Search Results (183)

Emerging RNA viruses such as influenza A virus (IAV), Zika virus (ZIKV), and dengue virus (DENV) continue to pose major challenges to animal and public health due to their high mutation rates, wide host ranges, and immune evasion strategies. In this study, we evaluated the in vitro antiviral activity of a marine bacterial extract derived from Parerythrobacter sp. M20A3S10 against IAV (H1N1; H3N2), influenza B virus (IBV), ZIKV, and DENV2. The extract demonstrated broad-spectrum antiviral effects with favorable selectivity indices across multiple host-derived epithelial cell lines. Notably, post-infection treatment significantly suppressed viral replication, suggesting a host-modulating or replication-inhibiting mechanism. While the extract’s active components have yet to be identified, bacteria from the Erythrobacteraceae family are known producers of bioactive metabolites with potential antiviral properties. These findings provide preliminary insight into the potential of marine-derived bacterial compounds in veterinary antiviral development and highlight the need for further characterization and in vivo validation. This work contributes to the understanding of virus–host interactions and the exploration of novel therapeutic strategies targeting the pathogenesis and immune modulation of veterinary RNA viruses. Full article

The purpose of this study was to investigate the taxonomic and phylogenomic placement of the proposed genus ‘Solwaraspora’ within the context of other marine genera using a dual-omics approach. Initially, we isolated bacteria from marine tunicates, squirts, and sponges, which were morphologically similar to an emerging genus (identified as ‘Micromonospora_E’ by the GTDB-tk2 database using whole genome sequence data) by colony shape, size, and clustering pattern, but only found five strains in our dataset belonging to this distinction. Due to the minimally explored nature of this genus, we sought to identify more bacterial strains with similar morphology to Micromonospora‘Micromonospora_E’ by whole genome sequencing (WGS). Within our collection, we noted 35 strains that met this criterion and extracted genomic information to perform WGS on these strains. With this information, we studied taxonomic and phylogenomic relationships among these organisms. Using the data gathered from WGS, we were able to identify an additional five strains labeled by the GTDB-tk2 database as Micromonospora‘Micromonospora_E’, as well as construct phylogenomic trees to examine the evolutionary relationships between these strains. ANI values were calculated between strains from our dataset and type strains of Micromonospora and Plantactinospora as well as against an outgroup Streptomyces strain. No type strains are available for ‘Solwaraspora’. Using MALDI-TOF MS, we positively identified ‘Solwaraspora’, which was supported by the phylogenomic tree showing Micromonospora’Micromonospora_E’ (‘Solwaraspora’) in a distinct clade from Plantactinospora and Micromonospora. Additionally, we discovered gene cluster families (GCFs) in alignment with genera, as well as a large representation of biosynthetic gene clusters (BGCs) coming from the ‘Solwaraspora’ strains. These findings suggest significant potential to discover novel chemistry from ‘Solwaraspora’, adding to the importance of investigating this new genus of bacteria. Full article

The Red Sea is rich in symbiotic microorganisms that have been identified as sources of bioactive compounds with antimicrobial, antifungal, and antioxidant properties. In this study, we aimed to explore the potential of marine sponge-associated bacteria as sources of antibacterial compounds, emphasizing their significance in combating antibiotic resistance (AMR). The crude extracts of Micrococcus, Bacillus, and Staphylococcus saprophyticus exhibited significant antibacterial activity, with inhibition zones measuring 12 mm and 14 mm against Escherichia coli, Staphylococcus aureus, Candida albicans, and other infectious strains. The DPPH assay showed that the bacterial isolates AN3 and AN6 exhibited notable antioxidant activity at a concentration of 100 mg/mL. To characterize the chemical constituents responsible for the observed bioactivity, a GC–MS analysis was performed on ethyl acetate extracts of the potent strains. The analysis identified a range of antimicrobial compounds, including straight-chain alkanes (e.g., Tetradecane), cyclic structures (e.g., Cyclopropane derivatives), and phenolic compounds, all of which are known to disrupt microbial membranes or interfere with metabolic pathways. The bioprospecting and large-scale production of these compounds are challenging. In conclusion, this study underscores the potential for marine bacteria associated with sponges from the Red Sea to be a source of bioactive compounds with therapeutic relevance. Full article

