Current Microbiology

Three novel bioluminescent bacterial strains, VNB-15T, VNB-16 and SChm4, were isolated from water of the Black Sea (Russia) and intestines of the Black Sea horse mackerel. Cells of the isolated strains are motile Gram negative slightly curved rods with single polar flagellum. The temperature range for growth was 10-35{degrees}C, the optimum being 20-25{degrees}C. The pH range for growth was 6.0-9.0, the optimum being 7.0-8.0. The bacteria were able to grow in the presence of 0.5 to 5.0% NaCl (w/v), the optimum being 1.0-4.0% (w/v). Phylogenetic analysis based on comparison of 16S rRNA sequences shows these strains to have kinship with the species Vibrio jasicida, Vibrio hyugaensis, Vibrio alginolyticus, Vibrio campbelli, Vibrio rotiferianus, Vibrio harveyi and Vibrio owensii with sequence similarity from 99.6 to 98.0%. Phylogenetic analysis based on comparison of the sequences of genes gyrB, recA, pyrH, gapA, rpoA, mreB, ftsZ, topA shows that the strains VNB-15T, VNB-16 and SChm4 to form a cluster within the V. harveyi clade and belong to a new species of the Vibrio genus. Comparison of the complete genomic sequence of VNB-15T with typical strains of nearby species also indicates that VNB-15T belongs to a separate species (maximum similarity 98% with V. hyugaensis and 96% with V. jasicida). VNB-15T differs from closely related species by its ability to utilize glucose, mannitol, inositol, sorbitol, rhamnose and sucrose, and to form lysine decarboxylase, ornithine decarboxylase, lipase, acid phosphatase, -glucosidase, {beta}-glucosidase and N-acetyl-{beta}-D-glucosaminidase enzymes. Based on phylogenetic analysis and phenotypic characteristics, Vibrio aquamarinus sp. nov. is proposed. The type strain is VNB-15T (= VKPM B-11245T = DSM 26054 T). RepositoriesThe GenBank accession numbers for the gapA, 16S rRNA, gyrB, pyrH, rpoA, recA, mreB, ftsZ, topA genes sequences of strain VNB-15T are JQ319116-JQ319121, KX242381, KX 242384, KX242387, respectively. The GenBank accession numbers for the gapA, gyrB, pyrH, recA, rpoA,16S rRNA, mreB, ftsZ, topA genes sequences of strain VNB-16 are KP221561-KP221566, KX242382, KX 242385, KX242388 respectively. The GenBank accession numbers for the 16S rRNA, gapA gyrB, rpoA, recA, pyrH, mreB, ftsZ, topA genes sequences of strain SChm4 are KX242375-KX242380, KX242383, KX 242386, KX242389, respectively. The GenBank/EMBL/DDBJ accession numbers for the housekeeping gene sequences used in this study are detailed in supplementary Table S1, Figures S1-S8. The genome of Vibrio aquamarinus sp. nov. VNB-15T, comprising two chromosomes and a plasmid, has been assembled and deposited in the NCBI database under the submission number SUB14585067

Marine non-cyanobacterial diazotrophs (NCDs) are recognized as globally distributed, however, few representatives have been isolated in pure cultures. As a result, understanding the physiology, growth rate, substrate preference and dinitrogen (N2) fixation capabilities proves difficult. Thalassolituus haligoni. sp. nov., BB40 was isolated from a fjord-like inlet within Kjipuktuk (Halifax), Nova Scotia. The fully sequenced genome displayed all necessary genes required for N2 fixation, and various carbon uptake pathways. The gram-negative flagellated rod shape bacterium displayed significantly higher growth rates in medium amended with nitrate (NO3-) or ammonia (NH3), compared to dissolved N2, as the sole nitrogen source. Biological N2 fixation rates were detectable across all conditions, measuring a range from 9.34 x 10-6 to 1.4 x 10-1 fmol N cell-1 day-1. Growth of the isolate was successful between 4 {degrees}C up to 35 {degrees}C, with a Topt of 20 {degrees}C for N2, and between 27 - 30 {degrees}C for fixed nitrogen (NO3- and NH3). The closest relatives to T. haligoni, were found to be the uncultured Arc-gamma-03 (99% average nucleotide identity (ANI)) and Oceanobacter antarcticus (81% ANI). T. haligoni also displays versatile capabilities for growth on various carbon, and nitrogen sources, and antibiotics. Collectively this study provides an in-depth physiological assessment of an Oceanospirillales diazotrophic species which we presently have limited knowledge of.

