Enhanced production of biobased, biodegradable, Poly(3-hydroxybutyrate) using an unexplored marine bacterium Pseudohalocynthiibacter aestuariivivens, isolated from highly polluted coastal environment.

The production and disposal of plastics from limited fossil reserves, has prompted research for greener and sustainable alternatives. Polyhydroxyalkanoates (PHAs) are biocompatible, biodegradable, and thermoprocessable polyester produced by microbes. PHAs found several applications but their use is limited due to high production cost and low yields. Herein, for the first time, the isolation and characterization of Pseudohalocynthiibacter aestuariivivens P96, a marine bacterium able to produce surprising amount of PHAs is reported. In the best growth condition P96 was able to reach a maximum production of 4.73 g/L, corresponding to the 87 % of total cell dry-weight. Using scanning and transmission microscopy, lab-scale fermentation, spectroscopic techniques, and genome analysis, the production of thermoprocessable polymer Polyhydroxybutyrate P(3HB), a PHAs class, endowed with mechanical and thermal properties comparable to that of petroleum-based plastics was confirmed. This study represents a milestone toward the use of this unexplored marine bacterium for P(3HB) production. [Abstract copyright: Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Antiviral Activity of Vitis vinifera Leaf Extract against SARS-CoV-2 and HSV-1

Vitis vinifera represents an important and renowned source of compounds with significant biological activity. Wines and winery bioproducts, such as grape pomace, skins, and seeds, are rich in bioactive compounds against a wide range of human pathogens, including bacteria, fungi, and viruses. However, little is known about the biological properties of vine leaves. The aim of this study was the evaluation of phenolic composition and antiviral activity of Vitis vinifera leaf extract against two human viruses: the Herpes simplex virus type 1 (HSV-1) and the pandemic and currently widespread severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). About 40 phenolic compounds were identified in the extract by HPLC-MS/MS analysis: most of them were quercetin derivatives, others included derivatives of luteolin, kaempferol, apigenin, isorhamnetin, myricetin, chrysoeriol, biochanin, isookanin, and scutellarein. Leaf extract was able to inhibit both HSV-1 and SARS-CoV-2 replication in the early stages of infection by directly blocking the proteins enriched on the viral surface, at a very low concentration of 10 μg/mL. These results are very promising and highlight how natural extracts could be used in the design of antiviral drugs and the development of future vaccines

Involvement of interleukin-21 in the regulation of colitis-associated colon cancer

IL-21 expression is increased in the gut of patients with colitis-associated colon cancer, and genetic ablation or antibody neutralization of IL-21 reduces tumor size and inflammation in mice treated with dextran sulfate sodium and azoxymethane

Exploring Oceans for Curative Compounds: Potential New Antimicrobial and Anti-Virulence Molecules against <i>Pseudomonas aeruginosa</i>

Although several antibiotics are already widely used against a large number of pathogens, the discovery of new antimicrobial compounds with new mechanisms of action is critical today in order to overcome the spreading of antimicrobial resistance among pathogen bacteria. In this regard, marine organisms represent a potential source of a wide diversity of unique secondary metabolites produced as an adaptation strategy to survive in competitive and hostile environments. Among the multidrug-resistant Gram-negative bacteria, Pseudomonas aeruginosa is undoubtedly one of the most important species due to its high intrinsic resistance to different classes of antibiotics on the market and its ability to cause serious therapeutic problems. In the present review, we first discuss the general mechanisms involved in the antibiotic resistance of P. aeruginosa. Subsequently, we list the marine molecules identified up until now showing activity against P. aeruginosa, dividing them according to whether they act as antimicrobial or anti-virulence compounds

Evaluation of Antimicrobial Properties and Potential Applications of <i>Pseudomonas gessardii</i> M15 Rhamnolipids towards Multiresistant <i>Staphylococcus aureus</i>