Background/Objectives: Lactic acid bacteria produce biofilms in meat products that contribute to the products’ deterioration, reduction in quality, and shortened shelf life. Although LAB are generally considered benign, certain strains create slime and cause significant drops in pH. The study’s goal was to identify and characterize LAB strains from sausage products that are capable of biofilm formation, and to evaluate the inhibitory effects of E. bicyclis methanol extract, its ethyl acetate fraction, and phloroglucinol, as well as to synthesize AuNPs, and assess their efficacy in controlling biofilm formation. Methods: Slime or biofilm-producing LAB bacteria were isolated from commercial sausages and identified using 16S rRNA gene sequencing. Lactobacillus sakei S10, which can tolerate high salt concentrations and cold temperatures, was chosen as a representative strain. The isolates were subsequently tested for hemolytic activity, salt and temperature tolerance, and carbohydrate consumption patterns. To evaluate antibiofilm potential, marine-derived compounds from Eisenia bicyclis, such as phloroglucinol (PG), crude methanolic extracts, ethyl acetate fractions, and gold nanoparticle (AuNP) formulations, were tested in situ on sausage surfaces against L. sakei S10 and common pathogens (Pseudomonas aeruginosa and Staphylococcus aureus). The biofilm-inhibitory effects of the extracts, PG, and PG-AuNPs were estimated using the colony-counting method. Results: The PG-AuNPs had an average particle size of 98.74 nm and a zeta potential of −29.82 mV, indicating nanoscale dimensions and considerable colloidal stability. Structural analysis confirmed their spherical form and crystalline structure, as well as the presence of phenolic groups in both reduction and stabilization processes. Among the studied treatments, the PG and PG-AuNPs had the strongest antibiofilm activities, dramatically lowering biofilm biomass, particularly for P. aeruginosa and L. sakei S10. However, the inhibitory effects were less prominent in in situ conditions than in in vitro testing, highlighting the complexity of real food matrices. Conclusions: The results of this study indicate that polyphenolic compounds obtained from marine sources, particularly in nano-formulated forms, have a great deal of potential as natural antibiofilm products. Enhancing the microbiological safety of processed meat products and extending their shelf life could be accomplished through the application of these polyphenolic compounds in food packaging or surface treatments. Full article

Background: Red macroalgal flour resulting from commercial phycocolloid extraction has been shown to include valuable preservative compounds. Methods: This study focused on the preservative effect of a gelatin-based packaging system including Gelidium sp. flour during refrigerated storage of Trachurus trachurus fillets. Different microbial and chemical indices related to quality loss were determined in fish muscle during a 6-day storage period at 4 °C. Results: Compared with gelatin-packaged control samples, those packaged in the system including the algal flour presented significantly lower microbial development (aerobic bacteria, psychrotrophic bacteria, and proteolytic bacteria) and significantly lower chemical indices related to microbial development (pH and trimethylamine). With respect to lipid oxidation, there was significantly greater retention of peroxides and significantly lower formation of secondary oxidation products in the samples packaged with the algal flour. Additionally, the algal flour group presented significantly less lipid hydrolysis. Conclusions: A preservative effect was derived from the addition of Gelidium flour to a gelatin-based packaging system during refrigerated storage of T. trachurus. This study supports the practical and valuable use of Gelidium sp. flour and addresses the current global interest in natural sources of preservative compounds and the use of marine byproducts. Full article

This study evaluated the antibacterial activity of aqueous and organic extracts from 78 marine organisms, including seaweeds and sponges, collected along the coast of Ceará, Brazil. Extracts were obtained by maceration using distilled water and 50% acetonitrile and tested against Staphylococcus aureus, Staphylococcus epidermidis (Gram-positive), and Escherichia coli (Gram-negative) using the disk diffusion method, and inhibition zone diameters were measured. Antibacterial activity was observed in 30.7% of the extracts, with organic extracts showing higher efficacy. Several sponge species, particularly those from the genus Aplysina, as well as Amphimedon compressa, Amphimedon viridis, Mycale sp., and Pseudosuberites sp., demonstrated notable inhibitory effects. While seaweed aqueous extracts showed no activity, some organic extracts—especially from Amansia multifida—were effective against Gram-positive strains. In general, Gram-positive bacteria were more susceptible than Gram-negative bacteria. These findings underscore the biotechnological potential of marine organisms from the Brazilian coast as promising sources of antibacterial compounds and support future efforts focused on the isolation, characterization, and toxicological evaluation of active metabolites for pharmaceutical and industrial applications. Full article