Currently, there are three recognized rhizobial genera belonging to the beta branch of the proteobacteria; Trinickia, Paraburkholderia, and Cupriavidus. These beta-rhizobia have been found associated with legume species mainly within the Mimosoideae and Papillonoideae. Most diversity, evolutionary, and functional studies have focused on Paraburkholderia, whereas few have addressed the diversity and evolution of symbiosis in the Cupriavidus genus. The present work aimed to provide an actual view of the symbiotic Cupriavidus diversity and to analyse the origin and evolution of their symbiotic genes. Using whole-genome information for phylogenetic reconstruction, we showed that the described symbiotic Cupriavidus strains belong to five distinct lineages, although they are intermixed with non-symbiotic species. The high synteny and sequence conservation of symbiotic genes suggest a common origin of acquisition for all rhizobial Cupriavidus described so far. However, we observed very low sequence conservation among (mega)plasmids carrying the symbiotic island, excluding the existence of a conserved symbiotic plasmid within beta-rhizobia. We can conclude that up to now there are five rhizobial species within the Cupriavidus genus, and we predict the description of new symbiotic species in the near future.

Stentor is a genus of large ciliates that can be found in ponds, lakes, rivers, and fresh waters all over the world. Since their initial discovery in 1744, Stentor strains have been isolated from all populated continents. To date, over 50 individual strains have been identified, yet not a single isolate from a marine environment has been verified. Over 200 years since the initial description of the Stentor genus, our study entails the first concrete discovery of a fully marine Stentor species, as evidenced by its morphological, ecological, and phylogenetic positioning amongst Stentor. This new marine organism, which we have named Stentor hondawara, was verified to be a new species of the Stentor genus that appears to have fully adapted to a uniquely marine lifestyle in a high-salinity environment. Using comparative genomics analysis between the whole-genome sequences of Stentor hondawara and two freshwater species of Stentor, we further detected several intriguing differences in the enrichment of gene orthologs between the marine Stentor hondawara and the freshwater species, Stentor coeruleus and Stentor pyriformis. The gene groups specifically enriched in Stentor hondawara encode a variety of proteins, including ion channels, pH-responsive proteins, osmoprotectants, amino acid biosynthesis enzymes, and signaling receptors. Additionally, using metagenomics, we detected and isolated, from within our initial genome assembly, the genome of a novel marine bacteria, which we propose is an endosymbiont of Stentor hondawara. This bacterial species is an uncharacterized member of the order Rhodospirillales and appears to be a nutritional factory for the host Stentor hondawara. Taken together, our study provides insight into how Stentor hondawara adapted to a marine environment distinct from the habitats of all the other currently known Stentor species living in freshwater.

The strain LEGE 10371, isolated from the surface of a marine sponge at Praia da Memoria, Portugal, was characterized as a new Thalassoporum species (Pseudanabaenales) using a polyphasic approach that included 16S rRNA gene phylogenetic analysis (Maximum Likelihood and Bayesian Inference), 16S-23S ITS secondary structures, p-distance calculations, MALDI-TOF MS profiling, and morphological analysis by optical and scanning electron microscopy, as well as ecological and biochemical characterization. Phylogenetically, LEGE 10371 clustered within the Thalassoporum clade, however distant from the other existent species of the genus. The p-distance analysis revealed low sequence identity with other Thalassoporum species, with a maximum value of 97.2% to Th. komareki. The MALDI-TOF profile displayed high-intensity peaks at approximately 3,000, 4,000, 6,000 and 8,000 m/z, representing strong candidates for diagnostic markers of the new species. Morphologically, the new species differ from the other species of the genus by presenting trichomes with more than 10 cells and lack of aerotopes. Biocompatibility of the fractions was evaluated in HaCaT keratinocytes, showing no cytotoxic effects at most tested concentrations. PCR screening targeting mcyE, sxtG, anaC, and cyrA confirmed the absence of the genetic potential for the production of major cyanotoxins. Chemical characterization revealed a pigment-rich profile dominated by chlorophyll-a and carotenoids, including {beta}-carotene, zeaxanthin, lutein, and mixoxanthophyll. Bioactivity assays showed superoxide anion radical scavenging by the aqueous fraction (IC2 {approx} 0.042-0.045 mg mL-{superscript 1}), strong nitric oxide radical scavenging by the acetonic fraction (IC = 0.045 mg mL-{superscript 1}), and lipoxygenase inhibition ([~]41%, for a fraction concentration of 0.25 mg mL-), suggesting a potential contribution of these fractions to modulate inflammation-related pathways. Additionally to this results, the polyphasic analysis permitted to confirm previous data that Pseudanabaena and Limnothrix represent the same generic entity. Both genera clustered together, presented high 16S rRNA gene identity (up to 99.9%) and share the same morphological and ecological features. Consequently, we formally proposed the synonimization of Limnothrix into Pseudanabaena.

