The Experts below are selected from a list of 1674 Experts worldwide ranked by ideXlab platform
K. Mitsubayashi - One of the best experts on this subject based on the ideXlab platform.
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Biochemical Methanol Gas Sensor (MeOH Bio-Sniffer) for Non-Invasive Assessment of Intestinal Flora from Breath Methanol
'MDPI AG', 2021Co-Authors: Koji Toma, T. Arakawa, Kanako Iwasaki, Geng Zhang, Kenta Iitani, Yasuhiko Iwasaki, K. MitsubayashiAbstract:Methanol (MeOH) in exhaled breath has potential for non-invasive assessment of intestinal flora. In this study, we have developed a biochemical gas sensor (bio-sniffer) for MeOH in the gas phase using fluorometry and a cascade reaction with two enzymes, alcohol oxidase (AOD) and Formaldehyde Dehydrogenase (FALDH). In the cascade reaction, oxidation of MeOH was initially catalyzed by AOD to produce Formaldehyde, and then this Formaldehyde was successively oxidized via FALDH catalysis together with reduction of oxidized form of β-nicotinamide adenine dinucleotide (NAD+). As a result of the cascade reaction, reduced form of NAD (NADH) was produced, and MeOH vapor was measured by detecting autofluorescence of NADH. In the development of the MeOH bio-sniffer, three conditions were optimized: selecting a suitable FALDH for better discrimination of MeOH from ethanol in the cascade reaction; buffer pH that maximizes the cascade reaction; and materials and methods to prevent leaking of NAD+ solution from an AOD-FALDH membrane. The dynamic range of the constructed MeOH bio-sniffer was 0.32–20 ppm, which encompassed the MeOH concentration in exhaled breath of healthy people. The measurement of exhaled breath of a healthy subject showed a similar sensorgram to the standard MeOH vapor. These results suggest that the MeOH bio-sniffer exploiting the cascade reaction will become a powerful tool for the non-invasive intestinal flora testing
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Monitoring of Residential Air Quality by Formaldehyde Biochemical Gas Sensor for Indoor Public Health High sensitive (sub-ppb) bio-sniffer for residential VOC assessment
2015Co-Authors: T. Yamashita, K. Miyajima, H. Kudo, K. Mitsubayashi, T. GesseiAbstract:Abstract — An optical fiber biochemical gas sensor (bio-sniffer) for assessment of indoor Formaldehyde was fabricated and tested. The bio-sniffer measures Formaldehyde vapor as fluorescence of reduced nicotinamide adenine dinucleotide (NADH), which is the product of Formaldehyde Dehydrogenase (FALDH) reaction. Usually, an enzyme loses its specific activity in the gas phase. This makes biochemical gas monitoring difficult. We used a micro flow-cell with a FALDH immobilized membrane to prevent the FALDH from deactivation. An ultraviolet light emitting diode (UV-LED) with peak emission of 335nm was employed as an excitation light source. Emission of the UV-LED was introduced to the optode through an optical fiber and fluorescence of NADH was picked up coaxially at the optode. In order to improve the sensitivity, a photomultiplier tube was utilized as a photodetector. Consequently, continuous FA monitoring with biochemical method was successfully conducted with high sensitivity and high selectivity. A real-sample test was also carried out with the bio-sniffer. According to the results, it is expected to be useful in fast and convenient monitoring of indoor FA. Keywords- residential Formaldehyde; bio-sniffer; volatile organic compound; public health. I
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Bio-optic gas sensor (Bio-sniffer) for residential Formaldehyde (with ppb-level lower sensitivity)
OFC NFOEC, 2012Co-Authors: T. Yamashita, Y. Suzuki, T. Gessei, K. Miyajima, T. Arakawa, H. Kudo, K. MitsubayashiAbstract:A bio-optic gas sensor (bio-sniffer) with UV-LED and Formaldehyde Dehydrogenase (FALDH) for gaseous Formaldehyde (FA) was developed and applied for on-site assessment of residential FA. The bio-sniffer measures FA as a fluorescence of reduced nicotinamide adenine dinucleotide (NADH) which is the product of Formaldehyde Dehydrogenase reaction. The detection limit of the bio-sniffer for gaseous FA was 2.5 ppb (parts per billion), which is enough lower for the purpose of evaluating residential FA from building materials and furniture. The bio-sniffer was also applied to measure phytoremediation of FA vapor with N. E. “Bostoniensis”. The FA level in the measurement chamber decreased down to the detection limit (2.5 ppb), which is lower level than FA level of room air (12 ppb), within 95 min and the value increased to FA level when the chamber was vented.
