Biomedical subjects

Bo Mattiasson

Publications and source records attributed to Bo Mattiasson.

At least 73 records · Page 4Linked to original sources

PubMed2004

Characterization of supermacroporous monolithic polyacrylamide based matrices designed for chromatography of bioparticles.

Supermacroporous monolithic acrylamide (AAm)-based cryogels were prepared by radical cryo-polymerizaton (polymerization in the moderately frozen system) of AAm with functional monomers and cross-linker N,N'-methylene-bis-acrylamide (MBAAm). Electron microscopy studies revealed supermacroporous structure of the developed cryogels with pore size of 5-100 microm. Cryogel porosity depended on cryo-polymerization conditions. More than 90% of the monolithic bed volume is the interconnected supermacropores filled with water and less than 10% of the monolithic volume is pore walls. The total protein binding capacity (lysozyme in the case of immobilized metal affinity chromatography (IMAC) column and bovine serum albumin (BSA) in the case of anion-exchange (AE) column) was independent of the flow rates till 600 cm/h. Chromatographic behavior of E. coli cells when a cell suspension was applied to ion-exchange cryogel columns depended on both the density of functional ligand and the porosity of the cryogel.

Acrylic Resins↗

PubMed2004

Agarose-coated anion exchanger prevents cell-adsorbent interactions.

A common problem during recovery of bioproducts by adsorption from particulate broths is fouling of the adsorbent material as a result of the interaction of cells and cell debris, which present negative charges, with the positively charged anion exchangers commonly used in bioprocesses. The effect of shielding an adsorbent with a layer of agarose on reducing the binding of cells while still allowing the low-molecular-mass bioproducts to be adsorbed was studied. Coating the anion-exchange resin Amberlite IRA-400 with agarose followed by cross-linking the agarose layer effectively prevented the binding of Escherichia coli, Saccharomyces cerevisiae, and Lactobacillus casei cells but allowed binding of lactic acid to the adsorbent. The cross-linked agarose layer was stable during recycling of the adsorbent.

Adsorption↗

PubMed2004

Monitoring and control of an anaerobic upflow fixed-bed reactor for high-loading-rate operation and rejection of disturbances.

A new control strategy has been introduced for operating anaerobic digestion processes efficiently at high load. The control system includes a cascade controller embedded into a rule-based supervisory system based on extremum-seeking control. Three process parameters, considered to be the most realistic variables for monitoring of the bioprocess, were selected (pH, biogas production rate, and the difference between the actual biogas flow and its setpoint). The control system examines these variables and varies the organic load by manipulating the influent flow. Good control performance was achieved during the start-up, during steady-state running operations, and during rejection of disturbances. The main advantages of this control approach can be attributed to its ability to adjust control parameters automatically, both for high-load operation and for rejection of disturbances. Furthermore, the influent flow can be tuned automatically according to variations in organic matter in the feed without the characteristics of the influent being considered.

Algorithms↗

PubMed2004

Synthesis of alkylgalactosides using whole cells of Bacillus pseudofirmus species as catalysts.

Whole cells of alkaliphilic Bacillus pseudofirmus AR-199, induced for beta-galactosidase activity, were used for the synthesis of 1-hexyl-beta-d-galactoside and 1-octyl-beta-d-galactoside, respectively, by transglycosylation reaction between lactose and the corresponding alcohol acceptor. The product yield was strongly influenced by the initial water content in the reaction mixture. Water content of 10% (v/v) was optimal providing 3.6-36 mM hexyl galactoside from 10 to 150 mM lactose, and no secondary product hydrolysis. Product yield could be enhanced by supplementing the reaction mixture with more cells or partly replacing the product with fresh substrate, but was decreased with time to the initial equilibrium level. Cell permeabilisation or disruption resulted in increased reaction rate and higher product yield but was followed by product hydrolysis. Octyl galactoside synthesis using whole cells was optimal at water content of 2% (v/v) with a yield of 26%. The cells were immobilised in cryogels of polyvinyl alcohol for use in continuous process, where hexyl galactoside was produced with a constant yield of 50% from 50mM lactose for at least a week.

Alcohols↗

PubMed2004

Lactate production in an integrated process configuration: reducing cell adsorption by shielding of adsorbent.

