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Polyhydroxyalkanoates (PHA) production from phenol in an acclimated consortium: Batch study and impacts of operational conditions. J Biotechnol 2018; 267:36-44. [PMID: 29305323 DOI: 10.1016/j.jbiotec.2018.01.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 12/08/2017] [Accepted: 01/02/2018] [Indexed: 11/22/2022]
Abstract
Microbial intracellular biopolymer PHA was synthesized from toxic pollutant phenol by an acclimated consortium. Various operational conditions were experimented for their effects on biomass growth and PHA accumulation. Carbon to nitrogen ratios from 5 to 40 (w/w) showed little impact, as did the levels of Fe, Ca and Mg in a short term. Acidic pH inhibited both growth and PHA synthesis, and an optimal dissolved oxygen level of 1-4 mg L-1 was identified. Low temperature (7 °C) significantly slowed but did not totally repress microbial activities. A 2% NaCl shock retarded reactions and 4% NaCl caused irreversible damage. Various initial phenol (S0) and biomass concentrations (X0) were combined to study the effect of food to microbe (F/M) ratio. High S0 and F/M exerted toxicity, reducing reaction rates but generating higher ultimate PHA wt% in biomass. Increasing X0 alleviated phenol inhibition and improved productivity and carbon conversion from phenol. A pseudo-optimized F/M ratio of 0.2-0.4 and a maximum PHA% rate of 1.15% min-1 were identified under medium S0/high X0. This study is the first to systematically investigate the feasibility of toxic industrial waste as the carbon source for PHA production, and likely the only one indicating potential for scaling-up and industrialization.
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Wosman A, Lu Y, Sun S, Liu X, Wan C, Zhang Y, Lee DJ, Tay J. Effect of operational strategies on activated sludge's acclimation to phenol, subsequent aerobic granulation, and accumulation of polyhydoxyalkanoates. JOURNAL OF HAZARDOUS MATERIALS 2016; 317:221-228. [PMID: 27281169 DOI: 10.1016/j.jhazmat.2016.05.074] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/27/2016] [Accepted: 05/25/2016] [Indexed: 06/06/2023]
Abstract
Aerobic granules, a relative novel form of microbial aggregate, are capable of degrading many toxic organic pollutants. Appropriate strategy is needed to acclimate seed sludge to the toxic compounds for successful granulation. In this study, two distinct strategies, i.e. mixed or single carbon sources, were experimented to obtain phenol-acclimated sludge. Their effects on reactor performance, biomass characteristics, microbial population and the granulation process were analyzed. Sludge fed with phenol alone exhibited faster acclimation and earlier appearance of granules, but possibly lower microbial diversity and reactor stability. Using a mixture of acetate and phenol in the acclimation stage, on the other hand, led to a reactor with slower phenol degradation and granulation, but eventual formation of strong and stable aerobic granules. In addition, the content of intracellular polyhydoxyakanoates (PHA) was also monitored, and significant accumulation was observed during the pre-granulation stage, where PHA >50% of dry weight was observed in both reactors.
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Affiliation(s)
- Afrida Wosman
- Department of Environmental Science and Engineering, Fudan University, 220 Handan Road, Yangpu District, Shanghai, 200433, China
| | - Yuhao Lu
- Department of Environmental Science and Engineering, Fudan University, 220 Handan Road, Yangpu District, Shanghai, 200433, China
| | - Supu Sun
- Department of Environmental Science and Engineering, Fudan University, 220 Handan Road, Yangpu District, Shanghai, 200433, China
| | - Xiang Liu
- Department of Environmental Science and Engineering, Fudan University, 220 Handan Road, Yangpu District, Shanghai, 200433, China
| | - Chunli Wan
- Department of Environmental Science and Engineering, Fudan University, 220 Handan Road, Yangpu District, Shanghai, 200433, China.
| | - Yi Zhang
- Department of Environmental Science and Engineering, Fudan University, 220 Handan Road, Yangpu District, Shanghai, 200433, China.
