[Serotypes of Salmonella isolated from the Luján River, Argentina]. / Serotipos de Salmonella aislados del Río Luján, Argentina.

In this work, the serotypes of Salmonella genus polluting the waters of Lujan River, situated in the north east of the province of Buenos Aires, Argentina, were studied. A total of 690 samples of water were collected and analysed from February 1988 through December 1989, at three different sites. They were obtained according to the Moore technique and then preenriched in buffered peptone water and enriched in Rappaport-Vassiliadis Soya peptone broth was carried out. The isolations were realised in brilliant green-desoxycholate agar and bismuth sulphite agar and the presumptive colonies to be Salmonella were tested by the standard biochemical identification. Salmonella spp. was isolated in 434 samples (62.9%). The predominant serotype was S. Anatum, followed in a decreasing order by S. Montevideo, S. Newport and S. Bredeney. A large amount of serotypes that are isolated with very low frequency and very rarely in other hidric courses in the country were: S. Westhampton, S. Poona and S. Saintpaul were found.

[Production of xanthan gum in immobilized cultures of Xanthomonas campestris]. / Producción de goma xántica en cultivos inmovilizados de Xanthomonas campestris.

The efficiency of xanthan production through surface processes was evaluated. The best porous material was selected first. Thereafter, a comparative study was performed using submerged agitated process vs other without agitation but containing the selected porous material. The culture medium used was white potatoes infusion, buffered with K2HPO4 and supplemented with glucose in diverse concentrations. Besides, to evaluate a different type of surface process, three vegetables were valued: Ipomaea batatus, Solanum tuberosum and Daucus carota, with an without glucose supplement. Larger xanthan production was achieved with immobilization of X. campestris vs the conventional method, when the liquid culture medium was used. The highest yield was obtained when the white potatoes infusion was supplemented with glucose 2.5%, yielding a conversion of this saccharide to xanthan up to 58%. When X. campestris was cultured on fragmented vegetables, the highest xanthan gum yield (5.6g) was obtained with Solanum tuberosum supplemented with glucose. This yield indicators that X. campestris used the glucose added as well as the constitutive polysaccharide of this vegetable.

Producción de goma xántica en cultivos inmovilizados de Xanthomonas campestris / [Production of xanthan gum in immobilized cultures of Xanthomonas campestris]

The efficiency of xanthan production through surface processes was evaluated. The best porous material was selected first. Thereafter, a comparative study was performed using submerged agitated process vs other without agitation but containing the selected porous material. The culture medium used was white potatoes infusion, buffered with K2HPO4 and supplemented with glucose in diverse concentrations. Besides, to evaluate a different type of surface process, three vegetables were valued: Ipomaea batatus, Solanum tuberosum and Daucus carota, with an without glucose supplement. Larger xanthan production was achieved with immobilization of X. campestris vs the conventional method, when the liquid culture medium was used. The highest yield was obtained when the white potatoes infusion was supplemented with glucose 2.5

, yielding a conversion of this saccharide to xanthan up to 58

. When X. campestris was cultured on fragmented vegetables, the highest xanthan gum yield (5.6g) was obtained with Solanum tuberosum supplemented with glucose. This yield indicators that X. campestris used the glucose added as well as the constitutive polysaccharide of this vegetable.

Producción de goma xántica en cultivos inmovilizados de Xanthomonas campestris / [Production of xanthan gum in immobilized cultures of Xanthomonas campestris]

The efficiency of xanthan production through surface processes was evaluated. The best porous material was selected first. Thereafter, a comparative study was performed using submerged agitated process vs other without agitation but containing the selected porous material. The culture medium used was white potatoes infusion, buffered with K2HPO4 and supplemented with glucose in diverse concentrations. Besides, to evaluate a different type of surface process, three vegetables were valued: Ipomaea batatus, Solanum tuberosum and Daucus carota, with an without glucose supplement. Larger xanthan production was achieved with immobilization of X. campestris vs the conventional method, when the liquid culture medium was used. The highest yield was obtained when the white potatoes infusion was supplemented with glucose 2.5

, yielding a conversion of this saccharide to xanthan up to 58

. When X. campestris was cultured on fragmented vegetables, the highest xanthan gum yield (5.6g) was obtained with Solanum tuberosum supplemented with glucose. This yield indicators that X. campestris used the glucose added as well as the constitutive polysaccharide of this vegetable.

