Abstract Biodigesters are designed to optimize biogas production using organic wastes, thereby attaining clean, low-cost renewable energy. In 2008, a group of ITCR researchers worked on developing a wireless electronic system for control and protection of biogas production. One of the specific objectives of this work was to find information about methods to increase biogas production. In this review we established the mathematical parameters related to biogas estimation of productivity. We then focused on the influence of chemical factors such as substrate composition, substrate combinations, addition of fat, and presence of inhibitors. We also studied the effect of physical factors such as temperature, solids removal, protein exclusion and phase separation during anaerobic digestion of organic matter. Finally we attempted to determine the role of biological factors such as the addition of thermophilic bacteria and the importance of methanogens.

ResumenBrucella abortuses un patógeno intracelular facultativo que pertenece a la subdivisión a2 de la clase Proteobacteria. Causa una brucelosis, una zoonosis ampliamente distribuida a nivel mundial. Los principales síntomas incluyen abortos y esterilidad en ganado, así como fiebre ondulante en humanos. En regiones endémicas como Centroamérica, la brucelosis tiene un alto impacto socioeconómico. En el Instituto Tecnológico de Costa Rica (ITCR) se desarrolló en fecha reciente un proyecto de investigación básica, con el objetivo de estudiar la regulación de algunos genes implicados en la virulencia, estructura e inmunogenicidad de B. abortus.Como parte de ese proyecto se elaboró el presente artículo de revisión de literatura. La virulencia de esta bacteria parece estar determinada por su habilidad para internalizarse, sobrevivir y replicarse dentro de fagocitos profesionales y no profesionales. B. abortusalcanza su nicho replicativo sin activar los mecanismos antimicrobianos de la inmunidad innata del hospedero. Esta bacteria posee sistemas de regulación génica a nivel transcripcional que le permiten una rápida adaptación al ambiente intracelular, entre ellos el sistema de transducción de señales de dos componentes BvrR/BvrS y el regulador de Quorum Sensing llamado Vjbr, así como otros factores de transcripción que, en conjunto, forman una compleja red de regulación génica.

AbstractBrucella abortusis a zoonotic intracellular facultative pathogen belonging to the subdivision a2 of class Proteobacteria. It causes a worldwide distributed zoonotic disease called brucellosis. The main symptoms are abortion and sterility in cattle, as well as an undulant febrile condition in humans. In endemic regions like Central America, brucellosis has a high socioeconomic impact. A basic research project was recently conducted at the ITCR with the purpose of studying gene regulation of virulence, structure and immunogenicity in B. abortus.The present review was written as part of this project. B. abortusvirulence seems to be determined by its ability to invade, survive and replicate inside professional and non-professional phagocytes. It reaches its intracellular replicative niche without the activation of host antimicrobial mechanisms of innate immunity. It also has gene regulation mechanisms for a rapid adaptation to an intracellular environment such as the two-component signal transduction system BvrR/BvrS and the quorum sensing regulator called Vjbr, as well as other transcription factors. All of them integrate a complex gene regulation network.