| | - Duu-Jong Lee
- Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
| | - JooHwa Tay
- Department of Civil Engineering, University of Calgary, Calgary, AB T2N 1N4, Canada
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Production of Poly (3-Hydroxybutyric Acid) by Ralstonia eutropha in a Biocalorimeter and its Thermokinetic Studies. Appl Biochem Biotechnol 2016; 179:1041-59. [DOI: 10.1007/s12010-016-2049-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 03/11/2016] [Indexed: 12/29/2022]
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Volova T, Zhila N, Shishatskaya E. Synthesis of poly(3-hydroxybutyrate) by the autotrophic CO-oxidizing bacterium Seliberia carboxydohydrogena Z-1062. J Ind Microbiol Biotechnol 2015; 42:1377-87. [PMID: 26254039 DOI: 10.1007/s10295-015-1659-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2015] [Accepted: 07/23/2015] [Indexed: 12/24/2022]
Abstract
The present study addresses growth parameters and physiological and biochemical characteristics of the aerobic CO-oxidizing carboxydobacterium Seliberia carboxydohydrogena Z-1062. Poly(3-hydroxybutyrate) yields were investigated in experiments with limiting concentrations of mineral nutrients (nitrogen or sulfur or nitrogen and sulfur) in batch culture of S. carboxydohydrogena Z-1062 grown on gas mixtures consisting of CO(2), O(2), H(2), and CO. CO concentrations of 10, 20, and 30 % v/v did not affect polymer synthesis, whose content after 56-h cultivation under limiting concentrations of nitrogen and sulfur was 52.6-62.8 % of biomass weight at a productivity of 0.13-0.22 g/L h. The inhibitory effect of CO on cell concentration was revealed at CO concentration of 30 % v/v. That also caused a decrease in substrate (H(2) and O(2)) use efficiency. Thus, this carboxydobacterium can be regarded as a potential producer of polyhydroxyalkanoates from industrial hydrogenous sources.
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Affiliation(s)
- Tatiana Volova
- Institute of Biophysics SB RAS, 50 Akademgorodok, Krasnoyarsk, 660036, Russian Federation. .,Siberian Federal University, 79 Svobodny Ave., Krasnoyarsk, 660041, Russian Federation.
| | - Natalia Zhila
- Institute of Biophysics SB RAS, 50 Akademgorodok, Krasnoyarsk, 660036, Russian Federation.,Siberian Federal University, 79 Svobodny Ave., Krasnoyarsk, 660041, Russian Federation
| | - Ekaterina Shishatskaya
- Institute of Biophysics SB RAS, 50 Akademgorodok, Krasnoyarsk, 660036, Russian Federation.,Siberian Federal University, 79 Svobodny Ave., Krasnoyarsk, 660041, Russian Federation
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5
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Biotechnological Production of Polyhydroxyalkanoates: A Review on Trends and Latest Developments. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/802984] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Polyhydroxyalkanoates (PHA) producers have been reported to reside at various ecological niches which are naturally or accidently exposed to high organic matter or growth limited conditions such as dairy wastes, hydrocarbon contaminated sites, pulp and paper mill wastes, agricultural wastes, activated sludges of treatment plants, rhizosphere, and industrial effluents. Few among them also produce extracellular by-products like rhamnolipids, extracellular polymeric substances, and biohydrogen gas. These sorts of microbes are industrially important candidates for the reason that they can use waste materials of different origin as substrate with simultaneous production of valuable bioproducts including PHA. Implementation of integrated system to separate their by-products (intracellular and extracellular) can be economical in regard to production. In this review, we have discussed various microorganisms dwelling at different environmental conditions which stimulate them to accumulate carbon as polyhydroxyalkanoates granules and factors influencing its production and composition. A brief aspect on metabolites which are produced concomitantly with PHA has also been discussed. In conclusion, exploring of capabilities like of dual production by microbes and use of wastes as renewable substrate under optimized cultural conditions either in batch or continuous process can cause deduction in present cost of bioplastic production from stored PHA granules.
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Regestein L, Maskow T, Tack A, Knabben I, Wunderlich M, Lerchner J, Büchs J. Non-invasive online detection of microbial lysine formation in stirred tank bioreactors by using calorespirometry. Biotechnol Bioeng 2013; 110:1386-95. [DOI: 10.1002/bit.24815] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 11/26/2012] [Accepted: 12/11/2012] [Indexed: 11/10/2022]
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Quorum quenching revisited--from signal decays to signalling confusion. SENSORS 2012; 12:4661-96. [PMID: 22666051 PMCID: PMC3355433 DOI: 10.3390/s120404661] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 03/23/2012] [Accepted: 03/26/2012] [Indexed: 12/12/2022]
Abstract
In a polymicrobial community, while some bacteria are communicating with neighboring cells (quorum sensing), others are interrupting the communication (quorum quenching), thus creating a constant arms race between intercellular communication. In the past decade, numerous quorum quenching enzymes have been found and initially thought to inactivate the signalling molecules. Though this is widely accepted, the actual roles of these quorum quenching enzymes are now being uncovered. Recent evidence extends the role of quorum quenching to detoxification or metabolism of signalling molecules as food and energy source; this includes “signalling confusion”, a term coined in this paper to refer to the phenomenon of non-destructive modification of signalling molecules. While quorum quenching has been explored as a novel anti-infective therapy targeting, quorum sensing evidence begins to show the development of resistance against quorum quenching.
