Epimicrobiome Shifts With Bleaching Disease Progression in the Brown Seaweed Saccharina japonica

Abstract

Recent bacterial induced bleaching disease events of the commercially farmed brown seaweed Saccharina japonica has resulted in significant reduction in healthy sporeling supply. However, to date the host associated epimicrobial community shifts with the disease progression have not been characterized. We investigated the dynamic shifts in the composition of the epibacterial communities of S. japonica with disease progression using 16S rRNA gene amplicon sequencing. We found that the alpha diversity was significantly higher in the control group than in the infected group over disease progression (P < 0.01). There was a significant shift in the composition and predicted functions of the epibacterial communities in both control and infected groups. Indicator species, belonging to Stenotrophomonas, Pseudomonas and Sphingomona were significantly higher in the control group than infected group, suggesting that these taxa are associated with healthy S. japonica. In contrast, Vibrio, Pseudoalteromonas and Colwellia were keystone taxa in the infected group at 24 h, and thus maybe considered to be the secondary opportunistic pathogens. Our study describes the changes of epibacterial communities associated with the progression of bleaching disease in S. japonica. This new information not only extends our baseline knowledge of the S. japonica epimicrobiome, but also paves the way for developing measures to mitigate disease outbreaks for the sustainable aquaculture of S. japonica.

Divergence of epibacterial community assemblage correlates with malformation disease severity in Saccharina japonica seedlings

“…In such a context, lower modularization for the severe MD networks may indicate a relatively wide range of niche preferences for the colonized bacteria, thus reflecting disruptions of the epiphytic bacterial communities and increased complexity from the perspective of species-species interactions. Similar cases have also been reported for both shrimp and kelp diseases (Dai et al, 2020;Ling et al, 2022). In particular, the diseased shrimp also harbored a more highly connected and more complex bacterial network of gut microbiota (Dai et al, 2020).…”

Kelp breeding in China: Challenges and opportunities for solutions

“…Additionally, recurrent breeding likely leads to compositional changes in kelp‐associated microbes. It is thus pivotal to explore how beneficial bacterial genera (e.g., Halomonas , Stenotrophomonas , 110 ) interact with sporophytes, including shifts in species richness, evenness, and community composition between different farming stages and ranges. In particular, the identification of a beneficial microbiome and how to select for it are indispensable to stimulate germination and influence stress resistance and fitness by interacting with kelp traits (e.g., flavour‐enhancement and nutrient‐enrichment).…”

“…For kelps, wild populations in the native range evolved over time by selectively assembling a S. japonica ‐beneficial microbe from surrounding waters as their partners 108 . However, after S. japonica was introduced to China, this association likely had been altered through several decades of domestication and adaptation to local environments 28,109,110 . The new kelp holobiont may have been established in China's farming ecosystem.…”

Adverse Environmental Perturbations May Threaten Kelp Farming Sustainability by Exacerbating Enterobacterales Diseases

“…7 Consequently, the indirect effects of environmental stressors are often reflected in altered physiological responses and reduced resilience of kelp, rendering them more susceptible to microbial pathogens. 8,9 In fact, environmental stress-mediated alterations to species interactions can have more profound and harmful consequences than the initial stressors themselves. 10 Unfortunately, most studies have traditionally focused solely on the direct effects of environmental changes on individual species, largely overlooking the potential adverse consequences arising from indirect effects.…”

“…While some research indicates certain kelp species can recover from short-term environmental stresses, these perturbations have ramifications beyond their immediate impacts, yielding profound and cascading effects on the cross-species interactions between kelp and its associated microbiota. − The symbiotic relationship between kelp and its microbiome plays a critical role in nutrient cycling, disease resistance, coevolution, and other fundamental processes that contribute to the overall health and resilience of the kelp population . Consequently, the indirect effects of environmental stressors are often reflected in altered physiological responses and reduced resilience of kelp, rendering them more susceptible to microbial pathogens. , In fact, environmental stress-mediated alterations to species interactions can have more profound and harmful consequences than the initial stressors themselves . Unfortunately, most studies have traditionally focused solely on the direct effects of environmental changes on individual species, largely overlooking the potential adverse consequences arising from indirect effects.…”