Avaliação da citotoxicidade e genotoxicidade de extratos de microrganismos isolados de ambientes naturais em raízes de cebola (Allium cepa L.)

Abstract

Microorganisms possess genetic and physiological plasticity that gives them the ability to adapt to diverse environmental conditions. In this context, the production of bioactive compounds by these microorganisms can confer this plasticity and, at the same time, draws attention to their study, as they may present a variety of therapeutic properties. For the study of mutagenesis, there are plants that are considered ideal, both in the laboratory and in in situ monitoring, thus acting as "bioindicators". Therefore, considering an extremely active and productive bacterial community that lives in diverse ecosystems and from the perspective that microorganisms are important sources of bioactive compounds, this work aimed to study the cytotoxic and genotoxic activity of microorganism extracts on onion cells, pointing to the production of molecules with antineoplastic potential. In this study, onions (Allium cepa L.) were placed in mineral water for 48 hours to grow roots, followed by 24 hours in a solution of bacterial or fungal extracts (10 ppm), using mineral water as a negative control and paracetamol (500 ppm) as a positive control. The root tips were analyzed by optical microscopy, evaluating the mitotic index (MI) as an indicator of cytotoxicity, and the genotoxic index (GI). Among the treatments with fungal extracts, only one showed a significant reduction in MI compared to the negative control. Among the bacterial samples isolated from Irauçuba, all showed a significant difference, with a reduction in MI. Of the treatments with Pseudomonas, all showed cytotoxicity equivalent to the positive control. Regarding the genotoxic index, the fungal samples did not show significant differences when compared to the negative control, indicating a low GI. The bacterial extracts, however, were almost equivalent to the positive control in terms of IGen. In particular, of the extracts isolated from Irauçuba, three samples showed a significant difference superior to the treatment with paracetamol, indicating a higher IGen than that corresponding to the positive control. The treatments with Pseudomonas showed a lower IGen than the positive control, with no significant difference compared to the negative control. During the analysis of the photomicrographs of the slides, it was possible to visualize chromosomal aberrations, indicating DNA damage and interference with the mitotic spindle.