Scielo RSS <![CDATA[Electronic Journal of Biotechnology]]> http://www.scielo.cl/rss.php?pid=0717-345820070003&lang=es vol. 10 num. 3 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<b>Managing agricultural biotechnology in Colombia</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300001&lng=es&nrm=iso&tlng=es The international scenario for biotechnology shows a rapid tendency at industrialized countries in the increase of publications, patents, enterprises and novel solutions for the industry, the environment, health and agriculture. Nevertheless, Colombia has an important delay in relation to the international scientific development and the capacity to generate wealth and services for its productive systems. This delay has been one of the concerns of the country's policy during the last years, and more precisely since 2002, when for the first time biotechnology was included in a National Development Plan as one of the mechanisms for competitiveness and the use of biodiversity and genetic resources. This paper is the result of a survey conducted in 2005 aimed to provide an overview of agrobiotechnology in Colombia to be included in the compendium of case studies organized by the FAO's Regional Office for Latin America and the Caribbean (LAC) and the Network for Technical Cooperation in Agricultural Biotechnology in Latin America and the Caribbean (REDBIO/FAO) <![CDATA[<b>A most effective method for selecting a broad range of short and medium-chain-length polyhidroxyalcanoate producing microorganisms</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300002&lng=es&nrm=iso&tlng=es A molecular approach was used for selecting polyhydroxyalcanoate (PHA)-accumulating potential Gram-negative bacteria from different genera by colony polymerase chain reaction (PCR). Three degenerate primers were designed for amplifying a fragment from PHA synthase gene (phaC) (Class I), phaC1 and phaC2 (Class II) genes for detecting PHA-producing bacteria. Thirty-four out of 55 bacterial strains from the old collection selected using Sudan black B staining were phaC+. PCR was used for directly selecting 35 new collection bacterial strains; these strains were phaC+ and their ability to produce PHA was confirmed by Sudan black B staining. Four specific primers were designed on genes of Class II PHA biosynthesis operon. These primers were used for evaluating 9 strains from the old phaC+ collection; 6 showed Class II PHA synthase organisation. 34 from the old and new bacterial isolation were characterised by 16S ribosomal gene (16S rDNA) gene partial sequencing. The tool proposed here can be used for better directing PHA production based on PHA biosynthesis genes and bacterial genera. Class I or II phaC genes were detected in 9 different genera and were able to infer the type of polymer produced. <![CDATA[<b>Biosorption of hexavalent chromium using tamarind (<i>Tamarindus indica</i>) fruit shell-a comparative study</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300003&lng=es&nrm=iso&tlng=es The adsorption of chromium (VI) ions from aqueous solutions has been investigated on crude tamarind fruit shell, HCl treated and Oxalic acid treated shells at room temperatures. The biosorbents are characterized by FT-IR, EDXRF and porosimetry. The biosorption experiments are conducted through batch system. The influence of different experimental parameters such as pH, effect of initial metal ion concentration and effect of dosage of adsorbent on biosorption are evaluated. The adsorption followed first order kinetics. The data are fitted well to Langmuir and Freundlich isotherm models. A comparison is drawn on the extent of biosorption between untreated and treated forms of the tamarind shells. Due to their outstanding adsorption capacities, tamarind shells are excellent sorbents for the removal of chromium ions <![CDATA[<b>Biosorption of lead by the brown seaweed <i>Sargassum filipendula </i>- batch and continuous pilot studies</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300004&lng=es&nrm=iso&tlng=es The biosorption of lead by the brown alga Sargassum filipendula was studied. pH 4.0 was the optimum value for the biosorption of lead. Isotherms indicated that for solutions containing 0.03 ± 0.001 up to 3.27 ± 0.04 mmol/L of lead, 2.0g/L was the optimum biomass concentration. The Langmuir model was fitted to represent the experimental data, and the kinetics of biosorption presented equilibrium in 30 min. The continuous system operated for 56 hrs presenting a 100% binding of ionic lead, which corresponds to an accumulation of 168 g lead, equivalent to a load of 1.7 mmol ionic lead/g Sargassum filipendula. The results that were obtained in a continuous system showed a gradual saturation of the biomass in the reactors <![CDATA[<b>Effect of temperature on the anaerobic digestion of palm oil mill effluent</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300005&lng=es&nrm=iso&tlng=es Two continuous stirred tank reactors (CSTRs) each fed with palm oil mill effluent (POME), operated at 37ºC and 55ºC, respectively, were investigated for their performance