Biotechnological Applications (biotechnological + application)

Distribution by Scientific Domains
Distribution within Life Sciences


Selected Abstracts


Production of fermentation aroma compounds by Saccharomyces cerevisiae wine yeasts: effects of yeast assimilable nitrogen on two model strains

FEMS YEAST RESEARCH, Issue 7 2008
Francisco M. Carrau
Abstract The contribution of yeast fermentation metabolites to the aromatic profile of wine is well documented; however, the biotechnological application of this knowledge, apart from strain selection, is still rather limited and often contradictory. Understanding and modeling the relationship between nutrient availability and the production of desirable aroma compounds by different strains must be one of the main objectives in the selection of industrial yeasts for the beverage and food industry. In order to overcome the variability in the composition of grape juices, we have used a chemically defined model medium for studying yeast physiological behavior and metabolite production in response to nitrogen supplementation so as to identify an appropriate yeast assimilable nitrogen level for strain differentiation. At low initial nitrogen concentrations, strain KU1 produced higher quantities of esters and fatty acids whereas M522 produced higher concentrations of isoacids, ,-butyrolactone, higher alcohols and 3-methylthio-1-propanol. We propose that although strains KU1 and M522 have a similar nitrogen consumption profile, they represent useful models for the chemical characterization of wine strains in relation to wine quality. The differential production of aroma compounds by the two strains is discussed in relation to their capacity for nitrogen usage and their impact on winemaking. The results obtained here will help to develop targeted metabolic footprinting methods for the discrimination of industrial yeasts. [source]


Bionanotechnology based on silica nanoparticles

MEDICINAL RESEARCH REVIEWS, Issue 5 2004
Weihong Tan
Abstract We have developed uniform core/shell nanoparticles, consisting of a silica layer coating and pigments or magnetite core, using a water-in-oil microemulsion method. The nanoparticles are highly luminescent and photostable with the size ranging from 5 nm to 400 nm. Bioconjugation of these silica nanoparticles adds unique biofunctions with various molecules such as enzymes, antibodies, and DNA molecules. Significant advantages have been shown in using bioconjugated nanoparticles for biosensing and bioimaging, such as cell staining, DNA detection and separation, rapid single bacterium detection, and biotechnological application in DNA protection. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 5, 621,638, 2004 [source]


"In-gel patch electrophoresis:" A,new method for environmental DNA purification

ELECTROPHORESIS, Issue 16 2005
Changhyun Roh
Abstract Most of the microorganism species are largely untapped and could represent an interesting reservoir of genes useful for biotechnological applications. Unfortunately, a major difficulty associated with the methods used to isolate environmental DNA is related to the contamination of the extracted material with humic substances. These polyphenolic compounds inhibit the DNA processing reactions and severely impede cloning procedures. In this work, we describe a rapid, simple, and efficient method for the purification of genomic DNA from environmental samples: we added a chromatography step directly embedded into an agarose gel electrophoresis. This strategy enabled the DNA extraction from various environmental samples and it appeared that the purity grade was compatible with digestion by restriction enzymes and polymerase chain reaction (PCR) amplifications. [source]


Optimization of culture conditions for glucose oxidase production by a Penicillium chrysogenum SRT 19 strain

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 1 2010
Ragini G. Bodade
Abstract The enzyme glucose oxidase (GOD) has been used for a variety of biotechnological applications in food and pharmaceutical industries. In this study, the optimization of extracellular GOD production was carried out in a Penicillium chrysogenum SRT 19 strain isolated from contaminated and decaying cheese samples. Maximum GOD production was attained at pH 6 and 20°C in fermentation broth after 72,h of incubation. The effects of metal ions and sugars were screened for the induction of higher GOD production. The results revealed that glucose and lactose give the highest production of enzyme (0.670 and 0.552,U/mL, respectively) as compared with other sugars (sucrose, cellulose, mannitol and fructose). Out of the seven metal ions studied, CaCO3 (1.123,U/mL) and FeSO4 (0.822,U/mL) act as modulators, while MgSO4 (0.535,U/mL), CuSO4 (0.498,U/mL), HgCl2 (0.476,U/mL), ZnSO4 (0.457,U/mL) and BaSO4 (0.422,U/mL) yield lower production. The study therefore suggests that a strain of P. chrysogenum SRT 19 can be used as a new strain for GOD production. [source]


Towards Higher Laccase Activities Produced by Aquatic Ascomycetous Fungi Through Combination of Elicitors and an Alternative Substrate