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Zinn M, Durner R, Zinn H, Ren Q, Egli T, Witholt B. Growth and accumulation dynamics of poly(3-hydroxyalkanoate) (PHA) in Pseudomonas putida GPo1 cultivated in continuous culture under transient feed conditions. Biotechnol J 2011; 6:1240-52. [DOI: 10.1002/biot.201100219] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 06/10/2011] [Accepted: 06/20/2011] [Indexed: 11/06/2022]
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Kang JC, Jee JH, Koo JG, Keum YH, Jo SG, Park KH. Anti-oxidative status and hepatic enzymes following acute administration of diethyl phthalate in olive flounder Paralichthys olivaceus, a marine culture fish. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2010; 73:1449-1455. [PMID: 20674977 DOI: 10.1016/j.ecoenv.2010.07.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 07/06/2010] [Accepted: 07/18/2010] [Indexed: 05/29/2023]
Abstract
Although diethyl phthalate (DEP) is one of the most frequently used phthalates in solvents and fixatives for numerous industrial products, almost no research has been done on its biochemical toxicity in aquatic animals. Olive flounder (Paralichthys olivaceus), an important culture fish in far eastern Asian countries, were treated with intraperitoneal DEP at 0, 100, 300 or 900 mg/kg for three consecutive days and biochemical effects were assessed in the liver, kidney and serum 24 h after the final dosing. Measured parameters were mostly restricted to oxidative status and toxicity of the organs. In the hepatic tissue, there were significant increases in lipid peroxide (LPO) at 100mg/kg and above. Other hepatic parameters, which were examined, changed only after 900 mg/kg: reduced glutathione content (GSH), glutathione reductase activity (GR), glutathione peroxidase (GPx) activity increased; catalase (CAT) activity decreased. DEP also induced elevation in LPO levels at above 100 mg/kg in renal tissues; however, there was only a decrease in GR and glutathione S-transferase (GST) activities with DEP 900 mg/kg in contrast to the liver. Enzyme activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in hepatic tissues decreased in a dose-dependent manner in response to DEP at above 300 mg/kg. DEP at 300-900 mg/kg, although not uniform among parameters, caused increases in serum alkaline phosphatase (ALP), lactate dehydrogenase (LDH), AST, ALT activities and osmolality value, suggesting that DEP at these doses induced hepatic cell damage. The results indicate that 100-900 mg/kg DEP induced oxidative stress and the fish seemed to activate compensatory anti-oxidant systems to cope with the imposed substance on the liver. Such compensatory activation was not evident in the kidney. Overall, DEP was only weakly toxic to olive flounder in terms of oxidative and hepatic damage.
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Affiliation(s)
- Ju-Chan Kang
- Department of Aquatic Life Medicine, Pukyong National University, Busan, Republic of Korea
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Maskow T, Kemp R, Buchholz F, Schubert T, Kiesel B, Harms H. What heat is telling us about microbial conversions in nature and technology: from chip- to megacalorimetry. Microb Biotechnol 2009; 3:269-84. [PMID: 21255327 PMCID: PMC3815370 DOI: 10.1111/j.1751-7915.2009.00121.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The exploitation of microorganisms in natural or technological systems calls for monitoring tools that reflect their metabolic activity in real time and, if necessary, are flexible enough for field application. The Gibbs energy dissipation of assimilated substrates or photons often in the form of heat is a general feature of life processes and thus, in principle, available to monitor and control microbial dynamics. Furthermore, the combination of measured heat fluxes with material fluxes allows the application of Hess' law to either prove expected growth stoichiometries and kinetics or identify and estimate unexpected side reactions. The combination of calorimetry with respirometry is theoretically suited for the quantification of the degree of coupling between catabolic and anabolic reactions. New calorimeter developments overcome the weaknesses of conventional devices, which hitherto limited the full exploitation of this powerful analytical tool. Calorimetric systems can be integrated easily into natural and technological systems of interest. They are potentially suited for high‐throughput measurements and are robust enough for field deployment. This review explains what information calorimetric analyses provide; it introduces newly emerging calorimetric techniques and it exemplifies the application of calorimetry in different fields of microbial research.