under varies organic loading rates (OLRs). The 37ºC reactor operated successfully at a maximum OLR of 12.25 g[COD]/L/day and a hydraulic retention time (HRT) of 7 days. The 55ºC reactor operated successfully at the higher loading rate of 17.01 g[COD]/L/day and had a HRT of 5 days. The 37ºC reactor achieved a 71.10% reduction of chemical oxygen demand (COD), a biogas production rate of 3.73 L of gas/L[reactor]/day containing 71.04% methane, whereas the 55ºC reactor achieved a 70.32% reduction of COD, a biogas production rate of 4.66 L of gas/L[reactor]/day containing 69.53% methane. An OLR of 9.68 g[COD]/L/day, at a HRT of 7 days, was used to study the effects of changing the temperature by 3ºC increments. The reactor processes were reasonably stable during the increase from 37ºC to 43ºC and the decrease from 55ºC to 43ºC. When the temperature was increased from 37ºC to 46ºC, the total volatile fatty acid (TVFA) concentration and biogas production was 2,059 mg as acetic acid/L and 1.49 L of gas/L[reactor]/day at day 56, respectively. When the temperature was reduced from 55ºC to 40ºC, the TVFA concentration and biogas production was 2,368 mg as acetic acid/L and 2.01 L of gas/L[reactor]/day at day 102, respectively. By first reducing the OLR to 4.20 g[COD]/L/day then slowly increasing the OLR back to 9.68 g[COD]/L/day, both reactors were restored to stable conditions at 49ºC and 37ºC respectively. The initial 37ºC reactor became fully acclimatized at 55ºC with an efficiency similar to that when operated at the initial 37ºC whereas the 55ºC reactor also achieved stability at 37ºC but with a lower efficiency <![CDATA[<b>Extent and structure of genetic diversity in a collection of the tropical multipurpose shrub legume <i>Cratylia argentea</i> (Desv.)</b><b> O. Kuntze as revealed by RAPD markers</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300006&lng=es&nrm=iso&tlng=es The tropical multipurpose shrub legume Cratylia argentea is well adapted to acid soils of low to medium fertility and has excellent drought-tolerance. Due to its high nutritive value it is particularly suited as forage for dry-season supplementation. A collection of 47 C. argentea accessions in a collection, derived from seed replicating of original accessions with differing geographic origin and morphological and agronomic characteristics was investigated using molecular markers (RAPD (random amplified polymorphic DNA)). Genetic diversity (H T = 0.145) in the collection was low, with 30% of differentiation among groups and high genetic similarity among accessions (GS = 0.805). Within-accession variability was high. One taxonomic mismatch and five possible duplicate accessions were identified. Our results suggest that the genetic diversity in the C. argentea accessions studied is relatively homogeneously distributed, indicating the likelihood of extensive outcrossing. The genetic diversity of original accessions should be assessed to determine if outcrossing has occurred during or before ex situ storage. This might also support any decision on whether accessions should be bulked rather than maintaining them individually <![CDATA[<b>Extraction of bulk DNA from </b><b>Thar Desert</b><b> soils for optimization of PCR-DGGE based microbial community analysis</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300007&lng=es&nrm=iso&tlng=es A reliable method for characterizing microbial communities on the basis of their differences in the 16S ribosomal RNA (rRNA) gene sequences in the hot arid zone sandy soils has been optimized. A desert plant (Calligonum polygonoides) was chosen to provide the rhizospheric soil samples, collected from three different agro-ecological locations. Total community DNA was efficiently extracted at small-scale level using direct lysis with hot sodium dodecyl sulphate (SDS), glass bead beating and finally subjecting the sandy soil to liquid nitrogen freeze-thaw cycles. To amplify V3 region of bacterial 16S rRNA gene, universal conserved primers were used. Second round polymerase chain reaction (PCR) was attempted to increase product concentration and to minimize the effect of inhibitory substances. To enhance the detection sensitivity of the denaturing gradient gel electrophoresis (DGGE), the effect of change in template DNA concentration was studied. The separation of bands were greatly enhanced in the fingerprints obtained after the second round of PCR representing low abundant species which were not differentiated at single optimized concentration of DNA <![CDATA[<b>Heavy metal uptake by agro based waste materials</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300008&lng=es&nrm=iso&tlng=es Presence of heavy metals in the aquatic systems has become a serious problem. As a result, there has been a great deal of attention given to new technologies for removal of heavy metal ions from contaminated waters. Biosorption is one such emerging technology which utilized naturally occurring waste materials to sequester heavy metals from industrial wastewater. The aim of the present study was to utilize the locally available agricultural waste