Search Results (186)

This study analyzes the relationship between fires and climate extremes in the Caatinga biome from 2012 to 2023 by integrating Fire Radiative Power (FRP) from VIIRS (S-NPP and NOAA-20), Vapor Pressure Deficit (VPD) and air temperature from ERA5, drought indices (SPI-1 and SPI-6), and heatwave events from the Xavier database. Daily percentiles of maximum (CTX90pct) and minimum (CTN90pct) temperatures were used to characterize heatwaves. Spatial and temporal dynamics of fire patterns were identified using the HDBSCAN algorithm, an unsupervised Machine Learning clustering method applied in three-dimensional space (latitude, longitude, and time). A marked seasonality was observed, with fire activity peaking from August to November, especially in October, when FRP reached ~1000 MW/h. The years 2015, 2019, 2021, and 2023 exhibited the highest fire intensities. A statistically significant upward trend in cluster frequency was detected (+1094.96 events/year; p < 0.001). Cross-correlations revealed that precipitation deficits (SPI) preceded FRP peaks by about four months, while VPD and air temperature exerted immediate positive effects. FRP correlated positively with heatwave frequency (r = 0.62) and negatively with SPI (r = −0.69). These findings highlight the high vulnerability of the Caatinga to compound drought and heat events, indicating that fire management strategies should account for both antecedent drought conditions, monitored through SPI, and real-time atmospheric dryness, measured by VPD, to effectively mitigate fire risks. Full article

Background/Objectives: The escalating antimicrobial resistance crisis underscores the urgent need to explore underexplored ecological niches as reservoirs of novel bioactive compounds. The Brazilian Caatinga, a unique semi-arid biome, represents a promising reservoir for microbial discovery. Methods: In this study, we report the polyphasic characterization of Streptomyces galbus I339, a strain isolated from Caatinga soil. Whole-genome sequencing and phylogenomic analysis confirmed its taxonomic identity. In silico mining of the genome was conducted to assess biosynthetic potential. This genetic promise was experimentally validated through an integrated metabolomic approach, including liquid chromatography-tandem mass spectrometry (LC-MS/MS), nuclear magnetic resonance (NMR) spectroscopy, and gas chromatography-mass spectrometry (GC-MS) profiling. The anti-mycobacterial activity of the crude extract was evaluated against Mycobacterium tuberculosis. Results: The strain S. galbus I339 possesses a 7.55 Mbp genome with a high GC content (73.17%). Genome mining uncovered a remarkable biosynthetic potential, with 45 biosynthetic gene clusters (BGCs) predicted, including those for known antibiotics like actinomycins, as well as numerous orphan clusters. Genome mining uncovered a remarkable biosynthetic potential, with 45 biosynthetic gene clusters (BGCs) predicted, including those for known antibiotics like actinomycins, as well as numerous orphan clusters. Metabolomic analyses confirmed the production of actinomycins and identified abundant diketopiperazines. Furthermore, the crude extract exhibited antimycobacterial activity, with a potent MIC of 0.625 µg/mL. Conclusions: The convergence of genomic and metabolomic data not only validates the expression of a fraction of this strain’s biosynthetic arsenal but also highlights a significant untapped potential, with the majority of BGCs remaining silent under the tested conditions. Our work establishes S. galbus I339 as a compelling candidate for biodiscovery and underscores the value of integrating genomics and metabolomics to unlock the chemical diversity of microbes from extreme environments. Full article

Fruit production in passionfruit species is primarily associated with cross-pollination, but the role of herkogamy, the spatial separation between stigmas and anthers, in reproductive success remains poorly understood. This study evaluated the influence of style deflexion on fruit set in Passiflora cincinnata Mast., a native species of the Brazilian Caatinga, using accessions conserved in a Passionfruit Germplasm Bank (BAG). Flowers were classified into three morphotypes: stigmas positioned below the anthers, stigmas aligned with the anthers, and stigmas positioned above the anthers. Pollen viability was evaluated using subsamples of randomly selected flowers within each floral morphotype. Across all accessions, 41.75% of flowers displayed stigma below the anthers, 26.32% exhibited aligned the stigma with the anthers, and 31.93% had stigma positioned above, with pollen viability consistently high (96.4–96.7%). Flowers in which stigmas were located below the anthers (negative deflexion) showed the highest fruit set under hand pollination (73.3%), whereas flowers with aligned or elevated stigmas produced only a few fruits (4.7%) in heterotypic crosses. These findings demonstrated that herkogamy strongly shapes reproductive outcomes in P. cincinnata. Integrating this knowledge into germplasm management, conservation, and breeding initiatives will be essential for improving passionfruit cultivation and promoting sustainable agricultural practices in semiarid ecosystems. Full article

