1
|
Zhang Y, Huang L, Guo J, Ji J, Wei T, Fu L. Study on Microfluidic Chip Flow Rate Uniformity for Cell Activity Detection. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:6548-6555. [PMID: 37093638 DOI: 10.1021/acs.langmuir.3c00514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
During the cell viability detection process inside a microfluidic chip, the more uniform the distribution of medium flow rates, the higher the accuracy of detection results. In order to achieve this goal, a multichannel microfluidic chip with uniform distribution of medium flow rates has been successfully designed. The multichannel microfluidic chip is designed with cell injection channels, vascular network-shaped medium injection channels, buffer zones, and a culture chamber. The medium flow rates inside culture chambers of the multichannel microfluidic chip and the common single-channel microfluidic chip are compared by COMSOL Multiphysics software and particle velocimetry experiment. The simulation and experimental results show that the medium flow rate distribution inside the culture chamber of the multichannel microfluidic chip is more uniform and changes more smoothly. When the medium perfusion flow rate is 0.5 μL/min, the maximum flow rate difference inside the culture chamber of the single-channel microfluidic chip is more than 13 times that of the multichannel microfluidic chip. Therefore, the multichannel microfluidic chip can ensure a uniform supply of medium inside the culture chamber, which is beneficial to improve the accuracy of cell viability detection.
Collapse
Affiliation(s)
- Yecheng Zhang
- Changzhou Institute of Technology, Changzhou 213032, Jiangsu, China
| | - Linkui Huang
- Jiangsu University, Zhenjiang 212013, Jiangsu, China
| | - Jianjiang Guo
- Changzhou Institute of Technology, Changzhou 213032, Jiangsu, China
| | - Jiao Ji
- Changzhou Institute of Technology, Changzhou 213032, Jiangsu, China
| | - Tianyu Wei
- Changzhou Institute of Technology, Changzhou 213032, Jiangsu, China
| | - Lei Fu
- Changzhou Institute of Technology, Changzhou 213032, Jiangsu, China
| |
Collapse
|
2
|
Li J, Zha X, Kang Y, Zhang Z, Yan L, Song L, Wang C, Yang J. Oxygen-carrying sequential preservation mitigates liver grafts ischemia-reperfusion injury. iScience 2022; 26:105858. [PMID: 36636350 PMCID: PMC9829800 DOI: 10.1016/j.isci.2022.105858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 11/01/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
Oxygen-dependent preservation has been proposed to protect liver grafts from ischemia-reperfusion injury (IRI), but its underlying mechanism remains elusive. Here, we proposed an oxygen-carrying sequential preservation (OCSP) method that combined oxygenated static cold storage (SCS) and normothermic mechanical perfusion. We demonstrated that OCSP, especially with high oxygen partial pressure level (500-650mmHg) during the oxygenated SCS phase, was associated with decreased IRI of liver grafts and improved rat survival after transplantation. A negative correlation between autophagy and endoplasmic reticulum stress response (ERSR) was found under OCSP and functional studies indicated OCSP suppressed ERSR-mediated cell apoptosis through autophagy activation. Further data showed that OCSP-induced autophagy activation and ERSR inhibition were oxygen-dependent. Finally, activated NFE2L2-HMOX1 signaling was found to induce autophagy under OCSP. Together, our findings indicate oxygen-dependent autophagy mitigates liver graft's IRI by ERSR suppression and modulates NFE2L2-HMOX1 signaling under OCSP, providing a theoretical basis for liver preservation using a composite-sequential mode.
