65 research outputs found
How Much Recurrent Outbreaks of the Moon Jellyfish May Impact the Dynamics of Bacterial Assemblages in Coastal Lagoons?
The moon jellyfish Aurelia coerulea (Scyphozoa) is one of the most common and largest jellyfish inhabiting coastal lagoons, confined bays, and marinas of temperate and subtropical coastal waters. The annual population dynamics of A. coerulea along with some bacterial parameters (bacterial size and biomass, total coliforms, faecal coliforms, intestinal enterococci, culturable Vibrio spp., and culturable bacteria at 37 degrees C), sea surface temperature (SST), salinity, and an array of nutrients (ammonia, nitrites, nitrates, phosphates, silicates, total nitrogen, and total phosphorus) were assessed in the Varano lagoon (Adriatic Sea) that is subject to anthropogenic pollution. Statistical analyses revealed that jellyfish outbreaks and their consequent biomass deposition significantly correlated to seawater temperature, total nitrogen, phosphates, and ammonia concentrations while negative correlations appeared with nitrite and nitrate concentrations. In addition, bacterial biomass and Vibrio abundance correlated with each other and temperature, jellyfish density, and total nitrogen. These findings suggest that environmental changes could trigger the occurrence of jellyfish bursts in the lagoon which, in turn, may act as one of the central drivers of processes regulating some bacterial components. The positive relationship between jellyfish flush-and-crash dynamics and SST suggests that ongoing global warming will seemingly increase jellyfish outbreaks
The Microbial Community Associated with Rhizostoma pulmo: Ecological Significance and Potential Consequences for Marine Organisms and Human Health
Jellyfish blooms are frequent and widespread in coastal areas worldwide, often associated
with significant ecological and socio-economic consequences. Recent studies have also suggested
cnidarian jellyfish may act as vectors of bacterial pathogens. The scyphomedusa Rhizostoma pulmo
is an outbreak-forming jellyfish widely occurring across the Mediterranean basin. Using
combination of culture-based approaches and a high-throughput amplicon sequencing (HTS), and
based on available knowledge on a warm-affinity jellyfish-associated microbiome, we compared the
microbial community associated with R. pulmo adult jellyfish in the Gulf of Taranto (Ionian Sea)
between summer (July 2016) and winter (February 2017) sampling periods. The jellyfish-associated
microbiota was investigated in three distinct compartments, namely umbrella, oral arms, and
mucus secretion. Actinobacteria, Bacteroidetes, Chlamydiae, Cyanobacteria, Deinococcus-Thermus,
Firmicutes, Fusobacteria, Planctomycetes, Proteobacteria, Rhodothermaeota, Spirochaetes,
Tenericutes, and Thaumarchaeota were the phyla isolated from all the three R. pulmo compartments
in the sampling times. In particular, the main genera Mycoplasma and Spiroplasma, belonging to the
class Mollicutes (phylum Tenericutes), have been identified in all the three jellyfish compartments.
The taxonomic microbial data were coupled with metabolic profiles resulting from the utilization
of 31 different carbon sources by the BIOLOG Eco-Plate system. Microorganisms associated with
mucus are characterized by great diversity. The counts of culturable heterotrophic bacteria and
potential metabolic activities are also remarkable. Results are discussed in terms of R. pulmo ecology,
the potential health hazard for marine and human life as well as the potential biotechnological
applications related to the associated microbiome
Antibacterial activity of marine macroalgae against fish pathogenic Vibrio species
Abstract
In mariculture, diseases of microbial origin can cause significant economic losses worldwide; the evolution of microorganism resistance to antibiotics has resulted in a growing need for new antibacterial compounds that are effective in veterinary medicine and characterized by limited undesirable side effects. Increased attention has recently been turned to seaweeds as a promising source for metabolites with antimicrobial activity. Vibriosis is a common disease, caused by bacteria of the genus Vibrio, that can result in high mortality in aquaculture. The aim of this study was to identify seaweeds with antibacterial activity against some pathogenic Vibrio species, in order to identify a possible alternative to the commonly used antibiotics in aquaculture. Chloroform/methanol lipidic extracts of six seaweed species (Chaetomorpha linum, Cladophora rupestris, Gracilaria dura, Gracilaria gracilis, Gracilariopsis longissima, Ulva prolifera) were tested for their antibacterial activities against six fish pathogenic Vibrio species using the disc diffusion method. Different susceptibilities to lipidic algal extracts were observed. All six of the seaweed extracts tested demonstrated inhibition of Vibrio ordalii. The best was that from Gracilariopsis longissima, showing activity against Vibrio ordalii, Vibrio salmonicida, Vibrio alginolyticus and Vibrio vulnificus. The results confirmed the potential use of seaweed extracts as a source of antibacterial compounds or as a health-promoting feed for aquaculture
Perceived social welfare as a driver of green products consumption: Evidences from an integrated multi-trophic aquaculture production