Non-pathogenic Xanthomonas (NPX) from a diverse plant hosts are being reported on an increasing basis. There are also reports of multiple species forming communities on a single host plant, such as rice, and, given their role as core endophytes in protecting plants from pathogens, it is essential to isolate and characterization of more NPX species from diverse host plants. Using phylogenomic analysis of publicly available Xanthomonas genome sequences, we identified a novel clade comprising NPX strains from diverse hosts. One of the strains previously reported from our lab is from healthy rice seeds and was reported to be non-pathogenic, with bio-protection function against the bacterial leaf blight pathogen. Genomic investigation confirmed the lack of type III secretion system and its effectors, consistent with their non-pathogenic nature. These strains also harbour core and unique biosynthetic loci identified in other non-pathogenic Xanthomonas (NPX) strains. Further investigation using multiple genomic-based taxonomic indices indicates that these strains represent a potential new species. Hence, we propose Xanthomonas imtechensis sp. nov. as a new species of the genus Xanthomonas, with the type strain being PPL568 = MTCC 13186 = CFBP 9040 = ICMP 24395.

The spread and rise of antimicrobial resistance poses a risk to public health due to limited effective treatment options. Alternative antimicrobials that are effective against gram-negative multi-drug resistant pathogens. The increasing rate of carbapenem resistance observed in Klebsiella pneumoniae, indicates the need for alternative antimicrobial options. Bacteriophages that target Klebsiella pneumoniae are promising alternative antimicrobial option, with successful treatments being reported. Here we characterized 30 lytic bacteriophages from various environmental sources and tested their effectiveness against nine clinically relevant carbapenem-resistant K. pneumoniae isolates. These phages were characterized through genomic sequencing, bioinformatic analysis, virulence in liquid medium, and host range on different mediums. Bioinformatic analysis revealed a diverse collection of phages that span 9 ICTV recognized families and 13 genera with genome sizes ranging from 39-349 kbp. The phages were able to inhibit bacterial growth, and no virulence or antibiotic resistance genes were detected within the phage genomes. Host range testing demonstrated phages with broad host range have varying infectivity when plated on different common growth mediums. This study includes candidate phages for further potential development as potential antimicrobial agents against CR-KP, and the complexity in understanding phage-host dynamics of non-capsule phages that target against K. pneumoniae.

The study presented here shows Biofilm quantification in microtiter plates in strains of Candida auris and Candida albicans evaluated by means of Crystal violet, MTT, ATP-Luminescence and NBTZ/BCIP assays. The results showed significant differences in biofilm formation between Candida auris and Candida albicans but also within Candida auris outbreak strains in contrast to Candida auris DSM 21092 reference strain.

Amino acid catabolism is a vital metabolic process in bacteria, providing energy, carbon and potentially nitrogen as resources, and affecting global cycles of these elements. The ability of a bacterium to catabolize an amino acid is often inferred from the presence of the relevant catabolic pathways in its genome, yet the "gene=function" inference is not straightforward. Here, we use growth assays in 96 well plates on individual amino acids and their combinations to directly measure the ability of a model marine bacterium, Alteromonas macleodii ATCC 27126, to utilize these resources for growth. With the exception of aspartate and glutamate, which did not support growth in any of our experiments, ATCC 27126 grew on all other amino acids. However, the probability of growth, together with growth yield and rate, differed depending on the entry point of the catabolic pathway to central carbon metabolism, with robust growth occurring only on amino acids catabolized into pyruvate or acetyl CoA. Growth on combinations of two amino acids revealed reproducible patterns, the clearest being inhibition of growth on other amino acids by asparagine, aspartate and their degradation product, oxaloacetate. Finally, growth was different in test tubes compared with 96 well plates. Our results reveal hidden complexity in amino acid utilization and suggest a "TCA-centric" viewpoint for amino acid utilization, perhaps reflecting the high metabolic flexibility of pyruvate and specific regulatory aspects of the TCA cycle in Alteromonas.