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fiber optic biochemical gas sensor bio sniffer for sub ppb monitoring of Formaldehyde vapor
Sensors and Actuators B-chemical, 2012Co-Authors: H. Kudo, T. Yamashita, Y. Suzuki, T. Gessei, K. Miyajima, T. Arakawa, Xin Wang, K. MitsubayashiAbstract:Abstract A high sensitive fiber-optic biochemical gas sensor (bio-sniffer) for sub-parts-per-billion (sub-ppb) monitoring of Formaldehyde (FA) vapor was constructed and tested. The bio-sniffer measures Formaldehyde vapor as fluorescence of reduced nicotinamide adenine dinucleotide (NADH), which is the product of Formaldehyde Dehydrogenase (FALDH) reaction. An ultraviolet light emitting diode (UV-LED) with peak emission of 335 nm was employed as an excitation light source. Emission of the UV-LED was introduced to the optode through an optical fiber and fluorescence of NADH was picked up coaxially at the optode. In order to achieve sub-ppb sensitivity, two types of detectors (a spectrometer and a photomultiplier tube (PMT)) were tested. The reaction system was also improved. Aldehyde Dehydrogenase (ALDH), which is more active with Formaldehyde, was first tested instead of FALDH. The product of ALDH reaction was again oxidized by formate Dehydrogenase (FDH) to enhance production of NADH. As a result of these improvements, real-time monitoring of FA was performed with a detection limit of 0.75 ppb, which is comparative to chromatographic methods. Such a high sensitive monitoring method is expected to improve the quality of indoor air management.
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biochemical gas sensor bio sniffer for ultrahigh sensitive gaseous Formaldehyde monitoring
Biosensors and Bioelectronics, 2010Co-Authors: H. Kudo, Y. Suzuki, T. Gessei, T. Arakawa, Daishi Takahashi, K. MitsubayashiAbstract:An ultrahigh-sensitive fiber-optic biochemical gas sensor (bio-sniffer) for continuous monitoring of indoor Formaldehyde was constructed and tested. The bio-sniffer measures gaseous Formaldehyde as fluorescence of nicotinamide adenine dinucleotide (NADH), which is the product of Formaldehyde Dehydrogenase (FALDH) reaction. The bio-sniffer device was constructed by attaching a flow cell with a FALDH immobilized membrane onto a fiber-optic NADH measurement system. The NADH measurement system utilizes an ultraviolet-light emitting diode (UV-LED) with peak emission of 335 nm as an excitation light source. The excitation light was introduced to an optical fiber probe, and fluorescence emission of neighboring NADH, which was produced by applying Formaldehyde vapor to the FALDH membrane, was concentrically measured with a photomultiplier tube. Assessment of the bio-sniffer was carried out using a standard gas generator. Response, calibration range and selectivity to other chemical substances were investigated. Circulating phosphate buffer, which contained NAD+, available for continuous monitoring of Formaldehyde vapor. The calibration range of the bio-sniffer was 2.5 ppb to 10 ppm, which covers the guideline value of the World Health Organization (80 ppb). High selectivity to other gaseous substances due to specific activity of FALDH was also confirmed. Considering its high sensitivity, a possible application of the bio-sniffer is continuous indoor Formaldehyde monitoring to provide healthy residential atmosphere.
David Resina - One of the best experts on this subject based on the ideXlab platform.