This study investigated consumers' perceptions of green products derived from a circular economy production, by shedding light on the role of perceived social welfare. Furthermore, the paper considered two moderators: perceptual variables on green products and psychological variables on the environment. The analysis was performed in the aquaculture sectorâspecifically referring to Integrated Multi-Trophic Aquaculture (IMTA) production as a research setting. Respondents received a structured questionnaire containing scales that measured perceived social welfare, environmentalism, green product's perception (in terms of price, quality and usefulness), purchase intention, and word-of-mouth. The results revealed an inverse relationship between perceived social welfare and the behavioral variables. Consumers were more attracted to and focused on the green product's usefulness than its price and quality. Moreover, the study found that environmentalism (in terms of environmental concern and perceived consumer effectiveness) moderate the effect of perceived social welfare on dependent variables. By exploring the role of perceived social welfare as a regressor, this study improves our understanding of consumers' behavior toward green products
Growth Performance of Mytilus galloprovincialis Lamarck, 1819 under an Innovative Integrated Multi-Trophic Aquaculture System (IMTA) in the Mar Grande of Taranto (Mediterranean Sea, Italy)
The cultivation of the Mediterranean mussel, Mytilus galloprovincialis Lamarck, 1819, has been tested in an innovative Integrated Multitrophic Aquaculture system (IMTA) in the Mar Grande of Taranto, as part of the EU-funded Remedialife project. This farming method could solve several problems including the low growth rate in mesotrophic environments while reducing the environmental impact of fish mariculture. Three productive cycles have been carried out. The first (2018â2019, traditional experiment) was conducted in three long lines around six cages of the fish farm in order to evaluate total mussel production under the innovative IMTA system and quality for human consumption by analyzing the concentration of culturable heterotrophic bacteria, total and fecal coliforms, Escherichia coli and Salmonella spp. in mussel tissues. In addition, 17 polycyclic aromatic hydrocarbons (PAHs), including 16 EPA priority compounds and seven polychlorinated biphenyls (PCBs), which are indicators of PCB contamination in the environment, were analyzed using gas chromatography in conjunction with a mass spectrometer. The second cycle (2020â2021, horizontal distance experiment) aimed to test the influence of fish cages on mussel growth by placing mussels near and far from the fish cages. The third cycle (2021â2022, vertical distance experiment) aimed to overcome the phenomenon of âheat wavesâ that can occur in the Mar Grande of Taranto during summer by testing the growth performance of mussels at two different depths (1 and 12 m). The following parameters were measured: Shell Length, L (mm); Shell Dry Weight, SDW (g); Flesh Dry Weight, FDW (g); Condition Index, IC = FDW/SDW. The results showed that the best growth performance was obtained near the fish cages and at a depth of 12 m. Moreover, the indicators of microbial contamination and concentrations of chemical compounds analyzed in mussel tissues cultured under the innovative IMTA system were in compliance with the reference values of European regulations
Screening of Three Echinoderm Species as New Opportunity for Drug Discovery: Their Bioactivities and Antimicrobial Properties
Echinoderms are a renewable resource with an economic value due to their increasing demand as food and/or source of bioactive molecules exerting antitumor, antiviral, anticoagulant, antioxidant, and antimicrobial activities. In this framework, the present study is aimed at investigating the antibacterial, antioxidant, and hemolytic activities in the three Echinoderm species Echinaster sepositus, Arbacia lixula, and Sphaerechinus granularis. The sea star E. sepositus showed lysozyme-like activity (mean diameter of lysis of 13.4±0.2âmm), an antimicrobial activity against the human emerging pathogens Staphylococcus aureus, Pseudomonas aeruginosa, and Candida famata, and a strong lytic activity (100±0.05%) towards the human red blood cells. Furthermore A. lixula and E. sepositus had the highest antioxidant activity (1792.75±233.7 and 1765.65±484.58ânmolTE/mL, resp.). From toxicological assays, it was shown that E. sepositus was not toxic towards HeLa cells and Vibrio fischeri, encouraging the exploitation of this species in the pharmaceutical field. Therefore, our findings have implications due to the ongoing explosion of antibiotic-resistant infections because of the new opportunistic pathogens and the need to discover antibacterial agents with new modes of action. Also the recorded antioxidant activity taking into account the need to find natural antioxidants useful for human health is intriguing
The influence of invasive jellyfish blooms on the aquatic microbiome in a coastal lagoon (Varano, SE Italy) detected by an Illumina-based deep sequencing strategy