Myrmecocystus honeypot ants rely on specialized workers, repletes, to store dissolved carbohydrates in their crops long term. The repletes store this liquid, which does not spoil in their crops, for many months at a time. When resources are scarce, repletes redistribute the stored nutrients to their colony members via trophallaxis. While we suspect that the gut microbiome of honeypot ants may aid in spoilage prevention, before we can investigate this, we must first characterize it. Here, we used 16S rRNA gene sequencing to determine the microbial community composition across six Myrmecocystus honeypot ant species, sampling multiple colonies, castes, and organs. We found that microbiome community composition was strongly shaped by species, with variation between colonies in M. arenarius, M. depilis, and M. mexicanus. Organ level differences were observed in the crop and midgut in M. mexicanus. Caste differences were observed in M. flaviceps and M. mexicanus. Replete crops of M. mexicanus and M. depilis were enriched in Fructilactobacillus, other lactic acid bacteria, and acetic acid bacteria, whereas halophiles were more prominent in the gut of species such as M. flaviceps and M. wheeleri. In this study we demonstrate that Myrmecocystus ants host species-specific gut microbiomes and identify an association between lactic acid bacteria, acetic acid bacteria, and halophiles within replete crops. While much work remains in understanding the roles of the microbes in the symbiosis with their host ants, the dominance of these particular taxonomic groups suggests an association with a high sugar environment and a potential microbial role in preventing spoilage of the crop contents.

ASS1 was isolated as a motile Stenotrophomonas strain from crude oil-contaminated soils in Tabasco, Mexico. We characterized this strain using physiological and biochemical traits. ASS1 grew at temperature 25-37 (optimally at 37 {degrees} C) and at pH 6 to 8 (optimally at pH 7 to 8). The assembled genome has a total length of 4.56MB with a G + C content of 66.6%. The 16S rRNA gene sequence analysis confirmed that this strain belongs to the genus Stenotrophomonas. Based on the 16S rRNA analysis, Stenotrophomonas geniculata ATCC 19374 is the closest species, and it shares 99.86% similarity with ASS1. Similarly, a phylogenomic tree based on core genome sequence revealed that the closest species to ASS1 is Stenotrophomonas geniculata ATCC 19374. The major fatty acids in ASS1 are C16:0, antesio C15:0, iso C12:0, iso C15:0, iso C17:0 and C18:0. The genome of ASS1 consists of 4,373,402 bp. The Average Nucleotide Identity (ANI) values for ASS1 which it shared with its closest phylogenetic neighbors, are Stenotrophomonas geniculata ATCC 19374 = JCM 13324 [T] 92.66 %, Stenotrophomonas maltophilia 13637[T] 92.15%, Stenotrophomonas maltophilia K279a 92.13% Stenotrophomonas maltophilia R551-3 92.15% Stenotrophomonas maltophilia MTCC 434 [T] 92.08% and Pseudomonas hibisicicola ATCC [T] 91.66%. ASS1 possesses genes that are essential for the degradation of Polycyclic Aromatic hydrocarbon. Genes such as 1, 2 dihydroxyl 1, 2 dihydronaphthalene dehydrogenase; MG068 17425, homologous to 2 hydroxyl chromene 2 carboxylate isomerases; MG 18055, homologous to salicylaldehyde dehydrogenase and MG068 20095, homologous to naphthalene 1, 2 dioxygenases were identified in ASS1. The dDDH value between ASS1 and its closest neighbor Stenotrophomonas geniculata ATCC 19374 = JCM 13324 [T] is 50%, which is the highest for all the typed species and as such we proposed that ASS1 is a novel species with the name Stenotrophomonas oleivorans sp. nov. sp. nov. and ASS1T as the typed strain

