<i>Delftia</i> sp LCW, a strain isolated from a constructed wetland shows novel properties for dimethylphenol isomers degradation

BACKGROUND: Dimethylphenols (DMP) are toxic compounds with high environmental mobility in water and one of the main constituents of effluents from petro- and carbochemical industry. Over the last few decades, the use of constructed wetlands (CW) has been extended from domestic to industrial wastewater treatments, including petro-carbochemical effluents. In these systems, the main role during the transformation and mineralization of organic pollutants is played by microorganisms. Therefore, understanding the bacterial degradation processes of isolated strains from CWs is an important approach to further improvements of biodegradation processes in these treatment systems. RESULTS: In this study, bacterial isolation from a pilot scale constructed wetland fed with phenols led to the identification of Delftia sp. LCW as a DMP degrading strain. The strain was able to use the o-xylenols 3,4-DMP and 2,3-DMP as sole carbon and energy sources. In addition, 3,4-DMP provided as a co-substrate had an effect on the transformation of other four DMP isomers. Based on the detection of the genes, proteins, and the inferred phylogenetic relationships of the detected genes with other reported functional proteins, we found that the phenol hydroxylase of Delftia sp. LCW is induced by 3,4-DMP and it is responsible for the first oxidation of the aromatic ring of 3,4-, 2,3-, 2,4-, 2,5- and 3,5-DMP. The enzyme may also catalyze both monooxygenation reactions during the degradation of benzene. Proteome data led to the identification of catechol meta cleavage pathway enzymes during the growth on ortho DMP, and validated that cleavage of the aromatic rings of 2,5- and 3,5-DMPs does not result in mineralization. In addition, the tolerance of the strain to high concentrations of DMP, especially to 3,4-DMP was higher than that of other reported microorganisms from activated sludge treating phenols. CONCLUSIONS: LCW strain was able to degraded complex aromatics compounds. DMPs and benzene are reported for the first time to be degraded by a member of Delftia genus. In addition, LCW degraded DMPs with a first oxidation of the aromatic rings by a phenol hydroxylase, followed by a further meta cleavage pathway. The higher resistance to DMP toxicity, the ability to degrade and transform DMP isomers and the origin as a rhizosphere bacterium from wastewater systems, make LCW a suitable candidate to be used in bioremediation of complex DMP mixtures in CWs systems

Inmunoestimulantes en teleosteos: Probióticos, b-glucanos y LPS

Immunostimulants mainly consist of microorganisms� structural elements whose principle is based on stimulating the innate immune system, leading to an improvement in animals� sanitary state and increased resistance to pathogens. â-glucans and lipopolysaccharides are some of the most used immunostimulants in the fish industry, including beneficial bacteria called probiotics. Studies on fish have been focused on the in vitro and in vivo evaluation of cellular and humoral responses, modulating gene transcription and the effects of resistance regarding pathogens of interest, usually having positive effects on the fishes� immunological state and resistance to disease. The proposed review was aimed at investigating the mechanisms of action of some of the most used immunostimulants, conceptualising their use in aquiculture and discussing recent work on the topic thereby forming the basis for proposing pertinent, feasible investigations for tackling some problems in the fish-farming health/sanitation area.Os imunoestimulantes sao principalmente elementos estruturais de microorganismos, que basam seu principio na estimulacao do sistema imune inato, apresentando melhoramento do estado da saude dos animais e maior resistencia a patogenos. Entre os imunoestimulantes mais utilizados em peixes estao as �À-glucanas, os lipopolissacarideos e incluso as bacterias beneficas, chamados probioticos. Estudos feitos em peixes tem-se centrado em avaliacoes in vitro e in vivo das