Tese
Formulação e avaliação de um bioherbicida a partir de fermentação submersa do fungo Diaporthe sp.
Fecha
2019-03-15Autor
Almeida, Thiago Castro de
Institución
Resumen
The search for new tools that help in the management of weeds can be through
biomolecules in bioherbicides produced by microorganisms, capable of controlling
weeds with low toxicity to the environment. Biomolecules are metabolites released
during microbial growth in fermentation, being thus found in low concentration and
easy degradation. In this sense, the objective of this work was to study the spray
drying formulation of a bioherbicide produced in submerged fermentation of the
fungus Diaporthe sp. Thus, the study of the variables agitation (rpm) and aeration
(vvm) in the fermentation in a bioreactor continuously stirred tank (STR) was carried
out through a planning design of the central rotational compound DCCR for the
variables agitation (rpm) and aeration (vvm), evaluating the control of each treatment
on germination and growth inhibition of cucumber seeds. Treatment 1 with the
variables 47.5 rpm 1.9 vvm obtained better results. In the evaluation of the solid
formulation in spray drying the influence of the feed rate (L.h-1
) and air flow (L.min-1
)
of the inert ingredient was studied. In the evaluation of the solid formulation in spray
drying the influence of the feed rate (L.h-1
) and air flow (L.min-1
) of the inert ingredient
was studied. Where through a DCCR for the variables food flow and air flow,
treatment 7 (0.2 L.h-1
and 2.5 L.min-1
) showed the highest yield for the formulation.
The efficiency of the spray drying formulation was evaluated through a completely
randomized DIC design with the type factors (liquid and solid), presence of adjuvant
(with or without) and percentage of the fermentative broth (5, 25 and 100% v/v) on
the test plant lettuce (Lactuca sativa), through a tri factorial 2 x 2 x 3, plus one control
without application. The percentage of phytotoxicity (%), dry mass (g) and activity of
the enzymes guaiacol peroxidase (POD) and superoxide dismutase (SOD) were
evaluated. The percentage of phytotoxicity (%) on the test plant lettuce (Lactuca
sativa) among the studied factors showed that the best result was with the use of the
spray formulation (solid), with adjuvant and 100 v/v% fermented broth. The treatment
of higher percentage of phytotoxicity (%) showed high activity of the antioxidant
enzymes SOD and POD. In this sense, it was observed that the biomolecules
promoted oxidative stress in the plants, and when the fermented broth was used in
the highest concentration of 100 v/v% biomolecules, the plants could not avoid
through the antioxidant enzymes SOD and POD the degradation and lesions of the test plant lettuce. The results demonstrated that the technique for solid spray drying
formulation was viable without degrading biomolecules with herbicidal action and that the fungus Diaporthe sp produced biomolecules with action.