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transcriptional response of p pastoris in fed batch cultivations to rhizopus oryzae lipase production reveals upr induction
Microbial Cell Factories, 2007Co-Authors: David Resina, Francisco Valero, Monika Bollok, Narendar K Khatri, Peter Neubauer, Pau FerrerAbstract:Background The analysis of transcriptional levels of the genes involved in protein synthesis and secretion is a key factor to understand the host organism's responses to recombinant protein production, as well as their interaction with the cultivation conditions. Novel techniques such as the sandwich hybridization allow monitoring quantitatively the dynamic changes of specific RNAs. In this study, the transcriptional levels of some genes related to the unfolded protein response (UPR) and central metabolism of Pichia pastoris were analysed during batch and fed-batch cultivations using an X-33-derived strain expressing a Rhizopus oryzae lipase under control of the Formaldehyde Dehydrogenase promoter (FLD1), namely the alcohol oxidase gene AOX1, the Formaldehyde Dehydrogenase FLD1, the protein disulfide isomerase PDI, the KAR2 gene coding for the BiP chaperone, the 26S rRNA and the R. oryzae lipase gene ROL.
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developing high cell density fed batch cultivation strategies for heterologous protein production in pichia pastoris using the nitrogen source regulated fld1 promoter
Biotechnology and Bioengineering, 2005Co-Authors: David Resina, Pau Ferrer, Oriol Cos, Francisco ValeroAbstract:A Pichia pastoris strain expressing a Rhizopus oryzae lipase gene under the transcriptional control of the promoter from the P. pastoris Formaldehyde Dehydrogenase 1 gene (PFLD) was utilized to study the feasibility of this expression system for recombinant protein production using methanol-free fed-batch high cell density cultivations. We have developed a simple and reliable fed-batch strategy using the PFLD system based on the use of methylamine and sorbitol as nitrogen and carbon sources, respectively, for the induction phase. Three different fed-batch fermentations were performed at three different constant growth rates, i.e., at a low growth rate (0.005/h), at an intermediate growth rate of (0.01/h), and at a constant residual sorbitol concentration of 8 g/L, i.e., allowing cells to grow at high (near µmax) growth rate (0.02/h). Important differences were observed between the lower and higher growth rate cultivation phases in terms of specific production rate (qp) profiles. In all three cases, maximum qp were reached soon after the start of the induction phase; after that maximum, an exponential decrease reaching final values close to zero were observed, except for the cells growing at near µmax. The best results in terms of YP/X, productivity and specific productivity were obtained when the microorganism was growing at the highest growth rate. Furthermore, such results were significantly better in relation to those obtained with the PAOX-based system expressing the same protein. © 2005 Wiley Periodicals, Inc.
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developing high cell density fed batch cultivation strategies for heterologous protein production in pichia pastoris using the nitrogen source regulated fld1 promoter
Biotechnology and Bioengineering, 2005Co-Authors: David Resina, Pau Ferrer, Oriol Cos, Francisco ValeroAbstract:A Pichia pastoris strain expressing a Rhizopus oryzae lipase gene under the transcriptional control of the promoter from the P. pastoris Formaldehyde Dehydrogenase 1 gene (PFLD) was utilized to study the feasibility of this expression system for recombinant protein production using methanol-free fed-batch high cell density cultivations. We have developed a simple and reliable fed-batch strategy using the PFLD system based on the use of methylamine and sorbitol as nitrogen and carbon sources, respectively, for the induction phase. Three different fed-batch fermentations were performed at three different constant growth rates, i.e., at a low growth rate (0.005/h), at an intermediate growth rate of (0.01/h), and at a constant residual sorbitol concentration of 8 g/L, i.e., allowing cells to grow at high (near micro(max)) growth rate (0.02/h). Important differences were observed between the lower and higher growth rate cultivation phases in terms of specific production rate (q(p)) profiles. In all three cases, maximum q(p) were reached soon after the start of the induction phase; after that maximum, an exponential decrease reaching final values close to zero were observed, except for the cells growing at near micro(max). The best results in terms of Y(P/X), productivity and specific productivity were obtained when the microorganism was growing at the highest growth rate. Furthermore, such results were significantly better in relation to those obtained with the PAOX-based system expressing the same protein.
