Estratégias de avaliação dos efeitos de metais pesados (cádmio e chumbo) e biossurfactante na fisiologia da germinação de sementes de Sorghum bicolor L. Moench.

Abstract

The environment faces considerable challenges related to forms of life, from animals, humans and plants, including compromising the food chain. Thus, the high concentration of heavy metals in the soil has been causing severe impacts to plants, mainly affecting leaves and seeds. In this context, the initial studies were aimed at evaluating the potential of the bacteria Pseudomonas fluorescens UCP 1514, Bacillus cereus UCP 1528, Bacillus subtilis UCP 1602 and Enterobacter cloacae UCP 1597 against concentrations of cadmium and lead, in compliance with the bioremediation process of Sorghum bicolor L. Moench. Thus, the degree of resistance to heavy metals by bacteria was evaluated. The results obtained indicated that the bacteria B. cereus UCP 1528 and B. subtilis are more resistant to high concentrations of cadmium and lead than the Gram-negative bacteria E. cloacae UCP 1597 and P. fluorescens UCP 1514. This information was confirmed by the literature. and form part of a book chapter. Other investigations were carried out with the objective of evaluating the physiological quality of Sorghum bicolor seeds with and without exposure to the heavy metal cadmium at concentrations of 0.5mM and 3mM, through electrical conductivity. The electrical conductivity results indicated a proportional increase with increasing cadmium concentration and imbibition times. Studies carried out with the germination of S. bicolor seeds under the action of biosurfactant, a significant increase was observed from the minimum concentration of biosurfactant (1.565% - CMC of 2%) expressing an increase of 35% in the total growth of the germination index (70.46 mm) compared to the control distilled water (51.86 mm) and at maximum concentration (100% - CMC of 2%) the biosurfactant demonstrated an even more pronounced impact resulting in total growth (83.85 mm) with an increase of 61% when compared to the water control group, highlighting the efficiency of this lipopeptide in inducing germination and phytoprotection against cadmium. During germination, it was observed that the biosurfactant and cadmium interaction intensified the phytoprotective effects for radicle development at the concentration (100% - CMC of 2%). Branching and hypocotyl increased in the presence of biosurfactant compared to exposure with cadmium alone. In this sense, the biosurfactant produced by E. cloacae demonstrated to be a stable and efficient biomolecule, playing a crucial role in the germination and phytoprotection of S. bicolor, enabling a promising action in the phytoremediation process and promotion of environmental sustainability, with quality agricultural practices. and security.