BACTERIOSTATIC AND BACTERICIDE ACTIVIES OF EUCALYPTUS Eucalyptus sp. PIROLENOUS EXTRACT IN FRONT OF ISOLATED Streptococcus agalactiae FROM Oreochromis niloticus
Commercial exploration of Oreochromis niloticus, Nile tilapia, has grown in recent years, reaching a worldwide production of millions of tonns annually, due to zootechnical characteristics suitable of the cultivation of the species. In this sense, research has also been gradually promoted in terms of sanitary management, in an attempt to keep up with the growing biosecurity challenges associated with more intensive production systems. Among the infectious agents of relevance to health in tilapiculture, we highlight Streptococcus agalactiae, Gram + bacteria that causes menginoencephalitis in animals, causing events with high mortality in the squad and severe damages to the producer. In this context, the development of preventive methods against streptococcosis becomes essential. In addition to concern with the development of more effective vaccines, the identification, characterization and use of dietary additives, such as extracts or oils derived from fresh vegetables or their industrial processing is a constant. Thus, the aim of this study was to investigate the possible bacteriostatic and bactericidal activities of pyrolenous extract (EP) of eucalyptus (Eucalyptus sp.) a product of industrial pulp processing, comparing EP samples from two batches of different ages through minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests. For MIC, diluted extract increasing serial ratios were applied to columns 1 to 10. Negative (11th) and positive (12th column) controls containing chlorafenicol antibiotic equally established (Figure 1). After 24 hours, from 100 µL of growth inhibition points, MBC was perfomed on BHI Agar (Figure 2). The results of MIC obtained were 6.5µg/µL for the 2019 EP (N) and 13µg/µL for the EP 2016 (V). Regarding MBC, the values found were 25µg/µL and 50µg/µL, respectively, for samples N and V. The results indicated the efficacy of PE against S. agalactiae strain, with age-dependent variation product.