Collapse
Affiliation(s)
- Jianbo Li
- Department of Critical Care Medicine, West China Hospital of Sichuan University, Chengdu 610041, China
| | - XiangJun Zha
- Department of Liver Surgery of West China Hospital and State Key Laboratory of Polymer Materials Engineering of Sichuan University, Chengdu610065, China
- Department of Liver Surgery and Liver Transplantation Center, West China Hospital of Sichuan University, Chengdu610041, China
| | - Yan Kang
- Department of Critical Care Medicine, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Zhongwei Zhang
- Department of Critical Care Medicine, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Lvnan Yan
- Department of Liver Surgery and Liver Transplantation Center, West China Hospital of Sichuan University, Chengdu610041, China
| | - Lujia Song
- Department of Respiratory and Critical Care Medicine, Med-X Center for Manufacturing, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, West China School of Medicine, Sichuan University, Chengdu, China
| | - Chengdi Wang
- Department of Respiratory and Critical Care Medicine, Med-X Center for Manufacturing, Frontiers Science Center for Disease-related Molecular Network, West China Hospital, West China School of Medicine, Sichuan University, Chengdu, China
- Corresponding author
| | - Jiayin Yang
- Department of Liver Surgery and Liver Transplantation Center, West China Hospital of Sichuan University, Chengdu610041, China
- Corresponding author
| |
Collapse
|
3
|
Redox-sensing regulator Rex regulates aerobic metabolism, morphological differentiation, and avermectin production in Streptomyces avermitilis. Sci Rep 2017; 7:44567. [PMID: 28303934 PMCID: PMC5355995 DOI: 10.1038/srep44567] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/09/2017] [Indexed: 11/13/2022] Open
Abstract
The regulatory role of redox-sensing regulator Rex was investigated in Streptomyces avermitilis. Eleven genes/operons were demonstrated to be directly regulated by Rex; these genes/operons are involved in aerobic metabolism, morphological differentiation, and secondary metabolism. Rex represses transcription of target genes/operons by binding to Rex operator (ROP) sequences in the promoter regions. NADH reduces DNA-binding activity of Rex to target promoters, while NAD+ competitively binds to Rex and modulates its DNA-binding activity. Rex plays an essential regulatory role in aerobic metabolism by controlling expression of the respiratory genes atpIBEFHAGDC, cydA1B1CD, nuoA1-N1, rex-hemAC1DB, hppA, and ndh2. Rex also regulates morphological differentiation by repressing expression of wblE, which encodes a putative WhiB-family transcriptional regulator. A rex-deletion mutant (Drex) showed higher avermectin production than the wild-type strain ATCC31267, and was more tolerant of oxygen limitation conditions in regard to avermectin production.
Collapse
|
4
|
Effects of metabolic pathway precursors and polydimethylsiloxane (PDMS) on poly-(gamma)-glutamic acid production by Bacillus subtilis BL53. ACTA ACUST UNITED AC 2014; 41:1375-82. [DOI: 10.1007/s10295-014-1477-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 06/16/2014] [Indexed: 11/26/2022]
Abstract
Abstract
The aims of this study were to evaluate the effects of the addition of metabolic precursors and polydimethylsiloxane (PDMS) as an oxygen carrier to cultures of Bacillus subtilis BL53 during the production of γ-PGA. Kinetics analyses of cultivations of different media showed that B. subtilis BL53 is an exogenous glutamic acid-dependent strain. When the metabolic pathway precursors of γ-PGA synthesis, l-glutamine and a-ketoglutaric acid, were added to the culture medium, production of the biopolymer was increased by 20 % considering the medium without these precursors. The addition of 10 % of the oxygen carrier PDMS to cultures caused a two-fold increase in the volumetric oxygen mass transfer coefficient (kLa), improving γ-PGA production and productivity. Finally, bioreactor cultures of B. subtilis BL53 adopting the combination of optimized medium E, added of glutamine, α-ketoglutaric acid, and PDMS, showed a productivity of 1 g L−1 h−1 of g-PGA after only 24 h of cultivation. Results of this study suggest that the use of metabolic pathway precursors glutamine and a-ketolgutaric acid, combined with the addition of PDMS as an oxygen carrier in bioreactors, can improve γ-PGA production and productivity by Bacillus strains .
Collapse
|
5
|
Flinspach K, Kapitzke C, Tocchetti A, Sosio M, Apel AK. Heterologous expression of the thiopeptide antibiotic GE2270 from Planobispora rosea ATCC 53733 in Streptomyces coelicolor requires deletion of ribosomal genes from the expression construct. PLoS One 2014; 9:e90499. [PMID: 24598591 PMCID: PMC3943966 DOI: 10.1371/journal.pone.0090499] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 02/03/2014] [Indexed: 01/09/2023] Open
Abstract
GE2270 is a thiopeptide antibiotic generated by extensive posttranslational modifications of a ribosomally generated precursor peptide. Thiopeptides are especially active against Gram-positive bacteria, including methicillin resistant Staphylococcus aureus (MRSA). In this study the GE2270 biosynthetic gene cluster (pbt) from Planobispora rosea ATCC 53733 was successfully expressed in the heterologous host strain Streptomyces coelicolor M1146. Notably, exconjugants containing the pbt gene cluster could only be obtained after deletion of the major part of the ribosomal genes flanking the gene cluster. This is a striking example that genes belonging to primary metabolism can prevent the successful conjugative transfer of DNA from phylogenetic distant species and thus complicate heterologous expression of secondary metabolite gene clusters. GE2270 production in the heterologous producer strain increased after introduction of the constitutive ermE* promoter upstream of the GE2270 resistance gene tuf from P. rosea. Insertion of the inducible tcp830 promoter resulted in inducible GE2270 production. When the regulatory gene pbtR was deleted, the resulting strain ceased to produce GE2270, suggesting an essential role of PbtR as a putative transcriptional activator of GE2270 expression.