The genus Streptomyces is the largest group within the phylum Actinobacteria, recognized for producing antibiotics and enzymes, with wide applications in medicine and biological control for crop protection against phytopathogens. In this study, the Streptomyces sp. Caat 5-35 strain, isolated from soil of the Caatinga biome in Brazil, and identified by analysis of the 16S rRNA gene, demonstrated its antagonistic effect in vitro in dual cultures against Phytophthora palmivora, Colletotrichum acutatum, Fusarium oxysporum, Rhizoctonia solani, Sclerotinia sclerotiorum, and Fusarium graminearum. Caat 5-35 inhibited mycelial growth ranging from 19% to 73.3%. Compounds purified by prep-HPLC from extracts were identified by spectral data analysis using UHPLC-triple-TOF-MS/MS, or nuclear magnetic resonance (NMR). This work demonstrated for the first time the anti-oomycete activity of albofungin, its derivatives, and albonoursin against P. palmivora. Moreover, the growth inhibition of Colletotrichum gloeosporioides by albonoursin and the antibacterial effect of 2-chloroadenosine and 5′-O-sulfamoyl-2-chloroadenosine against Pectobacterium carotovorum were demonstrated as novel findings. Caat 5-35 exhibited the ability to solubilize phosphates and produce cellulases on CMC agar. The findings of this study, in combination with in vitro bioassays on cacao pods (Theobroma cacao L.) inoculated with the antagonist strain and P. palmivora APB-35, demonstrate that Streptomyces sp. Caat 5-35 is a source of natural products with applications in agriculture and could serve as an alternative for crop protection. Full article

The cells in the central nervous system (CNS) can adapt to injury and inflammation through structural and functional changes, many of which are mediated by the kynurenine pathway (KP). Studies using glia–neuron co-cultures showed that the biflavonoid agathisflavone (FAB), purified from the leaves of Cenostigma pyramidale Tul., a plant native to the Brazilian caatinga, exerts strong neuroprotective effects. This study evaluated whether agathisflavone (1 µM) modulates these responses in human and murine astrocytes and microglia exposed to inflammatory activation with lipopolysaccharide (LPS, 1 µg/mL), excitotoxic activation of NMDA receptors with quinolinic acid (QUIN, 500 µM), or inhibition of the KP rate-limiting enzyme indoleamine 2,3-dioxygenase 1 (IDO1) with 1-methyl tryptophan (1-MT, 1.5 μM). Co-treatment with FAB increased astrocyte viability relative to LPS, QUIN, or 1-MT alone, by up to 35% (p < 0.05), while reducing GFAP overexpression and other features of reactive astrogliosis. FAB decreased the proportion of Iba-1⁺ microglia, indicating anti-inflammatory effects. When combined with QUIN or 1-MT, FAB reversed the elevation of iNOS (p < 0.0001) and reduced IL1β upregulation. FAB also modulated KP activity in a cell type-specific manner. In astrocytes, FAB with QUIN or with 1-MT increased IDO activity, whereas in microglia, FAB alone reduced it. In microglia, kynurenine-3-monooxygenase (KMO) expression was significantly increased under FAB+QUIN or FAB+1-MT (p < 0.0001). Finally, astrocyte-conditioned medium from FAB-treated cells increased the viability of neuron-like PC12 cells by up to 40%. Collectively, these findings show that FAB confers cytoprotective and anti-inflammatory actions on glial cells, modulates KP signalling in a context-dependent manner, and supports neuronal survival under neuroinflammatory conditions. Full article

