New Insights into the Culture Method and Antibacterial Potential of Gracilaria gracilis.

Enormous marine biodiversity offers an endless reservoir of chemicals for many applications. In this scenario, the extraction of seaweeds represents an interesting source of compounds displaying antimicrobial activity. In particular, among the different red algae, Gracilaria gracilis plays an important role due to the presence of important bioactives in its composition. In spite of these features, an efficient culture system is still absent. In the present study, a novel algal culture method was developed and compared to another more common cultural practice, widely reported in literature. A higher efficiency of the new method, both for daily growth rate and biomass, was assessed. Furthermore, the growth inhibitory activity of five extracts, obtained using ethanol, methanol, acetone, chloroform or diethyl ether as a solvent, from the cultured G. gracilis was tested against Gram-positive and Gram-negative pathogens. Algal extracts exhibited a considerable inhibitory activity against B. subtilis strains, while a slight inhibition was observed against V. fischeri. The different extracts showed significant differences in bacterial growth inhibition, with the highest activity that was recorded for the ethanol extract, followed by that of methanol. Based on the chemical characterization, these findings could be related to the antimicrobial activity played by the combination of total carbohydrates and polyphenols, which were determined at high levels in ethanol and methanol extracts, as well as by the highest number and levels of single polyphenols. Conversely, the lower growth inhibitory activities found in chloroform and diethyl ether extracts could be related to the isolation of minor lipid classes (e.g., neutral and medium polar lipids) composed by fatty acids, such as stearic, oleic and arachidonic acids, typically characterized by antimicrobial activity. In consideration of the results obtained, the present study has a double implication, involving both the field of cultural practices and the exploitation of natural sources for the isolation of antimicrobial agents useful both in pharmaceutical and food applications.

Assessment of Electrolytes and Metals Profile of the Faro Lake (Capo Peloro Lagoon, Sicily, Italy) and Its Impact on Mytilus galloprovincialis.

Faro Lake is a coastal meromictic lagoon with singular characteristics in the Mediterranean (Messina, Sicily - Italy). It is part of the Natural Oriented Reserve of Capo Peloro (38° 15' 57″ N; 15° 37' 50″ E). In this area, traditional mollusc farming activity persists, producing 'autochthonous' mussels. This study reports of the Mytilus galloprovincialis haemolymph chemical profile and water variables determination of 1 year-lasted survey (April 2016 - March 2017). The determinations of electrolytes (Na+ , Cl- , K+ , Ca2+ , Mg2+ , P inorganic) and heavy metals in both Faro lake water and haemolymph have been carried out. Heavy metals are elements with high density and are quite toxic in low concentrations, such as Aluminum (Al), Arsenic (As), Cobalt (Co), Chrome (Cr), Copper (Cu), Iron (Fe), Magnesium (Mg), Manganese (Mn), Lead (Pb), Tin (Sn), Zinc (Zn). Heavy metals toxicity depends, principally, on bioaccumulation processes. M. galloprovincialis is a good bio-indicator, ideal for assess levels of environmental pollution thanks to its biological, ecological and physiological characteristics. The results of this study showed a typical fluctuation range in haemolymph and water parameters, related to the water ones; chemical-physical parameters affected the ions (electrolytes and metals) levels in some period of the year. The study reports the interactions between biotic (Mytilus galloprovincialis) and abiotic (water parameters) components of Faro Lake, and creates reference data for further future study on the same area or on similar ones.

Evaluation of Functionality and Biological Responses of Mytilus galloprovincialis after Exposure to Quaternium-15 (Methenamine 3-Chloroallylochloride).

Although the irritant effects of quaternium-15 have been established, little is known about the toxicological consequences induced by this xenobiotic on aquatic invertebrates. The present article reports toxicological, histological and physiological effects of quaternium-15 following the exposure of Mytilus galloprovincialis for 18 days at three different concentrations (0.1, 1.0 and 2.0 mg/L). The results demonstrate that at higher concentrations histological damages to M. galloprovincialis gills occur, like melanosis, light exfoliations, increase of mucus production and infiltrative inflammation. In addition digestive gland cells of M. galloprovincialis, were not able to perform the regulation volume decrease (RVD) owing to osmotic stress following the exposure to the preservative. Overall, this first study on quaternium-15 highlights that it can jeopardize both the morphology and vital physiological processes in marine invertebrates, depending on the duration of exposure and the concentration of the preservative, indicating that further studies are necessary to increase our knowledge about the effects of this substance, commonly added to our products of daily use.

Shallow-Water Hydrothermal Vents as Natural Accelerators of Bacterial Antibiotic Resistance in Marine Coastal Areas.