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expression of a rhizopus oryzae lipase in pichia pastoris under control of the nitrogen source regulated Formaldehyde Dehydrogenase promoter
Journal of Biotechnology, 2004Co-Authors: David Resina, Alicia Serrano, Francisco Valero, Pau FerrerAbstract:Abstract A Rhizopus oryzae lipase gene has been expressed in Pichia pastoris as a reporter using the Formaldehyde Dehydrogenase 1 promoter ( PFLD1 ) of this organism, which has been reported to be strongly and independently induced by either methanol as sole carbon source or methylamine as sole nitrogen source. Levels of lipase expressed and secreted under the control of the PFLD1 at different induction conditions have been compared to those obtained with the commonly used alcohol oxidase 1 promoter ( PAOX1 ) in small (shake flask) and 1 l bioreactor batch cultures. PFLD1 -controlled heterologous gene expression was strongly repressed by excess of either glycerol or glucose–but not sorbitol–during growth using methylamine both as sole nitrogen source and inducing substrate. Co-induction of PFLD1 with methanol and methylamine resulted in a synergistic effect on extracellular lipase expression levels. In all tested conditions, the substitution of ammonium for methylamine as carbon source provoked a clear decrease in the specific growth rate and yield of biomass per gram of carbon source. Overall, this study demonstrates that the PFLD1 promoter is at least as efficient as the PAOX1 for extracellular expression of heterologous proteins in P. pastoris bioreactor cultures and provides a first basis for the further design of methanol-free high cell density fed-batch cultivation strategies for controlled overproduction of foreign proteins in P. pastoris .
T. Gessei - One of the best experts on this subject based on the ideXlab platform.
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Monitoring of Residential Air Quality by Formaldehyde Biochemical Gas Sensor for Indoor Public Health High sensitive (sub-ppb) bio-sniffer for residential VOC assessment
2015Co-Authors: T. Yamashita, K. Miyajima, H. Kudo, K. Mitsubayashi, T. GesseiAbstract:Abstract — An optical fiber biochemical gas sensor (bio-sniffer) for assessment of indoor Formaldehyde was fabricated and tested. The bio-sniffer measures Formaldehyde vapor as fluorescence of reduced nicotinamide adenine dinucleotide (NADH), which is the product of Formaldehyde Dehydrogenase (FALDH) reaction. Usually, an enzyme loses its specific activity in the gas phase. This makes biochemical gas monitoring difficult. We used a micro flow-cell with a FALDH immobilized membrane to prevent the FALDH from deactivation. An ultraviolet light emitting diode (UV-LED) with peak emission of 335nm was employed as an excitation light source. Emission of the UV-LED was introduced to the optode through an optical fiber and fluorescence of NADH was picked up coaxially at the optode. In order to improve the sensitivity, a photomultiplier tube was utilized as a photodetector. Consequently, continuous FA monitoring with biochemical method was successfully conducted with high sensitivity and high selectivity. A real-sample test was also carried out with the bio-sniffer. According to the results, it is expected to be useful in fast and convenient monitoring of indoor FA. Keywords- residential Formaldehyde; bio-sniffer; volatile organic compound; public health. I
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Bio-optic gas sensor (Bio-sniffer) for residential Formaldehyde (with ppb-level lower sensitivity)
OFC NFOEC, 2012Co-Authors: T. Yamashita, Y. Suzuki, T. Gessei, K. Miyajima, T. Arakawa, H. Kudo, K. MitsubayashiAbstract:A bio-optic gas sensor (bio-sniffer) with UV-LED and Formaldehyde Dehydrogenase (FALDH) for gaseous Formaldehyde (FA) was developed and applied for on-site assessment of residential FA. The bio-sniffer measures FA as a fluorescence of reduced nicotinamide adenine dinucleotide (NADH) which is the product of Formaldehyde Dehydrogenase reaction. The detection limit of the bio-sniffer for gaseous FA was 2.5 ppb (parts per billion), which is enough lower for the purpose of evaluating residential FA from building materials and furniture. The bio-sniffer was also applied to measure phytoremediation of FA vapor with N. E. “Bostoniensis”. The FA level in the measurement chamber decreased down to the detection limit (2.5 ppb), which is lower level than FA level of room air (12 ppb), within 95 min and the value increased to FA level when the chamber was vented.