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Affiliation(s)
- Thomas Maskow
- UFZ, Helmholtz Centre for Environmental Research, Department of Environmental Microbiology, Permoserstr. 15, 04318 Leipzig, Germany.
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Jungo C, Marison I, von Stockar U. Mixed feeds of glycerol and methanol can improve the performance of Pichia pastoris cultures: A quantitative study based on concentration gradients in transient continuous cultures. J Biotechnol 2007; 128:824-37. [PMID: 17303281 DOI: 10.1016/j.jbiotec.2006.12.024] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 12/12/2006] [Accepted: 12/19/2006] [Indexed: 10/23/2022]
Abstract
Transient continuous cultures constitute a means to speed up strain characterization, by avoiding the need for many time-consuming steady-state experiments. In this study, mixed substrate growth on glycerol and methanol of a Pichia pastoris strain expressing and secreting recombinant avidin was characterized quantitatively by performing a nutrient gradient with linear increase of the methanol fraction in the feed medium from 0.5 to 0.93 C-mol C-mol(-1) at a dilution rate of 0.06 h(-1). The influence of the methanol fraction in the feed medium on recombinant avidin productivity and on specific alcohol oxidase activity were also examined. Results showed that, compared with cultures on methanol as sole carbon source, the specific recombinant avidin production rate was the same provided the methanol fraction in the feed medium was higher than 0.6 C-mol C-mol(-1). The volumetric avidin production rate was even 1.1-fold higher with a methanol fraction in the feed medium of 0.62 C-mol C-mol(-1) as a result of the higher biomass yield on mixed substrate growth compared with methanol alone. Moreover, since heat production and oxygen uptake rates are lower during mixed substrate growth on glycerol and methanol, mixed substrate cultures present technical advantages for the performance of high cell density P. pastoris cultures. Results obtained in a high cell density fed-batch culture with a mixed feed of 0.65 C-mol C-mol(-1) methanol and 0.35 C-mol C-mol(-1) glycerol were in agreement with results obtained during the transient nutrient gradient.
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Affiliation(s)
- Carmen Jungo
- Ecole Polytechnique Fédérale de Lausanne, Laboratoire de Génie Chimique et Biologique, Station 6, 1015 Lausanne, Switzerland
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Wiacek C, Müller S, Benndorf D. A cytomic approach reveals population heterogeneity ofCupriavidus necator in response to harmful phenol concentrations. Proteomics 2006; 6:5983-94. [PMID: 17106909 DOI: 10.1002/pmic.200600244] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The understanding of functions of cells within microbial populations or communities is certainly needed for existing and novel cytomic approaches which grip the individual scale. Population behaviour results from single cell performances and is caused by the individual genetic pool, history, life cycle states and microenvironmental surroundings. Mimicking natural impaired environments, the paper shows that the Gram-negative Betaproteobacterium Cupriavidus necator dramatically altered its population heterogeneity in response to harmful phenol concentrations. Multiparametric flow cytometry was used to follow variations in structural cellular parameters like chromosome contents and storage materials. The functioning of these different cell types was resolved by ensuing proteomics after the cells' spatial separation by cell sorting, finding 11 proteins changed in their expression profile, among them elongation factor Tu and the trigger factor. At least one third of the individuals clearly underwent starving states; however, simultaneously these cells prepared themselves for entering the life cycle again. Using cytomics to recognise individual structure and function on the microbial scale represents an innovative technical design to describe the complexity of such systems, overcoming the disadvantage of small cell volumes and, thus, to resolve bacterial strategies to survive harmful environments by altering population heterogeneity.
