Cláudio Ernesto Taveira Parente

Candida palmioleophila is an emerging opportunistic yeast frequently misidentified within the Meyerozyma guilliermondii complex, potentially obscuring its clinical and ecological relevance. Although its clinical significance is increasingly recognized, the phenotypic characteristics of environmental isolates remain poorly explored. This study evaluated the eco-phenotypic profiles of 14 C. palmioleophila isolates recovered from two anthropogenically influenced environmental sources: poultry litter ( n = 6) and urbanized coastal environments ( n = 8). Antifungal susceptibility testing revealed high fluconazole MICs among all evaluated isolates (32 to > 128 µg/mL), while amphotericin B, caspofungin, and anidulafungin MICs ranged from 1 to 2 µg/mL, 0.25 to 1 µg/mL, and 0.06 to 0.5 µg/mL, respectively. No detectable association was observed between variation in antifungal MICs and biofilm biomass under the tested conditions. The isolates exhibited broad physiological tolerance, including growth at temperatures up to 40 °C, tolerance to high NaCl concentrations and cell-wall stress, as well as variation in cell-wall chitin content and intracellular lipid-body accumulation. Virulence-associated phenotypes included biofilm formation, high cell-surface hydrophobicity in most isolates, widespread esterase activity, variable phospholipase activity, and limited protease activity. Together, these findings expand current knowledge of the environmental phenotypic repertoire of C. palmioleophila and support broader environmental, clinical, and genomic surveillance to clarify its ecology, population structure, and potential transmission pathways.

In search of a Cr(VI) removal bioprocess, within a circular economy perspective, we combined two autochthonous bacterial consortia obtained from industrial residues and an agricultural waste (rice husk of Oryza sativa). After characterizing the rice husk (rh) properties, the bacterial growth and biofilm formation, we studied the taxonomical profile of the bacterial consortia (C55, C33, and C21, the last is a combination 2:1 of the previous ones). By using SEM analysis, we confirmed the presence of a smooth layer of exopolysaccharides (EPS) over the rice husk surface. Total bacterial biodiversity, assessed through MiSeq analysis, showed that the addition of Cr(VI) stimulated the growth of two main populations ( Cellulosimicrobium and Siminovitchia ) while inhibiting Peptoniphilus , Cutibacterium and Rhodococcus . We also evaluated chromium depletion, in batch experiments, with particular emphasis on its sorption to the agroresidue and its biotransformation by the biomass. When exposed to 200 mg.L ^-1 Cr(VI), the system containing both rh and the bacterial consortium completely removed Cr(VI) from the effluent with half-times between 53 and 67 h. The combination of Cr(VI) biosorption by rh and its biotransformation to Cr(III) by bacterial consortia confirmed an effective synergy capable of removing 92% of Cr(VI). This work supports the potential of an innovative bioprocess based on bacterial biofilms grown on rh for the mitigation of Cr(VI) contamination.

Poultry slaughterhouse wastewater (PSW) is a source of environmental pollutants, harboring pathogens and antibiotic resistance genes (ARGs). This study aimed to assess the effects of conventional biological treatment of PSW on the bacterial community and its efficiency in removing ARGs, as well as to evaluate the impact of its discharge on the receiving river. Samples were collected from raw sewage, treated effluent, and upstream and downstream river sites. Total metagenomic DNA was extracted for real-time PCR quantification of 16S rRNA, yccT gene (Escherichia coli), and ARGs, which were selected based on their ability to confer resistance to clinically relevant antibiotics and their prevalence in poultry-associated environments, including resistance to tetracyclines (tetM), beta-lactams (bla_TEM), sulfonamides (sul1), and quinolones (qnrS). Amplicon sequencing of 16S rRNA V3–V4 region was used to assess bacterial community structure. Treated effluent significantly altered the downstream microbiome, reducing bacterial richness by up to 72.3% and diversity by 25.4%. Effluent-associated phyla such as Pseudomonadota (37%), Bacillota (28%), and Bacteroidota (26%) became dominant in the downstream river samples. Enterobacterales increased after treatment, and E. coli increased by 2.93 logs downstream. All ARGs increased after treatment and remained elevated downstream, with qnrS and sul1 rising by 3.77 and 3.87 logs, respectively. These findings highlight PSW treatment plants as a potential point of selection and dissemination of antimicrobial resistance (AMR)-related bacteria and genes. Inefficient treatment contributes to shifts in river bacterial communities and the spread of AMR.

Coastal ecosystems are increasingly threatened by climate change and anthropogenic pressures, which can disrupt microbial communities and favor the emergence of pathogenic organisms. In this study, we applied metagenomic analysis to characterize fungal communities in sediment samples from an urban mangrove subjected to environmental stress. The results revealed a fungal community with reduced richness—28% lower than expected for similar ecosystems—likely linked to physicochemical changes such as heavy metal accumulation, acidic pH, and eutrophication, all typical of urbanized coastal areas. Notably, we detected an increase in potentially pathogenic genera, including Candida, Aspergillus, and Pseudoascochyta, alongside a decrease in key saprotrophic genera such as Fusarium and Thelebolus, indicating a shift in ecological function. The fungal assemblage was dominated by the phyla Ascomycota and Basidiomycota, and despite adverse conditions, symbiotic mycorrhizal fungi remained present, suggesting partial resilience. A considerable fraction of unclassified fungal taxa also points to underexplored microbial diversity with potential ecological or health significance. Importantly, this study does not aim to compare pristine and contaminated environments, but rather to provide a sanitary alert by identifying the presence and potential proliferation of pathogenic fungi in a degraded mangrove system. These findings highlight the sensitivity of mangrove fungal communities to environmental disturbance and reinforce the value of metagenomic approaches for monitoring ecosystem health. Incorporating fungal metagenomic surveillance into environmental management strategies is essential to better understand biodiversity loss, ecological resilience, and potential public health risks in degraded coastal environments.