Producción de goma xántica en cultivos inmovilizados de Xanthomonas campestris. / [Production of xanthan gum in immobilized cultures of Xanthomonas campestris]

The efficiency of xanthan production through surface processes was evaluated. The best porous material was selected first. Thereafter, a comparative study was performed using submerged agitated process vs other without agitation but containing the selected porous material. The culture medium used was white potatoes infusion, buffered with K2HPO4 and supplemented with glucose in diverse concentrations. Besides, to evaluate a different type of surface process, three vegetables were valued: Ipomaea batatus, Solanum tuberosum and Daucus carota, with an without glucose supplement. Larger xanthan production was achieved with immobilization of X. campestris vs the conventional method, when the liquid culture medium was used. The highest yield was obtained when the white potatoes infusion was supplemented with glucose 2.5

, yielding a conversion of this saccharide to xanthan up to 58

. When X. campestris was cultured on fragmented vegetables, the highest xanthan gum yield (5.6g) was obtained with Solanum tuberosum supplemented with glucose. This yield indicators that X. campestris used the glucose added as well as the constitutive polysaccharide of this vegetable.

Producción de goma xántica en cultivos inmovilizados de Xanthomonas campestris. / [Production of xanthan gum in immobilized cultures of Xanthomonas campestris]

The efficiency of xanthan production through surface processes was evaluated. The best porous material was selected first. Thereafter, a comparative study was performed using submerged agitated process vs other without agitation but containing the selected porous material. The culture medium used was white potatoes infusion, buffered with K2HPO4 and supplemented with glucose in diverse concentrations. Besides, to evaluate a different type of surface process, three vegetables were valued: Ipomaea batatus, Solanum tuberosum and Daucus carota, with an without glucose supplement. Larger xanthan production was achieved with immobilization of X. campestris vs the conventional method, when the liquid culture medium was used. The highest yield was obtained when the white potatoes infusion was supplemented with glucose 2.5

, yielding a conversion of this saccharide to xanthan up to 58

. When X. campestris was cultured on fragmented vegetables, the highest xanthan gum yield (5.6g) was obtained with Solanum tuberosum supplemented with glucose. This yield indicators that X. campestris used the glucose added as well as the constitutive polysaccharide of this vegetable.

Producción de gomas xánticas / Production of xanthan gums

En el período que va desde febrero has agosto de 1990, se realizó un relevamiento de Xanthomonas campestris en la zona de Luján, provincia de Buenos Aires, de 70 muestras de vegetales infectados. Se comprobó si las 50 cepas de Xanthomonas campestris obtenidas presentaban la capacidad de producir goma xantan, así como el porcentaje de conversión de sustrato en goma y el recuento de Xanthomonas campestris viables/ml de cultivo. Los mayores números de cepas productoras del polisacárido extracelular se obtuvieron de alfalfa. Asimismo, la Xanthomonas campestris pv. alfalfae presentó elevados números de células viables y porcentajes de conversión de glucosa en goma xántica (AU)

Producción de gomas xánticas / Production of xanthan gums

En el período que va desde febrero has agosto de 1990, se realizó un relevamiento de Xanthomonas campestris en la zona de Luján, provincia de Buenos Aires, de 70 muestras de vegetales infectados. Se comprobó si las 50 cepas de Xanthomonas campestris obtenidas presentaban la capacidad de producir goma xantan, así como el porcentaje de conversión de sustrato en goma y el recuento de Xanthomonas campestris viables/ml de cultivo. Los mayores números de cepas productoras del polisacárido extracelular se obtuvieron de alfalfa. Asimismo, la Xanthomonas campestris pv. alfalfae presentó elevados números de células viables y porcentajes de conversión de glucosa en goma xántica

[Production of xanthan gums]. / Producción de gomas xánticas.

Xanthomonas campestris was investigated in 70 samples of infected plants in the neighbourhood of Luján, province of Buenos Aires, between February and August, 1990. The production of xanthan gum was determined from 50 strains of Xanthomonas campestris, as well as the conversion efficiency of substrate concentration into gum and the number of colony forming units (CFU) of Xanthomonas campestris/ml of broth culture. The highest number of strains producing extracellular polysaccharide was obtained from alfalfa. Xanthomonas campestris pv. alfalfa gave elevated cell concentration and conversion efficiency of glucose in xanthan gum.

Producción de gomas xánticas. / [Production of xanthan gums]

Xanthomonas campestris was investigated in 70 samples of infected plants in the neighbourhood of Luján, province of Buenos Aires, between February and August, 1990. The production of xanthan gum was determined from 50 strains of Xanthomonas campestris, as well as the conversion efficiency of substrate concentration into gum and the number of colony forming units (CFU) of Xanthomonas campestris/ml of broth culture. The highest number of strains producing extracellular polysaccharide was obtained from alfalfa. Xanthomonas campestris pv. alfalfa gave elevated cell concentration and conversion efficiency of glucose in xanthan gum.