Collapse
MESH Headings
- Actinomycetales/genetics
- Anti-Bacterial Agents/biosynthesis
- Anti-Bacterial Agents/pharmacology
- Bacterial Proteins/biosynthesis
- Bacterial Proteins/genetics
- Bacterial Proteins/pharmacology
- Cloning, Molecular
- Cosmids/genetics
- DNA, Ribosomal/genetics
- Disk Diffusion Antimicrobial Tests
- Drug Resistance, Bacterial
- Gene Expression Regulation, Bacterial
- Genes, Bacterial
- Molecular Typing
- Multigene Family
- Peptides, Cyclic/biosynthesis
- Peptides, Cyclic/genetics
- Peptides, Cyclic/pharmacology
- Phylogeny
- Promoter Regions, Genetic
- RNA, Ribosomal, 16S/genetics
- Streptomyces coelicolor/drug effects
- Streptomyces coelicolor/genetics
- Thiazoles/pharmacology
- Transcriptional Activation
Collapse
Affiliation(s)
- Katrin Flinspach
- Pharmaceutical Institute, University of Tübingen, Tübingen, Germany
- German Centre for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
| | - Claudia Kapitzke
- Pharmaceutical Institute, University of Tübingen, Tübingen, Germany
| | | | | | - Alexander K. Apel
- Pharmaceutical Institute, University of Tübingen, Tübingen, Germany
- German Centre for Infection Research (DZIF), partner site Tübingen, Tübingen, Germany
- * E-mail:
| |
Collapse
|
6
|
Jia J, Zhang S, Wang P, Wang H. Degradation of high concentration 2,4-dichlorophenol by simultaneous photocatalytic-enzymatic process using TiO2/UV and laccase. JOURNAL OF HAZARDOUS MATERIALS 2012; 205-206:150-155. [PMID: 22236949 DOI: 10.1016/j.jhazmat.2011.12.052] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Revised: 11/24/2011] [Accepted: 12/19/2011] [Indexed: 05/31/2023]
Abstract
Removal of 2,4-dichlorophenol (2,4-DCP) by TiO2/UV photocatalytic, laccase, and simultaneous photocatalytic-enzymatic treatments were investigated. Coupling of native laccase with TiO2/UV showed a negative synergetic effect due to the rapid inactivation of laccase. Immobilizing laccase covalently to controlled porous glass (CPG) effectively enhanced the stability of laccase against TiO2/UV induced inactivation. By coupling CPG-laccase with the TiO2/UV the degradation efficiency of 2,4-DCP was significantly increased as compared with the results obtained when immobilized laccase or TiO2/UV were separately used. Moreover, the enhancement was more remarkable for the degradation of 2,4-DCP with high concentration, such that for the degradation of 5mM 2,4-DCP, 90% removal percentage was achieved within 2h with the coupled degradation process. While for the TiO2/UV and CPG-laccase process, the removal percentage of 2,4-DCP at 2h were only 26.5% and 78.1%, respectively. The degradation kinetics were analyzed using a intermediate model by taking into account of the intermediates formed during the degradation of 2,4-DCP. The high efficiency of the coupled degradation process therefore provided a novel strategy for degradation of concentrated 2,4-DCP. Furthermore, a thermometric biosensor using the immobilized laccase as biorecognition element was constructed for monitoring the degradation of 2,4-DCP, the result indicated that the biosensor was precise and sensitive.
