Publicações

B.B. Borrego, F.L. Oliveira, L.B.U. Melo, L.H. Gracioso, G.S. Hentschke, V.M. Vasconcelos, A. Grandis, M.S. Buckeridge, N.S. Caetano, E.A. Perpetuo

Abstract: Mangroves play a crucial ecological and ecosystem role, strongly linked to their microbial communities. However, their photoautotrophic members, particularly microalgae, remain largely unexplored. The unique natural characteristics of these ecosystems, combined with frequent anthropogenic impacts, impose selective pressures on the local microbiota, yielding strains with significant biotechnological potential. This study aimed to isolate, identify, and biochemically characterize the biomass of five microalgae from a mangrove in Baixada Santista (São Paulo, Brazil), focusing on a comprehensive analysis of carbohydrates. The isolated microalgae were identified using conventional genetic markers (18S and ITS), and their biochemical composition was evaluated after cultivation under stressful conditions. The non-structural and structural carbohydrates were characterized through soluble sugars (1.28–2.35%), starch (11.90–22.39%), non-cellulosic cell wall monosaccharides (11.57–18.85%), and cellulose (0.10–6.53%). All isolates belonged to the phylum Chlorophyta; one strain was identified as Chlorella, while the others were novel species within the Micractinium genus (M. brasiliense and M. mangrovii). Three strains exhibited phylogenetically similar characteristics, but their carbohydrate profiles showed distinct metabolic differences, prompting discussions on diversity and genomic regulation mechanisms. Notably, M. brasiliense strain B2 accumulated 46% total carbohydrates, with significant fractions being starch (19%) and non-cellulosic wall monosaccharides (18%). The responses observed under stressful conditions highlighted relevant aspects of cell wall characteristics, particularly in the genus Micractinium, thereby contributing to a still underexplored field. These findings underscore the biorefinery potential of these microalgae, particularly the applicability of their polysaccharide fractions, and highlight mangroves as promising sources of microbial strains with high biotechnological value.

https://doi.org/10.1016/j.algal.2025.104313

Matilde Marques, Francisco Pascoal, Helena Villela, Elsa Santos, Núria Baylina, Raquel S. Peixoto, Tina Keller-Costa and Rodrigo Costa

Abstract: Octocorals play a critical role in coral ecosystems, contributing to habitat complexity and marine biodiversity. Despite their ecological importance, the microbial communities associated with octocorals remain understudied, particularly under ex situ conditions. Methods: This study compared the prokaryotic communities of the tropical octocoral Litophyton sp., surrounding seawater, and sediments (“biotopes”) from a natural Red Sea reef and a long-term tropical aquarium mesocosm designed to emulate natural reef ecosystems (“habitats”). Using high throughput 16S rRNA gene sequencing, we assessed community composition, diversity, and core taxa. Results: Distinct prokaryotic assemblages were associated with each biotope, with core symbionts persisting across habitats. While seawater communities diverged between habitats, sediment communities were compositionally more similar, dominated by Nitrosopumilaceae, Pirellulaceae, Woeseiaceae, and Flavobacteriaceae. Litophyton sp. harbored specific symbionts consistently across habitats. Alpha-diversity in Litophyton sp. did not differ significantly between habitats (ANOVA with Tukey’s HSD, p > 0.05), and beta-diversity patterns were also not significant (PERMANOVA, p > 0.05). We identified 19 ASVs shared across Litophyton sp. habitats, dominated by Endozoicomonas, unclassified Campylobacterales, and Marivibrio. Several core families, such as Endozoicomonadaceae, Spirochaetaceae, and Kiloniellaceae, were consistently associated with Litophyton sp. across habitats, indicating stability of specific host-microbe associations even after 25 years in aquarium conditions. Phylogenetic analysis further demonstrated the selective maintenance of diverse Endozoicomonas lineages in aquarium-kept Litophyton specimens. Discussion: These findings suggest that large-scale aquarium ecosystems can preserve, to some extent, the structure and diversity of coral-associated microbiomes over extended time periods. By supporting key symbiotic taxa, multi-trophic integrated aquarium systems may serve as repositories for healthy coral-associated microbial communities and microbiome stewardship, underscoring their value in future conservation efforts to sustain the biodiversity of marine holobionts in the face of growing environmental challenges.

