Interacción de aislados bacterianos rizosféricos con metales de importancia ambiental

La amenaza de los metales pesados a la salud pública y el ambiente ha conllevado a la búsqueda de tecnologías que permitan la remoción o neutralización de su toxicidad. Dentro de las nuevas técnicas, los microorganismos presentan gran relevancia. El trabajo se propuso caracterizar las interacciones de 13 aislados bacterianos rizosféricos obtenidos de plantas hidrófitas de humedales naturales, con cuatro metales de interés: cromo (Cr6+), plomo (Pb2+), cadmio (Cd2+) y mercurio (Hg2+), para la selección de cepas con potencialidades para la remediación de aguas. Se determinó la resistencia de los aislados a los cuatro metales, seleccionando tres concentraciones y suplementando el medio agar nutritivo con sales de los metales, para lograr las concentraciones correspondientes (cromo y plomo 1.0, 2.0 y 3.0 mM; cadmio 0.6, 1.2 y 1.8 mM; mercurio 0.01, 0.02 y 0.03 mM). Se realizaron ensayos de biosorción frente a soluciones mixtas y se determinó la cantidad de metal removido por gramos de biomasa (q). El 100% de los aislados mostró resistencia a más de un metal. Se encontró remoción por algunas cepas, destacándose cuatro de ellas, que podrían formar un consorcio para la eliminación de plomo, cromo y mercurio. Los resultados presentan importancia, pues las concentraciones de metales estudiadas se encuentran por encima de las concentraciones máximas permisibles normadas en aguas según la Norma Cubana NC 27-1999 y otras normas internacionales; por lo tanto, las cepas que mostraron resistencia y remoción podrían resultar agentes biorremediantes prometedores para su empleo en el saneamiento de aguas contaminadas

Stevia rebaudiana Bertoni, an American plant used as sweetener: Study of its effects on body mass control and glycemia reduction in Wistar male and female rats.

Stevia rebaudiana Bertoni water extracts have been used as a natural sweetener and customary medicine by the indigenous inhabitants of South America for several hundred years. This plant was sent to Europe in the 16th century and was described by Peter Jacob Esteve in Spain. Recently the food industry has started to employ S. rebaudiana as sweetener using its glycosides after purification. Advertisement claims that Stevia glycosides is good for controling body mass and reducing glycemia. This study's objective was to evaluate the effect of S. rebaudiana leaf extract on Wistar rats as animal model to prove its effectiveness on body mass control, glycemia reduction, and other biochemical parameters. Three groups were randomly formed with 24 males and 24 females: A blank group without any sweetener, a control group drinking water with 10% glucose, and the test group ingesting a 0.94% water extract of S. rebaudiana. Body mass measurements as well as food and drink consumption were daily performed. The experiment lasted 120 days after the specimens were weaned and got used to eating solid food. Euthanasia was done and blood serum was collected to evaluate the following biochemical parameters: Glucose, triglycerides, cholesterol, insulin, glucagon, leptin, ghrelin, and glucose-dependent insulinotropic peptide, GIP. Results indicated that only female rats had statistical differences in body mass gain. No relevant effects either positive or negative were found in the biochemical parameters measured. The crude extracts of S. rebaudiana did not show any relevant changes in biochemical and hormonal profiles, changes nor body mass with respect to the blank and control groups of young and healthy rats in the age range of infancy to youth. According to the results obtained, the therapeutic properties that have been associated to S. rebaudiana consumption especially for body mass control and glycemia reduction, did not occur in young and healthy male and female rats in equivalent age to infants, young children, and youths

Fig 7 -

A. Male Wistar rats statistical analyses of serum insulin data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8. B. Female Wistar rats statistical analyses of serum insulin data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8. C. Male Wistar rats statistical analyses of serum glucagon data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8. D. Female Wistar rats statistical analyses of serum glucagon data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8. E. Male Wistar rats statistical analyses of serum leptin data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8. F. Female Wistar rats statistical analyses of serum leptin data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8. G. Male Wistar rats statistical analyses of serum ghrelin data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8. H. Female Wistar rats statistical analyses of serum ghrelin data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8. I. Male Wistar rats statistical analyses of serum glucose dependent insulinotropic peptide, GIP, data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8. J. Female Wistar rats statistical analyses of serum glucose dependent insulinotropic peptide, GIP, data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Its CI is at 95%. The following letters indicate significant differences p<0.05: a, b, c, d. Games-Howell Method n = 8.</p

Fig 3 -

A. Male Wistar rats daily food intake during 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Each line represents the trend in the evaluated period where each point comprises the average food intake of each group and its CI at 95%, n = 8. B. Female Wistar rats daily food intake during 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). Each line represents the trend in the evaluated period where each point comprises the average food intake of each group and its CI at 95%, n = 8. C. Male Wistar rats statistical analyses of final cumulative food intake data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). The following letters indicate significant differences p<0.05: a, b, c, d. Duncan test. D. Female Wistar rats statistical analyses of final cumulative food intake data 120 days after weaning consuming stevia infusion, drinking water sweetened with glucose (control), and plain water (blank). The following letters indicate significant differences p<0.05: a, b, c, d. Duncan test.</p