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fiber optic biochemical gas sensor bio sniffer for sub ppb monitoring of Formaldehyde vapor
Sensors and Actuators B-chemical, 2012Co-Authors: H. Kudo, T. Yamashita, Y. Suzuki, T. Gessei, K. Miyajima, T. Arakawa, Xin Wang, K. MitsubayashiAbstract:Abstract A high sensitive fiber-optic biochemical gas sensor (bio-sniffer) for sub-parts-per-billion (sub-ppb) monitoring of Formaldehyde (FA) vapor was constructed and tested. The bio-sniffer measures Formaldehyde vapor as fluorescence of reduced nicotinamide adenine dinucleotide (NADH), which is the product of Formaldehyde Dehydrogenase (FALDH) reaction. An ultraviolet light emitting diode (UV-LED) with peak emission of 335 nm was employed as an excitation light source. Emission of the UV-LED was introduced to the optode through an optical fiber and fluorescence of NADH was picked up coaxially at the optode. In order to achieve sub-ppb sensitivity, two types of detectors (a spectrometer and a photomultiplier tube (PMT)) were tested. The reaction system was also improved. Aldehyde Dehydrogenase (ALDH), which is more active with Formaldehyde, was first tested instead of FALDH. The product of ALDH reaction was again oxidized by formate Dehydrogenase (FDH) to enhance production of NADH. As a result of these improvements, real-time monitoring of FA was performed with a detection limit of 0.75 ppb, which is comparative to chromatographic methods. Such a high sensitive monitoring method is expected to improve the quality of indoor air management.
-
biochemical gas sensor bio sniffer for ultrahigh sensitive gaseous Formaldehyde monitoring
Biosensors and Bioelectronics, 2010Co-Authors: H. Kudo, Y. Suzuki, T. Gessei, T. Arakawa, Daishi Takahashi, K. MitsubayashiAbstract:An ultrahigh-sensitive fiber-optic biochemical gas sensor (bio-sniffer) for continuous monitoring of indoor Formaldehyde was constructed and tested. The bio-sniffer measures gaseous Formaldehyde as fluorescence of nicotinamide adenine dinucleotide (NADH), which is the product of Formaldehyde Dehydrogenase (FALDH) reaction. The bio-sniffer device was constructed by attaching a flow cell with a FALDH immobilized membrane onto a fiber-optic NADH measurement system. The NADH measurement system utilizes an ultraviolet-light emitting diode (UV-LED) with peak emission of 335 nm as an excitation light source. The excitation light was introduced to an optical fiber probe, and fluorescence emission of neighboring NADH, which was produced by applying Formaldehyde vapor to the FALDH membrane, was concentrically measured with a photomultiplier tube. Assessment of the bio-sniffer was carried out using a standard gas generator. Response, calibration range and selectivity to other chemical substances were investigated. Circulating phosphate buffer, which contained NAD+, available for continuous monitoring of Formaldehyde vapor. The calibration range of the bio-sniffer was 2.5 ppb to 10 ppm, which covers the guideline value of the World Health Organization (80 ppb). High selectivity to other gaseous substances due to specific activity of FALDH was also confirmed. Considering its high sensitivity, a possible application of the bio-sniffer is continuous indoor Formaldehyde monitoring to provide healthy residential atmosphere.
