Comparative study of airborne viable particles assessment methods in microbiological environmental monitoring.

A comparative study was done among available assessment methods to measure airborne viable particles in controlled rooms. Active methods were compared (sieve/nozzle impactor, slit-to-agar, centrifugal, filtration, and impinger). The comparative study was carried out by means of a two-way (factors: day and method) analysis of variance, after to logarithmical transformation of experimental results in order to fulfill the normality test of the variables. Statistically significant differences were found among the results of the five methods (P < 0.0001). In a post hoc study, by means of Tukey's test, no differences were found among centrifugal, filtration, and impinger methods. Differences were found among all the other methods (P < 0.05). It is concluded that centrifugal, filtration, and impinger methods (in which numerical results were higher than in the others) may be the most suitable methods for microbiological monitoring of a clean room. The mean results among the three selected active methods were compared with results on the settle plate (SP) (the passive method). A relationship was established between results of the passive method (CFU/h/plate 90 mmø) and the results of active methods (CFU/m3 air). By means of a lineal regression study, it was obtained a relation factor of 22.7; (95% CI: 19.7, 25.7). This factor is only valid for values between 3 and 16 in CFU/h/plate 90 mmø, and it is put on record that the experimental study took place in a room that fulfills Class D clean room specifications (WHO standards) in microbiological terms.

Calcium alginate microspheres of Bacillus subtilis.

Microspheres of Bacillus subtilis were prepared using sodium alginate. Some typical properties of microencapsulated systems, such as microorganism content, particle size, and germination time, were studied. Calcium alginate microspheres were obtained by the emulsification method, dripping into a solution of calcium salt. The conditions of the preparation steps were very soft to produce calcium alginate microspheres containing cells with no apparent changes in general biological properties. The hydrogel matrix provides protection without preventing communication with the surrounding medium.

Biodegradación de 2-clorofenol en reactores aeróbicos empleando microorganismos autóctonos

Los objetivos del presente trabajo fueron: Seleccionar e identificar microorganismos capaces de biodegradar 2-clorofenol en distintos procesos aeróbios; Determinar la cinética y la velocidad de degradación a escala laboratorio empleando reactores batch; Establecer la efectividad de un reactor de lecho fluidizado aeróbico relleno con carbón activado granular para remover 2-CP como única fuente de carbono, suministrando como nutrientes un fertilizante foliar agrícola de uso comercial; Evaluar la remoción de toxicidad a través de bioensayos

Influencia de diferentes derivados lácteos sobre el crecimiento de Listeria monocytogenes en medios selectivos / Influence of different dairy products on the growth kinetic of Listeria monocytogenes

Se estudió la influencia del añadido de crema de leche y leche parcialmente descremada sobre la cinética de crecimiento de Listeria monocytogenes en caldos de enriquecimiento para listerias, conteniendo diferentes concentraciones de acriflavina (15 y 7,5 mg/l). El crecimiento de Listeria monocytogenes en los caldos de enriquecimiento sufrió un retardo atribuible, al menos parcialmente, a la presencia de acriflavina. El añadido de crema de leche o leche parcialmente descremada al caldo de enriquecimiento que contiene 7,5 mg/l de acriflavina produjo un alargamiento de la fase de adaptación, pero las cosechas máximas alcanzadas a las 48 h no mostraron diferencias significativas. En presencia de 15 mg/l de acriflavina, se observó una pérdida inicial de la viabilidad de los cultivos, que fue potenciada por el agregado de crema de leche o leche parcialmente descremada al caldo de enriquecimiento. Además, la leche descremada produjo una disminución de la velocidad máxima de crecimiento que impidió alcanzar la cosecha máxima dentro de las 48 h. Los resultados obtenidos sugieren la necesidad de validar la metodología de recuperación de L. monocytogenes para cada producto, pues la eficiencia de recuperación podría ser afectada por la composición del mismo, sobre todo cuando la carga microbiana es baja (AU)

Desinfección de agua: acción comparativa del ozono y cloro sobre un amplio espectro bacteriano. / [Water disinfection: comparative activities of ozone and chlorine on a wide spectrum of bacteria]

Ozone and chlorine are agents that disinfect by destroying, neutralizing or inhibiting the growth of pathogenic microorganisms. The treatment of drinking water with ozone has shown to be more efficient against spores of Bacillus subtilis. It was observed that the ozone already in dose of 0.35 mg/l produced the reduction of at least 5 log in populations of approximately 1 x 10(6) cells/ml of Escherichia coli, Vibrio cholerae, Salmonella typhi, Yersinia enterocolitica, Pseudomonas aeruginosa, Aeromonas hydrophila, Listeria monocytogenes and Staphylococcus aureus. With a dose of 0.50 mg/l of chlorine, the reduction was much smaller for the tested microorganisms (except Vibrio cholerae), while the effect of 2 mg/l of chlorine was similar to the ozone treatment. For spores of Bacillus subtilis, the reduction observed with ozone concentrations of 0.35 and 0.70 mg/l was of almost 3 log, while no considerable effect was obtained with chlorine in the tested conditions. Our results have shown that both disinfectans were consumed during the treatment period, probably because of the own water demand and the added bacterial mass.

