No description available.

Syngas fermentation via gasification is a two-stage process, which contains gasification of feedstock into syngas and syngas bio-methanation by anaerobic microorganisms. This project is a study on syngas fermentation. The gasification feedstock can be difficult-to-degrade solid waste so; waste volumes are reduced while green energy is produced. The main target of this thesis was to study novel configurations of reverse membrane bioreactor (RMB) in order to retain microbial cells inside the digester and thereafter increase methane production. In the first experiment, microbial cells encased in PVDF sachets were proved to perform efficiently in batch mode in comparison to free cells at optimum temperature, 55 oC. Moreover, encased cells in co-digestion of syngas and organic waste exhibited higher methane amounts compared to pure syngas treatment. Encased cells were then tested in thermophilic semi-continuous process and showed better performance compared to the free cell reactor. The RMB containing encased cells retained successfully the cells during the 154 days of the experiment, while free cells were washed-out. The highest amounts of methane from RMB and the free cell reactor were produced during the 126th - 130th day (6 and 1.5 mmol/day, respectively). In the last experiment, a RMB containing 13 membrane layers of enclosed cells was studied and compared to a conventional reactor of free cells. The RMB performed successfully in syngas bio-methanation under semi-continuous conditions during 49 days. The highest methane amount produced was 10 mmol/day in both RMB and free cell reactor. / Program: Industriell bioteknik

In this study the aim was to optimize the production of the Affibody fusion-protein Z03358- ABD094-(S4G)3-IL2 with regard to the amount of soluble protein produced. However, problems with reproducibility with this protein and the chosen expression system were encountered. Therefore, expression of the His-tagged Affibody His6-(Z05477)2 was evaluated using the same expression system as well as expression in another well characterized expression system. Both target proteins are of therapeutic interest. One of the proteins is an IL2 fusion protein (Z03358-ABD094-(S4G)3-IL2) that bind the platelet-derived growth factor receptor β (PDGFR-β). PDGF signaling is of interest in cancer treatment where, among other things, the effects of PDGF on tumor angiogenesis is researched. The His6-(Z05477)2 protein has a classified target but is developed as a therapeutic in the area of inflammation and autoimmune disease. Both model proteins are known to be difficult to purify due to low solubility. The two E. coli expression systems investigated and compared were BL21(DE3) and Lemo21(DE3). The fusion protein Z03358-ABD094-(S4G)3-IL2 was produced in BL21(DE3) in inclusion bodies with a yield of 4.95 g/l. An optimized process for the expression of His6-(Z05477)2 using BL21(DE3) was developed with a yield of 6.6 g/l soluble protein after expression at 30°C for 6 h.

A proteína A de superfície de pneumococo (PspA) é indispensável para a virulência da bactéria e foi escolhida para a elaboração de uma nova vacina conjugada contra S. pneumoniae. Para tanto foi desenvolvido um processo industrial de produção e purificação do fragmento recombinante da PspA clado 3 em E. coli. Cultivos descontínuos alimentados foram estabelecidos com glicose ou glicerol em reator de 5L, obtendo-se 62g/L de células secas e 3g/L de PspA3. As células foram lisadas por homogeneizador contínuo de alta pressão com eficiência de 96,7%. A centrifugação foi definida como etapa de clarificação. A sequência cromatográfica troca aniônica seguida de afinidade por Ni+2 rendeu os melhores resultados de pureza (81%) e recuperação (70%). A cromatografia de troca catiônica foi selecionada como terceira etapa do processo, definindo assim um processo de produção e purificação escalonável que possibilitou a obtenção de PspA3 com alto grau de pureza (90%). / The pneumococcal surface protein A (PspA) is indispensable for virulence of S. pneumoniae and it was the first choice as carrier for a new conjugated vaccine against S.pneumoniae. Hence, the purpose of this work was to develop an industrial production and purification process of a recombinant fragment PspA clade 3 (rfPspA3) in E. coli. Fed-batch cultivations in 5 L bioreactors with defined medium were carried out using glucose or glycerol as carbon sources. It was obtained 62 g/L of dry cell weight and 3 g/L of rfPspA3. Cells were disrupted with 96.7% of efficiency by high pressure continuous homogenizer. Centrifugation was defined for the clarification step. The sequence with Q- followed by IMAC-Sepharose yielded the best purity and recovery of rfPspA3 (81 and 70%, respectively). Cation exchange was chosen for the last chromatography. In conclusion, an industrial production and purification process was developed and rfPspA3 was obtained with high purity (90%).