respostas celulares e humorais, a modulacao da transcricao de genes e os efeitos da resistencia aos agentes patogenicos de interesse, em geral, mostrando efeitos positivos sobre o estado imunitario dos peixes e a resistencia a doencas. A revisao proposta tenta indagar sobre os mecanismos de acao de alguns imunoestimulantes de mais uso, sua utilizacao em aquicultura e discutir acerca de trabalhos recentes sobre o assunto, que servira de base para a formulacao de pesquisas relevantes e viaveis para resolver alguns problemas na area da saude de peixes.Los inmunoestimulantes son principalmente, elementos estructurales de microorganismos, que basan su principio en la estimulacion del sistema inmune innato, mostrando mejoramiento del estado sanitario de los animales e incremento de la resistencia frente a patogenos. Dentro de los inmunoestimulantes mas utilizados en peces se encuentran los �À-glucanos, los lipopolisacaridos y se incluyen las bacterias beneficas, denominadas probioticos. Los estudios realizados en peces se han enfocado en evaluaciones in vitro e in vivo de las respuestas celulares y humorales, la modulacion de la transcripcion genica y los efectos de resistencia frente a patogenos de interes; mostrando de manera general efectos positivos sobre el estado inmunologico de los peces y resistencia a enfermedades. La revision propuesta intenta indagar sobre mecanismos de accion de algunos inmunoestimulantes de mayor uso, conceptualizar su uso en acuicultura y discutir acerca de trabajos recientes sobre el tema, lo cual servira de base en el planteamiento de investigaciones pertinentes y factibles para abordar algunas problematicas en el area sanitaria piscicola

Inmunoestimulantes en teleosteos: Probióticos, β-glucanos y LPS

Titulo en ingles:  Immunostimulants in teleost fish: probiotics, β-glucans and lipopolysaccharidesTitulo en portugues:  Imunoestimulantes em teleósteos: Probióticos, Beta-glucanas e LPSResumen:  Los inmunoestimulantes son principalmente, elementos estructurales de microorganismos, que basan su principio en la estimulación del sistema inmune innato, mostrando mejoramiento del estado sanitario de los animales e incremento de la resistencia frente a patógenos. Dentro de los inmunoestimulantes más utilizados en peces se encuentran los β-glucanos, los lipopolisacáridos y se incluyen las bacterias benéficas, denominadas probióticos. Los estudios realizados en peces se han enfocado en evaluaciones in vitro e in vivo de las respuestas celulares y humorales, la modulación de la transcripción génica y los efectos de resistencia frente a patógenos de interés; mostrando de manera general efectos positivos sobre el estado inmunológico de los peces y resistencia a enfermedades. La revisión propuesta intenta indagar sobre mecanismos de acción de algunos inmunoestimulantes de mayor uso, conceptualizar su uso en acuicultura y discutir acerca de trabajos recientes sobre el tema, lo cual servirá de base en el planteamiento de investigaciones pertinentes y factibles para abordar algunas problemáticas en el área sanitaria piscícola.Palabras clave: acuicultura, enfermedad, peces, sanidad, sistema inmune.Abstract:  Immunostimulants mainly consist of microorganisms’ structural elements whose principle is based on stimulating the innate immune system, leading to an improvement in animals’ sanitary state and increased resistance to pathogens. β-glucans and lipopolysaccharides are some of the most used immunostimulants in the fish industry, including beneficial bacteria called probiotics. Studies on fish have been focused on the in vitro and in vivo evaluation of cellular and humoral responses, modulating gene transcription and the effects of resistance regarding pathogens of interest, usually having positive effects on the fishes’ immunological state and resistance to disease. The proposed review was aimed at investigating the mechanisms of action of some of the most used immunostimulants, conceptualising their use in aquiculture and discussing recent work on the topic thereby forming the basis for proposing pertinent, feasible investigations for tackling some