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Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The current classification scheme of the causal agent of the bacterial wilt [Ralstonia solanacearum) (Smith) Yabuuchi] is based on the analysis of the endoglucanase gene sequence of the bacterium. The objective of this paper was to optimize the PCR amplification of this gene. PCR parameters were determined using the OLIGO software version 7.53 for in silico analyses. The effect of cell concentration on amplification efficiency was assessed by using serial dilutions of R. solanacearum suspensions. For the in vitro assays, a two step-PCR protocol was evaluated with the GoTaq® DNA Polimerasa kit. The cell concentration was a critical factor on amplification efficiency with an optimal value of 108 CFU.ml-1. Time was reduced for the initial denaturalization and final extension phases and hybridization and extension were combined in a single step resulting in a 57 minute shorter-PCR program than the original protocol. The phylogenetic analysis of this gene sequence will allow performing diversity studies of Cuban isolates of R. solanacearum, establishing comparative relationships with isolates of other geographical locations and updating the disease management strategies. [ABSTRACT FROM AUTHOR]

Copyright of Biomédica: Revista del Instituto Nacional de Salud is the property of Instituto Nacional de Salud of Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recombinant protein expression has been favored by the use of Escherichia coli due to its relatively low costs, high-density culture, easy genetic manipulation and also to compatible biotechnological tools. Strategies for recombinant expression in E. coli are presented in this paper. Genetic and physiologic factors are presented: number of copies of the expression vector, characteristic of the gene, ribonucleic acid (messenger) stability, promoter, host strain, clone stability, composition of the cultivation media, operation parameters in the bioreactor and cultivation and purification strategies. [ABSTRACT FROM AUTHOR]

The present study describes the behavior of meningococcal disease in 86 cases notified with isolation of Neisseria meningitidis in Cuba from 1998-2007, through spatial and temporal distribution of cases, phenotypic characterization of isolated strains and identification of some host risk factors that may affect phenotypic switching of strains. Percentages and the rate of changes of the strain phenotypic structure with different criteria were calculated. Children under one year old (30.2%) and meningitis (76.7%) were predominant. Case-fatality rate was 15.1%. The 58.1% of cases were ill with the same vaccine strain phenotype (B:4:P1.19,15). Phenotypic changes were detected in 41.9% of the isolates, mainly in children of 5-9 years old who live in western and central regions. Children that fell ill in July, September, December and April and live in Matanzas, Havana and Villa Clara provinces were associated to phenotypic switching of strains. [ABSTRACT FROM AUTHOR]

Copyright of Revista Colombiana de Biotecnología is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this work was to characterize phenotypically rhizobia isolates from forage legume Canavalia ensiformis. Twelve isolates (five possible members of the Rhizobium genus, seven possible members of Bradyrhizobium genus) and two commercial strains, BR 2001 and BR 2003a were characterized. For the phenotypic characterization of the bacterial isolates, their capacity to use six carbohydrates as carbon source, their tolerance to acid condition and different levels of NaC1, and the resistence to six antibiotic, were studied; as well as their growing in three incubation temperatures. In addition, the capacity of these isolates to produce polyhidroxibutirates (PHB) was determinated. All rhizobia isolates used lactose, glucose and mannitol as carbon source. One rapid growing isolate was the most tolerant to pH 4.5. The isolates possible members of the Rhizobium/Sinorhizobium genus were more tolerant to NaC1 than the isolates possible members of Bradyrhizobium genus. Three of the rapid growing isolates were resistent to six antibiotics. When the isolates were incubated at 370C, all of them except the CP3 isolate and one commercial strain, BR 2001, grown similar to control. The CP10 slow growing isolate had the capacity to produce the biggest PHB concentration (0.023 g.L-1). [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is considered one of the most important hospital germs; its isolation is common in hospitalized patients. In addition, this microorganism has a marked multi-resistance, which increases mortality. Treatment of these patients is often difficult, since in addition to its natural resistance, Pseudomonas can obtain resistance mechanisms to virtually all anti-microbial drugs available for its treatment; due to this, its appearance is increasingly frequent and necessitates the use of antibiotics such as carbapenems, which facilitates the acquisition of resistance mechanisms to these drugs. This study attempts to determine the production of metallobeta-lactamase (MBL) in clinical isolates of Pseudomonas aeruginosa, utilizing two phenotypic methods: the double discmethod (MDD) and the modified Hodge test (MHT). 726 clinical isolates of P. aeruginosa were analyzed; 20.11% (146) of these were resistant to imipenem (IPM) and meropenem (MEM); 139 were positive for the MDD, while 144 were positive for the MHT. These two methods permitted confirming the presence of an MBL-type carbapenemase in 98.63% of P. aeruginosa isolates; five isolates were negative for the MDD but positive for the MHT, indicating the presence of non-MBL-type carbapenemase in these isolates. Also, 2 isolates were obtained that, despite being resistant to IPM and MEM, were negative according to the two phenotypic methods used; this would indicate the presence of a non-enzymatic resistance mechanism conferring resistance to carbapenems. The use of phenotypic methods for detecting MBL in P. aeruginosa isolates is quite an acceptable option for use in routine laboratories where specialized molecular biology tests are not available. [ABSTRACT FROM AUTHOR]