Banana leaf diseases are a significant threat to Cavendish banana production. In the Philippines, the main disease has been diagnosed as Black sigatoka disease caused by Pseudocercospora fijiensis based on symptoms. However, our study showed that the main pathogen in Mindanao island, the largest banana-producing region in the Philippines, belongs to the genus Nigrospora, contradicting previous assumptions. We clarified the phylogenetic positions of 160 Nigrospora isolates based on molecular phylogenetic analyses using ITS, {beta}-tubulin, and tef1 sequences, and compared their morphology with known species. Molecular phylogenetic and morphological analysis revealed that Nigrospora isolates comprised N. chinensis, N. lacticolonia, N. cf. singularis, N. sphaerica, N. vesicularifera, and a novel species, N. nigrocolonia. Pathogenicity tests on banana leaves confirmed that these species are pathogenic. Species other than N. sphaerica were for the first time reported as pathogens of banana leaf. The results of the fungicide sensitivity test using 14 fungicides, including pyrimethanil, spiroxamine, and tebuconazole, for the Sigatoka disease showed 100% inhibition of all isolates at 100 ppm of active ingredients. However, low-sensitivity isolates were observed for the remaining 11 fungicides. Our findings indicated the need for a comprehensive review of banana leaf disease prevention strategies.

Leaf diseases pose a serious threat to faba bean production. Leaf blotch of faba bean, caused by Alternaria spp., has become increasingly widespread and destructive in several countries. Leaf diseases pose a serious threat to faba bean production. The infection of plant by pathogens can be influenced by various factors associated with the host plant, environmental conditions and presence of other microorganisms. The phyllosphere and endosphere play a critical role in plant health and disease development. This study aimed to evaluate the factors shaping the structure and diversity of fungal communities associated with faba beans. Plant samples were collected in 2004 from two intensively managed faba bean production fields in the central region of Latvia. Fungal assemblages were characterized using an ITS region metabarcoding approach based on Illumina MiSeq sequencing. Among the assigned amplicon sequence variant (AVS), 65% belonged to the phylum Ascomycota, while approximately 4% were classified as Basidiomycota. Alternaria and Cladosporium were the dominant genera across samples. The alfa and beta diversities of fungal communities was higher during flowering of faba beans to compare with ripening. The higher abundance of Basidiomycota yeasts were observed during flowering, in contrast, Cladosporium genus was significantly more abundant during ripening. Alternaria DNA was found on leaves that showed no symptoms of the disease. The diversity and composition of fungal communities were significantly influenced by sampling time and presence of leaf blotch, caused by Alternaria spp.

The genus Legionella comprises opportunistic pathogenic bacteria commonly found in natural and engineered water systems, where they interact with environmental microbes and protozoa, primarily in biofilms. Legionella pneumophila is the main causative agent of Legionnaires disease and is transmitted through inhalation of contaminated aerosols. Iron availability is a critical factor for L. pneumophila growth, persistence, and virulence, yet iron is often limited in aquatic environments. To overcome iron scarcity, many bacteria produce siderophores, secondary metabolites that scavenge ferric iron. Because siderophores are chemically diverse and species specific, they play a key role in inter-species competition and can withhold iron from competitors. Here, we investigated the effects of iron depletion and siderophore-mediated competition on L. pneumophila using commercial pyoverdines and extracellular metabolites from environmental Pseudomonas strains. Growth assays showed that L. pneumophila can grow under iron-limited conditions but with lag phases extended by more than 20 hours. Pyoverdines inhibited growth in a concentration-dependent manner, primarily increasing the time to mid-log phase (t_mid). Supernatants and crude pyoverdine extracts from siderophore-producing Pseudomonas strains caused the strongest inhibition, including lag-phase extensions of up to 55 hours or complete growth arrest. These results demonstrate that siderophore-producing bacteria can suppress L. pneumophila by limiting iron availability.