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Affiliation(s)
- Claudia Wiacek
- Department of Environmental Microbiology, UFZ-Centre for Environmental Research Leipzig-Halle, Leipzig, Germany
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Real Time Insights into Bioprocesses Using Calorimetry: State of the Art and Potential. Eng Life Sci 2006. [DOI: 10.1002/elsc.200520123] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Maskow T, Müller S, Lösche A, Harms H, Kemp R. Control of continuous polyhydroxybutyrate synthesis using calorimetry and flow cytometry. Biotechnol Bioeng 2006; 93:541-52. [PMID: 16245347 DOI: 10.1002/bit.20743] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The substrate-carbon flow can be controlled in continuous bioreactor cultures by the medium composition, for example, by the C/N ratio. The carbon distribution is optimal when a maximum fraction flows into the desired product and the residual is just sufficient to compensate for the dilution of the microbial catalyst. Undershooting of the latter condition is reflected immediately by changes in the Gibbs energy dissipation and cellular states. Two calorimetric measurement principles were applied to optimize the continuous synthesis of polyhydroxybutyrate (PHB) by Variovorax paradoxus DSM4065 during growth with constantly increasing supply rates of fructose or toxic phenol. Firstly, the changed slope of the heat production rate in a complete heat balanced bioreactor (CHB) indicated optimum carbon channeling into PHB. The extent of the alteration depended directly on the toxic properties of the substrate. Secondly, a flow through calorimeter was connected with the bioreactor as a "measurement loop." The optimum substrate carbon distribution was indicated by a sudden change in the heat production rate independent of substrate toxicity. The sudden change was explained mathematically and exploited for the long-term control of phenol conversion into PHB. LASER flow cytometry measurements distinguished between subpopulations with completely different PHB-content. Populations grown on fructose preserved a constant ratio of two subpopulations with double and quadruple sets of DNA. Cells grown on phenol comprised a third subpopulation with a single DNA set. Rising phenol concentrations caused this subpopulation to increase. It may thus be considered as an indicator of chemostress.
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Affiliation(s)
- Thomas Maskow
- Department of Environmental Microbiology (UMB), UFZ Centre for Environmental Research Leipzig-Halle GmbH, Germany.
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Maskow T, Olomolaiye D, Breuer U, Kemp R. Flow calorimetry and dielectric spectroscopy to control the bacterial conversion of toxic substrates into polyhydroxyalcanoates. Biotechnol Bioeng 2004; 85:547-52. [PMID: 14760695 DOI: 10.1002/bit.10903] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The microbial conversion of toxic substrates into valuable products in continuous culture requires the equivalent of a tight rope walk between formation of the desired product and intoxication of the microbial catalyst. The condition of the latter is reflected immediately by changes in heat flow rate and beta-dispersion in an electrical RF field. Therefore, these were applied to the example of the continuous growth-associated synthesis of polyhydroxyalcanoates (PHA) from phenol by the bacterial strain Variovorax paradoxus DSM 4065. By controlling the supply of phenol to the chemostat, the rates of degradation, biomass formation, and synthesis of target product, respectively, were increasingly elevated until the onset of poisoning the organisms. The boundary between the maximum rates and the initiation of intoxication coincided with a sudden change in the heat flux. Using this occurrence, it was possible to develop a control strategy and test it successfully for a time period of 80 h. After 40 h the process stabilized at mean values, i.e., at rates of 92% phenol degradation, 100% biomass formation, and 70 - 75% of PHA formation compared with the situation shortly before poisoning the organisms. Using a moving-average technique to filter the raw dielectric spectroscope data, changes were followed in biomass concentration of approximately 100 mg/L. However, this technique was not sensitive or rapid enough to control the process.
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Affiliation(s)
- Thomas Maskow
- Department of Environmental Microbiology, UFZ Centre for Environmental Research Leipzig-Halle GmbH, Permoserstra. 15, D-04318 Leipzig, Germany.
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Maskow T, Babel W. Calorimetrically obtained information about the efficiency of ectoine synthesis from glucose in Halomonas elongata. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1527:4-10. [PMID: 11420137 DOI: 10.1016/s0304-4165(01)00115-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Compatible solutes are becoming more and more attractive commercially. Thus, knowledge of the efficiency of synthesis of compatible solutes from different carbon substrates is very important. As the growth rate and rates of formation of compatible solutes correspond to the heat flux, calorimetric measurements are particularly suitable for providing this information. By growing microorganisms continuously in a calorimeter, and generating a feeding stream with gradually increasing salinity without changing any other growth conditions, we were able to determine the efficiency of growth-associated synthesis of compatible solutes. This was shown for Halomonas elongata DMSZ 2581(T) growing on glucose, which synthesizes (at 25 degrees C) 1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid (ectoine) as its main osmotic counterweight. The requirement of biologically usable energy for its growth-associated synthesis was found to be very low: a 100% efficiency of the conversion of the substrate-carbon into ectoine is both theoretically possible and was reached approximately in practice. The growth rate and yield coefficient were essentially independent of the ectoine formation rate, and the rate of substrate-carbon assimilation was far greater than the rate of dissimilation. The specific maximum growth rate was limited by the rate of formation of ectoine.
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Affiliation(s)
- T Maskow
- UFZ Centre for Environmental Research Leipzig-Halle GmbH, Department of Environmental Microbiology, Permoserstrasse 15, D-04318, Leipzig, Germany.
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