Método de la microgota: usado con agar cromogénico es un procedimiento útil para el monitoreo sanitario en acuicultura

Indexación: Web of Science, Scielo.The microdot method is a downscaling methodology of traditional tenfold serial dilution procedure used in microbiology. The microdot method uses 100 mu L for serial dilution and count colonies in a spot of 10 mu L. In this study we counted colonies directly in a chromogenic agar plate to determine, at the same time, the presence and cell concentration of target bacteria required for sanitary monitoring of Chilean export fishery products. Due to among importers countries the most concerning bacteria included in sanitary monitoring are Escherichia coli, Listeria monocytogenes and Staphylococcus aureus, we used the chromogenic agar; CHROMagar ECC, CHROMagar Listeria and Baird Parker agar, respectively. The results shows no differences between quantitative results obtained with microdot and traditional method during the quantification of a culture of Escherichia coli (1.5 L). The sensitivity and specificity of the microdot method in association with each chromogenic agar was demonstrated in vitro with reference strains. In addition, the usefulness in sanitary monitoring of aquaculture procedures was evaluated in Artemia salina tanks. This method did not detected sanitary problems in surface water. Although other colonies grown in the chromogenic agar plate, their morphological and chromogenic properties not correspond to Escherichia coli, Listeria monocytogenes and Staphylococcus aureus, being identified as Salmonella enterica subsp. enterica, Microbacterium sp., Bacillus sp. and Staphylococcus pasteuri by 16S rRNA gene sequence analysis. Hence, we propose the microdot chromogenic method as a low cost, specific and reliable procedure for sanitary monitoring of aquaculture procedures.El método de la microgota es una versión a menor escala del procedimiento tradicional de dilución en serie en base diez utilizados en microbiología. El método realiza diluciones en 100 µL y cuenta colonias crecidas en una gota de 10 µL. En este estudio se cuentan colonias directamente en placas cromogénicas para determinar densidad celular y presencia de bacterias requeridas en vigilancia sanitaria de productos pesqueros chilenos de exportación. Entre los requisitos de países importadores, la vigilancia sanitaria involucra frecuentemente a Escherichia coli, Listeria monocytogenes y Staphylococcus aureus, por lo que se utilizan los agares cromogénicos; CHROMagar ECC, CHROMagar Listeria y agar Baird Parker para su identificación. La comparación entre el método de microgota y el método tradicional no muestra diferencias al evaluar un cultivo de Escherichia coli (1,5 L). La sensibilidad y especificidad del método de microgota junto a cada agar cromogénico se demostró in vitro con cepas de referencia. Además, en estanques de Artemia salina se evaluó la utilidad de este método para el monitoreo sanitario. Este método no mostró problemas sanitarios en aguas superficiales, aunque otras colonias crecieron en la placa de agar cromogénico. Sus propiedades morfológicas y cromogénicas no corresponden a Escherichia coli, Listeria monocytogenes y Staphylococcus aureus, siendo identificadas según el análisis de la secuencia del gen 16S rRNA como Salmonella enterica subsp. enterica, Microbacterium sp., Bacillus sp. y Staphylococcus pasteuri. Por lo tanto, se propone el método de microgota cromogénico como un procedimiento de bajo costo, específico y fiable para el monitoreo sanitario en acuicultura.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-560X2016000400009&lng=e

Goat Type Selection and Molecular Markers; a Solution for Milk Production in Recently Desertified Zones

Goat farming has been severely affected by Desertification, limiting their water and food resources and inducing physiological heat stress that reduces the doe milk yield. Does well adapted to heat stress would be a possible solution, but creole or indigenous goats from desert or arid areas produce between 0.5 to 1.5 L of milk per day, which is lower than the 3 L of milk per day produced by dairy goats like the Saanen breed. Nevertheless, in this chapter, we will discuss the disadvantages of introducing common dairy goats in dry places. Instead, we propose the introduction of desert goats from the Middle East or India, because they produce high-quality milk with low feed intake, making a profitable goat farming activity, and an opportunity to include crossbreeding strategies to improve the herd milk yield. Creole goats, on other hand, has been an underestimated livestock animal with a rich and unveil genetic patrimony that migth improve the herd milk yield. The effect of improved diets and extensive husbandry conditions remains unexplored in desert creole goats, and the use of advanced knowledge in goat genomics, genetic expression, and a wide variety of molecular markers can improve the studies on creole goats for crossbreeding strategies identifying the best traits involved in high-quality milk production and adaptation to dry environments. In this way, the synergy between goat type selection and molecular markers should boost goat farming in recently new desert or arid zones, counteracting the detrimental effects produced by the desertification

Draft Genome Sequence of Bacillus safensis RP10, Isolated from Soil in the Atacama Desert, Chile.