Commiphora leptophloeos, a native Caatinga species with economic and medicinal potential, faces propagation challenges due to seed dormancy and extractive use. The germination test, the official method for seed quality assessment, is time-consuming, whereas the tetrazolium test (TZT) offers a rapid alternative for determining seed viability. This study aimed to establish and validate a TZT protocol for C. leptophloeos seeds. Seeds collected in 2025 were extracted after natural fruit drying and then stored in a cold chamber. The germination test was conducted with seeds without pyrenes at 30 °C. For the TZT, a completely randomized design was used in a 6 × 4 factorial scheme (six TZT concentrations × four immersion times), with adjustments in seed preparation and staining procedures. Higher concentrations (0.5% and 0.75%) combined with shorter immersion periods (2 h) provided the best results, especially 0.75% for 2 h, which yielded 89% viability. Very low concentrations combined with short periods resulted in little or no staining. Compared with the germination test (35%), the TZT showed greater sensitivity in detecting viable seeds. We conclude that the TZT is highly efficient for assessing the viability of C. leptophloeos seeds, with optimal responses at 0.5–0.75% TTC and 2–4 h immersion periods, and represents a strategic tool to support the conservation and sustainable use of this species. Full article

Crateva tapia L. is a native tree species of the Caatinga biome, with medicinal and allelopathic properties. This study aimed to characterize the biometric and morphological traits of fruits, seeds, seedlings, and young plants of C. tapia, as well as to evaluate the germination pattern of its seeds under different temperatures, in order to understand the reproductive strategies and optimal conditions for its propagation. The results are intended to support conservation efforts, ecological restoration, and the sustainable use of the species within the Caatinga biome. The research was carried out at the Seed Analysis Laboratory of the Federal University of Paraíba, Campus II, Areia–PB, Brazil. The biometric data were obtained from 100 fruits and 100 seeds obtained from eight mother plants. The imbibition curve was determined from the weight of the seeds during 216 h at different temperatures, and the germination test was performed concomitantly. The fruits were morphologically described regarding the external and internal aspects of the pericarp. The seeds were described according to their consistency, color, texture, shape, hilum, and embryo. The fruits of C. tapia vary in size, fresh mass, and number of seeds, characterized as amphisarcidium, indehiscent, and polyspermic. The seeds are small, brown, reniform, and biting, with a cotyledonary embryo with a poorly differentiated hypocotyl–radicle axis, with a well-developed hilum and surrounded by a fleshy mesocarp. The germination of C. tapia seeds is epigeal-phanerocotyledonous; the seedlings have white axial roots containing absorbent hairs. Full article

This study examines long-term trends in maximum (Tmax) and minimum (Tmin) near-surface air temperatures and precipitation across South America, focusing on Brazilian biomes and national capitals, using ERA5 reanalysis data for 1979–2024. To isolate the underlying climate signal, seasonal cycles were removed using Seasonal-Trend decomposition based on Loess (STL), which effectively separates short-term variability from long-term trends. Temperature trends were quantified using ordinary least squares (OLS) regression, allowing consistent estimation of linear changes over time, while precipitation trends were assessed using the non-parametric Mann–Kendall test combined with Theil–Sen slope estimation, a robust approach that minimizes the influence of outliers and serial correlation in hydroclimatic data. Results indicate widespread but spatially heterogeneous warming, with Tmax increasing faster than Tmin, consistent with reduced cloudiness and evaporative cooling. A meridional precipitation dipole is evident, with drying across the Cerrado, Pantanal, Caatinga, and Pampa, contrasted by rainfall increases in northern South America linked to ITCZ shifts. The Pantanal emerges as the most vulnerable biome, showing strong warming (+0.51 °C decade⁻¹) and the steepest rainfall decline (−10.45 mm decade⁻¹). Satellite-based fire detections (2013–2024) reveal rising wildfire activity in the Amazon, Pantanal, and Cerrado, aligning with the “hotter and drier” climate regime. In the capitals, persistent Tmax increases suggest enhanced urban heat island effects, with implications for public health and energy demand. Although ERA5 provides coherent spatial coverage, regional biases and sparse in situ observations introduce uncertainties, particularly in the Amazon and Andes, these do not alter the principal finding that the magnitude and persistence of the 1979–2024 warming lie well above the range of interdecadal variability typically associated with the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO). This provides strong evidence that the recent warming is not cyclical but reflects the externally forced secular warming signal. These findings underscore growing fire risk, ecosystem stress, and urban vulnerability, highlighting the urgency of targeted adaptation and resilience strategies under accelerating climate change. Full article