Abstract Small-scale cultivation methods are a necessity for the development of new biotechnological processes. The most common method for submerged microbial cultivation is a shake flask used with a batch operation protocol. Well plate cultivation formats have also increased their importance, due to the need to utilize high-throughput cultivations for efficient product development. However, batch cultivation is often not the optimal method for obtaining high cell densities and good product quality, due to unlimited microbial growth. The aim of this dissertation was to improve small-scale microbial cultivations for microbial growth and product formation. Hydrolytic enzymes were utilized to relieve nutrient limitation by hydrolysis of proteins in lactic acid bacteria cultures to improve lactic acid production from dairy side products. Hydrolytic enzymes were also utilized in the enzymatic release of glucose from starch to create a fed-batch-like cultivation system applicable on small scale. The wireless sensor system developed was applied in shake flask cultivations to monitor oxygen and pH levels. Enzymatic polymer processing was applicable for small-scale cultivations. Lactic acid production by Lactobacillus salivarius ssp. salicinius was enhanced four-fold when the proteins were hydrolyzed either by proteases or by proteolytic microbes. The fed-batch-mimicking controlled glucose feeding and growth control were obtained by means of the simultaneous enzymatic hydrolysis of starch-polymer during cultivation. Controlled growth, higher cell densities, decreased side product formation and increased amount of soluble protein product were obtained in Escherichia coli cultivations. When this method was applied to the cultivation and recombinant protein production of the methylotrophic yeast Pichia pastoris, higher cell densities and higher amounts of active protein were obtained. The glucose concentration remained low enough to avoid the substrate repression of the alcohol oxidase promoter. The fed-batch method is suitable for high-throughput cultivations since the method can be utilized in well plate formats without external feeding devices. The method can be utilized in the development of new biotechnological products, especially when the production system is sensitive to growth conditions, and growth control is preferred. / Tiivistelmä Pienen mittakaavan mikrobikasvatusmenetelmiä tarvitaan kehitettäessä uusia bioteknologisia prosesseja. Tavallisin menetelmä mikrobien liuoksessa tapahtuvaan kasvatukseen on panostyyppisesti tehtävä sekoituspullokasvatus. Kuoppalevykasvatukset ovat myös tulleet entistä tärkeämmiksi, koska tuotekehityksen tehostamiseksi on tarvetta käyttää high-throughput-menetelmiä. Tavoiteltaessa korkeita mikrobisolutiheyksiä ja tuotteen hyvää laatua, panostyyppinen kasvatus ei ole usein paras vaihtoehto, johtuen mikrobien rajoittamattomasta kasvusta. Tämän työn tarkoituksena oli parantaa mikrobien kasvua ja tuotteen muodostusta pienen mittakaavan kasvatuksissa. Meijeriteollisuuden sivutuotteiden proteiineja pilkottiin entsyymien avulla, jotta maitohappobakteerit pystyivät hyödyntämään proteiinit tehokkaammin ja tuottamaan enemmän maitohappoa. Hydrolyyttisiä entsyymejä hyödynnettiin myös glukoosin vapauttamiseen tärkkelyksestä, jolloin saatiin luotua pieneen mittakaavaan sopiva panossyöttötyyppinen kasvatusmenetelmä. Työn aikana kehitettyä langatonta mittausjärjestelmää hyödynnettiin sekoituspullokasvatuksissa happipitoisuuden ja pH:n seurantaan. Entsymaattinen polymeerien käsittely oli soveltuva menetelmä pienen mittakaavan kasvatuksiin. Maitohapon tuotto Lactobacillus salivarius ssp. salicinius -mikrobilla nelinkertaistui, kun ravinneproteiinit pilkottiin joko proteaasien tai proteolyyttisten mikrobien avulla. Panossyöttömenetelmää muistuttava hallittu glukoosin syöttö ja mikrobin kasvun hallinta saavutettiin pilkkomalla tärkkelystä glukoosiksi kasvatuksen aikana. Escherichia coli kasvatuksissa saavutettiin hallittu solumäärän kasvu, korkeammat solutiheydet, vähentynyt sivutuotteiden muodostus ja suurempi liukoisen tuoteproteiinin määrä. Tätä menetelmää sovellettiin myös vierasproteiinin tuottoon metylotrofisella Pichia pastoris -hiivalla, jolloin saavutettiin korkeammat solutiheydet ja suurempi aktiivisen tuoteproteiinin määrä. Glukoosin määrä kasvatusliuoksessa pysyi riittävän alhaisena, jotta se ei repressoinut hiivan alkoholioksidaasi-promoottoria. Panossyöttömenetelmä on sopiva high-throughput-mikrobikasvatuksiin, koska sitä voidaan käyttää kuoppalevyillä ilman syöttölaitteita. Menetelmää voidaan hyödyntää uusien bioteknisten tuotteiden kehittämisessä erityisesti silloin, kun tuottoisäntä on herkkä kasvuolosuhteiden suhteen ja mikrobin kasvua halutaan hallita.