Collapse
Affiliation(s)
- Jingbo Jia
- National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China
| | | | | | | |
Collapse
|
7
|
Rech FR, Volpato G, Ayub MAZ. Optimization of lipase production by Staphylococcus warneri EX17 using the polydimethylsiloxanes artificial oxygen carriers. J Ind Microbiol Biotechnol 2011; 38:1599-604. [PMID: 21340482 DOI: 10.1007/s10295-011-0950-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 02/07/2011] [Indexed: 11/24/2022]
Abstract
In this research, the combined effects of polydimethylsiloxane (PDMS) and different conditions of oxygen volumetric mass transfer coefficient (k(L)a) on lipase production by Staphylococcus warneri EX17 were studied and optimized in bioreactor cultures. Raw glycerol from biodiesel synthesis was used as the sole carbon source. Full-factorial central composite design and the response surface methodology were employed for the experimental design and analysis of the results. The optimal polydimethylsiloxane concentration and mass coefficient transfer (k(L)a) were found to be 13.5% (v/v) and 181 h(-1), respectively. Under these conditions, the maximal cell production obtained was 10.0 g/l, and the volumetric lipase activities of approximately 490 U/l, after 6 h of cultivation. These results are in close agreement with the model predictions. Results obtained in this work reveal the positive effects of PDMS on oxygen volumetric mass transfer coefficient (k(L)a) in the Staphylococcus warneri EX17 cultivation and lipase production.
Collapse
Affiliation(s)
- Fernanda Roberta Rech
- Food Science & Technology Institute, Federal University of Rio Grande do Sul, Av. Bento Goncalves, 9500, PO Box 15090, Porto Alegre, RS, 91501-970, Brazil
| | | | | |
Collapse
|
8
|
Flinspach K, Westrich L, Kaysser L, Siebenberg S, Gomez-Escribano JP, Bibb M, Gust B, Heide L. Heterologous expression of the biosynthetic gene clusters of coumermycin A1, clorobiocin and caprazamycins in genetically modified Streptomyces coelicolor strains. Biopolymers 2010; 93:823-32. [DOI: 10.1002/bip.21493] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
9
|
Bučko M, Gemeiner P, Vikartovská A, Mislovičová D, Lacík I, Tkáč J. Coencapsulation of Oxygen Carriers and Glucose Oxidase in Polyelectrolyte Complex Capsules for the Enhancement of D-Gluconic Acid and δ-Gluconolactone Production. ACTA ACUST UNITED AC 2010; 38:90-8. [DOI: 10.3109/10731191003634745] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Marek Bučko
- Department of Glycobiotechnology, Institute of Chemistry - Center for Glycomics, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Peter Gemeiner
- Department of Glycobiotechnology, Institute of Chemistry - Center for Glycomics, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Alica Vikartovská
- Department of Glycobiotechnology, Institute of Chemistry - Center for Glycomics, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Danica Mislovičová
- Department of Glycobiotechnology, Institute of Chemistry - Center for Glycomics, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Igor Lacík
- Polymer Institute, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Ján Tkáč
- Department of Glycobiotechnology, Institute of Chemistry - Center for Glycomics, Slovak Academy of Sciences, Bratislava, Slovak Republic
| |
Collapse
|
10
|
Siebenberg S, Bapat PM, Lantz AE, Gust B, Heide L. Reducing the variability of antibiotic production in Streptomyces by cultivation in 24-square deepwell plates. J Biosci Bioeng 2010; 109:230-4. [DOI: 10.1016/j.jbiosc.2009.08.479] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 08/07/2009] [Accepted: 08/10/2009] [Indexed: 11/27/2022]
|
11
|
Nahalka J, Dib I, Nidetzky B. Encapsulation of Trigonopsis variabilis D-amino acid oxidase and fast comparison of the operational stabilities of free and immobilized preparations of the enzyme. Biotechnol Bioeng 2008; 99:251-60. [PMID: 17680679 DOI: 10.1002/bit.21579] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A one-step procedure of immobilizing soluble and aggregated preparations of D-amino acid oxidase from Trigonopsis variabilis (TvDAO) is reported where carrier-free enzyme was entrapped in semipermeable microcapsules produced from the polycation poly(methylene-co-guanidine) in combination with CaCl2 and the polyanions alginate and cellulose sulfate. The yield of immobilization, expressed as the fraction of original activity present in microcapsules, was approximately 52 +/- 5%. The effectiveness of the entrapped oxidase for O2-dependent conversion of D-methionine at 25 degrees C was 85 +/- 10% of the free enzyme preparation. Because continuous spectrophotometric assays are generally not well compatible with insoluble enzymes, we employed a dynamic method for the rapid in situ estimation of activity and relatedly, stability of free and encapsulated oxidases using on-line measurements of the concentration of dissolved O2. Integral and differential modes of data acquisition were utilized to examine cases of fast and slow inactivation of the enzyme, respectively. With a half-life of 60 h, encapsulated TvDAO was approximately 720-fold more stable than the free enzyme under conditions of bubble aeration at 25 degrees C. The soluble oxidase was stabilized by added FAD only at temperatures of 35 degrees C or greater.