problems in the fish-farming health/sanitation area.Key words: aquiculture, disease, fish, health/sanitation, immune system.Resumo:  Os imunoestimulantes são principalmente elementos estruturais de microorganismos, que basam seu principio na estimulação do sistema imune inato, apresentando melhoramento do estado da saúde dos animais e maior resistência a patógenos. Entre os imunoestimulantes mais utilizados em peixes estão as β-glucanas, os lipopolissacarídeos e incluso as bactérias benéficas, chamados probióticos. Estudos feitos em peixes têm-se centrado em avaliações in vitro e in vivo das respostas celulares e humorais, a modulação da transcrição de genes e os efeitos da resistência aos agentes patogênicos de interesse, em geral, mostrando efeitos positivos sobre o estado imunitário dos peixes e a resistência a doenças. A revisão proposta tenta indagar sobre os mecanismos de ação de alguns imunoestimulantes de mais uso, sua utilização em aquicultura e discutir acerca de trabalhos recentes sobre o assunto, que servirá de base para a formulação de pesquisas relevantes e viáveis para resolver alguns problemas na área da saúde de peixes.Palavras chave: aqüicultura, doença, peixe, saúde, sistema imunológico.Titulo en ingles:  Immunostimulants in teleost fish: probiotics, β-glucans and lipopolysaccharidesTitulo en portugues:  Imunoestimulantes em teleósteos: Probióticos, Beta-glucanas e LPSResumen:  Los inmunoestimulantes son principalmente, elementos estructurales de microorganismos, que basan su principio en la estimulación del sistema inmune innato, mostrando mejoramiento del estado sanitario de los animales e incremento de la resistencia frente a patógenos. Dentro de los inmunoestimulantes más utilizados en peces se encuentran los β-glucanos, los lipopolisacáridos y se incluyen las bacterias benéficas, denominadas probióticos. Los estudios realizados en peces se han enfocado en evaluaciones in vitro e in vivo de las respuestas celulares y humorales, la modulación de la transcripción génica y los efectos de resistencia frente a patógenos de interés; mostrando de manera general efectos positivos sobre el estado inmunológico de los peces y resistencia a enfermedades. La revisión propuesta intenta indagar sobre mecanismos de acción de algunos inmunoestimulantes de mayor uso, conceptualizar su uso en acuicultura y discutir acerca de trabajos recientes sobre el tema, lo cual servirá de base en el planteamiento de investigaciones pertinentes y factibles para abordar algunas problemáticas en el área sanitaria piscícola.Palabras clave: acuicultura, enfermedad, peces, sanidad, sistema inmune.Abstract:  Immunostimulants mainly consist of microorganisms’ structural elements whose principle is based on stimulating the innate immune system, leading to an improvement in animals’ sanitary state and increased resistance to pathogens. β-glucans and lipopolysaccharides are some of the most used immunostimulants in the fish industry, including beneficial bacteria called probiotics. Studies on fish have been focused on the in vitro and in vivo evaluation of cellular and humoral responses, modulating gene transcription and the effects of resistance regarding pathogens of interest, usually having positive effects on the fishes’ immunological state and resistance to disease. The proposed review was aimed at investigating the mechanisms of action of some of the most used immunostimulants, conceptualising their use in aquiculture and discussing recent work on the topic thereby forming the basis for proposing pertinent, feasible investigations for tackling some problems in the fish-farming health/sanitation area.Key words: aquiculture, disease, fish, health/sanitation, immune system.Resumo:  Os imunoestimulantes são principalmente elementos estruturais de microorganismos, que basam seu principio na estimulação do sistema imune inato, apresentando melhoramento do estado da saúde dos animais e maior resistência a patógenos. Entre os imunoestimulantes mais utilizados em peixes estão as β-glucanas, os lipopolissacarídeos e incluso as bactérias benéficas, chamados probióticos. Estudos feitos em peixes