Diversity and Antimicrobial Activity of Vietnamese Sponge-Associated Bacteria

This study aimed to assess the diversity and antimicrobial activity of cultivable bacteria associated with Vietnamese sponges. In total, 460 bacterial isolates were obtained from 18 marine sponges. Of these, 58.3% belonged to Proteobacteria, 16.5% to Actinobacteria, 18.0% to Firmicutes, and 7.2% to Bacteroidetes. At the genus level, isolated strains belonged to 55 genera, of which several genera, such as Bacillus, Pseudovibrio, Ruegeria, Vibrio, and Streptomyces, were the most predominant. Culture media influenced the cultivable bacterial composition, whereas, from different sponge species, similar cultivable bacteria were recovered. Interestingly, there was little overlap of bacterial composition associated with sponges when the taxa isolated were compared to cultivation-independent data. Subsequent antimicrobial assays showed that 90 isolated strains exhibited antimicrobial activity against at least one of seven indicator microorganisms. From the culture broth of the isolated strain with the strongest activity (Bacillus sp. M1_CRV_171), four secondary metabolites were isolated and identified, including cyclo(L-Pro-L-Tyr) (1), macrolactin A (2), macrolactin H (3), and 15,17-epoxy-16-hydroxy macrolactin A (4). Of these, compounds 2-4 exhibited antimicrobial activity against a broad spectrum of reference microorganisms.

Marine Natural Products: Promising Candidates in the Modulation of Gut-Brain Axis towards Neuroprotection

In recent decades, several neuroprotective agents have been provided in combating neuronal dysfunctions; however, no effective treatment has been found towards the complete eradication of neurodegenerative diseases. From the pathophysiological point of view, growing studies are indicating a bidirectional relationship between gut and brain termed gut-brain axis in the context of health/disease. Revealing the gut-brain axis has survived new hopes in the prevention, management, and treatment of neurodegenerative diseases. Accordingly, introducing novel alternative therapies in regulating the gut-brain axis seems to be an emerging concept to pave the road in fighting neurodegenerative diseases. Growing studies have developed marine-derived natural products as hopeful candidates in a simultaneous targeting of gut-brain dysregulated mediators towards neuroprotection. Of marine natural products, carotenoids (e.g., fucoxanthin, and astaxanthin), phytosterols (e.g., fucosterol), polysaccharides (e.g., fucoidan, chitosan, alginate, and laminarin), macrolactins (e.g., macrolactin A), diterpenes (e.g., lobocrasol, excavatolide B, and crassumol E) and sesquiterpenes (e.g., zonarol) have shown to be promising candidates in modulating gut-brain axis. The aforementioned marine natural products are potential regulators of inflammatory, apoptotic, and oxidative stress mediators towards a bidirectional regulation of the gut-brain axis. The present study aims at describing the gut-brain axis, the importance of gut microbiota in neurological diseases, as well as the modulatory role of marine natural products towards neuroprotection.

Nature Potential for COVID-19: Targeting SARS-CoV-2 Mpro Inhibitor with Bioactive Compound