Genome analysis of Bacillus safensis RP10, a strain from the soil of Atacama Desert in northern Chile, reflects a bacterium adapted to live in soil containing high levels of heavy metals, high salt conditions, and low carbon and energy sources

Identification of species belonging to the Bifidobacterium genus by PCR-RFLP analysis of a hsp60 gene fragment

Abstract BACKGROUND: Bifidobacterium represents one of the largest genus within the Actinobacteria, and includes at present 32 species. These species share a high sequence homology of 16S rDNA and several molecular techniques already applied to discriminate among them give ambiguous results.The slightly higher variability of the hsp60 gene sequences with respect to the 16S rRNA sequences offers better opportunities to design or develop molecular assays, allowing identification and differentiation of closely related species. hsp60 can be considered an excellent additional marker for inferring the taxonomy of the members of Bifidobacterium genus. RESULTS: This work illustrates a simple and cheap molecular tool for the identification of Bifidobacterium species. The hsp60 universal primers were used in a simple PCR procedure for the direct amplification of 590 bp of the hsp60 sequence. The in silico restriction analysis of bifidobacterial hsp60 partial sequences allowed the identification of a single endonuclease (HaeIII) able to provide different PCR-restriction fragment length polymorphism (RFLP) patterns in the Bifidobacterium spp. type strains evaluated. The electrophoretic analyses allowed to confirm the different RFLP patterns. CONCLUSIONS: The developed PCR-RFLP technique resulted in efficient discrimination of the tested species and subspecies and allowed the construction of a dichotomous key in order to differentiate the most widely distributed Bifidobacterium species as well as the subspecies belonging to B. pseudolongum and B. animalis

Goat type: The key factor to produce goat milk with economic profitable purpose in arid and desert zones

ABSTRACT Produce goat milk with high standard in arid and desert zones is a difficult mission. The food and freshwater are scarce and high temperatures and low humidity finally affect milk yield. In addition, local cattle rancher has scarce technical knowledge about goat breeding and its management has been transmitted through generation mainly for auto-subsistence. Therefore, What is the first step to move this auto-consuming activity into to a profitable activity with economics gain?. We propose ; through the selection or creation of the right goat type well adapted to this environment and capable of produce between 2-3 L·d-1 of goat milk with high content of proteins. In this review we analyses the diversity of goat type and its genetics and other productive characteristic over milk production. Especial emphasis about αS1-casein gene polymorphism, its effect on quality milk and the characteristics of some goat types that habit in arid and desert zones, was discussed.RESUMEN Producir leche de cabra con altos estándares en zonas áridas y desérticas es una misión difícil. Los alimentos y el agua dulce son escasos y las altas temperaturas y baja humedad afectan finalmente el rendimiento lechero. Además, los ganaderos locales tienen escasos conocimientos técnicos sobre la cría de cabras y sus procesos de manejo han sido transmitidos a través de las generaciones principalmente para auto-subsistencia. Por lo tanto, ¿Cuál es el primer paso para mover esta actividad de auto consumo hacía una actividad productiva con ganancias económicas? Nosotros proponemos una respuesta; a través de la selección o creación de la cabra adecuada a este ambiente y que produzca entre 2-3 litros de leche por día y con alto contenido de proteína. En esta revisión analizamos la diversidad de tipos de cabra, su genética y otras características productivas sobre la producción de leche de cabra. Especial énfasis fue hecho acerca del polimorfismo del gen αS1-caseina, su efecto sobre la calidad de la leche y las características de algunos tipos de cabra que habitan en zonas áridas y desérticas

Cooperative Uptake of Microcin E492 by Receptors FepA, Fiu, and Cir and Inhibition by the Siderophore Enterochelin and Its Dimeric and Trimeric Hydrolysis Products

Microcin E492 uptake by FepA, Fiu, and Cir is cooperative, with FepA being the main receptor. No TonB-mediated interaction with the ferric catecholate receptors is needed for microcin to exert action at the cytoplasmic membrane. Microcin E492 uptake by the receptors is inhibited by the dimer and trimer of dihydroxybenzoylserine

Genomic and functional analyses of the 2-aminophenol catabolic pathway and partial conversion of its substrate into picolinic acid in Burkholderia xenovorans LB400.