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 3 2008
C. Junghanns
Abstract Laccases are versatile biocatalysts with various potential biotechnological applications, e.g. the treatment of industrial waste waters, the detoxification of environmental pollutants, or the functionalization of renewable polymeric materials. Central composition experimental design and response surface methodology was applied to optimize the production of laccase by the aquatic ascomycetous fungi, Phoma sp. UHH 5-1-03 and Coniothyrium sp.,Kl-S5, in shake flasks. A complex plant-based medium (tomato juice) and two elicitors (Remazol Brilliant Blue R [RBBR] and CuSO4) were tested in combination at three concentrations. The highest laccase activity of 6322,±,403,U/L was achieved on day,9 for Phoma sp. Coniothyrium sp. exerted a maximum laccase activity of 3035,±,111 U/L on day,4. Optimal conditions were 30,% tomato juice and 450,mg/L RBBR for both strains. A concentration of 250,,M CuSO4 led to highest laccase activities in cultures of Coniothyrium sp., and 50,,M CuSO4 was most effective for Phoma sp. A remarkable synergistic effect of tomato juice and RBBR on laccase production was observed for both strains. The upscaling potential of the optimal induction conditions was demonstrated in a lab-scale fermenter which resulted in maximum activities of 11030,±,177,U/L on day,6 for Phoma sp. and 11530,±,161,U/L on day,9 for Coniothyrium sp. This study therefore presents a promising alternative for laccase production in ascomycetes based on a cheap complex substrate in combination with two elicitors. [source]


Improving thermostability and catalytic activity of pyranose 2-oxidase from Trametes multicolor by rational and semi-rational design

FEBS JOURNAL, Issue 3 2009
Oliver Spadiut
The fungal homotetrameric flavoprotein pyranose 2-oxidase (P2Ox; EC 1.1.3.10) catalyses the oxidation of various sugars at position C2, while, concomitantly, electrons are transferred to oxygen as well as to alternative electron acceptors (e.g. oxidized ferrocenes). These properties make P2Ox an interesting enzyme for various biotechnological applications. Random mutagenesis has previously been used to identify variant E542K, which shows increased thermostability. In the present study, we selected position Leu537 for saturation mutagenesis, and identified variants L537G and L537W, which are characterized by a higher stability and improved catalytic properties. We report detailed studies on both thermodynamic and kinetic stability, as well as the kinetic properties of the mutational variants E542K, E542R, L537G and L537W, and the respective double mutants (L537G/E542K, L537G/E542R, L537W/E542K and L537W/E542R). The selected substitutions at positions Leu537 and Glu542 increase the melting temperature by approximately 10 and 14 °C, respectively, relative to the wild-type enzyme. Although both wild-type and single mutants showed first-order inactivation kinetics, thermal unfolding and inactivation was more complex for the double mutants, showing two distinct phases, as revealed by microcalorimetry and CD spectroscopy. Structural information on the variants does not provide a definitive answer with respect to the stabilizing effects or the alteration of the unfolding process. Distinct differences, however, are observed for the P2Ox Leu537 variants at the interfaces between the subunits, which results in tighter association. [source]


Development of a gene knockout system for Ralstonia eutropha H16 based on the broad-host-range vector expressing a mobile group II intron

FEMS MICROBIOLOGY LETTERS, Issue 2 2010
Jong Myoung Park
Abstract Ralstonia eutropha H16 is a Gram-negative lithoautotrophic bacterium and is one of the best biopolymer-producing bacteria. It can grow to high cell densities either under lithoautotrophic or under heterotrophic conditions, which makes it suitable for a number of biotechnological applications. Also, R. eutropha H16 can degrade various aromatic compounds for environmental applications. The mobile group II intron can be used for the rapid and specific disruption of various bacterial genes by insertion into any desired target genes. Here, we applied the mobile group II intron to R. eutropha H16 and developed a markerless gene knockout system for R. eutropha: RalsTron. As a demonstration of the system, the phaC1 gene encoding polyhydroxyalkanoate synthase was successfully knocked out in R. eutropha H16. Furthermore, this knockout system would be useful for knocking out genes in other bacteria as well because it is based on a broad-host-range vector and the mobile group II intron that minimally depends on the bacterial hosts. [source]


Aspergillus oryzae in solid-state and submerged fermentations

FEMS YEAST RESEARCH, Issue 2 2002
Progress report on a multi-disciplinary project
Abstract We report the progress of a multi-disciplinary research project on solid-state fermentation (SSF) of the filamentous fungus Aspergillus oryzae. The molecular and physiological aspects of the fungus in submerged fermentation (SmF) and SSF are compared and we observe a number of differences correlated with the different growth conditions. First, the aerial hyphae which occur only in SSFs are mainly responsible for oxygen uptake. Second, SSF is characterised by gradients in temperature, water activity and nutrient concentration, and inside the hyphae different polyols are accumulating. Third, pelleted growth in SmF and mycelial growth in SSF show different gene expression and protein secretion patterns. With this approach we aim to expand our knowledge of mechanisms of fungal growth on solid substrates and to exploit the biotechnological applications. [source]


Multifunctional Mesostructured Silica Microspheres from an Ultrasonic Aerosol Spray,