Pau Ferrer - One of the best experts on this subject based on the ideXlab platform.
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transcriptional response of p pastoris in fed batch cultivations to rhizopus oryzae lipase production reveals upr induction
Microbial Cell Factories, 2007Co-Authors: David Resina, Francisco Valero, Monika Bollok, Narendar K Khatri, Peter Neubauer, Pau FerrerAbstract:Background The analysis of transcriptional levels of the genes involved in protein synthesis and secretion is a key factor to understand the host organism's responses to recombinant protein production, as well as their interaction with the cultivation conditions. Novel techniques such as the sandwich hybridization allow monitoring quantitatively the dynamic changes of specific RNAs. In this study, the transcriptional levels of some genes related to the unfolded protein response (UPR) and central metabolism of Pichia pastoris were analysed during batch and fed-batch cultivations using an X-33-derived strain expressing a Rhizopus oryzae lipase under control of the Formaldehyde Dehydrogenase promoter (FLD1), namely the alcohol oxidase gene AOX1, the Formaldehyde Dehydrogenase FLD1, the protein disulfide isomerase PDI, the KAR2 gene coding for the BiP chaperone, the 26S rRNA and the R. oryzae lipase gene ROL.
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developing high cell density fed batch cultivation strategies for heterologous protein production in pichia pastoris using the nitrogen source regulated fld1 promoter
Biotechnology and Bioengineering, 2005Co-Authors: David Resina, Pau Ferrer, Oriol Cos, Francisco ValeroAbstract:A Pichia pastoris strain expressing a Rhizopus oryzae lipase gene under the transcriptional control of the promoter from the P. pastoris Formaldehyde Dehydrogenase 1 gene (PFLD) was utilized to study the feasibility of this expression system for recombinant protein production using methanol-free fed-batch high cell density cultivations. We have developed a simple and reliable fed-batch strategy using the PFLD system based on the use of methylamine and sorbitol as nitrogen and carbon sources, respectively, for the induction phase. Three different fed-batch fermentations were performed at three different constant growth rates, i.e., at a low growth rate (0.005/h), at an intermediate growth rate of (0.01/h), and at a constant residual sorbitol concentration of 8 g/L, i.e., allowing cells to grow at high (near µmax) growth rate (0.02/h). Important differences were observed between the lower and higher growth rate cultivation phases in terms of specific production rate (qp) profiles. In all three cases, maximum qp were reached soon after the start of the induction phase; after that maximum, an exponential decrease reaching final values close to zero were observed, except for the cells growing at near µmax. The best results in terms of YP/X, productivity and specific productivity were obtained when the microorganism was growing at the highest growth rate. Furthermore, such results were significantly better in relation to those obtained with the PAOX-based system expressing the same protein. © 2005 Wiley Periodicals, Inc.
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developing high cell density fed batch cultivation strategies for heterologous protein production in pichia pastoris using the nitrogen source regulated fld1 promoter
Biotechnology and Bioengineering, 2005Co-Authors: David Resina, Pau Ferrer, Oriol Cos, Francisco ValeroAbstract:A Pichia pastoris strain expressing a Rhizopus oryzae lipase gene under the transcriptional control of the promoter from the P. pastoris Formaldehyde Dehydrogenase 1 gene (PFLD) was utilized to study the feasibility of this expression system for recombinant protein production using methanol-free fed-batch high cell density cultivations. We have developed a simple and reliable fed-batch strategy using the PFLD system based on the use of methylamine and sorbitol as nitrogen and carbon sources, respectively, for the induction phase. Three different fed-batch fermentations were performed at three different constant growth rates, i.e., at a low growth rate (0.005/h), at an intermediate growth rate of (0.01/h), and at a constant residual sorbitol concentration of 8 g/L, i.e., allowing cells to grow at high (near micro(max)) growth rate (0.02/h). Important differences were observed between the lower and higher growth rate cultivation phases in terms of specific production rate (q(p)) profiles. In all three cases, maximum q(p) were reached soon after the start of the induction phase; after that maximum, an exponential decrease reaching final values close to zero were observed, except for the cells growing at near micro(max). The best results in terms of Y(P/X), productivity and specific productivity were obtained when the microorganism was growing at the highest growth rate. Furthermore, such results were significantly better in relation to those obtained with the PAOX-based system expressing the same protein.
