fungal hyphae. The growth and metabolic pathway of R. oryzae immobilized on the fibrous matrix also can be controlled by manipulating the medium composition, particularly the nitrogen source. It was found that biomass production was limited and lactic acid production increased in the absence of urea in the production phase. However, a lack of nitrogen source could reduce cell activity and product synthesis in long-term cultivation. Therefore, periodical addition of urea during the production phase is recommended to prevent biofilm overgrowth, delay sporulation, and maintain high cell viability and fermentation productivity.
journal of applied pharmaceutical science | 2013
Budsabathip Prasirtsak; Somboon Tanasupawat; Ruethairat Boonsombat; Kentaro Kodama; Nuttha Thongchul
Budsabathip Prasirtsak, Somboon Tanasupawat, Ruethairat Boonsombat, Kentaro Kodama and Nuttha Thongchul Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand. Department of Biochemistry and Microbiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand. Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand.
International Journal of Systematic and Evolutionary Microbiology | 2015
Tanatip Thamacharoensuk; Maki Kitahara; Moriya Ohkuma; Nuttha Thongchul; Somboon Tanasupawat
Two Gram-stain-positive, endospore-forming lactic acid bacteria, designated BK92(T) and BK117-1(T), were isolated from tree barks in Thailand. Cells were catalase-negative and facultatively anaerobic rods. 16S rRNA gene sequence analysis indicated that these strains belonged to the genus Sporolactobacillus . Strains BK92(T) and BK117-1(T) showed the highest 16S rRNA gene sequence similarity to Sporolactobacillus putidus QC81-06(T) with 97.7% and 97.1% similarity, respectively. Analysis of phylogenetic relationships based on 16S rRNA and gyrB gene sequencing revealed that the positions of strains BK92(T) and BK117-1(T) were clearly separated from all related species of the genus Sporolactobacillus . Strains BK92(T) and BK117-1(T) had low DNA-DNA relatedness between each other and also with S. putidus QC81-06(T) and Sporolactobacillus vineae SL153(T). The DNA G+C content of strains BK92(T) and BK117-1(T) was 46.6 mol% and 47.4 mol%, respectively. The major fatty acids of strains BK92(T) and BK117-1(T) were anteiso-C(17 : 0) and anteiso-C(15 : 0). They contained meso-diaminopimelic acid in cell-wall peptidoglycan and had menaquinone with seven isoprene units (MK-7) as the predominant menaquinone. Based on evidence including phenotypic, genotypic and chemotaxonomic studies, strains BK92(T) and BK117-1(T) should be classified as representatives of novel species of the genus Sporolactobacillus , for which the names Sporolactobacillus shoreae sp. nov. and Sporolactobacillus spathodeae sp. nov. are proposed, respectively. The type strains are BK92(T) ( = JCM 19541(T) = LMG 28365(T) = PCU 336(T) = TISTR 2234(T)) and BK117-1(T) ( = JCM 19542(T) = LMG 28366(T) = PCU 337(T) = TISTR 2235(T)).
International Journal of Systematic and Evolutionary Microbiology | 2016
Budsabathip Prasirtsak; Nuttha Thongchul; Vasana Tolieng; Somboon Tanasupawat
A Gram-stain-positive, catalase-positive, facultatively anaerobic, spore-forming, rod-shaped bacterium, strain NK26-11T, was isolated from soil in Thailand. This strain produced d-lactic acid from glucose homofermentatively, and grew at 20-45 °C and pH 5-8.5. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The major respiratory quinone was menaquinone 7 (MK-7), the DNA G+C content was 42.6 mol%, and the major cellular fatty acids were anteiso-C15 : 0 and anteiso-C17 : 0. On the basis of 16S rRNA gene sequences analysis, strain NK26-11T was closely related to Bacillus solimangrovi JCM 18994T (93.89 % 16S rRNA gene sequence similarity), Pullulanibacillus naganoensis LMG 12887T (93.32 %), Sporolactobacillus inulinus NRIC 1133T (92.99 %), Tuberibacillus calidus JCM 13397T (92.98 %) and Thalassobacillus devorans DSM 16966T ( < 90.93 %). Strain NK26-11T could be clearly distinguished from the closely related genera based on phenotypic characteristics and DNA G+C content, and thus represents a novel species of a new genus between the Bacillus and Sporolactobacillus cluster, for which the name Terrilactibacillus laevilacticus gen. nov., sp. nov. is proposed. The type strain of the type species is NK26-11T ( = LMG 27803T = TISTR 2241T = PCU 335T).