https://doi.org/10.1128/mra.00430-25

Tina Keller-Costa, Selene Madureira, Ana S. Fernandes, Lydia Kozma, Jorge Gonçalves, Cristina Barroso, Ali Budhi Kusuma, Conceição Egas, Rodrigo Costa

Abstract: We present the genome sequence of the octocoral-associated Roseobacter sp. EG26. We highlight features related to type II, III, IV, and VI secretion systems, ankyrin-repeat proteins, and taurine degradation, suggesting a preference for a host-associated lifestyle. Strain EG26 also possesses genes for the degradation of phenolic compounds with bioremediation potential.

https://doi.org/10.1128/mra.00430-25

Guilherme Scotta Hentschke, Miguel Semedo, Jimmy Ciancas, Claudia Hoepfner, Daniel Guzmán, Daniela S. Rivera and Vitor M. Vasconcelos

Abstract: The Bolivian Altiplano presents extreme environmental conditions, including high altitude, intense UV radiation, low precipitation, freezing temperatures, and saline to alkaline waters. Despite these harsh settings, cyanobacteria thrive in microbial mats, although their diversity remains poorly characterized. This study aimed to explore the morphological and molecular diversity of cyanobacterial mats and their associated microbiomes in saline and freshwater ecosystems of the Bolivian Altiplano. Morphological analyses revealed seven distinct cyanobacterial morphotypes affiliated with Nostocaceae, Coleofasciculaceae, Rivulariaceae, and Microcoleaceae. Amplicon-based analysis of the 16S rRNA gene identified 4.113 ASV for the bacterial community. Of these, 310 were identified as Cyanobacteria, with 134 classified as Cyanophyceae assigned to 32 genera. Phylogenetic reconstruction and sequence identity comparisons resolved 42 cyanobacterial genera across nine orders. Moreover, 30 ASVs grouped into 16 clades unrelated to any known genus, suggesting the presence of potentially novel cyanobacterial lineages. The microbiome associated with these mats was dominated by Alphaproteobacteria, Bacteroidia, Gammaproteobacteria, Clostridia, Cyanophyceae, and Campylobacteria. Functional predictions based on 16S rRNA gene profiles indicated a predominance of phototrophic and chemoheterotrophic metabolisms, along with sulfur respiration, nitrogen fixation, nitrate and nitrite reduction, and fermentation pathways. Notably, nitrogen-fixing cyanobacteria and bacterial groups with bioremediation potential were prevalent, highlighting the ecological importance and possible biotechnological applications of these microbial consortia. This is the first comprehensive metabarcoding analysis of cyanobacterial mats from Bolivia, including their associated microbiomes. Many new bacterial and cyanobacterial taxa remain to be described in these ecosystems. Based on the functional genomic analysis, this work also highlights the great unexplored biotechnological potential of Bolivia’s extreme environments and the functional roles of microbial mats in biogeochemical cycling under polyextreme conditions.

10.3389/fmicb.2025.1650455

João Morais, Guilherme Scotta Hentschke, Flavio Oliveira, Raquel Silva, Pedro N. Leão, Brahim Sabour and Vitor Vasconcelos

Abstract: Cyanobacteria biodiversity remains underexplored despite their ecological importance and potential applications. To address this, we investigated two Leptolyngbya-like strains, LEGE 07170 and LEGE 191244, collected from marine tide pools in Portugal and Morocco using polyphasic approach. Phylogenetic analyses indicates that the strains form a distinct clade with strong statistical support in the Oculatellales order. The 16S rRNA gene identity matrix shows that the maximum shared values with the phylogenetically closest genera Gansulinema, Kaiparowitsia, Shahulinema, Aerofilum and Thermoleptolyngbya is consistently below 94.5%. Morphologically, LEGE 07170 and LEGE 191244 are indistinguishable to each other. Both optical and TEM analyses showed vacuole-like structures at the cells cross-walls and this character morphologically distinguishes these strains from their phylogenetically related genera. The 16S–23S ITS secondary structures also differed the LEGE-CC strains from their closest related genera.

https://doi.org/10.11646/phytotaxa.708.2.5

Flavio Oliveira, Tiago Conde, Marisa Pinho, Tânia Melo, Guilherme Scotta Hentschke, Ralph Urbatzka, Hugo Pereira, Monya Costa, Vitor Vasconcelos, Maria Rosário Domingues