Rhizobial taxonomy and systematics have progressed substantially, nevertheless, few studies have been developed on venezuelan species. This study evaluated the phenotypic and genetic variation between 12 venezuelan indigenous rhizobial isolates and 10 international referential strains, by phenotypical traits and DNA molecular markers. in this regard, a PCR-RFLP of the 16S rDNA gene, the presence of large plasmids, metabolic assays in solid media, salinity resistance, pH and temperature growth conditions, and intrinsic antibiotic resistance were assayed. in reference to the phenotypic attributes, we recognized three main groups: A group i, which comprised all the strains metabolizing between 67.5%-90% of the C and N sources. They were also acid-tolerant, as well as acid producers, capable of growing at 40°C and in high salinity conditions (2-2.5% NaC1). With regard to the antibiotic sensitivity, this group was susceptible to a 30% of the antibiotic assayed. Strains belonging to Group ii exhibited a lower salt tolerance (0.1-1.5%NaCl), as well as a lower acid tolerance, since they grew well at pH values equal or higher than 5.0. This group appeared to be resistant to all of the antibiotics assayed and only metabolized between 52.5%-82.5% of the C and N sources. Group iii was represented by a single bacterial strain: it has a extremely low salt tolerance (0.1% NaC1). This strain grew at a pH equal or higher than 5.6, was susceptible to 50% of the antibiotics assayed and metabolized 72% of the C and N sources. On the basis of a PCR- RFLP of the 16S rDNA, three groups were also obtained. Members of the group A showed a close resemblance to Rhizobium tropici CiAT 899 and Sinorhizobium americanum CFN-Ei 156, while Group B was closely related to Bradyrhizobium spp. Group C, was also represented by only one isolate. The Trebol isolate, was the only one strain able to form nodules and does not appear to be related to any of the referential rhizobial strains, suggesting a possible symbiotic horizontal gene transfer. Finally, in this work, there are evidences of a genetic diversity in the venezuelan rhizobial strains. A different geographical origin is perhaps an important factor affecting the diversity of the indigenous rhizobia in this study. Rev. Biol. Trop. 59 (3): 1017-1036. Epub 2011 September 01. [ABSTRACT FROM AUTHOR]

Mycoplasma gallisepticum, the causal agent of the chronic respiratory disease of chickens, is the most economically significant for poultry industry. An 800pb DNA fragment of Mycoplasma gallisepticum which was amplified from the recombinant vector pTTQ18 was cloned into the expression vector pQE-32. The polypeptide was expressed as a fusion protein to 6X- histidine tag; hence its final size was 31kDa. It was detected by Western blott being recognized by a polyclonal antiserum to M. gallisepticum, as well as by a monoclonal antibody to histidine. The polypeptide was purified by nickel-nitrilotriacetic acid (Ni-NTA) metal-affinity cromatography yielding a final product of nearly 90% of purity. [ABSTRACT FROM AUTHOR]

Anaplasma marginale is a rickettsia of Ehrlichias genogroup II. It parasites mature erythrocytes in bovines. There is not still an effective control method against the disease; thus it is of great importance to develop an immunogene able to prevent infection by this pathogen. There is also a need of having more sensitive diagnostic techniques which allow the detection of carrier animals in order to be used in cattle international movement towards areas free of the disease; as well as to know the prevalence of the disease in tropical and subtropical regions. Gene msp5 is represented in the genome as a simple copy; it is highly preserved among all Anaplasma species and all A. marginale strains; thus it is an important candidate for being used in diagnostic. In this paper, the amplification by PCR of such gene was carried out for the detection of Anaplasma marginale in 113 animals without clinical symptoms, from which 96 were positive to this microorganism, being the assay highly sensitive and specific. [ABSTRACT FROM AUTHOR]

Anaplasma marginale is a pathogen for cattle, causing severe economic losses in tropical and subtropical regions. The major surface proteins of initial bodies are involved in pathogen-host and tick-pathogen interactions and have been used as markers for the genetic characterization of Anaplasma marginale strains and for phylogenetic studies. MSP1a protein varies between strains of different geographical regions in the number and sequence of tandem repeated sequences in the amino-terminal region. In this study, 24 Anaplasma marginale strains were characterized using the sequence described for MSP1a protein. These results support the heterogeneity of Anaplasma marginale strains in endemic regions and that the phylogenetic analysis of tandem repeated sequences of this MSP1a protein does not result in clusters related to the geographical origin of strains, but helps to understand the genetic diversity and evolution of Anaplasma marginale. [ABSTRACT FROM AUTHOR]