The problem of binding of microbial cells to an adsorbent matrix during in situ recovery of bioproducts from a fermentation broth has been addressed by shielding the adsorbent with a thin layer of a non-ionic polymer. Extractive bioconversion of lactic acid by integrating ion-exchange adsorption with the fermentation stage was studied. The effect of coating of the ion-exchanger with agarose on product recovery and cell adsorption was evaluated. Extractive fermentation with both uncoated and coated resin resulted in an increase in reactor productivity as compared to the normal fermentation. The free cell density in the system with agarose-coated beads was similar to that in control fermentation, but was significantly lower in the system with the uncoated ion-exchanger. Electron microscopic scanning of the bead surface after passage of the fermentation broth showed cells attached to the native adsorbent but not to the coated one.

Bacterial Adhesion↗

PubMed2004

On-line monitoring of a two-stage anaerobic digestion process using a BOD analyzer.

A computer-controlled biochemical oxygen demand (BOD) analyzer has been developed for fast estimation of biochemical oxygen demand (BODst) automatically with the purpose of on-line monitoring of a process for conversion of biomass under field conditions. The instrument was tested by on-line monitoring of the connecting stream between two stages of a two-stage anaerobic process in laboratory scale. In the first stage, hydrolysis of sugar beet leaves and its conversion into volatile fatty acids and other low molecular weight substrates took place. The effluent from the first reactor was used as a feed stream to the second stage, i.e. an anaerobic contact reactor. The feed stream was sampled intermittently, diluted and analyzed by the BOD analyzer automatically in order to estimate the organic loading rate to the reactor. The results from this study demonstrated that the BOD analyzer could be a stand-alone and promising sensor device for rapid on-line monitoring of easily biodegradable organic substances in biological treatment processes.

Anaerobiosis↗

PubMed2004

A biosensor for the analysis of acetonitrile.

A biosensor for monitoring acetonitrile was constructed. A mixed culture was taken from a degradation reactor and mounted on top of a Clark electrode. The amperometric biosensor was placed in a flow-through cell and integrated into a flow injection system. The metabolic response in terms of oxygen consumption was well correlated to the concentration of acetonitrile in standard solutions. However, when the reaction products, acetic acid and ammonia, were also present, the response was erratic, due to the additional metabolic reaction on acetate. By introducing a hydrophobic barrier it was possible to eliminate the negative influence of these charged products and thus to improve the operational selectivity of the sensor. The biosensor showed good stability for analysis during at least 6 days and future work will focus on using it for monitoring and control of degradation processes.

Acetonitriles↗

PubMed2004

Characterization of polyacrylamide based monolithic columns.

Supermacroporous monolithic polyacrylamide (pAAm)-based columns have been prepared by radical cryo-copolymerization (copolymerization in the moderately frozen system) of acrylamide with functional co-monomer, allyl glycidyl ether (AGE), and cross-linker N,N'-methylene-bis-acrylamide (MBAAm) directly in glass columns (ID 10 mm). The monolithic columns have uniform supermacroporous sponge-like structure with interconnected supermacropores of pore size 5-100 microm. The monoliths can be dried and stored in the dry state. High mechanical stability of the monoliths allowed sterilization by autoclaving. Column-to-column reproducibility of pAAm-monoliths was demonstrated on 5 monolithic columns from different batches prepared under the same cryostructuration conditions.

Acetone↗

PubMed2004

Anaerobic batch co-digestion of sisal pulp and fish wastes.

Co-digestion of various wastes has been shown to improve the digestibility of the materials and biogas yield. Batchwise digestion of sisal pulp and fish waste was studied both with the wastes separately and with mixtures in various proportions. While the highest methane yields from sisal pulp and fish waste alone were 0.32 and 0.39 m3 CH4/kg volatile solids (VS), respectively, at total solid (TS) of 5%, co-digestion with 33% of fish waste and 67% of sisal pulp representing 16.6% of TS gave a methane yield of 0.62 m3 CH4/kg VS added. This is an increase of 59-94% in the methane yield as compared to that obtained from the digestion of pure fractions at 5% TS.

Anaerobiosis↗

PubMed2004

Combined UV-biological degradation of PAHs.

The UV-photolysis of PAHs was tested in silicone oil and tetradecane. In most cases, the degradation of a pollutant provided within a mixture was lower than when provided alone due to competitive effects. With the exception of anthracene, the larger pollutants (4- and 5-rings) were always degraded first, proving that UV-treatment preferentially acts on large PAHs and thereby provides a good complement to microbial degradation. UV-photolysis was also found to be suitable for treatment of soil extract from contaminated soils. The feasibility of UV-biological treatment was demonstrated for the removal of a mixture of phenanthrene and pyrene in silicone oil. UV-irradiation of the silicone oil led to 83% pyrene removal but no phenanthrene photodegradation. Subsequent treatment of the oil in a two-phases partitioning bioreactor (TPPB) system inoculated with Pseudomonas sp. was followed by complete phenanthrene biodegradation but no further pyrene removal. Totally, the combined process allowed 92% removal of the PAH mixture. Further work should focus on characterizing the photoproducts formed and studying the influence of the solvent on the photodegradation process.