Staphylococcus aureus is a Gram-positive opportunistic human pathogen responsible for severe infections and thousands of deaths annually, mostly due to its multidrug-resistant (MDR) variants. The cell membrane has emerged as a promising new therapeutic target, and lipophilic molecules, such as biosurfactants, are currently being utilized. Herein, we evaluated the antimicrobial activity of a rhamnolipids mixture produced by the Antarctic marine bacterium Pseudomonas gessardii M15. We demonstrated that our mixture has bactericidal activity in the range of 12.5–50 µg/mL against a panel of clinical MDR isolates of S. aureus, and that the mixture eradicated the bacterial population in 30 min at MIC value, and in 5 min after doubling the concentration. We also tested abilities of RLs to interfere with biofilm at different stages and determined that RLs can penetrate biofilm and kill the bacteria at sub-MICs values. The mixture was then used to functionalize a cotton swab to evaluate the prevention of S. aureus proliferation. We showed that by using 8 µg of rhamnolipids per swab, the entire bacterial load is eradicated, and just 0.5 µg is sufficient to reduce the growth by 99.99%. Our results strongly indicate the possibility of using this mixture as an additive for wound dressings for chronic wounds

Molecular Network and Culture Media Variation Reveal a Complex Metabolic Profile in Pantoea cf. eucrina D2 Associated with an Acidified Marine Sponge

The Gram-negative Pantoea eucrina D2 was isolated from the marine sponge Chondrosia reniformis. Sponges were collected in a shallow volcanic vents system in Ischia island (South Italy), influenced by CO2 emissions and lowered pH. The chemical diversity of the secondary metabolites produced by this strain, under different culture conditions, was explored by a combined approach including molecular networking, pure compound isolation and NMR spectroscopy. The metabolome of Pantoea cf. eucrina D2 yielded a very complex molecular network, allowing the annotation of several metabolites, among them two biosurfactant clusters: lipoamino acids and surfactins. The production of each class of metabolites was highly dependent on the culture conditions, in particular, the production of unusual surfactins derivatives was reported for the first time from this genus; interestingly the production of these metabolites only arises by utilizing inorganic nitrogen as a sole nitrogen source. Major components of the extract obtained under standard medium culture conditions were isolated and identified as N-lipoamino acids by a combination of 1D and 2D NMR spectroscopy and HRESI-MS analysis. Assessment of the antimicrobial activity of the pure compounds towards some human pathogens, indicated a moderate activity of leucine containing N-lipoamino acids towards Staphylococcus aureus, Staphylococcus epidermidis and a clinical isolate of the emerging food pathogen Listeria monocytogenes

Molecular Networking combined with culture media variation reveal the metabolic potential of Pantoea eucrina isolated from a sponge living in a volcanic vents system

Ischia is an island located in the gulf of Naples (South Italy), and its environment represents a singular marine habitat because of the volcanic origin of the island. Here, the presence of underwater CO2 emissions, caused by the effect of secondary volcanism, creates a unique area of naturally lowered pH. Different sponges were collected in this acidified area and subjected to microbial isolation. Among the isolates, the Gram-negative strain Pantoea eucrina, isolated from the sponge Chondrosia reniformis, was selected for further studies. Its metabolome was explored by a combined approach involving culture media variation and Molecular Networking. This approach yielded a very complex molecular network, allowing the annotation of several metabolites, among them two biosurfactants clusters: lipoamino acids and surfactins. Noteworthy is the production of unusual new surfactin derivatives, which is reported here for the first time from Pantoea genus. Their production was only triggered by using inorganic nitrogen as sole nitrogen source, while it was totally abolished in the other conditions. Major metabolites belonging to N-lipoamino acids were characterized through HRMS/MS, 1D and 2D NMR spectroscopy, some of them were identified for the first time as natural products. Antimicrobial activity assessment of pure metabolites towards a panel of human pathogens indicated a relevant activity; in particular, the leucine containing N-lipoamino acids revealed to be very effective towards Staphylococcus aureus, Staphylococcus epidermidis and a clinical isolate of the emerging food pathogen Listeria monocytogenes

Novel Insights on Pyoverdine: From Biosynthesis to Biotechnological Application

Pyoverdines (PVDs) are a class of siderophores produced mostly by members of the genus Pseudomonas. Their primary function is to accumulate, mobilize, and transport iron necessary for cell metabolism. Moreover, PVDs also play a crucial role in microbes&rsquo; survival by mediating biofilm formation and virulence. In this review, we reorganize the information produced in recent years regarding PVDs biosynthesis and pathogenic mechanisms, since PVDs are extremely valuable compounds. Additionally, we summarize the therapeutic applications deriving from the PVDs&rsquo; use and focus on their role as therapeutic target themselves. We assess the current biotechnological applications of different sectors and evaluate the state-of-the-art technology relating to the use of synthetic biology tools for pathway engineering. Finally, we review the most recent methods and techniques capable of identifying such molecules in complex matrices for drug-discovery purposes