materials for heavy metal removal from industrial wastewater. The wastewater containing lead and hexavalent chromium was treated with biomass prepared from ficus religiosa leaves. It was fund that a time of one hr was sufficient for sorption to attain equilibrium. The equilibrium sorption capacity after one hr was 16.95 ± 0.75 mg g-1 and 5.66 ± 0.43 mg g-1 for lead and chromium respectively. The optimum pH was 4 for lead and 1 for chromium. Temperature has strong influence on biosorption process. The removal of lead decreased with increase in temperature. On the other hand chromium removal increased with increase in temperature up to 40ºC and then started decreasing. Ion exchange was the major removal mechanism along with physical sorption and precipitation. The biosorption data was well fitted to Langmuir adsorption model. The kinetics of biosorption process was well described by the pseudo 2nd order kinetics model. It was concluded that adsorbent prepared from ficus religiosa leaves can be utilized for the treatment of heavy metals in wastewater <![CDATA[<b>Induction of <i>in vitro </i>roots cultures of <i>Thypha latifolia</i> and <i>Scirpus americanus</i> and study of their capacity to remove heavy metals</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300009&lng=es&nrm=iso&tlng=es We have established the conditions to obtain in vitro root cultures of Thypha latifolia and Scirpus americanus and have investigated their capacity to remove Pb(II), Mn(II) and Cr(III) from the culture medium. The best conditions for the in vitro culture growth were: an inoculum of 0.2 g of T. latifolia roots and 0.05 g of S. americanus roots (fresh weight), Murashige-Skoog medium and 2 mg L-1of indolacetic acid. The T. latifolia and S. americanus root cultures were cultivated onto media containing Cr (15 µg L-1), Pb (60 µg L-1) or Mn (1.8 mg L-1). Both species were able to remove Pb and Cr near to 100% and 71-100% of Mn from the medium solution during the 6-8 days of experimentation. According to metal concentrations removed from the medium containing the growing root mass, the in vitro root culture of S. americanus can be considered as an accumulator for Pb (157.73 µg g-1), Cr (55.6 µg g-1) and Mn (5000 µg g-1). <![CDATA[<b>Industrial derivative of tallow</b>: <b>a promising renewable substrate for microbial lipid, single-cell protein and lipase production by <i>Yarrowia lipolytica</i></b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300010&lng=es&nrm=iso&tlng=es The aim of the present study was to assess the potential of valorisation of a solid industrial derivative of tallow, composed of saturated free-fatty acids ("stearin"), by fermentations carried out by the yeast Yarrowia lipolytica ACA-DC 50109 in order to produce microbial lipid, biomass and extra-cellular lipase. High quantities of biomass were produced (biomass yield of around 1.1 ± 0.1 g of total biomass produced per g of fat consumed) when the organism was grown in shake flasks, regardless of the concentration of extra-cellular nitrogen present. Cellular lipids accumulated in notable quantities regardless of the nitrogen availability of the medium, though this process was clearly favoured at high initial fat and low initial nitrogen concentrations. The maximum quantity of fat produced was 7.9 mg/ml corresponding to 52.0% (wt/wt) of lipid in the dry biomass. Lipase production was critically affected by the medium composition and its concentration clearly increased with increasing concentrations of fat and extra-cellular nitrogen concentration reaching a maximum level of 2.50 IU/ml. Lipase concentration decreased in the stationary growth phase. In bioreactor trials, in which higher agitation and aeration conditions were employed compared with the equivalent trial in the flasks, significantly higher quantities of biomass were produced (maximum concentration 30.5 mg/ml, yield of 1.6 g of total biomass produced per g of fat consumed) while remarkably lower quantities of cellular lipids and extra-cellular lipase were synthesised. Numerical models successfully simulated both conversion of substrate fat into biomass and production and subsequent hydrolysis of extra-cellular lipase and presented a satisfactory predictive ability verifying the potential for single-cell protein and lipase production by Yarrowia lipolytica ACA-DC 50109. In all cultures, the mycelial form of the culture was dominant with few single cells present <![CDATA[<b>Molecular description and similarity relationships among native germplasm potatoes (<i>Solanum tuberosum</i> ssp.