SOUTHERN JOURNAL OF SCIENCES

Background: Due to population growth and increased use of water resources, there has been a need to implement management measures to control and monitor river parameters. Aims: This study aims to demonstrate the application of mathematical modeling using the QUAL-UFMG model for studying nitrogen concentration in the Paraíba do Sul River located in Volta Redonda. Methods: Through mathematical modeling, it is possible to identify areas of greater impact, evaluate the effectiveness of control measures, and propose a strategy to improve water quality and preserve the balance of local aquatic ecosystems. Results: The results obtained during the study showed that the nitrogen parameters and their derivatives are within the pre-established limits set by CONAMA. Discussion: During the modeling, it was observed that there is a tendency for nitrate levels to increase along the points, indicating good self-purification of the river. Organic nitrogen values increase along the points, which is due to the contribution of sewage discharge along the course of the river, as organic nitrogen and ammonia have a physiological origin in domestic sewage. Conclusions: Through the QUAL-UFMG model, it was possible to validate the conducted analyses and create future projections of the water quality in the Paraíba do Sul River along the studied points.

Background: Sugarcane juice is an excellent substrate for the growth of a large and diverse microbiota, and poor quality of it can affect the health of consumers. This study aimed to evaluate the acidity parameters of the juice extracted from minimally processed sugarcane at three different points in Cuiabá - MT. Methods: In the juice samples, the following parameters were analyzed: Brix (soluble solids), pH, acetic (volatile) acidity, and sulfuric (total) acidity. Results: All the Brix values were above 18. The pH values were between 5 and 6. The total and volatile acidity was below 0.8. Discussion: The Brix values found in this study are similar to other studies (standard deviation of 1.7). The variety of sugarcane significantly influences the Brix and its sampling period. Inappropriate handling of sugarcane promotes the microbiological decrease of the final product. The pH values were satisfactory, but the changes in temperature in one of the juices (sudden change from 24 to 22.7ºC) caused its pH to differ from the value found for the others. The total and volatile acidity content is related to the storage time of the juice, which can be contaminated by bacteria and microorganisms, affecting the characteristics of the product. When the acidity value is more significant than 0.8, there was a change in these characteristics, which did not happen in this work. Conclusions: The Brix values indicate an adequate maturation of the analyzed juices. The pH values are in the ideal range for sugarcane juice. The volatile and total acidity is in the ideal range, indicating quality standards for sugarcane juice.

Background: Infectious diseases are a global problem, the second human cause of death. Infectious diseases caused by pathogenic bacteria have been treated with a high degree of efficacy. However, even when the 20th century was considered the “golden age” of antibiotics, bacteria developed a different resistance mechanism to antibiotics. In 2017, the WHO issued an alert about 12 bacteria with an urgent need to develop new antibiotics. Aims: The aim of the present review is to analyze the current knowledge of the antibacterial activity of natural extract-based treatments against the pathogens listed by WHO. Methods: A systematic review of the literature in PubMed was performed to search for publications describing the use of natural extracts as antibiotics over bacteria. We focused on the Gram-Negative group. The exclusion criteria consisted of limiting papers on natural extracts tested over the bacteria culture related to eight selected bacteria, according to an alert issued by WHO in 2017, and seven plant extracts. Results: All the Gram-Negative bacteria listed in 2017 by WHO have been treated, with different degrees of advance, with some of the plant extracts and plant-based compounds reviewed. In general, the first approach is using inhibition disks applied over the bacterial biofilm in solid culture media. Discussion: While Salmonellae and P. aeruginosa have been extensively studied, over N. gonorrhoeae, A. baumannii have been tested with fewer natural extracts. Edible herbs are more often used, as well as artemisa and wine byproducts. In all cases, they are in the early stages of study, not being tested in patients at present. Conclusions: Plant extracts and plant-based compounds are effective as antibacterial, with minimal effects on the host cell. Furthermore, they are sustainable, environmentally friendly, and renewable.