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expression of a rhizopus oryzae lipase in pichia pastoris under control of the nitrogen source regulated Formaldehyde Dehydrogenase promoter
Journal of Biotechnology, 2004Co-Authors: David Resina, Alicia Serrano, Francisco Valero, Pau FerrerAbstract:Abstract A Rhizopus oryzae lipase gene has been expressed in Pichia pastoris as a reporter using the Formaldehyde Dehydrogenase 1 promoter ( PFLD1 ) of this organism, which has been reported to be strongly and independently induced by either methanol as sole carbon source or methylamine as sole nitrogen source. Levels of lipase expressed and secreted under the control of the PFLD1 at different induction conditions have been compared to those obtained with the commonly used alcohol oxidase 1 promoter ( PAOX1 ) in small (shake flask) and 1 l bioreactor batch cultures. PFLD1 -controlled heterologous gene expression was strongly repressed by excess of either glycerol or glucose–but not sorbitol–during growth using methylamine both as sole nitrogen source and inducing substrate. Co-induction of PFLD1 with methanol and methylamine resulted in a synergistic effect on extracellular lipase expression levels. In all tested conditions, the substitution of ammonium for methylamine as carbon source provoked a clear decrease in the specific growth rate and yield of biomass per gram of carbon source. Overall, this study demonstrates that the PFLD1 promoter is at least as efficient as the PAOX1 for extracellular expression of heterologous proteins in P. pastoris bioreactor cultures and provides a first basis for the further design of methanol-free high cell density fed-batch cultivation strategies for controlled overproduction of foreign proteins in P. pastoris .
H. Kudo - One of the best experts on this subject based on the ideXlab platform.
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Monitoring of Residential Air Quality by Formaldehyde Biochemical Gas Sensor for Indoor Public Health High sensitive (sub-ppb) bio-sniffer for residential VOC assessment
2015Co-Authors: T. Yamashita, K. Miyajima, H. Kudo, K. Mitsubayashi, T. GesseiAbstract:Abstract — An optical fiber biochemical gas sensor (bio-sniffer) for assessment of indoor Formaldehyde was fabricated and tested. The bio-sniffer measures Formaldehyde vapor as fluorescence of reduced nicotinamide adenine dinucleotide (NADH), which is the product of Formaldehyde Dehydrogenase (FALDH) reaction. Usually, an enzyme loses its specific activity in the gas phase. This makes biochemical gas monitoring difficult. We used a micro flow-cell with a FALDH immobilized membrane to prevent the FALDH from deactivation. An ultraviolet light emitting diode (UV-LED) with peak emission of 335nm was employed as an excitation light source. Emission of the UV-LED was introduced to the optode through an optical fiber and fluorescence of NADH was picked up coaxially at the optode. In order to improve the sensitivity, a photomultiplier tube was utilized as a photodetector. Consequently, continuous FA monitoring with biochemical method was successfully conducted with high sensitivity and high selectivity. A real-sample test was also carried out with the bio-sniffer. According to the results, it is expected to be useful in fast and convenient monitoring of indoor FA. Keywords- residential Formaldehyde; bio-sniffer; volatile organic compound; public health. I
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Bio-optic gas sensor (Bio-sniffer) for residential Formaldehyde (with ppb-level lower sensitivity)
OFC NFOEC, 2012Co-Authors: T. Yamashita, Y. Suzuki, T. Gessei, K. Miyajima, T. Arakawa, H. Kudo, K. MitsubayashiAbstract:A bio-optic gas sensor (bio-sniffer) with UV-LED and Formaldehyde Dehydrogenase (FALDH) for gaseous Formaldehyde (FA) was developed and applied for on-site assessment of residential FA. The bio-sniffer measures FA as a fluorescence of reduced nicotinamide adenine dinucleotide (NADH) which is the product of Formaldehyde Dehydrogenase reaction. The detection limit of the bio-sniffer for gaseous FA was 2.5 ppb (parts per billion), which is enough lower for the purpose of evaluating residential FA from building materials and furniture. The bio-sniffer was also applied to measure phytoremediation of FA vapor with N. E. “Bostoniensis”. The FA level in the measurement chamber decreased down to the detection limit (2.5 ppb), which is lower level than FA level of room air (12 ppb), within 95 min and the value increased to FA level when the chamber was vented.