têm-se centrado em avaliações in vitro e in vivo das respostas celulares e humorais, a modulação da transcrição de genes e os efeitos da resistência aos agentes patogênicos de interesse, em geral, mostrando efeitos positivos sobre o estado imunitário dos peixes e a resistência a doenças. A revisão proposta tenta indagar sobre os mecanismos de ação de alguns imunoestimulantes de mais uso, sua utilização em aquicultura e discutir acerca de trabalhos recentes sobre o assunto, que servirá de base para a formulação de pesquisas relevantes e viáveis para resolver alguns problemas na área da saúde de peixes.Palavras chave: aqüicultura, doença, peixe, saúde, sistema imunológico

Concentración óptima de sustancias de bajo costo para mejorar el transporte de dos especies de peces ornamentales

In order to improve the quality of transport of two ornamental fish species of economic interest in the region of the Orinoco, Paracheirodon axelrodi and Otocinclus sp., the effect of different concentrations of low cost substances: eugenol (0.25 and 0.5 mg/L), sodium cloride (0.5, 1.5 and 2.5 g/L) and calcium carbonate (0.1, 0.5 and 1 g/L) by two periods Adiof transport (12 and 24 h), was evaluated on the water quality, ion loss to the water, resistance to hyperosmotic stress and survival after transport and 7 days later. As a result the addition of 0.5 mg/L of eugenol showed improved survival in 7 days after transport and a decreased ion loss to water in Otocinclus sp. It also reduced ammonium after 24 h transport in P. axelrodi. Additionally, the addition of 1.5 g/L salt was effective to improve survival after unpacking and after 7 days in both species, and greater resistance to hyperosmotic exposure in P. axelrodi. Finally, 0.1 g/L of calcium carbonate gave a higher resistance to hyperosmotic stress (P. axelrodi) and a better survival for both species, despite its poor solubility. It can be concluded that the three substances used in appropriate concentrations can improve the quality of transport, being the salt the substance with most beneficial effects on survival and stress resistance.A fim de melhorar a qualidade do transporte de duas espécies de peixes ornamentais de interesse econômico na região do Orinoco, Paracheirodon axelrodi e Otocinclus sp, testou-se o efeito de diferentes concentrações de substâncias de baixo custo: eugenol (0.25 e 0.5 mg/L), sal (0.5, 1.5 e 2.5 g/L) e carbonato de cálcio (0.1, 0.5 e 1 g/L) por dois períodos de transporte (12 e 24 h), sobre a qualidade da água, a perda de íons na água, a resistência a estrese hiperósmico e a sobrevivência após o transporte e depois de 7 dias. A adição de 0.5 mg/L de eugenol melhorou a sobrevivência após 7 dias do transporte e reduziu a perda de íons na água em Otocinclus sp. Também reduziu a amônia após 24 h de transporte em P.axelrodi. Além disso, a adição de 1.5 g de sal/L foi eficaz para melhorar a sobrevivência ao final do transporte e após 7 dias em ambas espécies, e proporcionou uma maior resistência à exposição hiperósmica em P. axelrodi. Finalmente 0.1 g/L de carbonato de cálcio deu uma maior resistência ao estresse hiperósmico em P. axelrodi e melhor sobrevida para ambas espécies, apesar de sua baixa solubilidade. Pode concluir-se que as três substâncias utilizadas em concentrações adequadas podem melhorar a qualidade do transporte, sendo o sal a substância de com más efeitos benéficos para a sobrevivência e resistência ao estresse.Con el propósito de mejorar la calidad del transporte de dos especies de peces ornamentales de interés económico de la región del Orinoco, Paracheirodon axelrodi y Otocinclus sp, se probó el efecto de diferentes concentraciones de sustancias de bajo costo: eugenol (0.25 y 0.5 mg/L); cloruro de sodio (0.5; 1.5 y 2.5 g/L) y carbonato de calcio (0,1; 0.5 y 1 g/L), por dos periodos de transporte (12 y 24 h), sobre la calidad de agua, pérdida de iones en el agua, resistencia a eventos de estrés hiperosmótico y sobrevivencia postransporte. La adición de 0.5 mg/L de eugenol mostró el mejoramiento en la sobrevivencia 7 días posteriores al transporte y una disminución en la pérdida de iones