2-aminophenol (2-AP) is a toxic nitrogen-containing aromatic pollutant. Burkholderia xenovorans LB400 possess an amn gene cluster that encodes the 2-AP catabolic pathway. In this report, the functionality of the 2-aminophenol pathway of B. xenovorans strain LB400 was analyzed. The amnRJBACDFEHG cluster located at chromosome 1 encodes the enzymes for the degradation of 2-aminophenol. The absence of habA and habB genes in LB400 genome correlates with its no growth on nitrobenzene. RT-PCR analyses in strain LB400 showed the co-expression of amnJB, amnBAC, amnACD, amnDFE and amnEHG genes, suggesting that the amn cluster is an operon. RT-qPCR showed that the amnB gene expression was highly induced by 2-AP, whereas a basal constitutive expression was observed in glucose, indicating that these amn genes are regulated. We propose that the predicted MarR-type transcriptional regulator encoded by the amnR gene acts as repressor of the amn gene cluster using a MarR-type regulatory binding sequence. This report showed that LB400 resting cells degrade completely 2-AP. The amn gene cluster from strain LB400 is highly identical to the amn gene cluster from P. knackmussi strain B13, which could not grow on 2-AP. However, we demonstrate that B. xenovorans LB400 is able to grow using 2-AP as sole nitrogen source and glucose as sole carbon source. An amnBA (-) mutant of strain LB400 was unable to grow with 2-AP as nitrogen source and glucose as carbon source and to degrade 2-AP. This study showed that during LB400 growth on 2-AP this substrate was partially converted into picolinic acid (PA), a well-known antibiotic. The addition of PA at lag or mid-exponential phase inhibited LB400 growth. The MIC of PA for strain LB400 is 2 mM. Overall, these results demonstrate that B. xenovorans strain LB400 posses a functional 2-AP catabolic central pathway, which could lead to the production of picolinic acid

In vivo assay to identify bacteria with \u3b2-glucosidase activity

Background: \u3b2-Glucosidase assay is performed with purified or semipurified enzymes extracted from cell lysis. However, in screening studies, to find bacteria with \u3b2-glucosidase activity among many tested bacteria, a fast method without cell lysis is desirable. In that objective, we report an in vivo \u3b2-glucosidase assay as a fast method to find a \u3b2-glucosidase producer strain. Results: The method consists in growing the strains for testing in a medium supplemented with the artificial substrate p-nitrophenyl-\u3b2-glucopyranoside (pNPG). The presence of \u3b2-glucosidases converts the substrate to p-nitrophenol (pNP), a molecule that can be easily measured in the supernatant spectrophotometrically at 405 nm. The assay was evaluated using two Bifidobacterium strains: Bifidobacterium longum B7254 strain that lacks \u3b2-glucosidase activity and Bifidobacterium pseudocatenulatum B7003 strain that shows \u3b2-glucosidase activity. The addition of sodium carbonate during pNP measurement increases the sensitivity of pNP detection and avoids the masking of absorbance by the culture medium. Furthermore, we show that pNP is a stable enzymatic product, not metabolized by bacteria, but with an inhibitory effect on cell growth. The \u3b2-glucosidase activity was measured as units of enzyme per gram per minute per dry cell weight. This method also allowed the identification of Lactobacillus strains with higher \u3b2-glucosidase activity among several lactobacillus species. Conclusion: This in vivo \u3b2-glucosidase assay can be used as an enzymatic test on living cells without cell disruption. The method is simple, quantitative, and recommended, especially in studies screening for bacteria not only with \u3b2-glucosidase activity but also with high \u3b2-glucosidase activity

Draft Genome Sequence of Bacillus safensis RP10, Isolated from Soil in the Atacama Desert, Chile.

Genome analysis of Bacillus safensis RP10, a strain from the soil of Atacama Desert in northern Chile, reflects a bacterium adapted to live in soil containing high levels of heavy metals, high salt conditions, and low carbon and energy sources