RESUMO
Halophilic bacteria are microorganisms that grow optimally in the presence of the very high concentration of sodium chloride. Halophiles are vital sources of various enzymes including hydrolases, which are very stable and catalytically highly efficient at high salt concentration and other extreme conditions such as high temperature, pH and presence of organic solvents. Several hydrolases such as amylases, proteases, and lipases have been obtained from halophilic bacteria and are commonly used for various industrial applications. We initiated a screening to isolate and characterize the halophilic bacteria from the Red Sea, which is one of the saltiest bodies of water in the world. Water and soil samples, collected from the Red Sea coast, Jeddah, Saudi Arabia, were screened for isolation of halophilic bacteria. Ten bacterial isolates were obtained, which were characterized by biochemical tests and 16S rRNA gene sequencing. Hydrolase producing bacteria among the isolates were screened by plate assay on starch and gelatin agar plates for amylase and protease, respectively. Two bacterial isolates i.e. Bacillus glycinifermentans S3 and Enterobacter cloacae W1were found to possess significant amylase and protease activity.
Bactérias halofílicas são microrganismos que crescem de maneira ideal na presença de uma concentração muito alta de cloreto de sódio. Halófilos são fontes vitais de várias enzimas, incluindo hidrolases, que são muito estáveis e cataliticamente altamente eficientes em alta concentração de sal e outras condições extremas, como alta temperatura, pH e presença de solventes orgânicos. Várias hidrolases como amilases, proteases e lipases foram obtidas a partir de bactérias halofílicas e são comumente usadas para várias aplicações industriais. Iniciamos uma triagem para isolar e caracterizar as bactérias halofílicas do Mar Vermelho, que é um dos corpos de água mais salgados do mundo. Amostras de água e solo, coletadas na costa do Mar Vermelho, Jeddah, na Arábia Saudita, foram examinadas quanto ao isolamento de bactérias halofílicas. Foram obtidos dez isolados bacterianos, caracterizados por testes bioquímicos e seqüenciamento do gene 16S rRNA. As bactérias produtoras de hidrolase entre os isolados foram triadas por ensaio em placa em placas de amido e ágar de gelatina para amilase e protease, respectivamente. Verificou-se que dois isolados bacterianos, isto é, Bacillus glycinifermentans S3 e Enterobacter cloacae W1, possuíam significativa atividade de amilase e protease.
Assuntos
Peptídeo Hidrolases , Halobacteriales , Salinidade , Amilases , HidrolasesRESUMO
Boeckella poopoensis Marsh, 1906 is the dominant copepod in saline lakes from northern Patagonia to southern Peru. It is a tolerant species, which has been registered at salinities between 20 and 90 g.L-1, and is important because it integrates the diet of flamingos and fishes of commercial and sport interest. The aims of this study were to analyze the characteristics of populations of B. poopoensis in the central region of Argentina and to establish their relationships with environmental parameters. Monthly samples during 2007 were taken in four temporary lakes of La Pampa province. Environmental parameters and density, size, biomass, number and size of eggs were determined. The salinity ranged between 13.38 and 32.90 g.L-1. In three lakes that had previously continuously contained water, B. poopoensis was registered throughout the whole study. In the fourth lake, which was filled in January, it was present only when salinity exceeded 15 g.L-1. The population of the lake that was filled differed from that of the other lakes in terms of the density and biomass of adults and copepodites. The number of ovigerous females represented a higher percentage of the population during the colonization of the lake that had been dried and these produced the highest number of eggs. In the three lakes in which B. poopoensis was always recorded, its characteristics were more influenced by the availability of food than by temperature or salinity. It was found that the strategies of the species vary throughout the hydroperiod; at the beginning, thrives when the salinity rises and impedes the presence of less tolerant species. At this point, the production of relatively small eggs is high, allowing rapid colonization. When the lakes become relatively stable, B. poopoensis allocates more energy to reach larger sizes and although egg production is not so high, they are larger, allowing it to maintain stable populations.
Boeckella poopoensis Marsh, 1906 es el copépodo dominante en lagos salinos desde el norte de Patagonia hasta el sur del Perú. Es una especie halotolerante registrada con salinidades entre 20 y 90 g.L-1 y es importante dado que integra la dieta de flamencos y de peces de interés comercial o deportivo. El objetivo del estudio fue analizar características de poblaciones de B. poopoensis en la región central de Argentina y establecer sus relaciones con los parámetros ambientales. Durante 2007 se tomaron muestras mensuales en cuatro lagos temporarios de la provincia de La Pampa. Se determinaron parámetros ambientales y la densidad, espectro de tallas, biomasa, número y tamaão de los huevos. La salinidad varió entre 13,38 and 32,90 g.L-1. En tres lagos que habían contenido agua en forma continua, B. poopoensis se registró durante todo el estudio. En el cuarto, que se llenó en enero, sólo estuvo presente cuando la salinidad superó 15 g.L-1. La densidad y biomasa de los adultos y copepoditos de la población del lago que se llenó difirieron de las de los otros. El número de hembras ovígeras representó un mayor porcentaje del total de la población durante la colonización del lago que había estado seco y fueron las que produjeron el mayor número de huevos. En los tres lagos en los que B. poopoensis se registró siempre, sus características fueron influidas más por la disponibilidad de alimento que por la temperatura o salinidad. Este estudio mostró que las estrategias de la especie varían a lo largo del hidroperíodo; al principio, prospera cuando la salinidad aumenta e impide la presencia de especies menos tolerantes. En este momento, la producción de abundantes huevos relativamente pequeãos permite una rápida colonización. Cuando los lagos alcanzan una relativa estabilidad, B. poopoensis destina más energía a alcanzar tamaãos mayores y, aunque la producción de huevos no es tan elevada son más grandes, permitiéndole mantener poblaciones estables.
RESUMO
In this study, two halophilic bacterial strains isolated from saline habitats in Argentina grew in the presence of gas oil. They were identified as Halomonas spp. and Nesterenkonia sp. by 16S ribosomal RNA sequencing. Chemotaxis towards gas oil was observed in Halomonas spp. by using swimming assays.
En el presente trabajo se aislaron dos cepas bacterianas halofílicas a partir de muestras obtenidas en ambientes salinos de Argentina, que crecieron en presencia de gasoil como única fuente de carbono. Las cepas aisladas se identificaron como Halomonas spp. y Nesterenkonia sp. mediante secuenciación del gen del ARN ribosomal 16S. En ensayos de swimming, las cepas del genero Halomonas spp. mostraron una respuesta quimiotáctica hacia el gas oil.
