Identification of Sponge-Associated Bacteria From the Coast of Kuwait and Their Potential Biotechnological Applications

Distinct microbial communities in an ascidian-crustacean symbiosis

Ascidians are marine invertebrates known to occasionally host symbiotic crustaceans. Although the microbiomes of both ascidians and free-living crustaceans have been characterized, there is no documentation of microbial communities in an ascidian-crustacean symbiosis. Samples of the solitary ascidian Ascidia sydneiensis and ambient seawater were collected in Belize. Four symbiotic amphipod crustaceans were retrieved from the branchial sac of the animal, and their microbiomes were compared with those from their ascidian host (tunic and branchial sac compartments) and seawater. Microbiome richness and diversity differed significantly between sample types, with amphipod microbiomes exhibiting significantly lower diversity than tunic and ambient seawater samples. Microbiome composition also differed significantly between sample types and among all pairwise comparisons, except for branchial sac and amphipod microbiomes. Differential operational taxonomic unit (OTU) analyses revealed that only 3 out of 2553 OTUs had significantly different relative abundances in amphipods compared with ascidian branchial sacs, whereas 72 OTUs differed between amphipod and tunic and 315 between amphipod and seawater samples. Thus, different body compartments of A. sydneiensis hosted distinct microbiomes, and symbiotic amphipods contained microbiomes resembling the region they inhabit (i.e., the branchial sac), suggesting that environmental filtering and co-evolutionary processes are determinants of microbiome composition within ascidian-crustacean symbioses.

New Imidazolium Alkaloids with Broad Spectrum of Action from the Marine Bacterium Shewanella aquimarina

The continuous outbreak of drug-resistant bacterial and viral infections imposes the need to search for new drug candidates. Natural products from marine bacteria still inspire the design of pharmaceuticals. Indeed, marine bacteria have unique metabolic flexibility to inhabit each ecological niche, thus expanding their biosynthetic ability to assemble unprecedented molecules. The One-Strain-Many-Compounds approach and tandem mass spectrometry allowed the discovery of a Shewanella aquimarina strain as a source of novel imidazolium alkaloids via molecular networking. The alkaloid mixture was shown to exert bioactivities such as: (a) antibacterial activity against antibiotic-resistant Staphylococcus aureus clinical isolates at 100 µg/mL, (b) synergistic effects with tigecycline and linezolid, (c) restoration of MRSA sensitivity to fosfomycin, and (d) interference with the biofilm formation of S. aureus 6538 and MRSA. Moreover, the mixture showed antiviral activity against viruses with and without envelopes. Indeed, it inhibited the entry of coronavirus HcoV-229E and herpes simplex viruses into human cells and inactivated poliovirus PV-1 in post-infection assay at 200 µg/mL. Finally, at the same concentration, the fraction showed anthelminthic activity against Caenorhabditis elegans, causing 99% mortality after 48 h. The broad-spectrum activities of these compounds are partially due to their biosurfactant behavior and make them promising candidates for breaking down drug-resistant infectious diseases.

Exploring bioactive compounds from a symbiotic bacterial strain of Spongiobacter sp

Marine sponges are a host of different symbiotic groups of bacteria playing crucial roles in the protection and survival of marine sponges. Marine symbiotic bacteria from sponges are promising sources of bioactive chemicals and are increasingly being investigated. Therefore, the present study was undertaken to analyze total compounds from active symbiotic bacterial strain from sponge, Pione vastifical. Potential bacterial strain EA276 previously isolated from P. vastifical and was identified as Spongiobacter sp. Among 57 isolates, only 42% exhibited antagonistic activity. Four major classes of bacteria were reported previously where γ-Proteobacteria, was the dominant class. From these active antagonistic bacterial isolates, a potential bacterial strain Spongiobacter sp. EA276 was selected, and total metabolites were identified using GC and LC-MS analyses. Using LC-MS analysis bioactive compounds Dichlorphenamide, Amifloxacin and Carbenicillin are identified in both positive and negative mode. Plant growth hormones, Indole-3-acetic acid and Methyl jasmonate were identified using GC-MS analysis from culture extract of strain Spongiobacter sp. EA276. Our results highlighted the significance of marine flora inhabiting sponges from the Red Sea as potential source of bioactive compounds and plant growth hormones of biological and agricultural significance.