RESUMO
Chemical reagents have become fundamental products in daily life use, they contribute in several ways to establish a high level of social development. In the case of higher education, the use of reagents allows learning thought laboratory practices. These practices must be carried out under preventative measures, in order to avoid negative impacts on the environment and human health; this generates the need to identify and classify the chemical substances used and the waste generated. This research was developed at the Faculty of Environmental Engineering at Universidad Santo Tomás in the Villavicencio campus, the objective was to apply the concepts of Green Chemistry in the laboratory guidelines, in addition to guaranteeing the proper management of the chemical waste generated. Initially, the hazard of twenty-one (21) laboratory guides based on the Globally Harmonized System (GHS) ninth revised edition (2021) was determined. Subsequently, an update was performed by applying Green Chemistry to ten (10) of the laboratory guides that represented the greatest hazards, and finally, a manual was established for the management of chemical waste resulting from laboratory practices. The results determined that in the subject of Inorganic Chemistry the guidelines Physical and Chemical Properties of the Matter presents the highest hazard index, due to lead nitrate, which was evaluated as the most hazard reagent, because of its carcinogenicity (1B) and reproductive toxicity (1A). The proposed update to the guidelines was possible by replacing the chemical substances used in order to reduce by 24% the risk associated with them and the by 50% the use of reagents in relation to the same laboratory guidelines defined in the first stage.
RESUMO
Bacteriophages represent an alternative solution to control bacterial infections. When interacting, bacteria and phage can evolve, and this relationship is described as antagonistic coevolution, a pattern that does not fit all models. In this work, the model consisted of a microcosm of Salmonella enterica serovar Enteritidis and φSan23 phage. Samples were taken for 12 days every 48 h. Bacteria and phage samples were collected; and isolated bacteria from each time point were challenged against phages from previous, contemporary, and subsequent time points. The phage plaque tests, with the genomics analyses, showed a mutational asymmetry dynamic in favor of the bacteria instead of antagonistic coevolution. This is important for future phage-therapy applications, so we decided to explore the population dynamics of Salmonella under different conditions: pressure of one phage, a combination of phages, and phages plus an antibiotic. The data from cultures with single and multiple phages, and antibiotics, were used to create a mathematical model exploring population and resistance dynamics of Salmonella under these treatments, suggesting a nonlethal, growth-inhibiting antibiotic may decrease resistance to phage-therapy cocktails. These data provide a deep insight into bacterial dynamics under different conditions and serve as additional criteria to select phages and antibiotics for phage-therapy.