Microbioma associado a plantas de carnaúba (Copernicia prunifera): ecologia e aplicações biotecnológicas

Abstract

Carnauba (Copernicia prunifera ), an endemic palm tree of the Brazilian semi arid region, holds high ecological, social, and economic relevance, being widely exploited for wax extraction. Despite its importance, studies addressing soil microbial functioning and the functional potential of the microbiome associate d with this palm tree are still limited, especially under different management conditions and water regimes. In this context, this study aimed to investigate how leaf extraction management and variation in the soil water regime influence soil enzymatic act ivity, bacterial community structure, and the functional potential of microorganisms associated with carnauba. Initially, a bibliometric analysis performed on the Web of Science database (2007 2022; 658 publications) revealed a significant growth in public ations starting from 2014, peaking between 2019 and 2021, mostly focused on the properties and industrial applications of carnauba wax. The study confirmed that research integrating this palm tree into soil sciences is still incipient, validating the need for the experimental investigations conducted in this work. The study was carried out in natural occurrence areas of carnauba in the semi arid region of Ceará, in the municipality of Caucaia, selected based on the combination of two main factors: the presence or absence of leaf extraction management and different soil water regimes (flooded and unflooded). The evaluation of enzymatic activity and stoichiometric relationships showed that the water regime exerts strong control over soil dynamics, reducing total organic carbon, microbial biomass carbon, and the activities of ꞵ glucosidase, arylsulfatase, and acid phosphatase in flooded areas, while urease activity was favored by water saturation. Extractivist management acted as a mitigating factor for these va riations, reducing the variability of enzymatic stoichiometry (C:P ratio) and promoting greater functional stability, although the input of residual biomass intensified microbial phosphorus limitation in managed areas. At the molecular level, 16S rRNA gene amplicon sequencing revealed that management and water regime act as interdependent environmental filters, explaining 43.1% of the total variation in the bacterial community. The interaction between management and seasonal flooding promoted a significant reduction in richness (Chao1) and diversity (Shannon and Simpson), resulting in less complex co occurrence networks dominated by specialist taxa and stress tolerant groups (such as the Bacillota phylum). In contrast, unmanaged and unflooded areas sustained richer, more stable microbiomes with a higher proportion of generalist bacteria. Functional prediction (FAPROTAX) confirmed that preserved areas favor functions associated with phototrophy and nitrogen fixation, while management combined with flooding int flooding intensified anaerobic processes and sulfur cycling. Furthermore, the investigation of ensified anaerobic processes and sulfur cycling. Furthermore, the investigation of the culturable bacteriome showed that carnauba harbors bacteria with plant growththe culturable bacteriome showed that carnauba harbors bacteria with plant growth--promoting potential, especially in root and rhizospheric compartments. Functions such as bipotential, especially in root and rhizospheric compartments. Functions such as biological ological nitrogen fixation, phosphorus and potassium solubilization, and the production of indolenitrogen fixation, phosphorus and potassium solubilization, and the production of indole--33--acetic acid and exopolysaccharides were identified, with variations associated with acetic acid and exopolysaccharides were identified, with variations associated with management conditions and water availability. Integrated, the findings omanagement conditions and water availability. Integrated, the findings of this thesis indicate f this thesis indicate that leaf extraction management, when associated with natural water variations, does not that leaf extraction management, when associated with natural water variations, does not compromise the microbial functionality of carnauba lands and can contribute to the stability compromise the microbial functionality of carnauba lands and can contribute to the stability of soil ecological processes. However, seasonal floof soil ecological processes. However, seasonal flooding exerts the most pronounced oding exerts the most pronounced influence on the microbiome, acting as a critical filter that requires spatial and temporal influence on the microbiome, acting as a critical filter that requires spatial and temporal monitoring to ensure the sustainability of extractivism. In addition, the identification of monitoring to ensure the sustainability of extractivism. In addition, the identification of multifunctional native bacteria opens pmultifunctional native bacteria opens promising perspectives for the development of bioinputs romising perspectives for the development of bioinputs adapted to the edaphoclimatic conditions of the semiadapted to the edaphoclimatic conditions of the semi--arid region, establishing solid bases for arid region, establishing solid bases for future molecular validations and field trials aimed at the biotechnological valorization of future molecular validations and field trials aimed at the biotechnological valorization of carnauba ecosycarnauba ecosystems.stems.