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2008
Li Li
Abstract Multifunctional mesostructured silica microspheres are prepared using ultrasonic aerosol spray in conjunction with solvent evaporation-induced assembly. Rare earth ion,phenanthroline complexes, magnetite particles, photoacid generators, and pH-sensitive dyes are chosen as luminescent, magnetic, and photosensitive components. The incorporation of these functional components into mesostructured silica microspheres can be readily realized by dispersing them in the precursor solution of the aerosol spray process. Luminescent microspheres that can emit at multiple wavelengths when excited at a single wavelength are produced by the addition of multiple rare earth complexes into the precursor solution. The addition of magnetite particles leads to the production of magnetic luminescent microspheres. Photoacid generators and pH-sensitive dyes are further employed to produce magnetic photosensitive microspheres that can release acid and change color upon UV light illumination. Such multifunctional microspheres could have exciting potential for many optical and biotechnological applications, such as multiplexed labeling, diagnosis, simultaneous imaging and therapy, cell capture and separation, targeted delivery, and optical data storage. [source]


Genetic correlation between chromium resistance and reduction in Bacillus brevis isolated from tannery effluent

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2009
T. Verma
Abstract Aims:, To investigate the genetic basis of Cr(VI) resistance and its reduction to Cr(III) in indigenous bacteria isolated from tannery effluent. Methods and Results:, Four bacteria resistant to high Cr(VI) levels were isolated and identified as Bacillus spp. Their Cr(VI) reduction ability was tested. To assess the genetic basis of Cr(VI) resistance and reduction, plasmid transfer and curing studies were performed. Among all, B. brevis was resistant to 180 ,g Cr(VI) ml,1 and showed the greatest degree of Cr(VI) reduction (75·8%) within 28 h and its transformant was resistant to 160 ,g Cr(VI) ml,1 and reduced 69·9% chromate. It harboured a stable 18 kb plasmid DNA. Transfer and curing studies revealed that both the chromate resistance and reduction were plasmid mediated. The presence of other metal cations did not have any significant effect on Cr(VI) bioreduction. Conclusions:,Bacillus brevis was resistant to elevated Cr(VI) levels and may potentially reduce it in short time from an environment where other metal ions are also present in addition to chromium ions. The strain tested shows a positive correlation between genetic basis of Cr(VI) resistance and reduction. Significance and Impact of the Study:, To our knowledge, this is the first study on the genetic correlation between chromium resistance and reduction in bacteria. Such strains may potentially be useful in biotechnological applications and in situ Cr(VI) bioremediation. [source]


Characterization of exopolysaccharides produced by three moderately halophilic bacteria belonging to the family Alteromonadaceae

JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2008
J.A. Mata
Abstract Aims:, To study the exopolysaccharides (EPSs) produced by three novel moderately halophilic species belonging to the family Alteromonadaceae to optimize EPS yields, characterize their physical and chemical properties and evaluate possible biotechnological applications for these polymers. Methods and Results:, EPSs synthesized by Idiomarina fontislapidosi F32T, Idiomarina ramblicola R22T and Alteromonas hispanica F23T were collected and analysed under optimum conditions: MY medium supplemented with 7·5% (w/v) salts; 32°C; and 1% (w/v) glucose. Polymers were synthesized mainly during the early stationary growth phase with yields ranging from 1 to 1·5 g l,1. The Idiomarina species each produced an anionic EPS composed mainly of glucose, mannose and galactose. A. hispanica synthesized an anionic EPS composed mainly of glucose, mannose and xylose. Solutions of all the polymers were low in viscosity and pseudoplastic in their behaviour. They showed emulsifying activity and the capacity to bind some metals. Conclusions:, The Alteromonadaceae species studied in this work produced EPSs with physical and chemical properties different from those produced by other halophilic and nonhalophilic bacteria, suggesting that the wide diversity of micro-organisms being encountered nowadays in hypersaline environments offers enormous potential resources for biotechnological applications. Significance and Impact of the Study:, We have optimized the EPS production and analysed new biopolymers produced by some recently described, moderately halophilic bacteria. These biopolymers are chemically and physically different from others already in use in biotechnology and offer hopes for new applications, especially in the case of A. hispanica, which may prove to be a viable source of xylo-oligosaccharides. [source]


Fungal tyrosinases: new prospects in molecular characteristics, bioengineering and biotechnological applications

JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2006
S. Halaouli
Abstract Tyrosinases are type-3 copper proteins involved in the initial step of melanin synthesis. These enzymes catalyse both the o -hydroxylation of monophenols and the subsequent oxidation of the resulting o -diphenols into reactive o -quinones, which evolve spontaneously to produce intermediates, which associate in dark brown pigments. In fungi, tyrosinases are generally associated with the formation and stability of spores, in defence and virulence mechanisms, and in browning and pigmentation. First characterized from the edible mushroom Agaricus bisporus because of undesirable enzymatic browning problems during postharvest storage, tyrosinases were found, more recently, in several other fungi with relevant insights into molecular and genetic characteristics and into reaction mechanisms, highlighting their very promising properties for biotechnological applications. The limit of these applications remains in the fact that native fungal tyrosinases are generally intracellular and produced in low quantity. This review compiles the recent data on biochemical and molecular properties of fungal tyrosinases, underlining their importance in the biotechnological use of these enzymes. Next, their most promising applications in food, pharmaceutical and environmental fields are presented and the bioengineering approaches used for the development of tyrosinase-overproducing fungal strains are discussed. [source]