al agua en Otocinclus sp., también mostró una reducción del amonio luego del transporte de 24 h en P. axelrodi. Adicionalmente, la adición de 1.5 g/L de sal resultó efectiva para mejorar la sobrevivencia posterior al desempaque y posterior a los 7 días en ambas especies, y mayor resistencia a la exposición hiperosmótica en P. axelrodi. Por último 0.1 g/L de carbonato de calcio otorgó una mayor resistencia a eventos de estrés (P. axelrodi) y mejor sobrevivencia de los peces (para ambas especies), a pesar de su poca solubilidad. Se puede concluir que las tres sustancias usadas en concentraciones adecuadas pueden mejorar la calidad del transporte, siendo la sal la sustancia con mayores efectos benéficos sobre la sobrevivencia y la resistencia al estrés, un siguiente paso para la recomendación de estas sustancias, sería evaluar su uso en mezclas para determinar una posible sinergia de estas sustancias

Estudio clínico y hematológico de una infección experimental con Aeromonas hydrophila y Edwardsiella tarda en tilapia, Oreochromis sp

Opportunistic bacteria as A. hydrophila and E. tarda are related to haemorrhagic septicaemia outbreaks in cultured tilapias in our country, being the aetiological agents of highest participation on the diagnosis of infection disease in cultures of Oreochromis sp., in Departamento del Meta. This article reports a clinical and hematological study of tilapia hybrid (50-70g) during the experimental infection with Aeromonas hydrophila and Edwardsiella tarda made by intraperitoneal inoculation of 7 x 10(8) CFU/ml and 2 x 10(8) CFU/ml of A. hydrophila and E. tarda, respectively. From 11 hours infected fish showed paleness, lethargy, gasping, increased respiratory frequency and loss of swim axis. At hematological examination, infected animals showed severe lymphopenia, increased monocytes, hemolysis, increased blastic cells, karyorrhexis, hypochromia and anisocytosis, which is characteristic of a hypochromic anemia and erythroclasia described in fish bacterial infection. At necropsy examination, fish inoculated with bacteria showed: hemorrhages on the base of fins and internal organs, pale and mottled liver, increased abdominal fluid and blood-stained fluid in intestine, unlike control animals that did not show these lesions. Additionally, hepatomegaly was observed in experimental infected animals, even though there were not significance differences in the hepatosomatic index of these animals with respect to control. In treatment of E. tarda, whitish nodules with multifocal distribution were observed in spleen. During the present study, hybrid tilapias infected with E. tarda y A. hydrophila, showed a clinical condition compatible with haemorrhagic septicaemia, possibly associated to extracellular products (ECP), such as hemolysins and aerolisyns, with hemolytic and cytotoxic activity in fish, among other factors. This work is an approximation to a model of study of bacterial disease of tilapia with pathogenic strains isolated in the region.Las bacterias oportunistas como A. hydrophila y E. tarda se relacionan con brotes de septicemia hemorrágica en tilapias de cultivo en nuestro país, siendo los agentes de mayor participación en enfermedades infecciosas en cultivos de Oreochromis sp en el Departamento del Meta. Este artículo reporta un estudio clínico y hematológico de tilapias híbridas (50 - 70g) durante la infección experimental con Aeromonas hydrophila y Edwardsiella tarda; realizada por medio de inoculaciones intraperitoneales de 7 x 10(8) UFC/ml y 2 x 10(8) UFC/ml, de A. hydrophila y E. tarda respectivamente. A partir de las 11 horas los peces infectados presentaron: palidez, letargo, boqueo, aumento de la frecuencia opercular y pérdida de eje de nado. En el examen hematológico, los animales infectados presentaron linfopenia severa, aumento de monocitos, hemólisis, abundantes células blásticas, marcada carriorrexis, hipocromía y anisocitosis, características de una anemia hipocrómica y eritroclasia descrita en infecciones bacterianas en peces. Al examen de necropsia, los peces inoculados con las bacterias evidenciaron: hemorragias en la base