Collapse
Affiliation(s)
- Jozef Nahalka
- Research Centre Applied Biocatalysis, Petersgasse 14, A-8010 Graz, Austria
| | | | | |
Collapse
|
12
|
Vikartovská A, Bučko M, Mislovičová D, Pätoprstý V, Lacík I, Gemeiner P. Improvement of the stability of glucose oxidase via encapsulation in sodium alginate–cellulose sulfate–poly(methylene-co-guanidine) capsules. Enzyme Microb Technol 2007. [DOI: 10.1016/j.enzmictec.2007.06.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
13
|
Knoll A, Bartsch S, Husemann B, Engel P, Schroer K, Ribeiro B, Stöckmann C, Seletzky J, Büchs J. High cell density cultivation of recombinant yeasts and bacteria under non-pressurized and pressurized conditions in stirred tank bioreactors. J Biotechnol 2007; 132:167-79. [PMID: 17681630 DOI: 10.1016/j.jbiotec.2007.06.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 05/27/2007] [Accepted: 06/14/2007] [Indexed: 11/21/2022]
Abstract
This study demonstrates the applicability of pressurized stirred tank bioreactors for oxygen transfer enhancement in aerobic cultivation processes. The specific power input and the reactor pressure was employed as process variable. As model organism Escherichia coli, Arxula adeninivorans, Saccharomyces cerevisiae and Corynebacterium glutamicum were cultivated to high cell densities. By applying specific power inputs of approx. 48kWm(-3) the oxygen transfer rate of a E. coli culture in the non-pressurized stirred tank bioreactor was lifted up to values of 0.51moll(-1)h(-1). When a reactor pressure up to 10bar was applied, the oxygen transfer rate of a pressurized stirred tank bioreactor was lifted up to values of 0.89moll(-1)h(-1). The non-pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities of more than 40gl(-1) cell dry weight (CDW) of E. coli, whereas the pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities up to 225gl(-1) CDW of A. adeninivorans, 89gl(-1) CDW of S. cerevisiae, 226gl(-1) CDW of C. glutamicum and 110gl(-1) CDW of E. coli. Compared to literature data, some of these cell densities are the highest values ever achieved in high cell density cultivation of microorganisms in stirred tank bioreactors. By comparing the specific power inputs as well as the k(L)a values of both systems, it is demonstrated that only the pressure is a scaleable tool for oxygen transfer enhancement in industrial stirred tank bioreactors. Furthermore, it was shown that increased carbon dioxide partial pressures did not remarkably inhibit the growth of the investigated model organisms.
Collapse
Affiliation(s)
- Arnd Knoll
- Biochemical Engineering, RWTH Aachen University, 52056 Aachen, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Zhang S, Norrlöw O, Dey ES. Improvement of NaNO2-oxidizing activity in Nitrobacter vulgaris by coentrapment in polyacrylamide containing polydimethylsiloxane copolymer and DEAE-sephadex. Appl Environ Microbiol 2005; 71:5888-92. [PMID: 16204501 PMCID: PMC1265958 DOI: 10.1128/aem.71.10.5888-5892.2005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2005] [Accepted: 04/29/2005] [Indexed: 11/20/2022] Open
Abstract
Removal of nitrite and nitrate from drinking water has attracted great attention in recent years because of the human health risk induced by the exposure to contaminated groundwater and surface water. We have therefore tested a model nitrite oxidation system by coentrapping the NaNO2 oxidizer Nitrobacter vulgaris with polydimethylsiloxane (PDMS) copolymer and DEAE-Sephadex in a polyacrylamide gel. The copolymer and the anion exchanger facilitate the diffusion of oxygen and NaNO2, respectively, into the gel matrix. To test the nitrite-oxidizing activity, the entrapped cells were coupled to a thermal sensor. Coentrapment of 5% (wt/vol) DEAE-Sephadex with Nitrobacter vulgaris increased the nitrite-oxidizing activity by a factor of 3.7 compared to entrapped cells alone, and by the addition of 0.86% (wt/vol) artificial oxygen carrier PDMS copolymer increased the activity further to 4.3 times higher. Operational and storage stability of the coentrapped N.vulgaris also improved. This suggests that this enhanced immobilized cell system can also be used for nitrite oxidation to nitrate in drinking water as an on-line thermally monitored bioreactor.
Collapse
Affiliation(s)
- Songping Zhang
- Pure and Applied Biochemistry, Lund University, Box 124, 221 00 Lund, Sweden
| | | | | |
Collapse
|