Biodegradation of rubber in cultures of Rhodococcus rhodochrous and by its enzyme latex clearing protein.

The biodegradation of rubber materials is considered as a sustainable recycling alternative, highlighting the use of microorganisms and enzymes in oxidative processes of natural rubber. Currently, the main challenge is the treatment of rubber materials such as waste tyres, where the mixture of rubber polymers with different additives and the cross-linked structure obtained due to the vulcanisation process positions them as highly persistent materials. This study characterises the degradation of different rubber-containing substrates in in vivo and in vitro processes using the bacterium Rhodococcus rhodochrous and the oxygenase latex clearing protein (Lcp) from the same strain. For the first time, the degradation of polyisoprene particles in liquid cultures of R. rhodochrous was analysed, obtaining up to 19.32% mass loss of the polymer when using it as the only carbon source. Scanning electron microscopy analysis demonstrated surface alteration of pure polyisoprene and vulcanised rubber particles after 2 weeks of incubation. The enzyme LcpRR was produced in bioreactors under rhamnose induction and its activity characterised in oxygen consumption assays at different enzyme concentrations. A maximum consumption of 28.38 µmolO2/min was obtained by adding 100 µg/mL LcpRR to a 2% (v/v) latex emulsion as substrate. The bioconversion of natural rubber into reaction degradation products or oligoisoprenoids was calculated to be 32.54%. Furthermore, the mass distribution of the oligoisoprenoids was analysed by liquid chromatography coupled to mass spectrometry (LC-MS) and 17 degradation products, ranging from C20 to C100 oligoisoprenoids, were identified. The multi-enzymatic degradation capacity of R. rhodochrous positions it as a model microorganism in complex degradation processes such as in the case of tyre waste.

Impacto de las políticas de educación sexual en la salud sexual y reproductiva adolescente en el sur de chile, período 2010 - 2017 / Impact of sexual education policies on adolescent sexual and reproductive health in southern Chile, period 2010 - 2017

RESUMEN Antecedentes: Desde los años 2001 y 2012 se incorporan contenidos sobre sexualidad en el currículum de 6º/7º básico y 2º/3o medio. A partir del año 2010 se legaliza que la población adolescente debe recibir educación sexual. Se propusieron siete programas en esta materia para establecimientos educacionales. Su implementación y sus resultados no han sido evaluados. Objetivo: Evaluar el impacto de las políticas de educación sexual implementadas en Chile, en la salud sexual y reproductiva de la población adolescente de la comuna de Concepción entre los años 2010 y 2017. Material y método: Estudio ecológico en establecimientos educacionales e indicadores de salud sexual y reproductiva en adolescentes. Incluyó 51 establecimientos y estadísticas de embarazo, uso de métodos anticonceptivos (MAC), casos de infecciones de transmisión sexual (ITS) y violencia sexual. Resultados: El 43% de éstos implementaron algún programa de educación sexual; El 80% ha incorporado los contenidos curriculares, y la misma cifra ha ejecutado iniciativas propias de sexualidad y asesorías externas con un alcance del 84%. Se observa un descenso del embarazo adolescente, aumento del uso de MAC, pero disminuyó el uso de condón masculino, y un aumento de los casos de gonorrea y VIH, así como las cifras de violencia sexual hacia adolescentes. Conclusiones: A pesar del descenso de algunos indicadores de salud sexual y reproductiva en adolescentes, es preocupante el aumento de las ITS y la disminución del uso de métodos que previenen su contagio, así como la violencia sexual que también es un riesgo para adquirir ITS.

ABSTRACT Background: In 2001 and 2012, contents on sexuality were added to the curriculum of the 6th and 7th grades of primary school, and to the 2nd and 3rd grades of secondary school. In 2010, sex education became compulsory for adolescents. There are seven sex education programs for schools, but their implementation and results have not been evaluated. Objective: To evaluate the impact of Chilean sex education policies on the sexual and reproductive health of teenagers from the commune of Concepción between 2010 and 2017. Material and methods: Ecological study, using schools and teenagers' sexual and reproductive health indicators. 51 schools were included in this study, and the indicators used were pregnancy statistics, use of contraceptives, cases of sexually-transmitted diseases (STDs), and sexual violence. Results: 43% of schools have implemented a sex education program. 80% have included the curriculum content. The same percentage of schools has implemented their own initiatives on the topic, while an 84% has asked for external counsel. Teenage pregnancy rates have decreased and the use of contraceptives has increased, but we also observed a decrease in the use of male condom and a higher rate of gonorrhea and HIV cases. The cases of sexual violence against adolescents have increased as well. Conclusions: Despite the decrease seen in some indicators, the higher rate of STDs and the lower use of methods to prevent them are alarming. The higher rate of sexual violence is worrying as well, as it is associated with STDs.