de las aletas y órganos internos, palidez e hígado moteado, aumento de líquido abdominal y líquido sanguinolento en el intestino, a diferencia de animales control que no presentaron estas lesiones. Adicionalmente, se observó hepatomegalia en animales infectados, aunque no hubo diferencias significativas en el índice hepatosomático de estos animales con respecto a animales control. En el tratamiento de E. tarda, en el bazo se observaron nódulos blanquecinos de distribución multifocal. Durante el presente estudio tilapias hibridas infectadas con E. tarda y A. hydrophila, mostraron un cuadro clínico compatible con septicemia hemorrágica, posiblemente ocasionado por a productos extracelulares (PEC) tales como hemolisinas y aerolisinas con actividad hemolítica y citotóxica en peces, entre otros factores. Este trabajo constituye una aproximación a un modelo de estudio de enfermedad bacteriana de tilapias con cepas patógenas aisladas en la región

Estudio clínico y hematológico de una infección experimental con Aeromonas hydrophila y Edwardsiella tarda en tilapia, Oreochromis sp

Titulo en ingles:  Clinical and hematological study of experimental infection with Aeromonas hydrophila and Edwardsiella tarda on tilapia Oreochromis sp.RESUMEN:   Las bacterias oportunistas como A. hydrophila y E. tarda se relacionan con brotes de septicemia hemorrágica en tilapias de cultivo en nuestro país, siendo los agentes de mayor participación en enfermedades infecciosas en cultivos de Oreochromis sp en el Departamento del Meta. Este artículo reporta un estudio clínico y hematológico de tilapias híbridas (50 - 70g) durante la infección experimental con Aeromonas hydrophila y Edwardsiella tarda; realizada por medio de inoculaciones intraperitoneales de 7 x 108 UFC/ml y 2 x 108 UFC/ml, de A. hydrophila y E. tarda respectivamente. A partir de las 11 horas los peces infectados presentaron: palidez, letargo, boqueo, aumento de la frecuencia opercular y pérdida de eje de nado. En el examen hematológico, los animales infectados presentaron linfopenia severa, aumento de monocitos, hemólisis, abundantes células blásticas, marcada carriorrexis, hipocromía y anisocitosis, características de una anemia hipocrómica y eritroclasia descrita en infecciones bacterianas en peces. Al examen de necropsia, los peces inoculados con las bacterias evidenciaron: hemorragias en la base de las aletas y órganos internos, palidez e hígado moteado, aumento de líquido abdominal y líquido sanguinolento en el intestino, a diferencia de animales control que no presentaron estas lesiones. Adicionalmente, se observó hepatomegalia en animales infectados, aunque no hubo diferencias significativ as en el índice hepatosomático de estos animales con respecto a animales control. En el tratamiento de E. tarda, en el bazo se observaron nódulos blanquecinos de distribución multifocal. Durante el presente estudio tilapias hibridas infectadas con E. tarda y A. hydrophila, mostraron un cuadro clínico compatible con septicemia hemorrágica, posiblemente ocasionado por a productos extracelulares (PEC) tales como hemolisinas y aerolisinas con actividad hemolítica y citotóxica en peces, entre otros factores. Este trabajo constituye una aproximación a un modelo de estudio de enfermedad bacteriana de tilapias con cepas patógenas aisladas en la región.Palabras clave: Bacteria, hematología, septicemia, tilapia híbrida.ABSTRACT:  Opportunistic bacteria as A. hydrophila and E. tarda are related to haemorrhagic septicaemia outbreaks in cultured tilapias in our country, being the aetiological agents of highest participation on the diagnosis of infection disease in cultures of Oreochromis sp., in Departamento del Meta. This article reports a clinical and hematological study of tilapia hybrid (50-70g) during the experimental infection with Aeromonas hydrophila and Edwardsiella tarda made by intraperitoneal inoculation of 7 x 108 CFU/ml and 2 x 108 CFU/ ml of A. hydrophila and E. tarda, respectively. From 11 hours infected fish showed paleness, lethargy, gasping, increased respiratory frequency and loss of swim axis. At hematological examination, infected