The incidence of coliform bacteria (CB), thermotolerant coliforms (TC), Escherichia coli, and Salmonella was determined for zucchini squash fruit. In addition, the behavior of four serotypes of Salmonella and a cocktail of three E. coli strains on whole and sliced zucchini squash at 25+/-2 degrees C and 3 to 5 degrees C was tested. Squash fruit was collected in the markets of Pachuca city, Hidalgo State, Mexico. CB, TC, E. coli, and Salmonella were detected in 100, 70, 62, and 10% of the produce, respectively. The concentration ranged from 3.8 to 7.4 log CFU per sample for CB, and >3 to 1,100 most probable number per sample for TC and E. coli. On whole fruit stored at 25+/-2 degrees C or 3 to 5 degrees C, no growth was observed for any of the tested microorganisms or cocktails thereof. After 15 days at 25+/-2 degrees C, the tested Salmonella serotypes had decreased from an initial inoculum level of 7 log CFU to <1 log, and at 3 to 5 degrees C they decreased to approximately 2 log. Survival of E. coli was significantly greater than for the Salmonella strains at the same times and temperatures; after 15 days, at 25+/-2 degrees C E. coli cocktail strains had decreased to 3.4 log CFU per fruit and at 3 to 5 degrees C they decreased to 3.6 log CFU per fruit. Both the Salmonella serotypes and E. coli strains grew when inoculated onto sliced squash: after 24 h at 25+/-2 degrees C, both bacteria had grown to approximately 6.5 log CFU per slice. At 3 to 5 degrees C, the bacterial growth was inhibited. The squash may be an important factor contributing to the endemicity of Salmonella in Mexico.
Se efectuó un estudio en el Parque Nacional El Chico, Hidalgo, con el objetivo de estimar labiomasa y el carbono aéreo almacenado en los árboles muertos en pie, en los árboles adultos vivos yen el renuevo establecido en forma natural de Abies religiosa “oyamel” después de 12 años de ocurridoun incendio forestal de tipo superficial que afectó 30,34 ha. Se realizó un inventario forestal de 15 sitioscirculares de 1000 m2 distribuidos de forma sistemática, para medir las variables de diámetro normal yaltura. Para determinar la biomasa se utilizó el valor de densidad de la madera de oyamel (360 kg/m3)y para el coeficiente de carbono se tomaron muestras que fueron analizadas con el equipo Solids TOCAnalyzer®, obteniendo un valor de 0,45. Las ecuaciones generadas para estimar biomasa y carbonoen árboles de Abies religiosa en un área afectada por un incendio forestal fueron B=0,06463*DN2,38322y C=0,029083*DN2,38322 respectivamente, ambas mostraron un buen ajuste (R2=0,99), por lo que sonadecuadas y confiables para usarse en áreas siniestradas con condiciones similares, para la mismaespecie y región, como Áreas Naturales Protegidas donde no es posible utilizar métodos destructivos.En las 30,34 ha siniestradas por el incendio forestal ocurrido en 1998 en el Parque Nacional El Chico,no se consumieron por el fuego un total de 665,05 t de carbono que no fueron liberadas hacia la atmósfera,sumándose una captura actual de 297,33 t de carbono por el renuevo establecido a 12 años deocurrido el siniestro
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