Detection and characterization of the novel bacteriocin entomocin 9, and safety evaluation of its producer, Bacillus thuringiensis ssp. entomocidus HD9

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2003
A. Cherif
Abstract Aims: To identify and characterize new bacteriocins from a collection of 41 strains belonging to 27 subspecies of Bacillus thuringiensis, and to evaluate the safety of the producers. Methods and Results:Bacillus thuringiensis ssp. entomocidus HD9 produced in the culture supernatant an antimicrobial activity against Gram-positive bacteria including Listeria monocytogenes, one of four pathogenic Pseudomonas aeruginosa and several fungi. Production of the antibacterial activity, named entomocin 9, started during mid-logarithmic growth reaching its maximum at the early stationary phase. Entomocin 9 retained more than 72% of activity after incubation for 20 min at 121°C. Activity was lost after proteinase K treatment, it was stable in a pH range between 3 and 9, and resistant to lyophilization. After partial purification with ammonium sulphate precipitation followed by gel-filtration and anion-exchange chromatography, an active protein of ca 12·4 kDa was isolated. The mode of action of entomocin 9 was bactericidal and caused cell lysis of growing cells. Despite the presence of a range of virulence related genes, including haemolysin BL, nonhaemolytic enterotoxin, cytotoxin K and several hydrolytic activities, B. thuringiensis HD9 was not toxic against Vero cells. Conclusions: Entomocin 9 is a novel heat-stable, bacteriocin produced by B. thuringiensis HD9. The absence of toxicity against Vero cells suggests the suitability of strain HD9 for a safe application in antimicrobial treatments. Significance and Impact of the Study: New finding on entomocin 9 would make B. thuringiensis attractive in biotechnological applications as an antimicrobial agent in agriculture and food industry. [source]


Resonance Raman spectra of the neutral and anionic radical semiquinones of flavin adenine dinucleotide in glucose oxidase revisited

JOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2006
Johannes P. M. Schelvis
Abstract Flavin radical semiquinones are intermediates in important physiological processes. Resonance Raman (RR) spectroscopy is an important tool to determine the interactions between these radical intermediates and their protein environment that regulate their reactivity and role in the reaction mechanisms. RR spectra of flavin radical semiquinones have been available for several flavoproteins, and those in the glucose oxidase (GO) seem significantly different from all the other available data. Since GO is often used not only as a standard for flavin-containing proteins but also in biotechnological applications, we decided to reexamine the RR spectra of the neutral and anionic radical semiquinone forms of the flavin adenine dinucleotide (FAD) cofactor in this enzyme. The new data show that the vibrational wavenumbers of the neutral and anionic radical semiquinone forms of FAD in GO are very similar to those in other flavoproteins. The discrepancies that were observed earlier seem related to contributions of the FAD in different redox and protonation states. We also obtained the first RR spectra of the oxidized FAD cofactor in GO. Analysis of the vibrations of the oxidized FAD and its anionic radical semiquinone in GO in H2O and D2O solutions indicates that the subtle differences between these spectra in GO and in other flavoproteins are related to the weak hydrogen-bonding environment of the FAD cofactor in GO. Copyright © 2006 John Wiley & Sons, Ltd. [source]


Heterologous production of the Piromyces equi cinnamoyl esterase in Trichoderma reesei for biotechnological applications

LETTERS IN APPLIED MICROBIOLOGY, Issue 6 2009
L. Poidevin
Abstract Aims:, The objective of the study was to produce and characterize the cinnamoyl esterase EstA from the anaerobic fungus Piromyces equi for potential industrial applications. Methods and Results:, The catalytic domain EstA was produced in Trichoderma reesei. Because the two fungi displayed different genome features, including different codon usage and GC content, a synthetic gene was designed and expressed, leading to the production of the corresponding protein at around 33 mg per litre in the T. reesei culture medium. After the recombinant protein was purified, biochemical characterization showed that EstA presents peak activity at pH 6·5 and at 50,60°C. Furthermore, EstA remained stable at pH 6,8 and below 50°C. EstA was compared to cinnamoyl esterases FaeA and FaeB from Aspergillus niger in terms of ferulic acid (FA) release from wheat bran (WB), maize bran (MB) and sugar beet pulp (SBP). Conclusion:, The synthetic gene was successfully cloned and overexpressed in T. reesei. EstA from P. equi was demonstrated to efficiently release FA from various natural substrates. Significance and Impact of the Study:, Recombinant EstA produced in an industrial enzyme producer, T. reesei, was biochemically characterized, and its capacity to release an aromatic compound (FA) for biotechnological applications was demonstrated. [source]