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fiber optic biochemical gas sensor bio sniffer for sub ppb monitoring of Formaldehyde vapor
Sensors and Actuators B-chemical, 2012Co-Authors: H. Kudo, T. Yamashita, Y. Suzuki, T. Gessei, K. Miyajima, T. Arakawa, Xin Wang, K. MitsubayashiAbstract:Abstract A high sensitive fiber-optic biochemical gas sensor (bio-sniffer) for sub-parts-per-billion (sub-ppb) monitoring of Formaldehyde (FA) vapor was constructed and tested. The bio-sniffer measures Formaldehyde vapor as fluorescence of reduced nicotinamide adenine dinucleotide (NADH), which is the product of Formaldehyde Dehydrogenase (FALDH) reaction. An ultraviolet light emitting diode (UV-LED) with peak emission of 335 nm was employed as an excitation light source. Emission of the UV-LED was introduced to the optode through an optical fiber and fluorescence of NADH was picked up coaxially at the optode. In order to achieve sub-ppb sensitivity, two types of detectors (a spectrometer and a photomultiplier tube (PMT)) were tested. The reaction system was also improved. Aldehyde Dehydrogenase (ALDH), which is more active with Formaldehyde, was first tested instead of FALDH. The product of ALDH reaction was again oxidized by formate Dehydrogenase (FDH) to enhance production of NADH. As a result of these improvements, real-time monitoring of FA was performed with a detection limit of 0.75 ppb, which is comparative to chromatographic methods. Such a high sensitive monitoring method is expected to improve the quality of indoor air management.
-
biochemical gas sensor bio sniffer for ultrahigh sensitive gaseous Formaldehyde monitoring
Biosensors and Bioelectronics, 2010Co-Authors: H. Kudo, Y. Suzuki, T. Gessei, T. Arakawa, Daishi Takahashi, K. MitsubayashiAbstract:An ultrahigh-sensitive fiber-optic biochemical gas sensor (bio-sniffer) for continuous monitoring of indoor Formaldehyde was constructed and tested. The bio-sniffer measures gaseous Formaldehyde as fluorescence of nicotinamide adenine dinucleotide (NADH), which is the product of Formaldehyde Dehydrogenase (FALDH) reaction. The bio-sniffer device was constructed by attaching a flow cell with a FALDH immobilized membrane onto a fiber-optic NADH measurement system. The NADH measurement system utilizes an ultraviolet-light emitting diode (UV-LED) with peak emission of 335 nm as an excitation light source. The excitation light was introduced to an optical fiber probe, and fluorescence emission of neighboring NADH, which was produced by applying Formaldehyde vapor to the FALDH membrane, was concentrically measured with a photomultiplier tube. Assessment of the bio-sniffer was carried out using a standard gas generator. Response, calibration range and selectivity to other chemical substances were investigated. Circulating phosphate buffer, which contained NAD+, available for continuous monitoring of Formaldehyde vapor. The calibration range of the bio-sniffer was 2.5 ppb to 10 ppm, which covers the guideline value of the World Health Organization (80 ppb). High selectivity to other gaseous substances due to specific activity of FALDH was also confirmed. Considering its high sensitivity, a possible application of the bio-sniffer is continuous indoor Formaldehyde monitoring to provide healthy residential atmosphere.