<p>Corona viruses were first identified in 1931 and SARS-CoV-2 is the most recent. COVID-19 is a pandemic that put most of the world on lockdown and the search for therapeutic drugs is still on-going. Therefore, this study uses <i>in silico</i> screening to identify natural bioactive compounds from fruits, herbaceous plants and marine invertebrates that are able to inhibit protease activity in SARS-CoV-2(PDB: 6LU7). We have used various screening strategies such as drug likeliness, antiviral activity value prediction, molecular docking, ADME (absorption, distribution, metabolism, and excretion), molecular dynamics (MD) simulation and MM/GBSA (molecular mechanics/generalized born and surface area continuum solvation). 17 compounds were shortlisted using Lipinski’s rule. 5 compounds revealed significantly good predicted antiviral activity values and out of them only 2 compounds, Macrolactin A and Stachyflin, showed good binding energy values of -9.22 and -8.00 kcal/mol within the binding pocket, catalytic residues (HIS 41 and CYS 145) of M^pro. These two compounds were further analyzed for their ADME properties. The ADME evaluation of these 2 compounds suggested that they could be effective as therapeutic agents for developing drugs for clinical trials. MD simulations showed that protein-ligand complexes of Macrolactin A and Stachyflin were stable for 100 nano seconds. The MM/GBSA calculations of M^pro – Macrolactin A complex indicated higher binding free energy (-42.58 ± 6.35 kcal/mol) with M^proprotein target receptor (6LU7). DCCM and PCA analysis on the residual movement in the MD trajectories confirmed the good stability on Macrolactin A bound state of 6LU7. This signify the stable conformation of 6LU7 with high binding energy with Macrolactin A. Thus, this study showed that Macrolactin A could be an effective therapeutical agent for SARS-CoV-2protease (6LU7) inhibition. Additional <i>in vitro </i>and<i> in vivo </i>validations are needed to determine efficacy and dose of Macrolactin A in biological systems.</p>

Nature Potential for COVID-19: Targeting SARS-CoV-2 Mpro Inhibitor with Bioactive Compound

<p>Corona viruses were first identified in 1931 and SARS-CoV-2 is the most recent. COVID-19 is a pandemic that put most of the world on lockdown and the search for therapeutic drugs is still on-going. Therefore, this study uses <i>in silico</i> screening to identify natural bioactive compounds from fruits, herbaceous plants and marine invertebrates that are able to inhibit protease activity in SARS-CoV-2(PDB: 6LU7). We have used various screening strategies such as drug likeliness, antiviral activity value prediction, molecular docking, ADME (absorption, distribution, metabolism, and excretion), molecular dynamics (MD) simulation and MM/GBSA (molecular mechanics/generalized born and surface area continuum solvation). 17 compounds were shortlisted using Lipinski’s rule. 5 compounds revealed significantly good predicted antiviral activity values and out of them only 2 compounds, Macrolactin A and Stachyflin, showed good binding energy values of -9.22 and -8.00 kcal/mol within the binding pocket, catalytic residues (HIS 41 and CYS 145) of M^pro. These two compounds were further analyzed for their ADME properties. The ADME evaluation of these 2 compounds suggested that they could be effective as therapeutic agents for developing drugs for clinical trials. MD simulations showed that protein-ligand complexes of Macrolactin A and Stachyflin were stable for 100 nano seconds. The MM/GBSA calculations of M^pro – Macrolactin A complex indicated higher binding free energy (-42.58 ± 6.35 kcal/mol) with M^proprotein target receptor (6LU7). DCCM and PCA analysis on the residual movement in the MD trajectories confirmed the good stability on Macrolactin A bound state of 6LU7. This signify the stable conformation of 6LU7 with high binding energy with Macrolactin A. Thus, this study showed that Macrolactin A could be an effective therapeutical agent for SARS-CoV-2protease (6LU7) inhibition. Additional <i>in vitro </i>and<i> in vivo </i>validations are needed to determine efficacy and dose of Macrolactin A in biological systems.</p>

Nature Potential for COVID-19: Targeting SARS-CoV-2 Mpro Inhibitor with Bioactive Compound

