Scielo RSS <![CDATA[Electronic Journal of Biotechnology]]> http://www.scielo.cl/rss.php?pid=0717-345820120003&lang=es vol. 15 num. 3 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<b>An economic valuation of a biotechnology R&D project in a developing economy</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300001&lng=es&nrm=iso&tlng=es Background: Biotechnology complements technological developments in main sectors of economies, such as health, energy, and agriculture, and thus contributes to economic development. It provides solutions to the problems that are frequently faced in developing economies, such as resource constraints, lower productivity and environmental concerns. In order to benefit from biotechnology, its associated markets need to develop and function well to support the developments and transactions of intangible assets, such as technology transfers, license agreements and research and development joint ventures. Economic valuation of the intangible assets is necessary for the development and functioning of these markets. It provides better understanding of value creation at micro scales and its economic and financial dynamics. The literature lacks valuation studies in biotechnology sectors in developing economies. This study performs economic valuation analysis of a research and development project of a Turkish biotechnology company operating in health sector. Turkey, as a developing economy, has slow progress in biotechnology despite its wealth of biological resources and genetic variety. Thus, the study provides an excellent case to analyze valuation issues in developing economies. It uses data from in-depth interviews from the company and employs real options and discounted cash flow (DCF) methods. Results: Developing countries and biotechnology sector introduce additional risks that need to be accounted for in valuation. These risks reduce the value of the project under real options and discounted cash flow methods. Since real options method permits the valuation of options that might arise during the R&D process and provides flexibility to managers to act, it results in higher values compared to discounted cash flow method. The grant from a public institution that partially financed the Project reduces the discount factor and thus increases the value of it. Conclusions: Economic values of biotechnology intangibles in developing countries are affected by country and sector risks and public financing. Thus, both microeconomic and macroeconomic policy interventions are important for the development of biotechnology in these economies. While public financing enables the risky R&D projects to take place, it makes them more valuable than they would be under no intervention. Long run effects of these interventions require diligent analyses. <![CDATA[<b>Characterization of extracellular cellulose-degrading enzymes from<i> Bacillus thuringiensis</i> strains</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300002&lng=es&nrm=iso&tlng=es The gram-positive spore-forming bacteria, Bacillus thuringiensis (Bt) strains produced novel cellulases which could liberate glucose from soluble cellulose, carboxymethyl cellulose (CMC), and insoluble crystalline cellulose. The maximal cellulase activities were obtained after 60 hrs incubation at 28ºC in a LB broth medium with 1% CMC. Maximum CMCase activities were got at 40ºC and pH 4.0, respectively, and more than 50% of its maximal activity was retained at 40-60ºC for 1 hr, while approximately 40% of its maximal activity was also retained after incubating at 70ºC for 1 hr. Most metal ions and reagents such as Ca2+, Mg2+, Cd2+, Pb2+, Zn2+, Cu2+, EDTA, and SDS inhibited the enzyme activities, but K+ and Mn2+ activated the activities. The enzymes from Bacillus thuringiensis strains could be applied in bioconversion of lignocellulosic biomass into fermentable sugars. <![CDATA[<b>Comparative study for the kinetics of extracellular xylanases from <i>Trichoderma harzianum</i> and <i>Chaetomium thermophilum</i></b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300003&lng=es&nrm=iso&tlng=es Xylanases assume special importance in the paper and pulp industry as they replace toxic chemicals such as chlorine and chlorine dioxide for developing eco-friendly processes. This study evaluated xylanases produced by two fungi, the mesophilic fungus Trichoderma harzianum and a thermophilic fungus Chaetomium thermophilum. Among the polymeric substrates studied for xylanase production by both the fungi, birch wood xylan was found to be the best inducer of xylanases. Xylanases induction was subject to glucose repression. Partially purified xylanases preparation from T. harzianum and C. thermophilum exhibited optimal activities at pH 5 and 6 and at 60ºC and 70ºC, respectively. The apparent Km and Vmax values for the partially purified xylanase from T. harzianum using oat spelt