A proteína A de superfície de pneumococo (PspA) é indispensável para a virulência da bactéria e foi escolhida para a elaboração de uma nova vacina conjugada contra S. pneumoniae. Para tanto foi desenvolvido um processo industrial de produção e purificação do fragmento recombinante da PspA clado 3 em E. coli. Cultivos descontínuos alimentados foram estabelecidos com glicose ou glicerol em reator de 5L, obtendo-se 62g/L de células secas e 3g/L de PspA3. As células foram lisadas por homogeneizador contínuo de alta pressão com eficiência de 96,7%. A centrifugação foi definida como etapa de clarificação. A sequência cromatográfica troca aniônica seguida de afinidade por Ni+2 rendeu os melhores resultados de pureza (81%) e recuperação (70%). A cromatografia de troca catiônica foi selecionada como terceira etapa do processo, definindo assim um processo de produção e purificação escalonável que possibilitou a obtenção de PspA3 com alto grau de pureza (90%). / The pneumococcal surface protein A (PspA) is indispensable for virulence of S. pneumoniae and it was the first choice as carrier for a new conjugated vaccine against S.pneumoniae. Hence, the purpose of this work was to develop an industrial production and purification process of a recombinant fragment PspA clade 3 (rfPspA3) in E. coli. Fed-batch cultivations in 5 L bioreactors with defined medium were carried out using glucose or glycerol as carbon sources. It was obtained 62 g/L of dry cell weight and 3 g/L of rfPspA3. Cells were disrupted with 96.7% of efficiency by high pressure continuous homogenizer. Centrifugation was defined for the clarification step. The sequence with Q- followed by IMAC-Sepharose yielded the best purity and recovery of rfPspA3 (81 and 70%, respectively). Cation exchange was chosen for the last chromatography. In conclusion, an industrial production and purification process was developed and rfPspA3 was obtained with high purity (90%).

The recombinant product is secreted to the periplasm in many processes where E. coli is used as host. One drawback with secretion is the undesired leakage of the periplasmic products to the medium. The aim of this work was to find strategies to influence the periplasmic retention of recombinant products. We have focused on the role of the specific growth rate, a parameter that is usually controlled in industrial bioprocesses. The hypothesis was that the stability of the outer membrane in E. coli is gained from a certain combination of specific phospholipids and fatty acids on one side and the amount and specificity of the outer membrane proteins on the other side, and that the specific growth rate influences this structure and therefore can be used to control the periplasmic retention. We found that is possible to control the periplasmic retention by the growth rate. The leakage of the product increased as the growth rate increased. It was however also found that a higher growth rate resulted in increased productivity. This resulted in equal amounts of product inside the cells regardless of growth rate. We also showed that the growth rate influenced the outer membrane composition with respect to OmpF and LamB while OmpA was largely unaffected. The total amount of outer membrane proteins decreased as the growth rate increased. There were further reductions in outer membrane protein accumulation when the recombinant product was secreted to the periplasm. The lowered amount of outer membrane proteins may have contributed to the reduced ability for the cell to retain the product in the periplasm. The traditional way to control the growth rate is through a feed of substrate in a fed-batch process. In this work we used strains with a set of mutations in the phosphotransferase system (PTS) with a reduced uptake rate of glucose to investigate if these strains could be used for growth rate control in batch cultivations without the use of fed-batch control equipment. The hypothesis was that the lowering of the growth rate on cell level would result in the establishment of fed-batch similar conditions. This study showed that it is possible to control the growth rate in batch cultivations by using mutant strains with a decreased level of substrate uptake rate. The mutants also produced equivalent amounts of acetic acid as the wild type did in fed-batch cultivation with the same growth rate. The oxygen consumption rates were also comparable. A higher cell density was reached with one of the mutants than with the wild type in batch cultivations. It is possible to control the growth rate by the use of the mutants in small-scale batch cultivations without fed-batch control equipment. / QC 20101108