Antibacterial resistance has become a major problem where new promising drugs are needed. The extracts obtained from marine invertebrates Mytilus galloprovincialis, Patella sp., Gibbula sp. and Arbacia lixula were tested against bacteria using the disc diffusion method. Citrobacter sp. from seawater and Paenibacillus sp., Bacillus sp. and Geobacillus sp. from soil were used as well as the reference bacterial strains Staphylococcus aureus NCTC 12981, S. aureus subsp. aureus Rosenbach ATCC 6538, Salmonella enterica subsp. enterica serovar Enteritidis ATCC 13076, Salmonella enterica subsp. enterica serotype Typhimurium NCTC 12023, Listeria monocytogenes ATCC 19111, Klebsiella aerogenes ATCC 13048 and Escherichia coli NCTC 12241. The most successful bacterial inhibitors, inhibiting 8 of 13 strains were extracts of M. galloprovincialis, Patella sp., Gibbula sp., Enteromorpha sp., C. sinuosa and U. lactuca, extract of A. lixula showed antibacterial activity against five bacteria, while extract of C. officinalis showed no antibacterial activity. These results indicate the potential of these marine organisms as a source of antibacterial compounds and may serve as a basis for further research and development of new antibacterial agents. Full article

Background: Fucoidan from Apostichopus japonicus (Aj-FUC) is a marine polysaccharide extracted from the high-quality sea cucumber, which has received increasing attention for its multiple biological activities. Methods: In this study, Aj-FUC was extracted, and its basic structure was characterized, while the alleviating efficacy of Aj-FUC on ulcerative colitis (UC) was investigated using C57BL/6 mice. The improvement of Aj-FUC on the fecal gut microbiota in healthy individuals and inflammatory bowel disease (IBD) patients was explored using in vitro simulated fecal fermentation. Results: The results reflected that Aj-FUC treatment attenuated the histopathological damage associated with colitis, reduced the levels of IL-6, IL-1β, and TNF-α. Aj-FUC treatment also upregulated the expression of ZO-1 and occludin, thereby aiding in the repair of the intestinal barrier. Furthermore, Aj-FUC enhanced the levels of short-chain fatty acids (SCFAs) and helped restore the balance of gut microbiota, particularly by increasing the relative abundance of Akkermansia. In vitro simulation of fecal fermentation showed that Aj-FUC could modulate the gut microbiota of IBD patients and increase the relative abundance of beneficial bacteria. Conclusions: In conclusion, this study highlights that Aj-FUC can alleviate UC by modulating the levels of inflammatory factors, improving the intestinal barrier, and regulating the intestinal flora in a variety of ways. Full article

The impact of macroalgae species on rumen function remains largely unexplored. This present study aimed to identify the biocompounds of the three types of marine macroalgae described: Macrocystis pyrifera (Brown), Ulva spp. (Lettuce), Mazzaella spp. (Red) and their effect on species-specific modulations of the rumen microbiome. The macroalgae were characterized using GC-MS. Twelve Rambouillet lambs were randomly assigned to one of four experimental diets (n = 3 per treatment): (a) control diet (CD); (b) CD + 5 g of Red algae; (c) CD + 5 g of Brown algae; and (d) CD + 5 g of Lettuce algae. After the lambs ended their fattening phase, they donated ruminal fluid for DNA extraction and 16S rRNA gene V3 amplicon sequencing. Results: The tagged 16S rRNA amplicon sequencing and statistical analysis revealed that the dominant ruminal bacteria shared by all four sample groups belonged to phyla Firmicutes and Bacteroidota. However, the relative abundance of these bacterial groups was markedly affected by diet composition. In animals fed with macroalgae, the fibrinolytic and cellulolytic bacteria Selenomonas was found in the highest abundance. The diversity in chemical composition among macroalgae species introduces a range of bioactive compounds, particularly VOCs like anethole, beta-himachalene, and 4-ethylphenol, which demonstrate antimicrobial and fermentation-modulating properties. Full article