The rapid expansion of multicellular native and alien species outbreaks in aquatic and terrestrial ecosystems (bioinvasions) may produce significant impacts on bacterial community dynamics and nutrient pathways with major ecological implications. In aquatic ecosystems, bioinvasions may cause adverse effects on the water quality resulting from changes in biological, chemical and physical properties linked to significant transformations of the microbial taxonomic and functional diversity. Here we used an effective and highly sensitive experimental strategy, bypassing the efficiency bottleneck of the traditional bacterial isolation and culturing method, to identify changes of the planktonic microbial community inhabiting a marine coastal lagoon (Varano, Adriatic Sea) under the influence of an outbreak-forming alien jellyfish species. Water samples were collected from two areas that differed in their level of confinement inside in the lagoon and jellyfish densities (W, up to 12.4 medusae mâ3; E, up to 0.03 medusae mâ3) to conduct a snapshot microbiome analysis by a metagenomic approach. After extraction of the genetic material in the environmental water samples, we deep-sequenced metagenomic amplicons of the V5âV6 region of the 16S rRNA bacterial gene by an Illumina MiSeq platform. Experiments were carried out in triplicates, so six libraries of dual indexed amplicons of 420 bp were successfully sequenced on the MiSeq platform using a 2 Ă 250 bp paired-end sequencing strategy. Approximately 7.5 million paired-end reads (i.e. 15 million total reads) were generated, with an average of 2.5 million reads (1.25 M pairs) per sample replicate. The sequence data, analyzed through a novel bioinformatics pipeline (BioMaS), showed that the structure of the resident bacterial community was significantly affected by the occurrence of jellyfish outbreaks. Clear qualitative and quantitative differences were found between the western and eastern areas (characterized by many or few jellyfish), with 84 families, 153 genera and 324 species in the W samples, and 104 families, 199 genera and 331 species in the E samples. Significant differences between the two sampling areas were particularly detected in the occurrence of 16 families, 22 genera and 61 species of microbial taxa. This is the first time that a NGS platform has been used to screen the impact of jellyfish bioinvasions on the aquatic microbiome, providing a preliminary assessment of jellyfish-driven changes of the functional and structural microbial biodiversity
The influence of invasive jellyfish blooms on the aquatic microbiome in a coastal lagoon (Varano, SE Italy) detected by an Illumina-based deep sequencing strategy
Screening of Chaetomorpha linum Lipidic Extract as a New Potential Source of Bioactive Compounds
Recent studies have shown that marine algae represent a great source of natural compounds with several properties. The lipidic extract of the seaweed Chaetomorpha linum (Chlorophyta, Cladophorales), one of the dominant species in the Mar Piccolo of Taranto (Mediterranean, Ionian Sea), revealed an antibacterial activity against Vibrio ordalii and Vibrio vulnificus, common pathogens in aquaculture, suggesting its potential employment to control fish and shellfish diseases due to vibriosis and to reduce the public health hazards related to antibiotic use in aquaculture. This extract showed also an antioxidant activity, corresponding to 170.960 ± 16. mmol Trolox equivalent/g (oxygen radical absorbance capacity assay—ORAC) and to 30.554 ± 2.30 mmol Trolox equivalent/g (Trolox equivalent antioxidant capacity assay—TEAC). The chemical characterization of the extract, performed by 1D and 2D NMR spectroscopy, highlighted the presence of free, saturated (SAFAs), unsaturated (UFAs) and polyunsaturated (PUFAs) fatty acids. The high content of ω-6 and ω-3 PUFAs confirmed also by gas chromatography indicates the potentiality of this algal species in the production of fortified food. The antibacterial activity seems related to the presence of linolenic acid present at high density, while the antioxidant activity could be likely ascribable to molecules such as carotenoids and chlorophylls (characterized also by thin-layer chromatography), known for this property. The presence of polyhydroxybutyrate, a biopolymer with potentiality in the field of biodegradable bioplastics was also detected. The exploitation of C. linum for a future biotechnological application is also encouraged by the results from a first attempt of cultivating this species in an integrated multi-trophic aquaculture (IMTA) system
The Potential Exploitation of the Mediterranean Invasive Alga Caulerpa cylindracea: Can the Invasion Be Transformed into a Gain?
Recently, there is a growing interest towards the development of strategies for invasive seaweed control and exploitation as source of secondary metabolites. Here, we investigated the potential of exploitation in biotechnology and recycling options in eradication programs of the lipidic extract of the Mediterranean invasive seaweed Caulerpa cylindracea (Chlorophyta). The chemical characterization was carried out by means of multinuclear and multidimensional NMR spectroscopy. The fatty acid profile of C. cylindracea assessed the presence of several types of molecules known for antioxidant activity such as carotenoids, chlorophylls, pheophytins, and sterols. The NMR spectroscopy showed also the characteristic signals of saturated, unsaturated, and free fatty acids as well as other metabolites including the biopolymer polyhydroxybutyrate. The lipidic extract exerted an antioxidant activity corresponding to 552.14 ± 69.13 mmol Trolox equivalent/g (ORAC) and to 70.3 ± 2.67 mmol Trolox equivalent/g (TEAC). The extract showed an antibacterial activity against several Vibrio species, suggesting its potential use in the control of diseases in mariculture. Our results show that C. cylindracea, representing a critical hazard in coastal areas, could be transformed into a gain supporting specific management actions to reduce the effects of human pressures
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