</b> <b><i>tuberosum</i> L.) using morphological data and AFLP markers</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300011&lng=es&nrm=iso&tlng=es Chile is considered to be a sub-center of origin for the cultivated potato, with native and introduced genetic material coexisting in the country. Thus, the different varieties present in Chiloe Island are characterized by a rich diversity of forms, sizes, colours and phenological characteristics. In the present work, the level of polymorphism and the genetic relationship were studied by means of molecular markers using the amplified fragment length polymorphism (AFLP) technique and twenty-seven morphological characters. Twenty varieties of potatoes from the Chiloe Island were analyzed. The commercial variety Desirée and one specie from the Etuberosa series, Solanum fernandezianum, collected in the Juan Fernandez Island were included as controls. A similarity tree-diagram was made, based on all the AFLP bands generated in the range between 65 and 290 base pairs. With these tools, it was possible to identify molecular differences and similarities that might be associated with important morphological traits such as the predominant forms of the tuber, flower colour and resistance to disease <![CDATA[<b><i>Trametes versicolor</i> growth and laccase induction with by-products of pulp and paper industry</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300012&lng=es&nrm=iso&tlng=es The cultivation of Trametes versicolor for laccase production and cell growth were strongly dependent on experimental conditions namely physical and chemical parameters as well as nutrient availability and inducer stimulation. Biomass growth was compared for a rich medium and for a defined medium in two different temperatures. The best temperature was 28ºC and the maximum specific growth rates were µmax = 0.083 h-1 for the rich medium and µmax = 0.043 h-1 for the defined medium. It was clearly shown that laccase production is not associated with cell growth, indicating that this ligninolytic enzyme must be produced in the defined medium by a secondary metabolism. In order to obtain laccase induction, addition of solid lignin, lignosulphonates, veratryl alcohol, xylidine and ethanol was tested at different concentrations. To optimise laccase activity, the combined effect of inducer addition and simultaneously glucose suppression was studied. The best result for laccase induction (1240 U/L) was obtained with solid lignin, a by-product of pulp and paper industry and the higher laccase activity attained (1583 U/L) was obtained with the combined effect of xylidine addition and glucose suppression. <![CDATA[Expression of bacterial genes in transgenic tobacco: <strong>methods, applications and future prospects </strong>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300013&lng=es&nrm=iso&tlng=es Tobacco is the most commonly used plant for expression of transgenes from a variety of organisms, because it is easily grown and transformed, it provides abundant amounts of fresh tissue and has a well-established cell culture system. Many bacterial proteins involved in the synthesis of commercial products are currently engineered for production in tobacco. Bacterial enzymes synthesized in tobacco can enhance protection against abiotic stresses and diseases, and provide a system to test applied strategies such as phytoremediation. Examples of bacterial gene expression in tobacco include production of antigen proteins from several human bacterial pathogens as vaccines, bacterial proteins for enhancing resistance against insects, pathogens and herbicides, and bacterial enzymes for the production of polymers, sugars, and bioethanol. Further improvements in the expression of recombinant proteins and their recovery from tobacco will enhance production and commercial use of these proteins. This review highlights the dynamic use of tobacco in bacterial protein production by examining the most relevant research in this field. <![CDATA[<b>A simple method for isolation of genomic DNA from fresh and dry leaves of <i>Terminalia arjuna </i>(Roxb.) Wight and Arnot</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300014&lng=es&nrm=iso&tlng=es Current protocols for isolation of genomic DNA from Terminalia arjuna have their own limitations due to the presence of high content of gummy polysaccharides and polyphenols. DNA isolated by these protocols is contaminated with a yellowish, sticky and viscous matrix. In our modified DNA isolation method polysaccharides and polyphenols are removed prior to the precipitation of the DNA. Then the genomic DNA was precipitated using isopropanol. This protocol yielded a high molecular weight DNA isolated from fresh as well as dry leaves of T. arjuna, which was free from contamination and colour. Isolated DNA can be used for restriction digestion and PCR amplification. The main objective of the present protocol is to provide a simple method of isolation of DNA, using in house prepared reagents <![CDATA[<b>Isolation of simple sequence repeats from groundnut</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582007000300015&lng=es&nrm=iso&tlng=es SSRs have proved to be the most powerful tool for variety identification in groundnut of similar origin, and have much potential in genetic and breeding studies. To facilitate SSR discovery in groundnut, we proposed a highly simplified SSR isolation protocol based on multiple enzyme digestion/ligation, mixed biotin-labeled probes and streptavidin coated magnetic beads hybridization capture strategy. Of the 272 colonies randomly picked for sequencing, 119 were found to have unique SSR inserts