Applied Biochemistry and Biotechnology | 2014
Sarintip Sooksai; Nuttha Thongchul
In heterofermentation of Rhizopus oryzae, ethanol is the major byproduct which reduces the production of a desired product, an optically pure l-lactic acid. To improve lactic acid production, regulating the alcohol fermentative pathway to limit ethanol production has been done by various techniques. In vitro study on alcohol dehydrogenase (ADH) inhibition in several organisms showed that 1,2-diazole and 2,2,2-trifluoroethanol were competitively bound at the active sites that eventually limited ethanol production. In this study, 1,2-diazole and 2,2,2-trifluoroethanol were present during fermentation of R. oryzae. It was found that both 1,2-diazole and 2,2,2-trifluoroethanol not only strongly affected ethanol formation but they also indirectly regulated lactate production as observed by the decreasing affinity for glucose flux toward lactate and ethanol production. The increase in both ethanol and lactate formation rates revealed 1,2-diazole and 2,2,2-trifluoroethanol not only regulated the reversible redox reaction by ADH, but they also caused the dynamic change in the conversion of all metabolites in the living R. oryzae in order to maintain the balanced flux for cellular growth and maintenance.
Annals of Microbiology | 2018
Pajareeya Songserm; Aphichart Karnchanatat; Somboon Tanasupawat; Suttichai Assabumrungrat; Shang-Tian Yang; Nuttha Thongchul
The metabolic responses of Aspergillus terreus NRRL1960 to stress conditions (low dissolved oxygen and pH with limited nitrogen and phosphate) in the two-phase fermentation were investigated in this study. The fermentation kinetics suggested that itaconate production was suppressed under low dissolved oxygen (DO) concentrations. A slight change in pH caused a significant change in itaconate production. The transcriptomic data revealed that under low DO concentration, the glycolytic pathway was uncoupled from the oxidative phosphorylation, resulting in the activation of substrate-level phosphorylation as an alternative route for ATP regeneration. The downregulation of pdh genes, the genes encoding ATP synthase and succinate dehydrogenase, confirmed the observation of the uncoupling of the oxidative TCA cycle from glycolysis. It was found that the upregulation of pyc resulted in a large pool of oxaloacetate in the cytosol. This induced the conversion of oxaloacetate to malate. The upregulation of the gene encoding fumarate hydratase with the subsequent formation of fumarate was found to be responsible for the regeneration of NADPH and ATP under the condition of a low dissolved oxygen level. The large pool of oxaloacetate drove itaconic acid production also via the oxidative TCA cycle. Nevertheless, the downregulation of ATP synthase genes resulted in the deficiency of the proton-pumping H+ ATPase and the subsequent stress due to the failure to maintain the physiological pH. This resulted in itaconate production at a low titer. The fermentation kinetics and the transcriptomic data provided in this study can be used for further process optimization and control to improve itaconate production performance.
Annals of Microbiology | 2017
Budsabathip Prasirtsak; Vasana Tolieng; Suttichai Assabumrungrat; Somboon Tanasupawat; Nuttha Thongchul
In this study, we screened and isolated D-lactic acid-producing bacteria from soil and tree barks collected in Thailand. Among the isolates obtained, Terrilactibacillus laevilacticus SK5-6 exhibited good D-lactate production in the primary screening fermentation (99.27 g/L final lactate titer with 0.90 g/g yield, 1.38 g/L⋅h, and 99.00% D-enantiomer equivalent). Terrilactibacillus laevilacticus SK5-6 is a Gram-positive, endospore-forming, homofermentative D-lactate producer that can ferment a wide range of sugars to produce D-lactate. Unlike the typical D-lactate producers, such as catalase-negative Sporolactobacillus sp., T. laevilacticus SK5-6 possesses catalase activity; therefore, a two-phase fermentation was employed for D-lactate production. During an aerobic preculture stage, a high-density cell mass was rapidly obtained due to aerobic respiration. When transferred to the fermentation stage at the correct physiological stage (inoculum age) and proper concentration of cell mass (inoculum size), T. laevilacticus rapidly converted glucose into D-lactate under anaerobic conditions, resulting in a high final lactate titer (102.22 g/L), high yield (0.84 g/g), and high productivity (2.13 g/L⋅h). When the process conditions were shifted from an aerobic to an anaerobic environment, unlike other lactate-producing bacteria, the mixed acid fermentation route was not activated in the culture of T. laevilacticus SK5-6 during the fermentation stage when some trace oxygen still remained. Our study demonstrates the excellent characteristics of this isolate for D-lactate production; in particular, a high product yield was obtained without byproduct formation. Based on these key characteristics of T. laevilacticus SK5-6, we suggest that this isolate is a novel D-lactate producer for use in industrial fermentation.