xylan as a substrate were 4.8 mg mL-1 and 0.526 µmol min-1 mg-1, respectively. Whereas values of the partially purified xylanase from C. thermophilum were 2.96 mg mL-1 and 0.25 µmol min-1 mg-1, respectively. These findings in this study have great implications for the future applications of xylanases. <![CDATA[<b><i>Xylella fastidiosa</i></b>: <b>An <i>in vivo</i> system to study possible survival strategies within citrus xylem vessels based on global gene expression analysis</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300004&lng=es&nrm=iso&tlng=es Xylella fastidiosa inhabits the plant xylem, a nutrient-poor environment, so that mechanisms to sense and respond to adverse environmental conditions are extremely important for bacterial survival in the plant host. Although the complete genome sequences of different Xylella strains have been determined, little is known about stress responses and gene regulation in these organisms. In this work, a DNA microarray was constructed containing 2,600 ORFs identified in the genome sequencing project of Xylella fastidiosa 9a5c strain, and used to check global gene expression differences in the bacteria when it is infecting a symptomatic and a tolerant citrus tree. Different patterns of expression were found in each variety, suggesting that bacteria are responding differentially according to each plant xylem environment. The global gene expression profile was determined and several genes related to bacterial survival in stressed conditions were found to be differentially expressed between varieties, suggesting the involvement of different strategies for adaptation to the environment. The expression pattern of some genes related to the heat shock response, toxin and detoxification processes, adaptation to atypical conditions, repair systems as well as some regulatory genes are discussed in this paper. DNA microarray proved to be a powerful technique for global transcriptome analyses. This is one of the first studies of Xylella fastidiosa gene expression in vivo which helped to increase insight into stress responses and possible bacterial survival mechanisms in the nutrient-poor environment of xylem vessels. <![CDATA[<b>Inhibitor tolerance and flocculation of a yeast strain suitable for second generation bioethanol production</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300005&lng=es&nrm=iso&tlng=es Background: Robust second generation bioethanol processes require microorganisms able to ferment inhibitory lignocellullosic hydrolysates. In this study, the inhibitor tolerance and flocculation characteristics of Saccharomyces cerevisiae CCUG53310 were evaluated in comparison with S. cerevisiae CBS8066. Results: The flocculating strain CCUG53310 could rapidly ferment all hexoses in dilute acid spruce hydrolysate, while CBS8066 was strongly inhibited in this medium. In synthetic inhibitory media, CCUG53310 was more tolerant to carboxylic acids and furan aldehydes, but more sensitive than CBS8066 to phenolic compounds. Despite the higher tolerance, the increase in expression of the YAP1, ATR1 and FLR1 genes, known to confer resistance to lignocellulose-derived inhibitors, was generally smaller in CCUG53310 than in CBS8066 in inhibitory media. The flocculation of CCUG53310 was linked to the expression of FLO8, FLO10 and one or more of FLO1, FLO5 or FLO9. Flocculation depended on cell wall proteins and Ca2+ ions, but was almost unaffected by other compounds and pH values typical for lignocellulosic media. Conclusions: S. cerevisiae CCUG53310 can be characterised as being very robust, with great potential for industrial fermentation of lignocellulosic hydrolysates relatively low in phenolic inhibitors. <![CDATA[<b>Effects of fermentation substrates and conservation methods on the viability and antimicrobial activity of <i>Weissella confusa</i> and its metabolites</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300006&lng=es&nrm=iso&tlng=es Lactic acid bacteria produce metabolites with antagonistic activity against other bacteria. However, growth conditions and conservation methods may reduce the viability and antimicrobial activity of lactic acid bacteria. This study evaluated the effects of fermentation substrate, lyophilization (freeze-drying) and refrigeration on the viability and antimicrobial activity of Weissella confusa strain and its metabolites against pathogens responsible for bovine mastitis. W. confusa strain was grown in MRS broth and milk supplemented with yeast extract and glucose (MYEG). The collected fractions were preserved by lyophilization or under refrigeration at 4ºC. Every seven days, the viability of W. confusa strain and the stability of its metabolites were evaluated against Staphylococcus aureus and Streptococcus agalactiae by disc diffusion assays. In both fermentation substrates, the combination of lyophilized strain and metabolites retained