Biology subjects

Ares, A.

Publications and source records attributed to Ares, A..

4 recordsLinked to original sources

bioRxiv2026

Functional Profiling of Kiwifruit Phyllosphere Bacteria: Copper Resistance and Biocontrol Potential as a Foundation for Microbiome-Informed Strategies

Bacterial canker, caused by Pseudomonas syringae pv. actinidiae (Psa) is a major threat to global kiwifruit production. Copper-based bactericides remain widely used, but increasing resistance underscores the need for alternative strategies. Understanding the functional capabilities of phyllosphere bacteria under copper pressure is critical for designing sustainable alternatives. This study provides a culture-based functional inventory of bacteria associated with Actinidia chinensis var. deliciosa leaves from Portuguese orchards under long-term copper management, aiming to identify native taxa with traits relevant to plant health and resilience. A total of 1,058 isolates were recovered and grouped into 261 RAPD clusters, representing 58 species across 29 genera. Representative strains were screened for plant growth-promoting (PGP) traits (IAA, siderophore production, phosphate solubilization, ammonia production), copper tolerance, and in vitro antagonism against Psa. Copper resistance was widespread (53.3% of isolates with MIC [≥]0.8 mM), including the first evidence of a highly copper-resistant PSA in Portuguese kiwifruit orchards and an exceptionally resistant non-pathogenic strain (Erwinia iniecta, MIC 2.8 mM). A subset of 25 isolates combined all PGP traits. In parallel, several isolates exhibited antagonism against Psa, including Bacillus pumilus, which consistently inhibited pathogen growth. Notably, some antagonistic isolates overlapped with the multifunctional PGP subset, highlighting promising candidates for integrated biocontrol strategies. These findings reveal the kiwifruit phyllosphere as a reservoir of functionally diverse and copper-resilient bacteria, highlighting both ecological risks and opportunities for microbiome-based biocontrol innovation. This work establishes a functional baseline for future in planta validation and microbiome-informed disease management strategies.

microbiology↗

bioRxiv2024

Urbanization of a subtropical island (Okinawa, Japan) alters physicochemical characteristics and disrupts microbial community dynamics in nearshore ecosystems

Subtropical and tropical islands are undergoing rapid urbanization as human populations and tourism expand worldwide. Urbanization disrupts coastal ecosystems by replacing forests and other natural habitats with roads, parking lots, and buildings. These impervious surfaces increase the amount of runoff and pollution that reaches coastal ecosystems. Urbanization also comes with increased industry, waste treatment needs, fishing and aquaculture pressure, and coastline engineering. Despite the major changes to coasts that accompany urbanization, specific impacts on marine ecosystems can be difficult to measure due to missing baselines. Here, we take advantage of a large gradient in urbanization on the subtropical island of Okinawa, Japan, to evaluate the impact of urbanization on nearshore ecosystems. We measured physicochemical parameters and assessed bacterial community composition every two weeks for one year at two nearshore sites adjacent to watersheds with >70% urban land use and two nearshore sites adjacent to watersheds with >70% rural land use. Our results show that urbanization increases freshwater input and nutrient loading to nearshore ecosystems and profoundly alters the microbial community, overriding the natural seasonal succession observed at rural sites. At urban sites, we detected multiple bacterial species that are fecal indicators and human or marine organism pathogens. The altered physicochemical conditions and microbial communities at urban sites can contribute to the degradation of nearby coral reefs. Results highlight the importance of a "ridge-to-reef" management mindset, as restoring natural coastlines could buffer the impact of urbanization on the marine environment.

ecology↗

bioRxiv2021

Sequestration and efflux largely account for Cd and Cu resistance in the deep sea Epsilonproteobacterium Nitratiruptor sp. SB155 2

In deep sea hydrothermal vent environments, metal- and metalloid-enriched fluids and sediments abound, making these habitats ideal to study metal resistance in prokaryotes. In this investigation, the architecture of the epsilonproteobacterium, Nitratiruptor sp. SB155-2 transcriptome in combination with sub-cellular analysis using scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy (STEM-EDX) was examined to better understand mechanisms of tolerance for cadmium (Cd) and copper (Cu) at stress-inducing concentrations. Transcriptomic expression profiles were remarkably different in the presence of these two metals, displaying 385 (19%) and 629 (31%) genes differentially expressed (DE) in the presence of Cd and Cu, respectively, while only 7% of DE genes were shared, with genes for non-specific metal transporters and genes involved in oxidative stress-response predominating. The principal metal-specific DE pathways under Cu stress, including those involving sulfur, cysteine, and methionine, are likely required for high-affinity efflux systems, while flagella formation and chemotaxis were over-represented under Cd stress. Consistent with these differences, STEM-EDX analysis revealed that polyphosphate-like granules (pPLG), the formation of CdS particles, and the periplasmic space may be crucial for Cd sequestration. Overall, this study provides new insights regarding metal-specific adaptations of Epsilonproteobacteria to deep sea hydrothermal vent environments. Significance originality statementDeep sea hydrothermal vents are unique environments in which metals and metalloids abound. Despite being a dominant phylum in these environments, adaptations enabling Epsilonproteobacteria to thrive in metal-rich environments remain poorly understood. In this study, a combination of high-throughput, whole-transcriptome RNA-seq analysis, scanning transmission electron microscopy, and energy-dispersive X-ray spectroscopy provide a comprehensive picture of molecular and morphological adaptations controlling metal efflux and sequestration systems of this bacterium in response to cadmium and copper. Many of these responses are metal-specific.

microbiology↗

bioRxiv2019

Extreme storm-induced run-off causes rapid, context-dependent shifts in nearshore subtropical bacterial communities

Climate change scenarios predict tropical cyclones will increase in both frequency and intensity, which will escalate the amount of terrestrial run-off and mechanical disruption affecting coastal ecosystems. Bacteria are key contributors to ecosystem functioning, but relatively little is known about how they respond to extreme storm events, particularly in nearshore subtropical regions. In this study, we combine field observations and mesocosm experiments to assess bacterial community dynamics and changes in physicochemical properties during early- and late-season tropical cyclones affecting Okinawa, Japan. Storms caused large and fast influxes of freshwater and terrestrial sediment--locally known as red soil pollution--and caused moderate increases of macronutrients--especially SiO2 and PO43-. We detected shifts in relative abundances of marine bacteria and the introduction of terrestrially-derived bacteria, including putative coral and human pathogens, during storm events. Soil input alone did not substantially affect marine bacterial communities in mesocosms, indicating that other components of run-off or other storm effects likely exert a larger influence on bacterial communities. The storm effects were short-lived and bacterial communities quickly recovered following both storm events. The early- and late-season storms caused different physicochemical and bacterial community changes, demonstrating the context-dependency of extreme storm responses in a subtropical coastal ecosystem.

microbiology↗