Characterization of a bacteriocin produced by Prevotella nigrescens ATCC 25261

LETTERS IN APPLIED MICROBIOLOGY, Issue 5 2004
J. Kaewsrichan
Abstract Aims:, To characterize the antimicrobial activity produced by Prevotella nigrescens ATCC 25261, and to evaluate its safety on cultured gingival fibroblasts. Methods and Results:, An antimicrobial activity was obtained from purifying the culture supernatant of Pr. nigrescens ATCC 25261. Purification of the active compound was achieved with ammonium sulphate precipitation followed by anion-exchange and gel filtration chromatography. As revealed by SDS-PAGE, the active fraction was relatively homogeneous, showing a protein with an approximate molecular weight of 41 kDa. The antimicrobial compound, named nigrescin, exhibited a bactericidal mode of action against Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythensis, and Actinomyces spp. Nigrescin was stable in a pH range between 6·5 and 9·5, at 100°C for 10 min, and resistant to lyophilization. But its activity was lost after proteinase K treatment. Despite at very high concentrations beyond the minimum inhibitory concentration (MIC), nigrescin was not toxic to the gingival fibroblasts. Conclusion:, Nigrescin is a novel bacteriocin produced by Pr. nigrescens ATCC 25261. It exhibits antimicrobial activity against species that are implicated in periodontal diseases. The absence of toxicity on the gingival fibroblasts suggests the possibility in using of nigrescin for an application in periodontal treatment. Significance and Impact of the Study:, Novel evidence on nigrescin would make Pr. nigrescens ATCC 25261 attractive in biotechnological applications as an antimicrobial agent in clinical dentistry. [source]


Advances in Campylobacter biology and implications for biotechnological applications

MICROBIAL BIOTECHNOLOGY, Issue 3 2010
Byeonghwa Jeon
Summary Campylobacter jejuni is a major foodborne pathogen of animal origin and a leading cause of bacterial gastroenteritis in humans. During the past decade, especially since the publication of the first C. jejuni genome sequence, major advances have been made in understanding the pathobiology and physiology of this organism. It is apparent that C. jejuni utilizes sophisticated mechanisms for effective colonization of the intestinal tracts in various animal species. Although Campylobacter is fragile in the environment and requires fastidious growth conditions, it exhibits great flexibility in the adaptation to various habitats including the gastrointestinal tract. This high adaptability is attributable to its genetically, metabolically and phenotypically diverse population structure and its ability to change in response to various challenges. Unlike other enteric pathogens, such as Escherichia coli and Salmonella, Campylobacter is unable to utilize exogenous glucose and mainly depends on the catabolism of amino acids as a carbon source. Campylobacter proves highly mutable in response to antibiotic treatments and possesses eukaryote-like dual protein glycosylation systems, which modify flagella and other surface proteins with specific sugar structures. In this review we will summarize the distinct biological traits of Campylobacter and discuss the potential biotechnological approaches that can be developed to control this enteric pathogen. [source]


Functional analysis of aromatic biosynthetic pathways in Pseudomonas putida KT2440

MICROBIAL BIOTECHNOLOGY, Issue 1 2009
M. Antonia Molina-Henares
Summary Pseudomonas putida KT2440 is a non-pathogenic prototrophic bacterium with high potential for biotechnological applications. Despite all that is known about this strain, the biosynthesis of essential chemicals has not been fully analysed and auxotroph mutants are scarce. We carried out massive mini-Tn5 random mutagenesis and screened for auxotrophs that require aromatic amino acids. The biosynthesis of aromatic amino acids was analysed in detail including physical and transcriptional organization of genes, complementation assays and feeding experiments to establish pathway intermediates. There is a single pathway from chorismate leading to the biosynthesis of tryptophan, whereas the biosynthesis of phenylalanine and tyrosine is achieved through multiple convergent pathways. Genes for tryptophan biosynthesis are grouped in unlinked regions with the trpBA and trpGDE genes organized as operons and the trpI, trpE and trpF genes organized as single transcriptional units. The pheA and tyrA gene-encoding multifunctional enzymes for phenylalanine and tyrosine biosynthesis are linked in the chromosome and form an operon with the serC gene involved in serine biosynthesis. The last step in the biosynthesis of these two amino acids requires an amino transferase activity for which multiple tyrB -like genes are present in the host chromosome. [source]


Apical callus formation and plant regeneration controlled by plant growth regulators on axenic culture of the red alga Gracilariopsis tenuifrons (Gracilariales, Rhodophyta)