Made available in DSpace on 2016-06-02T19:55:31Z (GMT). No. of bitstreams: 1 4085.pdf: 6460777 bytes, checksum: 9367318799fc091b43ee6716e5057271 (MD5) Previous issue date: 2011-12-22 / Financiadora de Estudos e Projetos / High cell density cultivations of recombinant E. coli are a fast and economical way to produce recombinant proteins. Through this bioprocess, products with high added value and pharmaceuticals of great importance such as insulin, human and bovine growth hormone, protein antigens for formulation of vaccines, enzymes, among others, are obtained. However, keeping these cultivations within the desired conditions becomes a major challenge, since some variables such as dissolved oxygen concentration (DOC) and substrate concentration are difficult to control. Therefore, the development and implementation of an automatic monitoring and control tool are key requirements for the performance of high density cultivation. The present work has as main objectives to study feeding strategies for high cell density cultivation of recombinant Escherichia coli and develop a computational tool capable of ensuring the implementation of the chosen strategies, performing the monitoring, control and supervision of the cultivations. Fed batch cultivations were carried out under the supervision of the tool in a 5 L in-house bioreactor, equipped with sensors for temperature, dissolved oxygen, pH, pressure and biomass (sensor that measures the concentration of viable cells based on permittivity measurements), peristaltic pumps and connected to the gas analyzer. The tool was developed with LabView 8.0 and MatLab 6.5, being the acquisition and communication with the different bioreactor accessories via compact Field Point. Twenty two fed-batch cultivations with 5 different clones of E. coli, BL21(D3) expressing the enzyme penicillin G acylase (PGA) as well as antigenic proteins of S. pneumoniae (PspA3, PspA245 and PspA4Pro) and E. rhusiopathiae (SpaA) were performed during the development of the tool and the studies of feeding strategy. Both defined medium (HDF modified) as complex medium (ZYM-5052 modified), usually having glycerol as main carbon source and IPTG or lactose as inducers were used. In all cultivations, samples were collected to quantify the concentration of cells (dry weight method in filter of 0.22 m and optical density at 600 nm), organic acids, glucose, glycerol and lactose (HPLC) as well as protein expression (densitometry and NIPAB method for PGA) and plasmid stability (plating). The tool SUPERSYS_HCDCR (registered as a free software) developed, implemented and validated in the performed cultivations, carries out the basic functions of bioreactor supervision software, such as monitoring and data acquisition of pressure, temperature, pH, DOC, fraction of CO2 and O2 in the outlet gas as well as real-time estimate of the respiratory quotient, the rate of oxygen consumption and CO2 production. However, it also has the following special features, including: i) automatic control of air and oxygen flow according to cellular demand, ii) automatic activation of the feed pump at the end of the batch; iii) automatic control of feeding flow rate as function of the specific growth rate inferred in real time; iv) automatic control of feeding flow rate constrained by the concentration of dissolved oxygen, v) audible alarms indicating failures in the process; vi) failure messages sent via email; vii) automatic control of dissolved oxygen concentration; viii) control of the bioreactor pressure; and ix) control of bath temperature. Regarding the studies of feeding strategies aimed at biomass productivity increase in high cell density cultivations of recombinant E. coli, using the supervision tool developed together with changes in the composition of the synthetic culture medium available in the literature, a cellular concentrations greater than 150 g/L was achieved in less than 24 hours of cultivation, corresponding to a productivity of 9.2 g/Lh. This value, which is higher than the reported in the literature, was obtained without