Project description:Seaweed aquaculture is an expanding industry with innovative applications beyond the traditional uses as human foods and phycocolloids. Asparagopsis armata, a red seaweed, is cultivated as a feed supplement to reduce methane emission from ruminants. The manipulation of microbiota with seaweed beneficial microorganisms (SBMs) has shown promise in enhancing disease resistance and growth in seaweeds and has potential to aid the cultivation of A. armata. In this study, we developed a growth assay for the rapid selection of bacteria that promote the growth of A. armata tetrasporophytes. We tested bacterial strains from the genera Phaeobacter and Pseudoalteromonas for their impact on the growth of A. armata, as these bacteria have been recognized for their beneficial traits in other seaweeds. All strains significantly enhanced the specific growth rate (SGR) of A. armata tetrasporophytes compared to controls without bacterial treatment. Bacterial 16S rRNA gene amplicon sequencing confirmed the presence of the inoculated growth-promoting SBMs (SBM-Gs) in A. armata cultures with no significant impacts on the resident microbial community. Co-occurrence network analysis of the resulting communities demonstrated that the inoculated Phaeobacter spp. formed distinct modules, exclusively interacting with resident Phaeobacter species, while the Pseudoalteromonas sp. was absent from the network. These results demonstrate that microbial inoculation is an effective strategy for incorporating SBM-Gs into the A. armata microbiota to promote growth. The tested SBM-Gs may exert their influence by interacting with specific resident species or by directly affecting host physiology, resulting in minimal undesired effects on the microbiome.
Project description:Macroalgae-associated bacteria have already proved to be an interesting source of compounds with therapeutic potential. Accordingly, the main aim of this study was to characterize Asparagopsis armata-associated bacteria community and evaluate their capacity to produce substances with antitumor and antimicrobial potential. Bacteria were selected according to their phenotype and isolated by the streak plate technique. The identification was carried out by the RNA ribosomal 16s gene amplification through PCR techniques. The antimicrobial activities were evaluated against seven microorganisms (Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae, Candida albicans) by following their growth through spectrophotometric readings. Antitumor activities were evaluated in vitro on human cell lines derived from hepatocellular (HepG-2) and breast carcinoma (MCF-7) using the MTT method. The present work identified a total of 21 bacteria belonging to the genus Vibrio, Staphylococcus, Shewanella, Alteromonadaceae, Bacillus, Cobetia, and Photobacterium, with Vibrio being the most abundant (42.86%). The extract of Shewanella sp. ASP 26 bacterial strain induced the highest antimicrobial activity, namely against Bacillus subtilis and Staphylococcus aureus with an IC50 of 151.1 and 346.8 μg/mL, respectively. These bacteria (Shewanella sp.) were also the ones with highest antitumor potential, demonstrating antiproliferative activity on HepG-2 cells. Asparagopsis armata-associated bacteria revealed to be a potential source of compounds with antitumor and antibacterial activity.