Estudio comparativo de cuatro métodos de aislamiento de salmonelas de aguas superficiales / Comparative study of 4 methods for isolating Salmonella from surface waters

El presente trabajo es la primera etapa de un proyecto destinado a determinar la presencia de serovariedades de Salmonella en aguas del Río Lujáan, que recorre la zona urbana de la ciudad homónima, en la provincia de Buenos Aires. Consiste en realizar un estudio comparativo de cuatro métodos de detección de salmonelas a partir de 200 muestras de dicho río: caldos tetrationato-verde brilhante; manitol y selenito; Rappaport 25 y Rappaport-Vassiliadis modificado, con y sin preenriquecimiento de las muestras en agua peptonada fosfatada. Para las tomas, se aplicó la técnica del pliego de gasa sumergido, en tres puntos de muestreo: uno en la planta urbana, otro a 2 km aguas arriba de la misma y el último a 2 km aguas abajo de la ciudad. La mejor combinación de medios de enriquecimiento y de aislamiento estuvo dada por caldo Rappaport-Vassiliadis modificado y agar verde brilhante con 0,25% de desoxicolato de sodio, luego de preenriquecer las muestras en agua peptonada fosfatada. Se aisló Salmonella en el 46% de las muestras examinadas, identificándose 16 serovariedades. Entre otras, se hallaron: S. Typhimurium, S. Enteritidis, S. Infantis, S. Mbandaka, S. Israel y S. Sub-especie IV 18 z36 : Z38:-

Estudio comparativo de cuatro métodos de aislamiento de salmonelas de aguas superficiales / Comparative study of 4 methods for isolating Salmonella from surface waters

El presente trabajo es la primera etapa de un proyecto destinado a determinar la presencia de serovariedades de Salmonella en aguas del Río Lujáan, que recorre la zona urbana de la ciudad homónima, en la provincia de Buenos Aires. Consiste en realizar un estudio comparativo de cuatro métodos de detección de salmonelas a partir de 200 muestras de dicho río: caldos tetrationato-verde brilhante; manitol y selenito; Rappaport 25 y Rappaport-Vassiliadis modificado, con y sin preenriquecimiento de las muestras en agua peptonada fosfatada. Para las tomas, se aplicó la técnica del pliego de gasa sumergido, en tres puntos de muestreo: uno en la planta urbana, otro a 2 km aguas arriba de la misma y el último a 2 km aguas abajo de la ciudad. La mejor combinación de medios de enriquecimiento y de aislamiento estuvo dada por caldo Rappaport-Vassiliadis modificado y agar verde brilhante con 0,25% de desoxicolato de sodio, luego de preenriquecer las muestras en agua peptonada fosfatada. Se aisló Salmonella en el 46% de las muestras examinadas, identificándose 16 serovariedades. Entre otras, se hallaron: S. Typhimurium, S. Enteritidis, S. Infantis, S. Mbandaka, S. Israel y S. Sub-especie IV 18 z36 : Z38:- (AU)

[Comparative study of 4 methods for isolating Salmonella from surface waters]. / Estudio comparativo de cuatro métodos de aislamiento de salmonelas de aguas superficiales.

The study presented here is the first stage of a project designed to determine the presence of Salmonella serotypes in Lujan river waters, which flow beside the urban area of the homonymous city, in the province of Buenos Aires. It consisted in a comparative study of four methods for Salmonellae detection in 200 samples: Tetrathionate-brilliant green; mannitol-selenite; Rappaport 25 and modified Rappaport-Vassiliadis broth, each of them with and without pre-enrichment in buffered peptone water. The submerged gauze technique was applied to the sampling in three different spots of the river: at the town center, two km water above, and two down-stream from the city. Best results were obtained when modified Rappaport-Vassiliadis enrichment broth and brilliant green agar with 0.25% of sodium deoxycholate were used, after pre-enrichment of the samples in buffered peptone water. Salmonella were isolated from 46% of the samples studied, and 16 serotypes were identified: S. Typhimurium, S. Enteritidis, S. Infantis, S. Mbandaka, S. Israel and S. Subspecies IV 18 z36: z38:-, among them.

Estudio comparativo de cuatro métodos de aislamiento de salmonelas de aguas superficiales. / [Comparative study of 4 methods for isolating Salmonella from surface waters]

The study presented here is the first stage of a project designed to determine the presence of Salmonella serotypes in Lujan river waters, which flow beside the urban area of the homonymous city, in the province of Buenos Aires. It consisted in a comparative study of four methods for Salmonellae detection in 200 samples: Tetrathionate-brilliant green; mannitol-selenite; Rappaport 25 and modified Rappaport-Vassiliadis broth, each of them with and without pre-enrichment in buffered peptone water. The submerged gauze technique was applied to the sampling in three different spots of the river: at the town center, two km water above, and two down-stream from the city. Best results were obtained when modified Rappaport-Vassiliadis enrichment broth and brilliant green agar with 0.25

of sodium deoxycholate were used, after pre-enrichment of the samples in buffered peptone water. Salmonella were isolated from 46

of the samples studied, and 16 serotypes were identified: S. Typhimurium, S. Enteritidis, S. Infantis, S. Mbandaka, S. Israel and S. Subspecies IV 18 z36: z38:-, among them.