The expansion of algaroba (Neltuma juliflora), an invasive exotic species widely adapted to arid and semi-arid environments, has caused significant ecological and geomorphological changes on the northern coast of Rio Grande do Norte in Brazil. This study aimed to analyze the greening process associated with the expansion of algaroba in the Rosado Dunes Environmental Protection Area (APADR) between 2004 and 2024. Images from the SPOT 5PSM, CBERS 4, and CBERS 4A satellites were used, processed by supervised classification in QGIS software version 3.38. The multitemporal analysis revealed a significant change in the landscape, with a reduction in areas of native vegetation (caatinga and restinga) and an increase in dunes and beaches, urban areas, and invasive species. The area occupied by algaroba expanded from 70 ha (0.5%) in 2004 to 435 ha (3.1%) in 2024, representing an increase of more than six times in two decades. This expansion has had direct impacts on biodiversity, sediment dynamics, and groundwater availability, in addition to compromising connectivity between the dunes and the beach environment. The results point to the need for public policies aimed at controlling invasive species and sustainably managing native vegetation, with a view to conserving biodiversity and the integrity of the coastal and semi-arid geosystems of APADR. Full article

The aim of this study was to assess phenotypic variation and its implications for genetic diversity in natural populations of Spondias tuberosa. Fruits were harvested from 38 mother plants from three natural populations, and the physical traits of the fruits, endocarps, and physiological quality of the seeds were evaluated in a completely randomized design with four replicates of 25 fruits per genotype. The data were subjected to analysis of variance, and the means were grouped via the Scott–Knott method. Genetic diversity was evaluated via UPGMA and Tocher clustering methods, which are based on the Mahalanobis distance (D²) and canonical variables, whereas the relative importance of the characters was evaluated via the Singh method. The results indicated high phenotypic variability, with fruit length was the main discriminant trait among genotypes. The groupings formed six (UPGMA) and 12 groups (Tocher), indicating greater divergence within populations. The analysis of phenotypic data provides a solid basis for understanding the ecological dynamics of and supporting sustainable management practices for S. tuberosa, in line with bioeconomic objectives. This study highlights the importance of preserving phenotypic variability in populations, which is essential for the adaptation of species to environmental changes and for improving local bioeconomies. Full article

This study aimed to assess the potential of machine learning models applied to high spatial resolution images from UAVs for estimating the aboveground biomass (AGB) of forage grass cultivated in the Brazilian semiarid region. The fresh and dry AGB were determined in Cenchrus ciliare plots with an area of 0.04 m². Spectral data were obtained using a multispectral sensor (Red, Green, and NIR) mounted on a UAV, from which 45 vegetation indices were derived, in addition to a structural variable representing plant height (H95). Among these, H95, GDVI, GSAVI2, GSAVI, GOSAVI, GRDVI, and CTVI exhibited the strongest correlations with biomass. Following multicollinearity analysis, eight variables (R, G, NIR, H95, CVI, MCARI, RGR, and Norm G) were selected to train Random Forest (RF), Support Vector Machine (SVM), and XGBoost models. RF and XGBoost yielded the highest predictive performance, both achieving an R² of 0.80 for AGB—Fresh. Their superiority was maintained for AGB—Dry estimation, with R² values of 0.69 for XGBoost and 0.67 for RF. Although SVM produced higher estimation errors, it showed a satisfactory ability to capture variability, including extreme values. In modeling, the incorporation of plant height, combined with spectral data obtained from high spatial resolution imagery, makes AGB estimation models more reliable. The findings highlight the feasibility of integrating UAV-based remote sensing and machine learning algorithms for non-destructive biomass estimation in forage systems, with promising applications in pasture monitoring and agricultural land management in semi-arid environments. Full article

This study presents the production, characterization, and potential pharmaceutical application of a bioemulsifier synthesized by Aspergillus niger UCP 1064 by submerged fermentation using agro-industrial residues (cassava wastewater and soluble starch). The compound exhibited a high emulsification index (EI₂₄ > 88%) against hydrophobic substrates, effectively reduced surface tension, and remained stable across a wide range of pH (2–12), temperatures (5–100 °C), and salinity levels (0–20% NaCl). Microscopic analysis confirmed the formation of stable oil-in-water (O/W) emulsions, while biochemical tests identified the compound as a glycolipoprotein. Rheological assays demonstrated a significant reduction in oil viscosity, enhancing fluidity. Through factorial design and response surface methodology, production conditions were optimized, achieving yields of up to 3.18 g/L. A theoretical scale-up indicated technical feasibility for pharmaceutical applications; however, challenges such as process reproducibility, sterility, and regulatory compliance persist. These findings highlight the bioemulsifier’s potential as a sustainable and biocompatible alternative for drug delivery systems. Full article

