Semi-scale production of PHAs from waste frying oil by Pseudomonas fluorescens S48

The present study aimed at developing a strategy to improve the volumetric production of PHAs by Pseudomonas fluorescens S48 using waste frying oil (WFO) as the sole carbon source. For this purpose, several cultivations were set up to steadily improve nutrients supply to attain high cell density and high biopolymer productivity. The production of PHAs was examined in a 14 L bioreactor as one-stage batch, two-stage batch, and high-cell-density fed-batch cultures. The highest value of polymer content in one-stage bioreactor was obtained after 60 h (33.7%). Whereas, the two-stage batch culture increased the polymer content to 50.1% after 54 h. High-cell-density (0.64 g/L) at continuous feeding rate 0.55 mL/l/h of WFO recorded the highest polymer content after 54 h (55.34%). Semi-scale application (10 L working volume) increased the polymer content in one-stage batch, two-stage batch and high cell density fed-batch cultures by about 12.3%, 5.8% and 11.3%, respectively, as compared with that obtained in 2 L fermentation culture. Six different methods for biopolymer extraction were done to investigate their efficiency for optimum polymer recovery. The maximum efficiency of solvent recovery of PHA was attained by chloroform-hypochlorite dispersion extraction. Gas chromatography (GC) analysis of biopolymer produced by Pseudomonas fluorescens S48 indicated that it solely composed of 3-hydrobutyric acid (98.7%). A bioplastic film was prepared from the obtained PHB. The isolate studied shares the same identical sequence, which is nearly the complete 16S rRNA gene. The identity of this sequence to the closest pseudomonads strains is about 98-99%. It was probably closely related to support another meaningful parsiomony analysis and construction of a phylogenetic tree. The isolate is so close to Egyptian strain named EG 639838.

Identificación y caracterización de bacilos gramnegativos no fermentados aislados en el medio hospitalario / Identification and characterization of nonfermenting gramnegative bacili isolated from a hospital environment

Se estudio un total de 251 cepas aisladas en el medio hospitalario con diagnóstico presuntivo de bacilos gramnegativos no fermentadores, enviadas por los Laboratorios de Infecciones Nosocomiales de los Centros Provinciales de Higiene y Epidemiología de Ciudad de La Habana, Santiago de Cuba, Holguín, Guantánamo, Camagüey e Isla de la Juventud desde septiembre de 1992 hasta junio de 1993. Se empleó un esquema inicial para corroborar el diagnóstico primario de estas cepas, los medios de producción de pigmentos King A y King B para la identificación de Pseudomonas aeruginosas y pruebas bioquímicas claves para el diagnóstico microbiológico de otros no fermentadores, se utilizó la piocinotipia y la serotipia para la caracterización posterior de la especie aeruginosa. Resultaron confirmadas 238 cepas y de ellas, el 88,23 por ciento correspondió a la especie aeruginosa cuyos piocinotipo y serotipo predominantes fueron al 10a y 011, respectivamente. Otros bacilos encontrados con frecuencia fueron Pseudomonas cepacia (25 por ciento); Pseudomonas fluorescens (17,8 por ciento) y Acinetobacter calcoaceticus var. anitratus 17,8 por ciento