Fungal infections significantly threaten public health, and many strains are resistant to antifungal drugs. Marine Actinobacteria have been identified as the generators of powerful bioactive compounds with antifungal activity and can be used to address this issue. In this context, strains of Actinomycetes were isolated from the marine area of Rachgoun Island, located in western Algeria. The isolates were phenotypically and genetically characterized. The most potent antifungal isolate was selected, and its crude extract was purified and characterized by the GC/MS method. The results revealed that the STR2 strain showed the strongest activity against at least one target fungal species tested on a panel of fungal pathogens, including Candida albicans, Aspergillus fumigatus, Aspergillus niger, and Fusarium oxysporum. The molecular assignment of the STR2 strain based on the 16S rRNA gene positioned this isolate as a Streptomyces bacillaris species. The presence of safranal (2,3-dihydro-2,2,6-trimethylbenzaldehyde) in the crude chloroform extract of Streptomyces bacillaris STR2 strain was discovered for the first time in bacteria using chromatographic analysis of its TLC fractions. Moreover, certain molecules of biotechnological interest, such as phenols, 1,3-dioxolane, and phthalate derivatives, were also identified. This study highlights the potential of marine actinomycetes to produce structurally unique natural compounds with antifungal activity. Full article

Microorganisms that exist in the seawater form microbial biofilms on materials used in marine construction, especially on metal surfaces submerged in seawater, where they form biofilms and cause severe corrosion. Biofilms are mainly composed of bacteria and their secreted polymeric substances. In order to understand how biofilms promote metal corrosion, planktonic and biofilm cells of Desulfovibrio bizertensis SY-1 (D. bizertensis) from Q235 steel were collected and analyzed as to their intracellular proteome and extracellular polymeric substances (EPS). The intracellular proteome analysis showed that the cellular proteins were strongly regulated in biofilm cells compared to planktonic cells, e.g., along with flagellar proteins, signaling-related proteins were significantly increased, whereas energy production and conversion proteins and DNA replication proteins were significantly regulated. The up-and-down regulation of proteins revealed that biofilm formation by bacteria on metal surfaces is affected by flagellar and signaling proteins. A significant decrease in DNA replication proteins indicated that DNA is no longer replicated and transcribed in mature biofilms, thus reducing energy consumption. Quantitative analysis and lectin staining of the biofilm on the metal’s surface revealed that the bacteria secreted a substantial amount of EPS when they began to attach to the surface, and proteins dominated the main components of EPS. Further, the infrared analysis showed that the secondary structure of the proteins in the EPS of the biofilm was mainly dominated by β-sheet and 3-turn helix, which may help to enhance the adhesion of EPS. The functional groups of EPS analyzed using XPS showed that the C element of EPS in the biofilm mainly existed in the form of combinations with N. Furthermore, the hydroxyl structure in the EPS extracted from the biofilm had a stronger hydrogen bonding effect, which could maintain the stability of the EPS structure and biofilm. The study results revealed that D. bizertensis regulates the metabolic pathways and their secreted EPS structure to affect biofilm formation and cause metal corrosion, which has a certain reference significance for the study of the microbially influenced corrosion (MIC) mechanism. Full article

Elysia crispata (Sacoglossa, Gastropoda) is a tropical sea slug known for its ability to incorporate functional chloroplasts from a variety of green macroalgae, a phenomenon termed kleptoplasty. This sea slug, amenable to laboratory cultivation, produces mucus, a viscous secretion that serves diverse purposes including protection, locomotion, and reproduction. In this study, we profiled the antimicrobial, antioxidant, and anti-inflammatory activities of the mucus of this sea slug. Results revealed inhibitory activity against several bacterial strains, more pronounced for Gram–negative bacteria. Particularly interesting was the strong inhibitory effect against Pseudomonas aeruginosa, a bacterial species classified by the WHO as a high-priority pathogen and associated with high-risk infections due to its frequent multidrug-resistant profile. Similar inhibitory effects were observed for the mucus native protein extracts, indicating that proteins present in the mucus contributed significantly to the antimicrobial activity. The mucus also showed both antioxidant and anti-inflammatory activities. The latter activities were associated with the low molecular weight (<10 kDa) fraction of the mucus rather than the native protein extracts. This study opens the way to further research on the biotechnological applications of the mucus secreted by this unique marine organism, particularly as an antimicrobial agent. Full article