PHYCOLOGICAL RESEARCH, Issue 3 2000
Nair S. Yokoya
SUMMARY Axenic cultures of Gracilariopsis tenuifrons (Bird et Oliveira) Fredericq et Hommersand (Gracilariales, Rhodophyta) were established in ASP12-NTA solid medium (0.4% agar and 1.0% sucrose) supplemented with plant growth regulators to evaluate the effects on apical callus formation and plant regeneration. Indole-3-acetic acid (IAA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BA) were added individually or in combinations (IAA : BA) over a range of concentrations from 0.5 to 5 mg L,1. Growth of apical and intercalary segments was stimulated by high concentrations of 2,4-D (5 mg L,1) and a high IAA to BA ratio (IAA : BA = 5:1 mg L,1) respectively. Apical calluses were originated from divisions of apical and cortical cells located at apical regions of thallus segments and lateral branches. Low concentration of IAA (0.5 mg L,1) or a high IAA to BA ratio (IAA : BA = 5:1 mg L,1) were the optimal treatments for inducing apical callus formation in apical segments, while high concentration of IAA (5 mg L,1) stimulated the highest callus induction rate in intercalary segments. Conversely, equal parts IAA and BA (IAA : BA = 1:1 mg L,1) and low concentration of 2,4-D (0.5 mg L,1) stimulated growth of apical calluses from apical and intercalary segments, respectively. Two processes of regeneration were observed: direct regeneration (upright axis originated from cells of proximal region of intercalary segments) and indirect regeneration (adventitious plantlet originated from cells of apical calluses). Direct regeneration was promoted significantly by treatment with a low IAA to BA ratio (IAA : BA= 1:5 mg L,1), and treatments with IAA (0.5 mgL,1) or 2,4-D (0.5 or 5 mg L,1) significantly stimulated the elongation of upright axis. Plant growth regulators are essential to inducing indirect regeneration, and a high concentration of IAA (5 mg L,1) and BA (5 mg L,1) were the optimal treatments for inducing the regeneration of plantlets from apical calluses in apical and intercalary segments, respectively. Regenerating plantlets grew into plants morphologically similar to those formed from germinating spores, and became fertile after 6 weeks. The results suggest that auxins and cytokinins are involved in developmental regulatory processes in G. tenuifrons. The regeneration process from calluses in species of Gracilariales was observed for the first time in the present study. The culture system described for G. tenuifrons could be useful for micropropagation and for biotechnological applications in agarophytic algae. [source]


The expression and promoter specificity of the birch homologs for PISTILLATA/GLOBOSA and APETALA3/DEFICIENS

PHYSIOLOGIA PLANTARUM, Issue 2 2005
Mika Lännenpää
B-function genes determine the identity of petals and stamens in the flowers of model plants such as Arabidopsis and Antirrhinum. Here, we show that a putative B-function gene BpMADS2, a birch homolog for PISTILLATA, is expressed in stamens and carpels of birch inflorescences. We also present a novel birch gene BpMADS8, a homolog for APETALA3/DEFICIENS, which is expressed in stamens. Promoter-GUS analysis revealed that BpMADS2 promoter is active in the receptacle of Arabidopsis flower buds while BpMADS8 promoter is highly specific in mature stamens. BpMADS2 promoter::BARNASE construct prevented floral organ development in Arabidopsis and tobacco. In birch, inflorescences with degenerated stamens and carpels were obtained. BpMADS8::BARNASE resulted in degeneration of stamens in Arabidopsis and birch causing male sterility. In tobacco, only sepals were developed instead of normal flowers. The results show that the BpMADS2::BARNASE construct can be used to specifically disrupt floral organ development in phylogenetically distant plant species. The stamen-specific promoter of BpMADS8 is a promising tool for biotechnological applications in inducing male sterility or targeting gene expression in the late stamen development. [source]


Somatic Embryogenesis in Leguminous Plants

PLANT BIOLOGY, Issue 2 2000
P. Lakshmanan
Abstract: This review examines recent advances in the induction and development of somatic embryos in leguminous plants. Emphasis has been given to identify the current trends and successful strategies for the establishment of somatic embryogenic systems, particularly in the economically important species. It appears that, in legumes, somatic embryogenesis can be realized relatively easily especially in young meristematic tissues such as immature embryos and developing leaves. In the majority of the species examined, chlorophenoxyacetic acids remained the most active inductive compounds; however, the new generation growth regulators such as thidiazuron are emerging as successful alternatives for high-frequency direct regeneration of somatic embryos, even from well differentiated explant tissues. Low-frequency embryo production, poor germination and conversion of somatic embryos into plantlets and somaclonal variation are the major impediments limiting the utility of somatic embryogenesis for biotechnological applications in legumes. These limitations, however, may be considerably reduced in the near future, as more newly developed growth regulators with specific morphogenic targets become available for experimentation. From the published data, it is apparent that more effort should be given to develop repetitive embryogenic systems with high frequency of germination and regeneration, since such systems will find immediate application in mass propagation and other crop improvement programmes. As our understanding of various morphogenic processes, including growth and differentiation of zygotic embryos, is fast expanding, it is conceivable that development of highly efficient somatic embryogenic systems with practical application can be anticipated, at least for the important leguminous crops, in the foreseeable future. [source]