animals showed severe lymphopenia, increased monocytes, hemolysis, increased blastic cells, karyor- rhexis, hypochromia and anisocytosis, which is characteristic of a hypochromic anemia and erythroclasia described in fish bacterial infection. At necropsy examination, fish inoculated with bacteria showed: hem- orrhages on the base of fins and internal organs, pale and mottled liver, increased abdominal fluid and blood-stained fluid in intestine, unlike control animals that did not show these lesions. Additionally, hepatome- galy was observed in experimental infected animals, even though there were not significance differences in the hepatosomatic index of these animals with respect to control. In treatment of E. tarda, whitish nodules with multifocal distribution were observed in spleen. During the present study, hybrid tilapias infected with E. tarda y A. hydrophila, showed a clinical condition compatible with haemorrhagic septicaemia, possibly associated to extracellular products (ECP), such as hemolysins and aerolisyns, with hemolytic and cyto- toxic activity in fish, among other factors. This work is an approximation to a model of study of bacterial disease of tilapia with pathogenic strains isolated in the region.Key words: Bacteria, hematology, septicaemia, Oreochromis sp., tilapia hybrid.Titulo en ingles:  Clinical and hematological study of experimental infection with Aeromonas hydrophila and Edwardsiella tarda on tilapia Oreochromis sp.RESUMEN:   Las bacterias oportunistas como A. hydrophila y E. tarda se relacionan con brotes de septicemia hemorrágica en tilapias de cultivo en nuestro país, siendo los agentes de mayor participación en enfermedades infecciosas en cultivos de Oreochromis sp en el Departamento del Meta. Este artículo reporta un estudio clínico y hematológico de tilapias híbridas (50 - 70g) durante la infección experimental con Aeromonas hydrophila y Edwardsiella tarda; realizada por medio de inoculaciones intraperitoneales de 7 x 108 UFC/ml y 2 x 108 UFC/ml, de A. hydrophila y E. tarda respectivamente. A partir de las 11 horas los peces infectados presentaron: palidez, letargo, boqueo, aumento de la frecuencia opercular y pérdida de eje de nado. En el examen hematológico, los animales infectados presentaron linfopenia severa, aumento de monocitos, hemólisis, abundantes células blásticas, marcada carriorrexis, hipocromía y anisocitosis, características de una anemia hipocrómica y eritroclasia descrita en infecciones bacterianas en peces. Al examen de necropsia, los peces inoculados con las bacterias evidenciaron: hemorragias en la base de las aletas y órganos internos, palidez e hígado moteado, aumento de líquido abdominal y líquido sanguinolento en el intestino, a diferencia de animales control que no presentaron estas lesiones. Adicionalmente, se observó hepatomegalia en animales infectados, aunque no hubo diferencias significativ as en el índice hepatosomático de estos animales con respecto a animales control. En el tratamiento de E. tarda, en el bazo se observaron nódulos blanquecinos de distribución multifocal. Durante el presente estudio tilapias hibridas infectadas con E. tarda y A. hydrophila, mostraron un cuadro clínico compatible con septicemia hemorrágica, posiblemente ocasionado por a productos extracelulares (PEC) tales como hemolisinas y aerolisinas con actividad hemolítica y citotóxica en peces, entre otros factores. Este trabajo constituye una aproximación a un modelo de estudio de enfermedad bacteriana de tilapias con cepas patógenas aisladas en la región.Palabras clave: Bacteria, hematología, septicemia, tilapia híbrida.ABSTRACT:  Opportunistic bacteria as A. hydrophila and E. tarda are related to haemorrhagic septicaemia outbreaks in cultured tilapias in our country, being the aetiological agents of highest participation on the diagnosis of infection disease in cultures of Oreochromis sp., in Departamento del Meta. This article reports a clinical and hematological study of tilapia hybrid (50-70g) during the experimental infection with Aeromonas hydrophila and Edwardsiella tarda made by intraperitoneal inoculation of 7 x 