Bioprospecção de actinomicetos para fins agrícolas e ambientais
Kaydedildi:
| Yazar: | |
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| Yayın Tarihi: | 2025 |
| Materyal Türü: | Doctoral thesis |
| Dil: | por |
| Kaynak: | Repositório Institucional da UPF |
| Download full: | https://repositorio.upf.br/handle/123456789/10172 |
Özet: | Actinomycetes constitute a group of Gram-positive bacteria distinguished by their filamentous morphology. Currently, the primary industrial application of actinomycetes lies in antibiotic production. However, these bacteria exhibit significant potential for various applications, particularly in the agricultural and environmental sectors. Streptomyces is the principal genus of actinomycetes, responsible for the production of the majority of secondary metabolites known and utilized by the pharmaceutical industry. Numerous studies have highlighted the potential of Streptomyces spp. in agriculture, particularly for promoting plant growth through phytohormones production, enhancing nutrient availability, controlling a broad spectrum of phytopathogens, and mitigating abiotic stresses. Despite this potential, there are no records of bio-inputs based on Streptomyces spp. in Brazil, indicating a promising field for exploration. One approach to enhance the sustainability of bio-input production involves cultivating microorganisms using waste and by-products from food and beverage industries, such as those generated by winemaking - a sector of significant economic importance at the state level. In this context, part of this thesis aimed to develop an alternative cultivation medium (ACM) for a Streptomyces isolate using spent yeast generated during the wine clarification process and leachate from composting piles from grape waste. This isolate, identified as Streptomyces sp. BEI-18A via 16S rRNA sequencing, was obtained from the composting piles and selected for study as a plant growth promoter due to its high production of siderophores. The highest cellular concentration of Streptomyces sp. BEI-18A was achieved in an ACM containing 3 g L⁻¹ spent yeast, 2 g L⁻¹ sucrose, 1 g L⁻¹ soybean extract, and 10% (v/v) composting leachate. Cultivation of the isolate in this ACM resulted in a bio-input based on Streptomyces sp. BEI-18A, which significantly enhanced several phytometric parameters in soybeans and wheat. The second part of this study focused on developing a material for the treatment of Cr(VI)-contaminated aqueous matrices. This material was produced by immobilizing another actinomycete isolate, identified as Rhodococcus sp. BEI-13A, onto biochar derived from the pyrolysis of grape waste. The selection of this isolate was based on preliminary growth tests conducted in the presence of chromium, as well as extensive scientific evidence supporting the efficacy of Rhodococcus spp. in bioremediation processes for various pollutants. In this study, the biochar-immobilized Rhodococcus sp. BEI-13A was evaluated for its capacity to decontaminate Cr(VI) from water. The highest chromium decontamination efficiency achieved was 18.55% under the following conditions: pH 6, 3 g L⁻¹ immobilized material, 350 mg L⁻¹ chromium concentration, 25°C, and 48 hours of incubation. In summary, through the bioprospecting and application of actinomycetes explored in this work, it was possible to develop a bio-input for plant growth promotion (Streptomyces sp. BEI-18A) and a material with potential for Cr(VI) decontamination from aqueous matrices (biochar-immobilized Rhodococcus sp. BEI-13A). This thesis sought to foster sustainability in agriculture and wastewater treatment technologies. By integrating waste and effluent valorization, circular economy principles, and sustainable agricultural practices, this work contributes to achieving several United Nations Sustainable Development Goals (SDGs). |