Environmental degradation and soil desertification are among the most severe environmental issues of recent decades worldwide. Over time, these processes have led to increasingly extreme and highly dynamic climatic conditions. In Brazil, the Northeast Region is characterized by semi-arid and arid areas that exhibit high climatic variability and are extremely vulnerable to environmental changes and pressures from human activities. The application of geotechnologies and geographic information system (GIS) modeling is essential to mitigate the impacts and pressures on the various ecosystems of Northeastern Brazil (NEB), where the Caatinga biome is predominant and critically threatened by these factors. In this context, the objective was to map and assess the spatiotemporal patterns of land use and land cover (LULC), detecting significant trends of loss and gain, based on surface reflectance data and precipitation data over two decades (2000–2019). Remote sensing datasets were utilized, including Landsat satellite data (LULC data), MODIS sensor data (surface reflectance product) and TRMM data (precipitation data). The Google Earth Engine (GEE) software was used to process orbital images and determine surface albedo and acquisition of the LULC dataset. Satellite data were subjected to multivariate analysis, descriptive statistics, dispersion and variability assessments. The results indicated a significant loss trend over the time series (2000–2019) for forest areas (Z_MK = −5.872; Tau = −0.958; p < 0.01) with an annual loss of −3705.853 km² and a total loss of −74,117.06 km². Conversely, farming areas (agriculture and pasture) exhibited a significant gain trend (Z_MK = 5.807; Tau = 0.947; p < 0.01), with an annual gain of +3978.898 km² and a total gain of +79,577.96 km², indicating a substantial expansion of these areas over time. However, it is important to emphasize that deforestation of the region’s native vegetation contributes to reduced water production and availability. The trend analysis identified an increase in environmental degradation due to the rapid expansion of land use. LULC and albedo data confirmed the intensification of deforestation in the Northern, Northwestern, Southern and Southeastern regions of NEB. The Northwestern region was the most directly impacted by this increase due to anthropogenic pressures. Over two decades (2000–2019), forested areas in the NEB lost approximately 80.000 km². Principal component analysis (PCA) identified a significant cumulative variance of 87.15%. It is concluded, then, that the spatiotemporal relationship between biophysical conditions and regional climate helps us to understand and evaluate the impacts and environmental dynamics, especially of the vegetation cover of the NEB. Full article

Antimicrobial resistance represents a critical global health challenge, intensifying the urgency of discovering novel antibiotics. Actinomycetota species, the most prolific source of clinical antibiotics, remain underexplored in unique ecosystems. In this study, we isolated 340 Actinomycetota strains from soils of the Brazilian semiarid Caatinga biome. Screening revealed that 122 isolates (35.9%) exhibited antimicrobial activity against clinically relevant pathogens (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans). Notably, 19 isolates showed activity against Mycobacterium tuberculosis H37Ra. MALDI-TOF MS analysis successfully provided genus-level identification for a subset of isolates, with approximately 32% assigned to the Streptomyces genus. However, the limited resolution of the database for the majority of the strains indicates high phylogenetic diversity and suggests the presence of potentially novel species. Metabolomic profiling via LC-MS/MS and GNPS molecular networking suggested the production of known antibiotics such as actinomycins, cyclomarins and anthracyclines and unveiled distinct molecular families putatively assigned to undescribed metabolites. Our work establishes the Caatinga biome as a valuable reservoir of bioactive Actinomycetota, encoding both known and potentially novel antimicrobial compounds. These results underscore the potential of underexplored and extreme environments in the quest to overcome antibiotic resistance. Full article

This article aims to report and analyze the main findings of a study on how constraints affect the engagement and creativity of non-designers in co-creation activities. It focuses particularly on identifying the limits and potentials of using a physical interface to address tectonic and renewable energy aspects within the design process. To explore these issues, this study adopted a qualitative case study approach, combining co-design charrettes mediated by a physical interface with a mapping process used as the primary analytical and evaluative framework. The interface allows users to anticipate the structural behavior and construction aspects of small roundwood structures from the Brazilian Caatinga biome, as well as the operation of solar energy systems—all without prior technical training. Despite its limitations, this study offers three main contributions: (a) it demonstrates that interfaces and charrettes can include non-designers in technical design processes; (b) it highlights the pedagogical, technical, and political potential of these tools in democratizing architectural decisions; and (c) it emphasizes the value of constraints as generative elements in creative processes—a topic still underexplored in the co-design literature. Full article