Environmental contamination by heavy metals (HMs) poses several indirect risks to human health, including the co-spreading of genetic traits conferring resistance to both HMs and antibiotics among micro-organisms. Microbial antibiotic resistance (AR) acquisition is enhanced at sites anthropogenically polluted by HMs, as well as in remote systems naturally enriched in HMs, such as hydrothermal vents in the deep sea. However, to date, the possible role of hydrothermal vents at shallower water depths as hot spots of microbial AR gain and spreading has not been tested, despite the higher potential risks associated with the closer vicinity of such ecosystems to coasts and human activities. In this work, we collected waters and sediments at the Panarea shallow-water hydrothermal vents, testing the presence of culturable marine bacteria and their sensitivity to antibiotics and HMs. All of the bacterial isolates showed resistance to at least one antibiotic and one HM and, most notably, 80% of them displayed multi-AR on average to 12 (min 8, max 15) different antibiotics, as well as multi-HM tolerance. We show that our isolates displayed high similarity (≥99%) to common marine bacteria, affiliating with Actinobacteria, Gammaproteobacteria, Alphaproteobacteria and Firmicutes, and all displayed wide growth ranges for temperature and salinity during in vitro physiological tests. Notably, the analysis of the genomes available in public databases for their closest relatives highlighted the lack of genes for AR, posing new questions on the origin of multi-AR acquisition in this peculiar HM-rich environment. Overall, our results point out that shallow-water hydrothermal vents may contribute to enhance AR acquisition and spreading among common marine bacteria in coastal areas, highlighting this as a focus for future research.

Response of vanadium bioaccumulation in tissues of Mugil cephalus (Linnaeus 1758).

Vanadium accumulation levels in different tissues (muscle and organs) of the striped mullet Mugil cephalus (Linnaeus, 1758) and possible relationships with blood parameters were evaluated in a Natural Protected Area (Lake Faro, Sicily, Italy), during the winter of 2017. Hematological parameters (red blood cell, RBC; white blood cell, WBC; hemoglobin concentration, Hb; hematocrit, Hct; mean corpuscular volume, MCV; mean corpuscular hemoglobin, MCH; mean corpuscular hemoglobin concentration, MCHC; thrombocytes, TC), biometric indices (weight, total and fork length), and vanadium levels in muscles and organs (gills, liver, stomach and intestine) were determined. Statistical analyses showed significant differences in concentrations of vanadium of the analyzed tissue of M. cephalus and a positive relationship between vanadium concentration in the liver and some hematological parameters (RBC, Hb and Hct) and biometric indices. Our results underline the importance of fish blood parameters as sensitive indicators of toxic impact of environmental factors such as metals. This study, focusing on an ongoing topic, represents a valuable contribution to research concerning the monitoring and prevention of vanadium pollution in aquatic organisms and environments.

Plastics occurrence in the gastrointestinal tract of Zeus faber and Lepidopus caudatus from the Tyrrhenian Sea.

The present study investigates the occurrence of plastic pollution in two commercially important marine teleosts (Zeus faber and Lepidopus caudatus) from the northern coasts of Sicily (Tyrrhenian Sea). Plastics occurrence in the gastrointestinal tract was higher in Lepidopus caudatus (78.1%) than Zeus faber (51.4%). Debris characterization, carried out by micro-Raman spectroscopy, allowed identified the main types of found polymers as: polypropylene (PP), polyamide (PA), nylon and, to a lesser extent, polyethylene (PE). Of the two fish species studied, the silver scabbardfish appeared to be the more vulnerable to plastic ingestion. Our study represents a starting point that may pave the way for future investigation of the fate, accumulation and transfer of plastic debris to upper trophic levels, to verify their potential toxicity and to better understand strategies to mitigate this phenomenon.

Effect of sodium dodecyl sulfate (SDS) on stress response in the Mediterranean mussel (Mytilus Galloprovincialis): regulatory volume decrease (Rvd) and modulation of biochemical markers related to oxidative stress.

In this study the effects of an anionic surfactant, sodium dodecyl sulfate (SDS), are assessed on the Mediterranean mussel (Mytilus galloprovincialis), exposed for 18 days at a concentration ranging from 0.1 mg/l to 1 mg/l. The effects are monitored using biomarkers related to stress response, such as regulatory volume decrease (RVD), and to oxidative stress, such as reactive oxygen species (ROS), endogenous antioxidant systems and Hsp70 levels. The results demonstrate that cells from the digestive gland of M. galloprovincialis, exposed to SDS were not able to perform the RVD owing to osmotic stress. Further, SDS causes oxidative stress in treated organisms, as demonstrated by the increased ROS production, in comparison to the controls (p<0.05). Consequently, two enzymes involved in ROS scavenging, superoxide dismutase (SOD) and catalase (CAT) have higher activities and the proportion of oxidized glutathione (GSSG) is higher in hepatopancreas and mantle of treated animals, compared to untreated animals (p<0.05). Furthermore Hsp70 demonstrates an up-regulation in all the analyzed tissues of exposed animals, attesting the stress status induced by the surfactant with respect to the unexposed animals. The results highlight that SDS, under the tested concentrations, exerts a toxic effect in mussels in which the disruption of the osmotic balance follows the induction of oxidative stress.

Evaluation of Water Variables in No-Take Zone of Ustica Marine Protected Area (Southern Tyrrhenian Sea)

ABSTRACT In this research, the seasonal fluctuations of the main water variables in the no-take area (A zone) of the Ustica MPA were investigated. This study aims to monitor the water quality of the Ustica MPA, to analyze all the hydrological parameters useful to the physical-chemical characterization of water and to use TRIX index to characterize the trophic level of the coastal marine area. The final results shown that Ustica is an area of relevant environmental and ecological value and is a good example of a Marine Protected Area, which is not excessively affected by the human presence even during the touristic season. This study represents the first records based on well-organized protocol in order to assess water column characteristics of the studied area. This paper could be used as a reference document for future studies regarding the same or similar areas.