Kelp microbiomes benefits to the test: bacterial isolation, characterization, and an application test to increase kelp stress resilience under global change conditions.

Isolation of target microorganisms and subsequently inoculation experiments are potential techniques to enhance kelp performance and/or confer resistance or resilience to future environmental conditions. The study aims to evaluate if isolated bacteria can contribute to the kelp health and resistance to increased temperatures of juvenile Laminaria ochroleuca sporophytes from two contrasting habitats. A total of 65 bacterial isolates were identified from Laminaria ochroleuca sporophytes and gametophytes. A bacterial consortium was composed by ten selected bacterial including: two Halomonas., Maribacter, Sulfitobacter and Paraglaciecola, and one Zobelia, and one Colwellia sp. The kelp sporophytes from Morocco and Italy were exposed to a temperature treatment with and without bacterial consortium inoculation. The physiological response was assessed by determining the host’s growth and photosynthetic performance. The findings suggest there is a population-specific response regarding sporophytes growth in presence of bacterial consortium after nine days. However, at the end of the experiment, the results suggest that bacteria negatively affect the sporophyte growth in both populations independently of the temperature.