Molecular genetics of fructan metabolism in perennial ryegrass

PLANT BIOTECHNOLOGY JOURNAL, Issue 5 2005
Jaye Chalmers
Summary Fructans are the main storage carbohydrates of temperate grasses, sustaining regrowth immediately after defoliation, as well as contributing to the nutritive value of feed. Fructan metabolism is based on the substrate sucrose and involves fructosyltransferases (FTs) for biosynthesis and fructan exohydrolases (FEHs) for degradation. Sucrose is also utilized by invertases (INVs), which hydrolyse it into its constituent monosaccharides for use in metabolism. The isolation, molecular characterization, functional analysis, and phylogenetic relationships of genes encoding FTs, FEHs, and INVs from temperate grasses are reviewed, with an emphasis on perennial ryegrass (Lolium perenne L.). The roles these enzymes play in fructan accumulation and remobilization, and future biotechnological applications in molecular plant breeding are discussed. [source]


Atomic Force Microscopy as a Tool for Biomedical and Biotechnological Studies,

ARTIFICIAL ORGANS, Issue 5 2003
Geraldo Antônio Guerrera Cidade
Abstract: This work presents different applications in progress with the aid of the atomic force microscopy (AFM) technique for biomedical and biotechnological applications, comprising both the acquisition of three-dimensional images and spectroscopic force measurements, in the following systems: first, low-density lipoprotein (LDL),glycosaminoglycans; second, lectins-polysaccharides; third, mycobacterium leprae cellular wall and Vesicular Stomatites Virus (VSV) with fibronectin laminin, and lipidic membranes; fourth, DNA,complex; and fifth, actin, as well as the development of surface functionalizing protocols and image restoration by means of mathematical techniques. [source]


Biotechnology in the Japanese media: Comparative analysis of newspaper articles on genetic engineering in Japan and Europe

ASIAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 1 2006
Aiko Hibino
The present study examined how the representations of biotechnology using genetic engineering have been developed in Japan relying on media analysis. Specifically, using the online database of the Asahi Shimbun, one of the major opinion-forming newspapers in Japan, the annual numbers of articles concerning biotechnology were tallied from 1985 to 2000, and an analysis was conducted of the content of 850 articles from 10 particular years. Specifically, a framework in which a biotechnological issue was presented was focused on; the changes of dominant frames and the relationships between frames and specific biotechnological applications (e.g. medicine, agrifood and cloning) were investigated. The results showed that: (i) the number of articles increased sharply in particular since 1996,1997; (ii) although general attitudes toward biotechnology were persistently positive, a frame of biotechnological article became more diverse (i.e. the prospect frames were considerably dominant in the earlier phases, but the concern frames also became prominent in the later phases); and (iii) several articles were found which reported cloned animals in a frame of emotional attachment, a frame unique to Japan. These results were compared with those of European countries and discussed from a perspective of the theory of collective symbolic coping. [source]


Structure of native laccase B from Trametes sp.

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2010
AH28-
Fungal laccases are oxidoreductases that belong to the multinuclear copper-containing oxidases. They are able to oxidize a wide range of substrates, preferably phenolic compounds, which makes them suitable for employment in the bioremediation of soil and water as well as in other biotechnological applications. Here, the structural analysis of natural laccase B (LacB) from Trametes sp. AH28-2 is presented. This structure provides the opportunity to study the natural post-translational modifications of the enzyme. The overall fold shows a high homology to those of previously analyzed laccases with known three-dimensional structure. However, LacB contains a new structural element, a protruding loop near the substrate-binding site, compared with the previously reported laccase structures. This unique structural feature may be involved in modulation of the substrate recognition of LacB. [source]


Crystallization and preliminary X-ray diffraction data of ,-galactosidase from Saccharomyces cerevisiae

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 1 2010
Rafael Fernández-Leiro
Saccharomyces cerevisiae,-galactosidase is a highly glycosylated extracellular protein that catalyzes the hydrolysis of ,-galactosidic linkages in various glucids. Its enzymatic activity is of interest in many food-related industries and has biotechnological applications. Glycosylated and in vitro deglycosylated protein samples were both assayed for crystallization, but only the latter gave good-quality crystals that were suitable for X-ray crystallography. The crystals belonged to space group P4212, with unit-cell parameters a = b = 101.24, c = 111.52,Å. A complete diffraction data set was collected to 1.95,Å resolution using a synchrotron source. [source]


Directed self-immobilization of alkaline phosphatase on micro-patterned substrates via genetically fused metal-binding peptide

BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2009
Turgay Kacar
Abstract Current biotechnological applications such as biosensors, protein arrays, and microchips require oriented immobilization of enzymes. The characteristics of recognition, self-assembly and ease of genetic manipulation make inorganic binding peptides an ideal molecular tool for site-specific enzyme immobilization. Herein, we demonstrate the utilization of gold binding peptide (GBP1) as a molecular linker genetically fused to alkaline phosphatase (AP) and immobilized on gold substrate. Multiple tandem repeats (n,=,5, 6, 7, 9) of gold binding peptide were fused to N-terminus of AP (nGBP1-AP) and the enzymes were expressed in E. coli cells. The binding and enzymatic activities of the bi-functional fusion constructs were analyzed using quartz crystal microbalance spectroscopy and biochemical assays. Among the multiple-repeat constructs, 5GBP1-AP displayed the best bi-functional activity and, therefore, was chosen for self-immobilization studies. Adsorption and assembly properties of the fusion enzyme, 5GBP1-AP, were studied via surface plasmon resonance spectroscopy and atomic force microscopy. We demonstrated self-immobilization of the bi-functional enzyme on micro-patterned substrates where genetically linked 5GBP1-AP displayed higher enzymatic activity per area compared to that of AP. Our results demonstrate the promising use of inorganic binding peptides as site-specific molecular linkers for oriented enzyme immobilization with retained activity. Directed assembly of proteins on solids using genetically fused specific inorganic-binding peptides has a potential utility in a wide range of biosensing and bioconversion processes. Biotechnol. Bioeng. 2009;103: 696,705. © 2009 Wiley Periodicals, Inc. [source]


In silico genome-scale metabolic analysis of Pseudomonas putida KT2440 for polyhydroxyalkanoate synthesis, degradation of aromatics and anaerobic survival

BIOTECHNOLOGY JOURNAL, Issue 7 2010
Seung Bum Sohn
Abstract Genome-scale metabolic models have been appearing with increasing frequency and have been employed in a wide range of biotechnological applications as well as in biological studies. With the metabolic model as a platform, engineering strategies have become more systematic and focused, unlike the random shotgun approach used in the past. Here we present the genome-scale metabolic model of the versatile Gram-negative bacterium Pseudomonas putida, which has gained widespread interest for various biotechnological applications. With the construction of the genome-scale metabolic model of P. putida KT2440, PpuMBEL1071, we investigated various characteristics of P. putida, such as its capacity for synthesizing polyhydroxyalkanoates (PHA) and degrading aromatics. Although P. putida has been characterized as a strict aerobic bacterium, the physiological characteristics required to achieve anaerobic survival were investigated. Through analysis of PpuMBEL1071, extended survival of P. putida under anaerobic stress was achieved by introducing the ackA gene from Pseudomonas aeruginosa and Escherichia coli. [source]


Cooperation and cheating in microbial exoenzyme production , Theoretical analysis for biotechnological applications

BIOTECHNOLOGY JOURNAL, Issue 7 2010
Stefan Schuster
Abstract The engineering of microorganisms to produce a variety of extracellular enzymes (exoenzymes), for example for producing renewable fuels and in biodegradation of xenobiotics, has recently attracted increasing interest. Productivity is often reduced by "cheater" mutants, which are deficient in exoenzyme production and benefit from the product provided by the "cooperating" cells. We present a game-theoretical model to analyze population structure and exoenzyme productivity in terms of biotechnologically relevant parameters. For any given population density, three distinct regimes are predicted: when the metabolic effort for exoenzyme production and secretion is low, all cells cooperate; at intermediate metabolic costs, cooperators and cheaters coexist; while at high costs, all cells use the cheating strategy. These regimes correspond to the harmony game, snowdrift game, and Prisoner's Dilemma, respectively. Thus, our results indicate that microbial strains engineered for exoenzyme production will not, under appropriate conditions, be outcompeted by cheater mutants. We also analyze the dependence of the population structure on cell density. At low costs, the fraction of cooperating cells increases with decreasing cell density and reaches unity at a critical threshold. Our model provides an estimate of the cell density maximizing exoenzyme production. [source]


Insect-symbiont systems: From complex relationships to biotechnological applications

BIOTECHNOLOGY JOURNAL, Issue 12 2009
Sandra Chaves
Abstract Microbial symbiosis is a ubiquitous aspect of life and was a major element in the ability of insects to explore several adverse environments. To date, the study of symbiosis in insects has been impaired by the unculturability of most symbionts. However, some molecular methods represent powerful tools to help understand insect-microorganism associations and to disclose new symbiont-host systems. Beyond playing an essential role in nutrition and development of the insects, symbionts can produce bioactive compounds that protect the host against adverse environmental conditions, predators and/or direct competitors. Since the search for natural bioactive products and new enzymes is a developing area, understanding the diversity and nature of symbiont-host relationships paves the way for the exploitation of new resources in biotechnology. Furthermore, genetic transformation of the symbionts with genes that code for compounds that are toxic for pathogenic and phytopathogenic agents is also a promising area of application of the insect-symbiont relationships. The search for new bioactive compounds, the use of symbionts for pest and disease control and the molecular strategies applied for these purposes are issues of particular interest for innovative biotechnological applications and are addressed in the present review. [source]