1.1Antimicrobial resistant infections present a concerning and expanding healthcare problem that is compounded by the reduction of antimicrobial research by the pharmaceutical industry. Additionally, the currently used antimicrobials consistently present less than ideal clinical treatment outcomes. This contention is supported by in vitro analysis in appropriate models. Here, in mature methicillin resistant Staphylococcus aureus (MRSA) in vitro cultures, we tested multiple antimicrobials and showed that for a biofilm grown for 72 hours, no antimicrobial tested was able to completely eradicate the biofilm even after 24 hours of exposure. However, the addition of an enzymatic biofilm-dispersal agent (DNase I or Proteinase K), greatly improved the performance of vancomycin and tigecycline in this in vitro model. Despite the improved performance in the presence of the dispersal agent, a high concentration of antimicrobial, 2000 {micro}g/mL, was needed to completely eradicate the infection as demonstrated by analyses using both a traditional XTT assay as well as a subculture assay to account for persister cells. It was shown that the addition of DNase I improved the diffusion of vancomycin through the biofilm. This suggests vancomycin efficacy is limited by the biofilm. The presented work provides a potential avenue for future treatments of MRSA lung infections by utilizing a traditional antibiotic combined with a passive dispersive agent.

The microbiota and microbiome associated with zooplankton remains rather understudied compared to other animal groups and/or taxa. The present study aimed at investigating the whole-body bacterial microbiota of Daphnia spp. in two contrasting Greek lakes, the shallow and hypertrophic Lake Koronia vs. the deep and mesotrophic Lake Vegoritida, including both egg-bearing and non-egg-bearing individuals. In both lakes, 2,060 bacterial operational taxonomic units (OTUs) were found, with 223 of them being conditionally rare (crOTUs) with low contribution even for the dominant phyla, with L. Vegoritida having more crOTUs than L. Koronia. The individuals microbiota had inconsiderable overlap with the surrounding water microbiota in both lakes. The two lakes showed significant differences in their Daphnia -associated microbiota. L. Koronia had richer OTUs and rather homogeneous bacterial communities, with higher occupancy. Overall, no significant differences in between the microbiota of egg-bearing and non-egg-bearing Daphnia individuals in both lakes. However, regarding the most important OTUs (miOTUs), the L. Koronia miOTUs were highly overlapped between the individuals with and without eggs, with only one missing from the individuals without eggs. In L. Vegoritida the individuals without eggs had only six miOTUs and while egg-bearing individuals had nine different ones; the two lakes had no shared miOTUs., considerable differences occurred.. A total of 27 miOTUs, was found and belonged to the Pseudomonadota, unclassified Bacteria, Cyanobacteria, Bacteroidota, Bacillota and Actinomycetota. Those miOTUs, where assignment to the genus level was possible, they were related to Cyanobium, Mucilaginibacter, Flavobacterium and Staphylococcus. This study showed that lake morphotype and ecological status can exert some impact on Daphnia-associated bacterial microbiota, with more pronounced effects on egg-bearing and non-egg-bearing individuals.

BackgroundWildlife rehabilitation can influence host-associated microbiota, yet little is known about how the gut microbiome of insectivorous bats responds to rehabilitation during temporary managed care. This study applied shotgun metagenomics to evaluate the impact of temporary managed care on the gut microbiome of wild and rehabilitated bats in Yorkshire, UK. ResultsWe analysed 25 faecal metagenomes from Myotis daubentonii, Pipistrellus pipistrellus, Nyctalus noctula and N. leisleri, including wild baseline bats and bats sampled during temporary managed care (1-49 days in rehabilitation). Microbial communities clustered strongly by host species and roost location, but not by rehabilitation status. Bacterial alpha diversity did not differ between wild bats, and bats in care (H = 2.30, p = 0.32). Archaeal communities were highly uniform across samples, showing far lower interindividual variation than bacterial communities (12.2% vs. 41.8% coefficient of variation). Rehabilitated bats showed increased relative abundance of Yersiniaceae and Lactobacillaceae, while environmental families such as Pseudomonadaceae and Erwiniaceae decreased, indicating modest but non-disruptive changes consistent with a controlled diet and reduced environmental exposure. ConclusionsAcross temporary managed care, the core gut microbiome of insectivorous bats remained stable, demonstrating notable microbial resilience. These findings provide an important baseline for monitoring microbiome health in wildlife rehabilitation and supporting post-release conservation programmes in the UK and beyond.

