Germplasm banking of temperate kelp species will be an important tool for temperate macroalgae aquaculture to establish resiliency, and scaling, and as a conservation tool for maintaining genetic diversity in wild populations struggling under pressures stemming from global climate change. Gametophyte culture has been practiced in other kelp production regions, principally for Saccharina japonica, and has allowed for a fully closed lifecycle and the advent of selective breeding programs that have greatly improved product quality and yields. Long term maintenance and scaling of gametophyte cultures for Saccharina latissima hold similar promise, however their applications to at-scale production of seed and selectively bred lines are only just beginning. There are many challenges to overcome in order to operationalize commercial scale gametophyte-based nurseries and seed production.
The Aquaculture Research Institute at the University of Maine has established SMART: the Sustainable Macroalgae Aquaculture Research and Technology program, with the goal of optimizing techniques for gametophyte-based nurseries and germplasm banking. Early challenges have highlighted the need to understand the dynamics of contaminants within GP cultures, specifically those relating to the microbiome of the cultures, and the results and consequences of corrective interventions. Little is known about the microbiome of gametophytes in culture conditions, how these communities shift over time, and how communities shift following perturbations.
Here, we present an initial microbiome challenge experiment utilizing a mixed female S. latissima gametophyte culture (a blend of six clonal cultures) exposed to varying levels of the antibiotic kanamycin. Kanamycin is aminoglycoside bacteriocidal antibiotic commonly used in research and human medicine to treat severe bacterial infections. Replicate 1g cultures were distributed across three treatments; High Kanamycin (10ml/l), Low Kanamycin (5ml/l) from a 1g/100ml stock solution, and Control, with 5 replicates each. Prior to treatment, replicates were sampled (both water and tissue) for microbiome characterization via Amplicon sequencing 16s rRNA, as well as water samples for metabolomic analysis. Treatments were resampled at 1 week, post treatment representing cessation of treatment, and 2, 4, and 6 weeks after the conclusion of treatment. Initial insights on microbiome and metabolomic response are discussed.