Alkanes↗

PubMed2004

An automated spectrophotometric system for monitoring buffer capacity in anaerobic digestion processes.

Anaerobic digestion is a suitable method for the treatment of wastewater and organic wastes, yielding biogas as a useful by-product. A common way of preventing instability problems and avoiding acidification in anaerobic digesters is to keep the organic load to the digester far below its maximum capacity. An improved way of operating digesters would be to use monitoring and control systems for increased organic load under controlled conditions such that the digester performance is improved. The partial alkalinity, which indicates the bicarbonate concentration, has in many cases been found to be a suitable parameter to monitor. Here, an automated monitoring system for alkalinity measurements is described. It is shown to be applicable for measuring a wide range of bicarbonate concentrations. The system shows potential for monitoring anaerobic digesters as it responds to the alkalinity of digester effluent, as well as being stable over a relatively long time span with few maintenance requirements.

Automation↗

PubMed2004

Lipase-producing microorganisms from a Kenyan alkaline soda lake.

Lipolytic enzyme production of 150 isolated strains from samples of Lake Bogoria (Kenya) was examined. Among these, fifteen isolates were selected on the basis of their lipolytic activities and subjected to morphological and 16S rRNA gene sequencing analyses for their identification. All the microorganisms have been selected under culture conditions with pH ranges between 7-10 and temperatures of 37-55 degrees C. Most of them showed optimal growth at 37 degrees C and tolerated salinity up to 10% (w/v). Ten of the isolates were Gram-negative, nine of which were closely related to the Pseudomonas cluster and one to the Halomonas cluster sharing high similarity profile with Halomonas desiderata. The remaining Gram-positive isolates were closely related to the Bacillus cluster, and were grouped with Bacillus halodurans, Bacillus alcalophilus and Bacillus licheniformis. Four members of the Bacillus cluster and the Halomonas sp. produced lipolytic activity under alkaline conditions, while others did so at neutral pH values.

Bacillus↗

PubMed2004

Separation of heavy metals from water solutions at the laboratory scale.

Separation of heavy metals from water may be done by sulphide precipitation. In order to make the metal sulphides more valuable for reuse, they should be as pure as possible. To separate the metals from each other during the precipitation process different parameters as pH, sulphide concentration and redox potential may be controlled. Adjustment of the redox potential to specific values results in separation of copper from cadmium even at the same pH. In the copper precipitation step 98.7 +/- 0.5% was precipitated and the remaining part was transferred to the cadmium precipitation step where 0.7 +/- 0.5% of the copper precipitated. The main part of cadmium (95.6 +/- 1.3%) was precipitated in the second step. These results show that it is possible to separate copper from cadmium by the use of redox potential control.

Cadmium↗

PubMed2004

Starch hydrolysing Bacillus halodurans isolates from a Kenyan soda lake.

Fourteen obligate alkaliphilic and halotolerant bacterial isolates, exhibiting extracellular amylase activity at 55 degrees C and pH 10, were isolated from hot springs around Lake Bogoria, Kenya. From 16S rDNA sequence analysis, nine isolates shared 100% identity with Bacillus halodurans strain DSM 497T, while the rest shared 99% identity with alkaliphilic Bacillus species A-59. PCR of the intergenic spacer region between 16S and 23S rRNA genes (ISR-PCR) divided the isolates into two groups, while tDNA-PCR divided them into three groups. Bacillus halodurans DSM 497T had a different ISR pattern from the isolates, while it had a tDNA-PCR profile similar to the group that shared 99% identity with alkaliphilic Bacillus species A-59. All isolates hydrolysed soluble starch as well as amylose, amylopectin and pullulan. The amylase activity (1.2-1.8 U ml(-1)) in the culture broths had an optimum temperature of 55-65 degrees C, was stimulated by 1 mm Ca2+, and was either partially (16-30%) or completely inhibited by 1 mM EDTA. Activity staining of the cell-free culture supernatant from the isolates revealed five alkaline active amylase bands.

Amylases↗

PubMed2004

A new thermostable alpha-L-arabinofuranosidase from a novel thermophilic bacterium.