Bordetella pertussis is the causal agent of whooping cough (pertussis), a highly contagious respiratory illness. Although the initial vaccines against the disease consisted of killed cells, nowadays many countries use acellular variants less reactogenic and more efficacious. Pertactin (Prn) is one of the B. pertussis's antigens implicated in protective immunity of most of these acellular vaccines. Prn is a polymorfic autotransporter protein of around 60 kD and 13 different variants have been described so far; Prn1 and Prn2 are two of the most studied variants. For obtaining acellular vaccine components it is necessary to develop high-levels antigen expression systems. With this purpose, one of the strategies followed is increasing the rate of transcription for these protein's genes and their number of copies in the cell. In this work prn1 and prn2 genes were inserted into the broad-host-range plasmid pMMB67EH under the regulation of fhaB and tac promoters. As a result it was obtained B. pertussis strains capable of expressing between 11 and 23 times more Prn than analyzed wild ones. It was also obtained E. coli strains in which Prn was detected in association with the cellular surface. The detection and quantification of pertactin antigen was performed by ELISA. [ABSTRACT FROM AUTHOR]

Heavy-metal dissemination in superficial sediments and subground water is considered as a worldwide problem and its solution constitutes a challenge for the environmental cleaning-up. Several heavy-metals are essential nutrients required in trace concentrations for bacteria (range of nanomolar); however they are toxic in concentrations higher than micromolar. Heavy metals are considered as a biological threat for microorganisms because these elements are not biodegradable, contrary to organic pollutants. Only microorganisms encoding heavy metal resistance genetic determinants are able to survive in environments with high concentrations of these elements. Currently, heavy metals containing wastes are treated basically by chemical and physical methods but these are complicated, expensive and their efficiency is low. Release of great volumes of liquid and solid wastes which still contain high amounts of heavy metals is another of the disadvantages of the aforementioned methods. Bioremediation of effluents and waste waters using heavy metal resistant microorganisms based technologies may provide an alternative for environmental protection. Microorganisms might be effective metal accumulators and evidences support that the biomass-based clean-up processes are economically viable. However , many aspects of metal-microbe interactions remain unknown and unexploited in biotechnology. The application of bioremediation processes required a deeper knowledge of the biotransformation pathways and genetic determinants encoded by organisms from indigenous microbial communities of these ecosystems. The aim of this paper is to review the molecular mechanisms of heavy metal resistance described in bacteria and their applications in bioremediation. [ABSTRACT FROM AUTHOR]

Escherichia coli is an important cause of diarrhoea in newborn and post weaning pigs, and it is responsible for significant economical losses at large-scale farms worldwide. In the present work, a characterization of Escherichia coli isolates was carried out in samples from pigs with diarrhoea syndrome in Villa Clara province. To accomplish this characterization, different diagnostic methods such as detection of genes encoding virulence factors, serotyped and study on pulsing-field gel electrophoresis (PFGE) were applied. Results showed that in the diarrhoeic processes caused by Escherichia coli affecting pigs during post-birth and post-weaning stages in different swine farms of Villa Clara province, the patotypes O141 H-STaSTb VT2 and O157 H19 VT2 were predominant. The relatively low incidence of enterotoxigenic E. coli (ETEC) and verotoxigenic E. coli (VTEC) in the analyzed samples allowed to infer that other etiological agents could be acting together with the group of E. coli isolate from the affected animals. Escherichia coli isolates from samples of pigs with diarrhoea in the population studied showed a restricted number of serogroups and serotypes and the majority of the seropatotypes evaluated presented a great genetic diversity due to the different clones with distinct electrophoresis patterns showed clone relationship among the isolates of one of the most prevailing detected serotypes in the farms located was evidenced in different geographical zones [ABSTRACT FROM AUTHOR]

Bacterial resistance is a public health problem causing high rates of morbidity and mortality in hospital settings. To the extent that different antibiotics are used, bacteria resistant to multiple drugs are selected. The development of new molecular genomic and proteomic tools such as real-time PCR, DNA pyrosequencing, mass spectrometry, DNA microarrays, and bioinformatics allow for more in-depth knowledge about the physiology and structure of bacteria and mechanisms involved in antibiotic resistance. These studies identify new targets for drugs and design specific antibiotics to provide more accurate treatments to combat infections caused by bacteria. Using these techniques, it will also be possible to rapidly identify genes that confer resistance to antibiotics, and to identify complex genetic structures, such as integrons that are involved in the spread of genes that confer multidrug-resistance. [ABSTRACT FROM AUTHOR]

El artículo discute la etiología de la enfermedad periodontal y las bacterias que se encuentran en la placa bacteriana subgingival. Se analizan las estructuras de la población bacteriana y la diversificación genética en las especies bacterianas. El artículo proporciona varias imágenes de las estructuras genéticas de las poblaciones bacterianas clonal, panmíctica y epidémica.