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H Gutierrez

Publications and source records attributed to H Gutierrez.

12 recordsLinked to original sources
PubMed2001

Optimization of astaxanthin production by Phaffia rhodozyma through factorial design and response surface methodology.

Sequential methodology based on the application of three types of experimental designs was used to optimize the astaxanthin production of the mutant strain 25-2 of Phaffia rhodozyma in shake flask cultures. The first design employed was a factorial design 2(5), where the factors studied were: pH, temperature, percent of inoculum, carbon and nitrogen concentrations, each one at two levels. This design was performed in two medium types: rich YM medium and minimal medium, based on date juice (Yucca medium). With this first design the most important factors were determined (carbon concentration and temperature) that were used in the second experimental strategy: the method of steepest ascent was applied in order to rapidly approach the optimum. Finally, a second-order response surface design was applied using temperature and carbon concentration as factors. The optimal conditions stimulating the highest astaxanthin production were: 19.7 degrees C temperature; 11.25 g l(-1) carbon concentration; 6.0 pH; 5% inoculum and 0.5 g l(-1) nitrogen concentration. Under these conditions the astaxanthin production was 8100 microg l(-1), 92% higher than the production under the initial conditions.

Basidiomycota↗
PubMed1999

Iodanthine, a pyrrolizidine alkaloid from senecio iodanthus and senecio bracteatus

A phytochemical study of Senecio iodanthus and Senecio bracteatus afforded the new pyrrolizidine alkaloid iodanthine (3) in addition to the four known alkaloids retroisosenine (1), bulgarsenine (2), mulgediifoliine (4), and (12S)-12-hydroxyretroisosenine (6). The structure and absolute stereochemistry of the new compound (3) were determined by its spectral properties and confirmed by an X-ray diffraction analysis.

Journal Article↗
PubMed1986

[Not Available].

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Americas↗
PubMedDate not supplied

[Ecology of Lutzomyia longipalpis (Lutz & Neiva, 1912) and possibilities of the existence of visceral leishmaniasis in Costa Rica].

A semiarid area of northwest Costa Rica where Lutzomyia longipalpis is common in corrals around houses is described. Monthly captures of the sandfly during two consecutive years for fixed periods of time indicated that the insect bites avidly cows, horses, pigs, dogs and humans. From a total of 14,215 specimens, 90.5% were males and the species is markedly more abundant during the dry season decreasing considerably when rain comes. The possibility that visceral leishmaniasis could become in the future established in the area is discussed, in view of the fact that it already exists endemically in other Central American countries.

Animals↗