acetate accumulation and allowing high production of recombinant protein. / Cultivos de alta densidade celular de E. coli recombinante constituem uma tecnica rapida e economica para producao de proteinas recombinantes. Por meio deste bioprocesso, sao obtidos produtos de alto valor agregado e de grande importancia na industria farmaceutica, tais como insulina, hormonios de crescimento humano e bovino, antigenos proteicos para formulacao de vacinas, enzimas, dentre outros. Entretanto, manter estes cultivos dentro das condicoes desejadas se torna um grande desafio, em funcao da dificuldade de controlar variaveis como a concentracao de oxigenio dissolvido (COD) e a concentracao de substrato nos niveis desejados. Por isso, o desenvolvimento e a implementacao de sistemas automaticos de supervisao e controle sao requisitos fundamentais para o bom desempenho de um cultivo de alta densidade. O presente trabalho teve como principais objetivos estudar estrategias de alimentacao para cultivos de alta densidade celular de Escherichia coli recombinante e desenvolver uma ferramenta computacional para suporte na execucao das estrategias escolhidas, realizando o monitoramento, controle e supervisao dos cultivos. Os cultivos em batelada alimentada realizados sob supervisao da ferramenta foram conduzidos em biorreator de 5 L, equipado com sensores de temperatura, oxigenio dissolvido, pH, pressao e biomassa (sensor que mede a concentracao de celulas viaveis a partir dos dados de permissividade), bombas peristalticas e conectado a analisador de gases. A ferramenta foi desenvolvida com os programas LabView 8.0 e MatLab 6.5, sendo a aquisicao e a comunicacao com os diferentes acessorios do biorreator realizada via compact Field Point (National Instruments). Vinte e dois cultivos em batelada alimentada com 5 diferentes clones de E. coli, BL21(D3) expressando a enzima penicilina G acilase (PGA) assim como proteinas antigenicas de Streptococcus pneumoniae (PspA3, PspA245 e PspA4Pro) e de Erysipelothrix rhusiopathiae (SpaA) foram realizados durante o desenvolvimento da ferramenta e dos estudos de estrategia de alimentacao, empregando tanto meio definido (HDF modificado) como meio complexo (ZYM-5052 modificado), tendo glicerol ou glicose como principal fonte de carbono e IPTG ou lactose como indutores. Em todos os cultivos, amostras foram coletadas para quantificar a concentracao de celulas (metodo de massa seca em filtro de 0,22m e leitura da densidade otica a 600 nm), de acidos organicos, glicose, glicerol e lactose (HPLC) e a expressao da proteina (densitometria e metodo NIPAB para a PGA) e a estabilidade de plasmideo (plaqueamento). A ferramenta SUPERSYS_HCDCR (registrada como software livre) desenvolvida, implementada e validada nos cultivos realizados, desempenha as funcoes basicas de softwares de supervisao de biorreatores, tais como: monitoramento e aquisicao de dados de pressao, temperatura, pH, COD, fracao de CO2 e de O2 nos gases de saida; estimativa em tempo real do quociente respiratorio, das velocidades de consumo de oxigenio e de producao de CO2. Esta ferramenta apresenta as seguintes funcionalidades especiais: i) controle automatico das vazoes de ar e de oxigenio de acordo com a demanda celular; ii) acionamento automatico da bomba de alimentacao ao final da batelada; iii) controle automatico da vazao de alimentacao em funcao da velocidade especifica de crescimento inferida em tempo real; iv) controle automatico da alimentacao com restricoes pela concentracao de oxigenio dissolvido; v) alarmes sonoros indicando falhas no processo; vi) envio de mensagens de falhas por email; vii) controle automatico da concentracao de oxigenio dissolvido; viii) controle de seguranca da pressao do biorreator, e ix) controle da temperatura do banho. Em relacao aos estudos das estrategias de alimentacao visando ao aumento da produtividade em biomassa em cultivos de alta densidade celular de E. coli recombinante, com o auxilio da ferramenta de supervisao desenvolvida aliada a modificacoes na composicao do meio de cultivo sintetico disponivel na literatura, foram alcancadas concentracoes celulares maiores que 150 g/L em menos de 24 h de tempo total de cultivo, levando a uma produtividade de 9,2 g/Lh, a qual e superior aos valores relatados na literatura, sem acumulo de acetato e possibilitando elevada producao da proteina recombinante.