<p>Corona viruses were first identified in 1931 and SARS-CoV-2 is the most recent. COVID-19 is a pandemic that put most of the world on lockdown and the search for therapeutic drugs is still on-going. Therefore, this study uses <i>in silico</i> screening to identify natural bioactive compounds from fruits, herbaceous plants and marine invertebrates that are able to inhibit protease activity in SARS-CoV-2(PDB: 6LU7). We have used various screening strategies such as drug likeliness, antiviral activity value prediction, molecular docking, ADME (absorption, distribution, metabolism, and excretion), molecular dynamics (MD) simulation and MM/GBSA (molecular mechanics/generalized born and surface area continuum solvation). 17 compounds were shortlisted using Lipinski’s rule. 5 compounds revealed significantly good predicted antiviral activity values and out of them only 2 compounds, Macrolactin A and Stachyflin, showed good binding energy values of -9.22 and -8.00 kcal/mol within the binding pocket, catalytic residues (HIS 41 and CYS 145) of M^pro. These two compounds were further analyzed for their ADME properties. The ADME evaluation of these 2 compounds suggested that they could be effective as therapeutic agents for developing drugs for clinical trials. MD simulations showed that protein-ligand complexes of Macrolactin A and Stachyflin were stable for 100 nano seconds. The MM/GBSA calculations of M^pro – Macrolactin A complex indicated higher binding free energy (-42.58 ± 6.35 kcal/mol) with M^proprotein target receptor (6LU7). DCCM and PCA analysis on the residual movement in the MD trajectories confirmed the good stability on Macrolactin A bound state of 6LU7. This signify the stable conformation of 6LU7 with high binding energy with Macrolactin A. Thus, this study showed that Macrolactin A could be an effective therapeutical agent for SARS-CoV-2protease (6LU7) inhibition. Additional <i>in vitro </i>and<i> in vivo </i>validations are needed to determine efficacy and dose of Macrolactin A in biological systems.</p>

Random compound mutagenesis breeding of Bacillus amyloliquefaciens X030 with high resistance to pathogenic bacteria on grass carp

Background: Bacillus amyloliquefaciens X030 (BaX030) was obtained by screening from peanut fields in Henan Province, China. It had broad-spectrum antibacterial activity against fish pathogens Aeromonas hydrophila and Aeromonas veronii. In order to improve its antibacterial effect, BaX030 was carried out the compound mutagenesis that atmospheric and room temperature plasma (ARTP) combined with nitrosoguanidine (NTG). Results: The result showed the yield of macrolactin A and oxydifficidin of the mutant N-11 were increased by 2.01 times and 3.68 times, respectively. Re-sequencing found that the corresponding 9th and 15th gene clusters had 4 and 6 SNP mutations, respectively, the 15th gene cluster also had 7 InDel mutations. Scanning electron microscopy observed that the N-11 became thin and long. The results of qRT-PCR indicated that feeding the N-11 can increase the expression of immune factors in the liver or kidney tissue of grass carp. It can also significantly reduce the mortality and the surface symptoms of grass carp that was infected by two pathogens through HE staining and protection experiments.Conclusion: This is the first report that after ARTP-NTG compound mutagenesis, a high-yielding strain of macrolactin A and oxydifficidin were increased by 2.01 times and 3.68 times compared with the original strain, respectively, which laid the foundation for elucidating its biological regulation, they had antibacterial effects on Aeromonas hydrophila and Aeromonas veronii. We combined re-sequencing to find the mutation sites of gene clusters and. The probiotic strain N-11 can quickly activate the immune protection mechanism of grass carp to resist pathogenic bacteria.

Selection of sponge-associated bacteria with high potential for the production of antibacterial compounds

The potential of sponge-associated bacteria for the biosynthesis of natural products with antibacterial activity was evaluated. In a preliminary screening 108 of 835 axenic isolates showed antibacterial activity. Active isolates were identified by 16S rRNA gene sequencing and selection of the most promising strains was done in a championship like approach, which can be done in every lab and field station without expensive equipment. In a competition assay, strains that inhibited most of the other strains were selected. In a second round, the strongest competitors from each host sponge competed against each other. To rule out that the best competitors selected in that way represent similar strains with the same metabolic profile, BOX PCR experiments were performed, and extracts of these strains were analysed using metabolic fingerprinting. This proved that the strains are different and have various metabolic profiles, even though belonging to the same genus, i.e. Bacillus. Furthermore, it was shown that co-culture experiments triggered the production of compounds with antibiotic activity, i.e. surfactins and macrolactin A. Since many members of the genus Bacillus possess the genetic equipment for the biosynthesis of these compounds, a potential synergism was analysed, showing synergistic effects between C14-surfactin and macrolactin A against methicillin-resistant Staphylococcus aureus (MRSA).