Capacidad de bacterias halófilas para capturar sodio in vitro y su posible aplicación en bioremediación en suelos salinos-sódicos / Ability of halophile bacteria to capture in Vitro sodium and its possible application in bioremediation of saline-sodic soil

Las prácticas agrícolas inadecuadas han sido la causa del aumento de los suelos salinos–sódicos en todo el planeta. Su recuperación se ha hecho principalmente cambiando el sodio por otro catión, generalmente calcio, remediando en forma mecánica y usando plantas halotolerantes. Aunque estas prácticas controlan en alguna medida el problema, no se ha podido hacer una recuperación efectiva en estos suelos. Este trabajo presenta como alternativa, el uso de bioremediación con bacterias halófilas. El objetivo de la investigación fue evaluar la capacidad de cinco especies de bacterias halófilas para capturar iones sodio in vitro y diseñar una propuesta para su posible aplicación en bioremediación de suelos sódicos y salinos. La captura del sodio se demostró comparando la concentración inicial de la solución de sodio sin inocular y la concentración de la misma con la bacteria inoculada a través de la técnica de espectroscopia de absorción atómica. Las bacterias que demostraron la capacidad de captura de sodio in vitro fueron: Vibrio alginolyticus, Vibrio metschnikovii, Flavimonas oryzihabitans y Agrobacterium tumefasciens. Serratia marcescens no demostró captura. La comprobación de la captura de sodio permitió hacer dos propuestas: diseñar un bioreactor con un consorcio microbiano que incluya las bacterias que capturaron sodio en el experimento y bacterias autóctonas presentes en los suelos salinos y sódicos; utilizar ingeniería genética para implantar el gen de bomba de sodio de la especie con mejor captura, en especies nativas existentes en este tipo de suelos.

Siderophores of halophilic archaea and their chemical characterization.

Nine halophilic archaea viz., Halobacterium salinarum, Halobacterium sp.1, Halobacterium sp.2, Halobaculum sp., Halococcus saccharolyticus, Halorubrum saccharovorum, Haloterrigena turkmenica, Halogeometricum sp. and Natrialba sp. isolated from marine salterns around Bhavnagar coast were screened for siderophore production. Five isolates viz., Halococcus saccharolyticus, Halorubrum saccharovorum, Haloterrigena turkmenica, Halogeometricum sp. and Natrialba sp. produced siderophores as evidenced by positive reaction in FeCl3 test, CAS assay and CAS agar plate test. Determination of chemical nature of siderophores by chemical assays and bioassays identified them as carboxylates. Quantification of siderophores indicated Halorubrum saccharovorum to be the maximum siderophore producer (2.62 RE mg/ml) and Halococcus saccharolyticus to be the least (1.33 RE mg/ml). The present study is the first report on siderophore production in Indian haloarchaeal strains. Mechanism of iron assimilation in four non-siderophore isolates still needs to be investigated further.

Kinetic mechanism of glucose dehydrogenase from Halobacterium salinarum.

The kinetic mechanism of glucose dehydrogenase (EC 1.1.1.47) from Halobacterium salinarum was studied by initial velocity and product inhibition methods. The results suggest that both, in the forward and reverse direction, the reaction mechanism is of Bi Bi sequential ordered type involving formation of ternary complexes. NADP+ adds first and NADPH formed dissociates from the enzyme last. For the reverse direction, NADPH adds first and NADP+ leaves last. Product inhibition experiments indicate that (a), the coenzymes compete for the same site and form of the enzyme and (b), ternary abortive complexes of enzyme-NADP(+)-glucono-delta-lactone and enzyme-NADPH-glucose are formed. All the other inhibitions are noncompetitive.

tRNA rRNA sequence matches from inter- and intraspecies comparisons suggest common origins for the two RNAs

1. Comparisons were made of the results of searches within and among different species of organisms for sequence matches between transfer RNAs and ribosomal RNAs. The purpose was to determine whether the matching sequences might result form selection acting on the two RNAs within a common cellular environment. 2. The results indicate that most matches do not reflect such selection. The matches described we more frequent than those found in searches among randomized sequences and the frequency of intraspecific matches was not significantly higher than that of interspecific matches. 3. The matches ara thought to identify conserved vestiges of a molecule or molecules ancestral to both classes of RNAs (Bloch, D.P., McArthur, B. and Mirrop, S (1985), BioSystems, 17:209-225). The matching sequences are interpreted as homologies

novel obligate halo-thermophilic bacterium from Egyptian soils

An extreme halophilic thermophilic bacterium was isolated from an Egyptian soil. It is pigmented, pleomorphic, Gram negativer rods. It grows well at an optimum concentration of 25-30% NaCl with a minimum of 15% and a maximum of 35% NaCl. The optimum temperature for growth is 45 degrees. The organism is suggestive of being belonging to the genus Halobacterium, while distinguished from the currently recognized species, since it is an obligate requiring casein and/or casamino acids for growth; it is able to hydrolyase starch; it is unable to grow on the standard medium which support the growth of many isolates of the halobacteriaceae; it is susceptible to nitrofurantoin and it is resistant to all the tested antibiotics. On the basis of its obligacy for casein and/or casamino acids as well as its thermophilic nature. It was suggested to be a novel strain belonging to the genus halobacterium

Cell surface hydrophobicity of halobacteria

La cromatografía de interacción hidrofóbica se ha aplicado al estudio de la hidrofobicidad de la superficie celular de las halobacterias aisladas de varios sitios en Baja California Sur, México. Los resultados muestran que esta técnica puede usarse para distinguir cepas de halobacterias. También aplicamos este método para evaluar las diferencias entre Halobacterium halobium, H. salinarum y H. cutirubrum, consideradas en la 9ª edición del manual de Bergey como una sola especie. Los resultados obtenidos refuerzan la idea de que estos microorganismos son aislamientos diferentes de la misma especie