Abstract Efficient production of biologically functional recombinant proteins is a cornerstone of modern biotechnological research. Laboratory-scale protein production is most commonly accomplished in simple shaking bioreactors such as shake flasks. However, productivity of these cultures is often severely limited by low biomass yield and non-optimal growth conditions regarding medium composition, pH and oxygen supply. In many cases, poor culture performance can constitute a major research bottleneck. This study aims to improve recombinant protein production in shaking Escherichia coli cultures by use of enzyme-controlled, fed-batch-like glucose feeding in a rich medium, and by investigating the effects of culture aeration on different aspects of protein production. The results show that the enzymatic fed-batch medium can provide higher cell densities, volumetric protein yields and, in some cases, improved product solubility or activity compared to traditionally used media. While these improvements could be obtained in ordinary shaking vessels, the results also demonstrate that cultivation in shake flasks with elevated aeration capacity can further improve cell density and volumetric productivity in the fed-batch medium. However, enhanced aeration may also have an adverse effect on the expression of certain proteins such as Fab antibody fragments. Maximum volumetric Fab yield was achieved under reduced aeration rates, and lower oxygen availability also contributed to substantially increased accumulation of periplasmically produced Fab fragments into extracellular medium. Hence modification of aeration conditions and medium composition can be used to control periplasmic/extracellular product localization as outlined in this study. Moreover, high aeration was detrimental to expression in a glycerol-based lactose autoinduction medium, but this strict dependency on aeration level could be mitigated and robustness of expression improved by an autoinduction medium based on the enzymatic glucose feeding as the supporting carbon source instead of glycerol. The results of this study can be utilized to improve volumetric productivity, protein solubility and control of product localization in small-scale protein production, as well as to facilitate robust and efficient high-throughput protein expression for such applications as structural and functional characterization. / Tiivistelmä Biologisesti aktiivisten vierasproteiinien tehokas tuottaminen on yksi bioteknologisen tutkimuksen kulmakivistä. Laboratoriomittakaavan proteiinituotto toteutetaan yleisimmin yksinkertaisissa ravistelubioreaktoreissa, kuten ravistelupulloissa. Näiden viljelmien tuottavuutta rajoittaa kuitenkin usein biomassan matala saanto sekä epäoptimaaliset olosuhteet kasvualustan koostumuksen, pH:n ja hapen suhteen. Monissa tapauksissa viljelmän heikko tuottavuus muodostaa tutkimukselle merkittävän pullonkaulan. Tämän tutkimuksen tavoite on parantaa vierasproteiinien tuottoa Escherichia coli –ravisteluviljelmissä hyödyntäen entsymaattisesti kontrolloitua, panossyöttökasvatusta jäljittelevää glukoosisyöttöä rikkaassa kasvualustassa, sekä selvittää ilmastuksen vaikutusta proteiinituoton eri osatekijöihin. Tulosten mukaan glukoosisyöttöön perustuva kasvualusta mahdollistaa korkeamman solutiheyden sekä proteiinituoton verrattuna tavallisimmin käytettyihin kasvualustoihin. Joissain tapauksissa myös proteiinin liukoisuus tai aktiivisuus voi parantua. Vaikka nämä edut pystyttiin saavuttamaan myös tavanomaisissa ravistelupulloissa, voidaan panossyöttökasvualustan solutiheyttä ja tuottoa tilavuutta kohti edelleen lisätä käyttämällä korkeamman ilmastustehokkuuden ravistelupulloja. Toisaalta tehostetun ilmastuksen havaittiin olevan mahdollisesti haitallista tiettyjen proteiinien, kuten Fab-vasta-ainefragmenttien, tuotolle. Fab-fragmenttien maksimaalinen tuotto saavutettiin ilmastustehokkuutta laskemalla. Lisäksi matalampi hapen saatavuus edisti periplasmaan ohjattujen Fab-fragmenttien kerääntymistä solunulkoiseen kasvualustaan. Näin ollen ilmastusolosuhteita ja kasvualustan koostumusta muokkaamalla voidaan vaikuttaa tuotteen lopulliseen sijoittumiseen. Korkean ilmastustehokkuuden havaittiin myös olevan haitallista proteiinituotolle glyserolipohjaisessa autoinduktiokasvualustassa. Tätä riippuvuutta ilmastuksen tasosta pystyttiin vähentämään ja autoinduktion luotettavuutta parantamaan käyttämällä kasvualustaa jossa hiililähteenä toimii glyserolin sijaan entsymaattinen glukoosisyöttö. Tutkimuksen tuloksia hyödyntäen voidaan parantaa vierasproteiinien saantoa, liukoisuutta ja periplasmisen/solunulkoisen kerääntymisen säätelyä, sekä mahdollistaa luotettava ja tehokas proteiinituotto viljelmien suurta lukumäärää vaativiin sovelluksiin, kuten proteiinien rakenteen ja toiminnan tutkimukseen.

科学研究費補助金 研究種目:一般研究(C) 課題番号:05650796 研究代表者:山根 恒夫 研究期間:1993-1994年度