Viabilidad de Bacillus subtilis auxotrofos en ausencia de sus metabolitos esenciales. / [Viability of Bacillus subtilis auxotrophs in the absence of their essential metabolites]

The effect of tryptophan and uracil starvation on the viability of the transformant B. subtilis BSA 170 trp- ura- and its parent strains Bacillus subtilis PB 168 trp -C and Bacillus subtilis PB 3308 ura- was examined. These studies were performed at the conditions for competence development, during 16 hours. Our results showed that B. subtilis BSA 170 was resistant to tryptophan-less death during all the assay and was also resistant to uracil-less death during three hours. After this time, viability measurements revealed less colony forming units per milliliter, and decrease of the culture absorbances. The uracil-less death required the presence of tryptophan suggesting that protein synthesis is needed. The parental strains exhibit similar behavior. Bacillus subtilis PB 168 was resistant to tryptophan-less death and B. subtilis PB 3308 showed decrease of the viability after uracil starvation comparable to that of the transformant strain.

Efecto tóxico del óxido de etileno en individuos expuestos / Toxic effect of the ethylene oxide in exposed individuals

El óxido de etileno es un potente inductor de daño al material genético ensayado en sistemas tales como vegetales, Drosophila, rata y líneas celulares humanas. Al ser usado como esterilizante en instrumental de cirugía, se realiza el estudio del personal expuesto al mismo, detectándose un aumento significativo en la frecuencia de aberraciones cromosómicas hepático en los mencionados individuos (AU)

Bacillus subtilis BSA 170 trp-ura-:Un nuevo mutante nutricional con requerimientos absolutos de triptofano y uracilo exogenos para su crecimiento. / Bacillus subtilis BSA 170 trp-ura-:a new nutritional mutant with absolute requirements of exogen trypthophan and uracil for its growth

Se construyo un mutante nutricional de Bacillus subtilis que requiere triptofano y uracilo exogenos para su crecimiento.Dicho mutante, denominado Bacillus subtilis BSA 170 trp-ura-, fue obtenido por transformante extraido de B. subtilis PB "3308 ura" y seleccionado por replicas en medios nutricionalmente selectivos. Ademas, una poblacion de Bacillus subtilis BSA 170 trp -ura- es capaz de desarrollar competencia para transformacion cuando es tratada de acuerdo a la metodologia propuesta por Young y Spizizen. Los estudios de transformabilidad de los marcadores trp (triptofano) y ura (uracilo) demostraron que cada uno de ellos transforma eficientemente en presencia de ADN transformante extraido de B. subtilis PB 19, prototrofo, posibilitando su empleo como celulas receptoras en estudios posteriores

Bacillus subtilis BSA 170 trp- ura-: un nuevo mutante nutricional con requerimientos absolutos de triptofano y uracilo exógenos para su crecimiento. / [Bacillus subtilis BSA 170 trp- ura-: a new nutritional mutant with absolute requirements for exogenous tryptophan and uracil for its growth]

A new Bacillus subtilis mutant was prepared, with a double nutritional requirement for uracil and tryptophan. The mutant, designed Bacillus subtilis BSA 170 trp- ura-, was constructed by transformation method, acting B. subtilis strain PB 168 trp- as recipient and B. subtilis strain PB 3308 ura- as transforming DNA donor cells. The BSA 170 trp- ura- strain was selected by replication of transformed population on nutritionally selective media. Competence development induction and genetic markers transformability were tested. The new mutant was competent by Young and Spizizens methodology. Furthermore, both markers, uracil and tryptophan, may be transformed when B. subtilis BSA 170 trp- ura- competent cells are treated with transforming DNA isolated from B. subtilis PB 19, prototroph. Transformation frequency rate for each marker alone was far larger than that reached for both taken together.

Accion clastogenica de un compuesto antraquinonico en linfocitos humanos. / Clastogenic action of an anthraquinone compound in human lymphocytes

Algunos autores han senalado una accion mutagenica para los compuestos antraquinonicos en sistemas microbianos, ya sea en forma directa o por activacion metabolica por sistema microsomal. Los compuestos mencionados tienen una amplia difusion como colarantes alimenticios, cosmeticos, farmacos y laxantes. En el presente trabajo se realizo un estudio in vitro del efecto clastogenico de un derivado antraquinonico sintetico, la l-8 Dihidroxiantraquinona y el solvente en el que se solubiliza la droga, el Dimetilsulfoxido, en cultivo de linfocitos de sangre periferica humanos Los resultados obtenidos permiten concluir que la droga ensayada presenta accion clastogenica en el sistema de ensayo aqui utilizad

Estudio comparativo de métodos microbianos para la detección de tóxicos genéticos. / [Comparative study of microbial methods for the detection of genetic toxicity]

It is important to have a rapid and accurate method to detect the toxic action of drugs and chemical compounds used by man. A comparative study with two microbial systems was carried out: one using Salmonella typhimurium and the other using Bacillus subtilis. The 1-8-dihydroxyantraquinone was the tested drug and the N-methyl-N-nitro-N-nitrosoguanidine and the 2-aminofluorene were used as control substances. These compounds were used as such or after previous transformation by a microsomal system. The results obtained showed that both systems: the S. typhimurium and the B. subtilis work in a similar way, but the latter allows a more direct action of drug on the genetic material. The effect of the solvents: ethanol and dimethylsulfoxide was analysed, because they affected the transformation and reversion processes that were carried out.