An alpha-L-arabinofuranosidase gene was identified in a sequenced genome of a novel thermophilic bacterium, which belongs to the recently described phylum of Thermomicrobia. Amino acid sequence comparison of the enzyme (designated AraF) revealed similarity to glycoside hydrolases of family 51. The gene was cloned into Escherichia coli and its recombinant product expressed and purified. The enzyme appeared to be a hexamer. AraF was optimally active at 70 degrees C (over 10 min) and pH 6 having 92% residual activity after 1 h at 70 degrees C. AraF had a Km) value of 0.6 mM and V(max) value of 122 U mg(-1) on p-nitrophenyl-alpha-L-arabinofuranoside. AraF was almost equally active on branched arabinan and debranched arabinan, properties not previously found in alpha-L-arabinofuranosidases in GH family 51.

Bacterial Proteins↗

PubMed2004

Halomonas boliviensis sp. nov., an alkalitolerant, moderate halophile isolated from soil around a Bolivian hypersaline lake.

Halomonas boliviensis sp. nov. is proposed for two moderately halophilic, psychrophilic, alkalitolerant bacteria, LC1(T) (=DSM 15516(T)=ATCC BAA-759(T)) and LC2 (=DSM 15517=ATCC BAA-760), both of which were isolated from a soil sample around the lake Laguna Colorada, located at 4300 m above sea level in the south-west region of Bolivia. The bacteria are aerobic, motile, Gram-negative rods that produce colonies with a cream pigment. Moreover, they are heterotrophs that are able to utilize various carbohydrates as carbon sources. The organisms reduce nitrate and show tryptophan deaminase activity. The genomic DNA G+C contents were 51.4 mol% for isolate LC1(T) and 52.6 mol% for isolate LC2. Based on 16S rDNA sequence analysis, isolates LC1(T) and LC2 were identified as members of the genus Halomonas and clustered closely with Halomonas variabilis DSM 3051(T) and Halomonas meridiana DSM 5425(T). However, DNA-DNA relatedness between the new isolates and the closest related Halomonas species was low.

Base Composition↗

PubMed2004

Chromohalobacter sarecensis sp. nov., a psychrotolerant moderate halophile isolated from the saline Andean region of Bolivia.

A moderately halophilic, aerobic, motile, Gram-negative, rod-shaped bacterium (strain LV4(T)) was isolated from saline soil around the lake Laguna Verde in the Bolivian Andes. The organism is a heterotroph, able to utilize various carbohydrates as a carbon source. It showed tryptophan deaminase, oxidase and catalase activity, but was unable to produce indole or H(2)S; nitrate was not reduced. The G+C content of the genomic DNA was 56.1 mol%. The pH range for growth was 5-10, temperature range was 0-45 degrees C and the range of NaCl concentrations was 0-25 % (w/v). On the basis of 16S rRNA gene sequence analysis, strain LV4(T) was found to be closely related to Chromohalobacter canadensis DSM 6769(T) and Pseudomonas beijerinckii DSM 7218(T); however, its DNA-DNA relatedness with these type strains was low. Strain LV4(T) resembled other Chromohalobacter species with respect to various physiological, biochemical and nutritional characteristics but also exhibited differences. Thus, a novel species, Chromohalobacter sarecensis sp. nov., is proposed, with LV4(T) (=CCUG 47987(T)=ATCC BAA-761(T)) as the type strain.

Amino Acid Oxidoreductases↗

PubMed2003

Purification of histidine-tagged single-chain Fv-antibody fragments by metal chelate affinity precipitation using thermoresponsive copolymers.

Metal chelate affinity precipitation (MCAP) has been successfully developed as a simple purification process for proteins that have affinity for metal ions. The present lack of widespread applications for this technique as compared to immobilized metal affinity chromatography (IMAC) may be related to the scarcity of well-characterized metal affinity macroligands (AML) and their applications to the number of different purification systems. In the present work we describe a detailed study of a new purification system using metal-loaded thermoresponsive copolymers as AML. The copolymers of vinylimidazole (VI) with N-isopropylacrylamide (NIPAM) were synthesized by radical polymerization with imidazole contents of 15 and 24 mol%. When loaded with Cu(II) and Ni(II) ions the copolymers selectively precipitated extracellularly expressed histidine-tagged single-chain Fv-antibody fragments (His(6)-scFv fragments) from the fermentation broth free from E. coli cells. Precipitation was induced by salt at mild temperatures and the bound antibody fragments were recovered by dissolving the protein-polymer complex in EDTA buffer and subsequent reprecipitation of the polymer. His(6)-scFv fragments were purified with yields of 91 and 80% and purification folds of 16 and 21 when Cu(II) and Ni(II) copolymers were used, respectively. The protein precipitation capacity of the Ni(II) copolymer showed a dependence on the VI concentration in the copolymer. The SDS-PAGE pattern showed significant purification of the antibody fragments.

Acrylic Resins↗