Publications
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Yeast Species Associated with Industrial Cultures of the Marine Microalgae Tisochrysis lutea: Temperature Profiles and Auxin Production
Matos, M., Fernandes, M. A., Coelho, N., Santos, T. F., Varela, J., Rodrigues, A. M. C., & Sá-Correia, I.
Abstract: This study provides the first systematic characterization of culturable yeast diversity associated with large-scale cultivation of Tisochrysis lutea. This marine haptophyte is widely used in aquaculture for its high content of essential fatty acids, pigments, and other bioactive compounds. Culture sampling was conducted at Necton S.A. facilities (Olhão, Portugal) over full production cycles from 5 L flasks until tubular photobioreactors during the months of May and June. The study aimed to identify and isolate the present yeast species and evaluate their physiological traits relevant to potential co-cultivation strategies. All retained isolates belonged to the phylum Basidiomycota, with six species identified: Rhodotorula sphaerocarpa (45%), R. mucilaginosa (20%), R. diobovata (13%), Vishniacozyma carnescens (16%), Naganishia diffluens (3%), and Moesziomyces aphidis (3%). Temperature growth profiles (10–40 °C), tolerance to artificial sea water, and auxin production were characterized, revealing that, except for V. carnescens, the yeast isolates grow optimally at 25–30 °C, within the ideal range for T. lutea cultivation. Results suggest that some of these marine yeasts, particularly R. sphaerocarpa and R. mucilaginosa isolates, could serve as biological enhancers of algal productivity, in situ. This foundational work supports future efforts to develop targeted yeast management or co-cultivation strategies, with the goal of improving biomass yield and metabolite production in industrial T. lutea photobioreactors.
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New terrestrial cyanobacterial species from the vicinity of the CIIMAR building on the Portuguese Coast
Guilherme Scotta Hentschke, Flavio de Oliveira, João Morais & Vitor Vasconcelos
Abstract: The area around the CIIMAR building, at the Porto de Leixões Cruise Terminal on the northern Portuguese coast, is a hub for cyanobacterial diversity due to its continuous maritime traffic. This makes the site ideal for uncovering new taxa and documenting already known species. Terrestrial cyanobacteria are underexplored in the northern Portugal coast: here we describe four new species and report on cyanobacterial diversity around the CIIMAR building. The study is based on a polyphasic analysis of 13 isolates, belonging to seven genera in the orders Leptolyngbyales (1 strain), Desertifilales (1), Oculatellales (1), Oscillatoriales (2), Chroococcidiopsidales (3), Geitlerinematales (1) and Nostocales (4). Among these, four were classified as new species in the genera Aliterella, Gloeocapsopsis, Compactococcus and Desertifilum. Additionally, the species Desertifilum salkalinema, D. fontinale and D. dzianense were synonymized with the type D. tharense. The isolate LEGE 221420 has a parietal and/or fascicular arrangement of thylakoids, unprecedented in cyanobacteria, confirming that this character is unstable and cannot serve as a taxonomic marker at the genus level.
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A genomic view of the bacterial family Endozoicomonadaceae in marine symbioses
Daniela M. G. da Silva, Rodrigo Costa & Tina Keller-Costa
Abstract: Endozoicomonadaceae bacteria are found in association with marine organisms across ocean ecosystems. Interactions may range from mutualistic to parasitic depending on host species and ecological context. Their genomic repertoire suggests metabolic versatility and capacity for rapid adaptation and transitioning between free-living and host-associated lifestyles. Some lineages, however, undergo genome reduction, are host-specific, and lack cultivability. Here we present an advanced genomic perspective and updated view on the functional diversity of Endozoicomonadaceae along the mutualism-parasitism continuum. We discuss their roles in marine symbioses, potential for microbiome engineering, and highlight knowledge gaps of their ecology to be addressed in future research.
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Unveiling metabolic diversity through phylogenetic analysis and carbohydrate composition of microalgae isolated from mangroves in Brazil
Borrego, B. B., Oliveira, F. L., Melo, L. B. U., Gracioso, L. H., Hentschke, G. S., Grandis, A., Buckeridge, M. S., & Perpetuo, E. A.
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 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.
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Selective shaping of prokaryotic communities and core symbiont maintenance suggest large-scale aquarium facilities as reservoirs of microbiome diversity in octocorals
Marques M., Pascoal F., Villela H., Santos E., Baylina N., Peixoto R.S., Keller-Costa T. & Costa R.
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.
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Genome sequence of the marine bacterium Roseobacter sp. EG26, isolated from the octocoral Eunicella gazella, suggests aptitude for a host-associated lifestyle
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.
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Cyanobacterial mats and their associated microbiomes in saline and freshwater lakes from the Bolivian Altiplano
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.
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Description of Vacuolonema iberomarrocanum gen. et sp. nov. (Oculatellales, Cyanobacteria): a new marine cyanobacterial taxon from the Portuguese and Moroccan Atlantic coast
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.