Mixotrophy is emerging as a default nutritional strategy in phytoplankton but research seems so far isolated and mostly focussing on single phytoplankton groups or strains. Here we combined data from 24 oceanic and 22 freshwater strains - as well as results from other studies - to analyze phytoplanktons ability to utilize dissolved organic compounds and highlight potential influencing factors. The results emphasize that mixotrophy is ubiquitous in phytoplankton across functional groups and taxa isolated from various habitats, and not strictly dependent on light or nutrient deficiencies. Several factors such as taxonomic affiliation, temperature and growth phase can affect mixotrophic behavior but no consistent patterns have emerged regarding their effects. Hence, mixotrophic traits remain so far unpredictable. There is some indication that the strains origin - potentially through adaptation to habitat DOM availability - might predetermine phytoplanktons mixotrophic skills. For example, freshwater strains used overall more compounds than oceanic strains in our study and Ostreococcus exhibited a different use pattern depending on its origin. Nevertheless, many aspects of mixotrophy in phytoplankton - e.g. metabolic pathways - remain cryptic. By summarizing available knowledge and knowledge gaps, the present synthesis provides a guideline for upcoming research further exploring mixotrophy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/703725v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@12ac311org.highwire.dtl.DTLVardef@6c98deorg.highwire.dtl.DTLVardef@1a837ddorg.highwire.dtl.DTLVardef@eb9b53_HPS_FORMAT_FIGEXP M_FIG C_FIG

The Mediterranean Sea harbors a rich diversity of macroalgae with pharmacological potential. In this study, metabolite composition, antioxidant and antifungal activities of methanol and ethyl acetate extracts from Rugulopteryx okamurae, Dictyota fasciola, Batophora sp., Codium fragile, and Palisada tenerrima from the southeastern coast of Spain were evaluated. R. okamurae, Batophora sp. and C. fragile are non-native. All extracts exhibited antioxidant activity, particularly those obtained with methanol. R. okamurae and Batophora sp. showed the highest activity, inhibiting the DPPH{middle dot}radical by more than 40% at 1 mg/ml. All extracts contained phenolics and flavonoids, which may contribute to the observed antioxidant activity. Moreover, the methanolic extracts of R. okamurae and P. tenerrima exhibited in vitro fungistatic activity against the wilt pathogen Fusarium oxysporum f. sp. cubense tropical race 4. R. okamurae extracts showed the strongest antifungal activity against F. oxysporum f. sp. cubense TR4, with inhibition values of 23.3% and 30.5% at doses of 10 and 20 mg/well, respectively. The methanolic P. tenerrima also showed notable activity (19.8% and 20.7% inhibition), whereas other extracts displayed lower effect. LC-MS/MS analysis of R. okamurae extract revealed a diverse metabolite profile including oxylipin-type metabolites, terpenoid-like compounds and carotenoids. Our findings highlight coastal macroalgae from SE Spain as sources of bioactive compounds and support the valorization of biomass from invaders such as R. okamurae.

BackgroundThere is currently no approved antiviral therapy against measles virus (MeV). Repurposing available compounds with broad antiviral activity may rapidly identify candidate drugs for clinical evaluation. Here we evaluated the antiviral activity of the clinically approved drugs azelastine hydrochloride and zafirlukast as well as the flavonoids quercetin and isoquercetin against MeV in preventative and therapeutic in vitro studies. MethodsCompounds were tested for antiviral activity against MeV in preventative (prophylactic and virucidal) and therapeutic (steady-state and persistent) assays in Vero/hSLAM cells. Viral loads and cell viability were measured 48h post-infection, and dose-response curves were used to calculate EC50 values. Flavonoids were also tested in the presence of 1 mM ascorbic acid. ResultsAzelastine hydrochloride did not show evidence of antiviral activity against MeV under these conditions, whereas zafirlukast, quercetin, and isoquercetin showed therapeutic activity against MeV. The addition of ascorbic acid enhanced the therapeutic potency of quercetin to 4.2-4.8 {micro}M and of isoquercetin to 10.7-10.9 {micro}M. Antiviral activity was dose-dependent when administered post-infection. ConclusionAmong the four compounds tested, quercetin showed the most potent therapeutic antiviral activity against MeV in vitro. Isoquercetin and zafirkulast also showed therapeutic activity. These findings support further evaluation of quercetin, isoquercetin, and zafirlukast as candidate antiviral drugs for MeV and highlight the utility of in vitro platforms for rapid antiviral drug screening.