antimicrobial activity against the two pathogens for 42 days. Also, W. confusa strain retained adequate viability and antimicrobial activity when grown in MYEG and stored under refrigeration conditions. It was concluded that MYEG and refrigeration are acceptable low cost options to preserve the viability of W. confusa for its potential commercial use in the prevention and treatment of bovine mastitis. <![CDATA[<b>Modelling of the biofiltration of reduced sulphur compounds through biotrickling filters connected in series</b>: <b>Effect of H<sub>2</sub>S</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300007&lng=es&nrm=iso&tlng=es Background: The behaviour of two biotrickling filters connected in serie (BTF) inoculated with Acidithiobacillus thiooxidans and Thiobacillus thioparus, biodegrading hydrogen sulphide (H2S) and dimethyl sulphide (DMS) simultaneously were studied. A model which considers gas to liquid mass transfer and biooxidation in the biofilm attached to the support is developed. Additionally, a fixed bed biotrickling filter where the microorganism is immobilized in a biofilm which degrades a mixture of H2S and DMS is implemented. Validation of the model was carried out using experimental data obtained at different H2S and DMS loads. Results: The inhibitory effect caused by the presence of H2S on the DMS is observed, which is evidenced by the decrease of the DMS removal efficiency from 80 to 27%, due to the preference that T. thioparus has by simple metabolism. H2S is not affected by the DMS, with removal efficiencies of 95 to 97%, but it decreases at high concentrations of the compound, due to the inhibition of metabolism by high H2S input loads. The model which describes the BFT fits successfully with the experimental results and it has a high sensitivity to inhibition parameters. Conclusion: It is shown that the microorganism has a high affinity for H2S, producing substrate inhibition when the concentration is high. The H2S is able to inhibit the DMS biooxidation, whereas the DMS does not affect the H2S biooxidation. <![CDATA[<b>Bioconversion of cassava starch by-product into <i>Bacillus</i> and related bacteria polyhydroxyalkanoates</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300008&lng=es&nrm=iso&tlng=es Background: Unlike petroleum-based synthetic plastics, biodegradable biopolymer generation from industrial residue is a key strategy to reduce costs in the production process, as well as in the waste management, since efficient industrial wastewater treatment could be costly. In this context, the present work describes the prospection and use of bacterial strains capable to bioconvert cassava starch by-product into biodegradable polyhydroxyalkanoates (PHAs). Results: The first step of this study was the bacterial competence screening which was conducted with 72 strains covering 21 Bacillus and related species. The microorganism growth in a medium with a starch substrate was measured by an innovative MTT assay, while the ability of the bacteria to secrete amylase and produce PHA was evaluated by the Nile Red Dye method. Based on growth and potential for PHA production, four isolates were selected and identified as Bacillus megaterium by 16S rRNA sequencing. When cultivated in hydrolyzed cassava starch by-product, maximum production reached 4.97 g dry biomass/L with 29.7% of Poly-(3-hydroxybutyrate) (characterized by FTIR). Conclusions: MTT assay proved to be a reliable methodology for monitoring bacterial growth in insoluble media. Selected amylolytic strains could be used as an alternative industrial process for biodegradable plastics production from starchy residues, reducing costs for biodegradable biopolymer production and wastewater treatment operations. <![CDATA[<b>Effect of a commercial pectinmethylesterase on tomato paste consistency</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582012000300009&lng=es&nrm=iso&tlng=es Background: Consistency is one of the main traits that define commercial quality and price of tomato paste. Pectins are partially responsible for consistency in tomato paste, therefore enzymatic pectin modification could be used to increase paste consistency. Results: This work reports the effects of a commercial enzymatic preparation of pectin-methyl-esterase (PME) (NovoShape™) on tomato paste consistency taking into account variables as enzyme/substrate ratio (0,1% w/w - 1% w/w), reaction time (0 hr - 3 hrs) and reaction temperature (40ºC-60ºC). The results indicate that NovoShape™ increased consistency when reaction temperature ranged from 40 to 50ºC with an enzyme/substrate ratio of 0.5 to 1 (l PME solution/g tomato paste on dry base). On the other hand, enzymatic treatment was not effective at 60ºC with an enzyme/substrate ratio of 0.1%. Conclusions: Based on these results, addition of NovoShape™ is a good technological approach to increase tomato paste consistency.