Marine sponges are well-known for hosting rich microbial communities. Sponges are the most prolific source of marine bioactive compounds, which are frequently synthesized by their associated microbiota. Calyx nicaeensis is an endemic Mediterranean sponge with scarce information regarding its (bioactive) secondary metabolites. East Mediterranean specimens of mesophotic C. nicaeensis have never been studied. Moreover, no research has inspected its associated bacteria. Thus, we studied the sponge’s bacterial diversity and examined bacterial interspecific interactions in search of a promising antibacterial candidate. Such novel antimicrobial agents are needed since extensive antibiotic use leads to bacterial drug resistance. Bacteria cultivation yielded 90 operational taxonomic units (OTUs). A competition assay enabled the testing of interspecific interactions between the cultured OTUs. The highest-ranked antagonistic bacterium, identified as Paenisporosarcina indica (previously never found in marine or cold habitats), was mass cultured, extracted, and separated using size exclusion and reversed-phase chromatographic methods, guided by antibacterial activity. A pure compound was isolated and identified as 3-oxy-anteiso-C₁₅-fatty acid-lichenysin. Five additional active compounds await final cleaning; however, they are lichenysins and surfactins. These are the first antibacterial compounds identified from either the C. nicaeensis sponge or P. indica bacterium. It also revealed that the genus Bacillus is not an exclusive producer of lichenysin and surfactin. Full article

Rabbit meat production faces challenges due to the prevalence of gastrointestinal diseases in rabbits, exacerbated by restrictions on antibiotic use in European animal production. Marine macroalgae, rich in bioactive compounds such as soluble polysaccharides, represent promising solutions to this problem. However, research on the effects of macroalgae and the underlying mechanisms in rabbits is limited, especially in commercial settings. This study aimed to evaluate the impact of Saccharina latissima (dehydrated) and Ulva lactuca (dehydrated and hydrolyzed extract) on rabbit on growth performance and gut health in a commercial farm context. A total of 96 litters (8 rabbits/litter) of crossbred rabbits weaned at 33 days of age were randomly assigned to 4 experimental groups (control, Saccharina latissima dehydrated, Ulva lactuca dehydrated and Ulva lactuca hydrolyzed extract; 24 replicates/treatment) and monitored from weaning to slaughter at 61 days of age. The key indicators of gut health were assessed 14 days post-weaning by counting coccidia, isolating specific microflora and examining histological samples. Additionally, the relevant intestinal markers (microbiome composition, mucin content and gene expression related to immune response and tight junction proteins) were determined in order to elucidate the potential mechanisms involved. The inclusion of macroalgae in the diet did not influence growth performance of the animals. S. latissima had a positive effect in reducing coccidia counts (p = 0.10) and improving mucosal morphology (p < 0.001), which can possibly be attributed to modulation of the microbiota and improved mucosal functionality. Ulva lactuca had a favorable effect on gut tight junction proteins (p < 0.001), enhancing intestinal barrier function. These findings suggest the potential of macroalgae to modify the intestinal microbiome by reducing the presence of inflammatory bacteria. Further research is warranted to elucidate the mechanisms involved and optimize macroalgae supplementation in rabbit nutrition for enhanced gut health. Full article

A variety of metabolites produced by marine microorganisms are gaining high value for their significant biological properties. Therefore, the search for active secondary metabolites from marine bacteria against pathogenic microorganisms has become essential for alternative and effective strategies. In this study, Halomonas saccharevitans, a marine-derived bacterium, was cultured and fermented on a liquid medium. The ethyl acetate (EtOAc) crude extract was then fractioned yielded five fractions to study their biological effect. Two fractions had significantly higher activity, i.e., absolute n-hexane against Staphylococcus aureus and Pseudomonas aeruginosa and absolute methanol (MeOH) against Escherichia coli and Bacillus subtilis, with promising MIC values. The time–kill kinetics assay for the very susceptible bacteria against active fractions was also examined. The antifungal assay of the active fractions had the highest activity against Aspergillus niger and Candida albicans with the examined variable MFC values. The cytotoxic assay against HepG2 cells showed promising activities, resulting in a 78% inhibition of cell viability. Moreover, the antioxidant activities showed reasonable inhibition values at 21.87 ± 0.85% and 98.25 ± 1.45%, compared to the control. Molecular docking revealed a high affinity between major detected compounds with free binding energies. The active fractions were characterized by the presence of diverse chemically esters, phenolics, essential oils, and other organic compounds detected by GC–MS. In conclusion, H. saccharevitans, derived from the Red Sea, might be useful as an alternative source for the possible production of bioactive substances with a variety of biomedical application. Full article