Abstract: Cyanobacteria are gram-negative prokaryotic microorganisms composed of both broad morphological and phylogenetic diversity inherited from diverse ecosystems like aquatic, terrestrial, or extremophilic environments. In this study, three cyanobacteria strains from the Blue Biotechnology and Ecotoxicology Culture Collection (LEGE-CC) were obtained from different environments in Portugal. Polyphasic analysis was applied for taxonomic identification. The proximate composition analysis indicated the lipid content (6.2% to 9.1% dry weight (DW)), protein content (28.2% to 62.9% DW), and carbohydrate content (19.5% to 46.1% DW). The fatty acid (FA) profiles of the strains revealed the presence of 19 different FAs, with FA 16:0 found in the highest abundance. The lipidomic analysis revealed 230 lipid species, with Laspinema sp. LEGE 06078 displaying the highest diversity (125 lipid species). These included species-specific and common lipids species that denote biochemical uniqueness that are also carriers of omega-3 FA (n−3). Biological assays exhibited strong antioxidant activity against ABTS^•+ and DPPH^• in Laspinema sp. LEGE 06078, while Sphaerospermopsis sp. LEGE 00249 was renowned for reducing lipids in zebrafish larvae. The findings are of immense significance on the lipidomics diversity of cyanobacteria in terms of nutrition, health, and biotechnology, such as addressing obesity and sustainable resource production.

https://doi.org/10.3390/molecules30122504

Guilherme Scotta Hentschke , Célia Leite Sant’Anna , Vitor Vasconcelos

Abstract: This study aims to reevaluate the diversity of 16S rRNA gene sequences associated with Scytonema (Nostocales, Cyanobacteria). For that, we first conducted a search for ‘Scytonema’ sequences available in GenBank (NCBI) and aligned the results with reference strains from other Nostocales genera. The alignment totalized 383 OTUs and 800 nucleotide positions analyzed. A FastTree phylogenetic analysis revealed that the ‘Scytonema’ sequences are distributed across 15 distinct clades in addition to the Scytonema sensu stricto clade. These additional clades are positioned among Nostocales genera and phylogenetically distant from the type species, S. hofmanni. Within these clades, we had access to the strain Scytonema sp. CCIBt3568, identified as S. schmidtii, which we believe should be separated from Scytonema, and described as a new genus in the future. Additionally, Bayesian Inference and Maximum Likelihood phylogenies were performed with 97 OTUs and 971 bp, and the polyphyletic status of Scytonema as currently recognized was confirmed.

https://www.scienceopen.com/document?vid=b9b25139-d662-459a-b989-7e8caa7d42fc

Maria Lígia Sousa, Leonor Ferreira, Dora Ferreira, Abel M. Forero , Raquel Castelo-Branco , Nikoletta Szemerédi , Gabriella Spengler , Jaime Rodríguez Author , Carlos Jiménez , Pedro N. Leão , Vitor Vasconcelos, Mariana Reis

Abstract: Essential trace metals are vital for cellular processes such as respiration, DNA replication, and photosynthesis. Cyanobacteria must tightly regulate metal homeostasis to prevent deficiency or toxicity, yet their metallophores remain overlooked. Here, we report lusichelins A-E (1-5), new metallophores isolated from the marine cyanobacterium Lusitaniella coriacea LEGE 07167. Their structures and configurational assignments were determined using NMR, mass spectrometry, TD-DFT calculations, and retrobiosynthetic insights. Lusichelins feature a unique structural arrangement with thiazoline/thiazole rings connected by a vinyl group, an aliphatic carbon chain, or directly, enabling potential for hexadentate metal coordination. Genomic analysis identified a hybrid PKS/NRPS biosynthetic gene cluster consistent with the structure of lusichelins and bearing traits characterisitic of metallophore biosynthesis. Notably, lusichelin production was influenced by salt composition in the culture medium rather than iron availability, suggesting an atypical regulatory mechanism. Functionally, lusichelins acted as copper detoxifiers, and lusichelin B (2) exhibited cytotoxicity against colon carcinoma cells while reversing multidrug resistance via ABCB1 efflux pump modulation. These findings expand the understanding of cyanobacterial metallophores in microbial metal homeostatis and highlight their potential in biological applications

https://doi.org/10.26434/chemrxiv-2025-63fgd