108 CFU/ml and 2 x 108 CFU/ ml of A. hydrophila and E. tarda, respectively. From 11 hours infected fish showed paleness, lethargy, gasping, increased respiratory frequency and loss of swim axis. At hematological examination, infected animals showed severe lymphopenia, increased monocytes, hemolysis, increased blastic cells, karyor- rhexis, hypochromia and anisocytosis, which is characteristic of a hypochromic anemia and erythroclasia described in fish bacterial infection. At necropsy examination, fish inoculated with bacteria showed: hem- orrhages on the base of fins and internal organs, pale and mottled liver, increased abdominal fluid and blood-stained fluid in intestine, unlike control animals that did not show these lesions. Additionally, hepatome- galy was observed in experimental infected animals, even though there were not significance differences in the hepatosomatic index of these animals with respect to control. In treatment of E. tarda, whitish nodules with multifocal distribution were observed in spleen. During the present study, hybrid tilapias infected with E. tarda y A. hydrophila, showed a clinical condition compatible with haemorrhagic septicaemia, possibly associated to extracellular products (ECP), such as hemolysins and aerolisyns, with hemolytic and cyto- toxic activity in fish, among other factors. This work is an approximation to a model of study of bacterial disease of tilapia with pathogenic strains isolated in the region.Key words: Bacteria, hematology, septicaemia, Oreochromis sp., tilapia hybrid

Delftia sp. LCW, a strain isolated from a constructed wetland shows novel properties for dimethylphenol isomers degradation.

BACKGROUND: Dimethylphenols (DMP) are toxic compounds with high environmental mobility in water and one of the main constituents of effluents from petro- and carbochemical industry. Over the last few decades, the use of constructed wetlands (CW) has been extended from domestic to industrial wastewater treatments, including petro-carbochemical effluents. In these systems, the main role during the transformation and mineralization of organic pollutants is played by microorganisms. Therefore, understanding the bacterial degradation processes of isolated strains from CWs is an important approach to further improvements of biodegradation processes in these treatment systems. RESULTS: In this study, bacterial isolation from a pilot scale constructed wetland fed with phenols led to the identification of Delftia sp. LCW as a DMP degrading strain. The strain was able to use the o-xylenols 3,4-DMP and 2,3-DMP as sole carbon and energy sources. In addition, 3,4-DMP provided as a co-substrate had an effect on the transformation of other four DMP isomers. Based on the detection of the genes, proteins, and the inferred phylogenetic relationships of the detected genes with other reported functional proteins, we found that the phenol hydroxylase of Delftia sp. LCW is induced by 3,4-DMP and it is responsible for the first oxidation of the aromatic ring of 3,4-, 2,3-, 2,4-, 2,5- and 3,5-DMP. The enzyme may also catalyze both monooxygenation reactions during the degradation of benzene. Proteome data led to the identification of catechol meta cleavage pathway enzymes during the growth on ortho DMP, and validated that cleavage of the aromatic rings of 2,5- and 3,5-DMPs does not result in mineralization. In addition, the tolerance of the strain to high concentrations of DMP, especially to 3,4-DMP was higher than that of other reported microorganisms from activated sludge treating phenols. CONCLUSIONS: LCW strain was able to degraded complex aromatics compounds. DMPs and benzene are reported for the first time to be degraded by a member of Delftia genus. In addition, LCW degraded DMPs with a first oxidation of the aromatic rings by a phenol hydroxylase, followed by a further meta cleavage pathway. The higher resistance to DMP toxicity, the ability to degrade and transform DMP isomers and the origin as a rhizosphere bacterium from wastewater systems, make LCW a suitable candidate to be used in bioremediation of complex DMP mixtures in CWs systems