Microbial community composition and metabolic potential during a succession of algal blooms from Skeletonema sp. to Phaeocystis sp.

Abstract

Elucidating the interactions between algal and microbial communities is essential for understanding the dynamic mechanisms regulating algal blooms in the marine environment. Shifts in bacterial communities when a single species dominates algal blooms have been extensively investigated. However, bacterioplankton community dynamics during bloom succession when one algal species shift to another is still poorly understood. In this study, we used metagenomic analysis to investigate the bacterial community composition and function during algal bloom succession from Skeletonema sp. to Phaeocystis sp. The results revealed that bacterial community structure and function shifted with bloom succession. The dominant group in the Skeletonema bloom was Alphaproteobacteria, while Bacteroidia and Gammaproteobacteria dominated the Phaeocystis bloom. The most noticeable feature during the successions was the change from Rhodobacteraceae to Flavobacteriaceae in the bacterial communities. The Shannon diversity indices were significantly higher in the transitional phase of the two blooms. Metabolic reconstruction of the metagenome-assembled genomes (MAGs) showed that dominant bacteria exhibited some environmental adaptability in both blooms, capable of metabolizing the main organic compounds, and possibly providing inorganic sulfur to the host algae. Moreover, we identified specific metabolic capabilities of cofactor biosynthesis (e.g., B vitamins) in MAGs in the two algal blooms. In the Skeletonema bloom, Rhodobacteraceae family members might participate in synthesizing vitamin B1 and B12 to the host, whereas in the Phaeocystis bloom, Flavobacteriaceae was the potential contributor for synthesizing vitamin B7 to the host. In addition, signal communication (quorum sensing and indole-3-acetic acid molecules) might have also participated in the bacterial response to bloom succession. Bloom-associated microorganisms showed a noticeable response in composition and function to algal succession. The changes in bacterial community structure and function might be an internal driving factor for the bloom succession.

Seasonal and Spatial Variability in the Bacterial Diversity in Haizhou Bay in the Southern Yellow China Sea

“…Most eukaryotic phytoplankton are VB-deficient types, as they require exogenous B vitamins for growth maintenance [65]. A previous study showed that Rhodobacteraceae dominate in diatom bloom caused by Skeletonema [66]. Based on functional gene inference in the study, Rhodobacteraceae may be involved in the synthesis of vitamin B 1 and B 2 for the host.…”

Recent advances and fundamentals of microalgae cultivation technology

“…is accompanied by the microbiota changes from the dominant Alphaproteobacteria to Bacteroidia and Gammaproteobacteria as well as from the Rhodobacteraceae to Flavobacteriaceae accordingly. [ 56 ] Alterations in the metabolism of sulfur, porphyrin, tryptophan, biotin, and quorum‐sensing signals were seen in the bacteria that corresponded to the predominant species of algae. [ 56 ] It would be interesting to look into whether comparable changes in dominant algae species and corresponding bacteria can be modeled in vitro, as no functional investigations were reported.…”

“…[ 56 ] Alterations in the metabolism of sulfur, porphyrin, tryptophan, biotin, and quorum‐sensing signals were seen in the bacteria that corresponded to the predominant species of algae. [ 56 ] It would be interesting to look into whether comparable changes in dominant algae species and corresponding bacteria can be modeled in vitro, as no functional investigations were reported.…”

“…We categorized these findings according to the fundamental factors that regulate microalgae growth and properties including bioreactor type and supply of light and nutrients, [50][51][52] symbiotic microalgae-microbiotic interactions in which bacteria provide nitrogen fixation and nitrification as well as vitamins, whereas microalgae synthesize carbons, [53][54][55][56] CO 2 supplementation or genetic modifications of CO 2 fixation, [57][58][59][60] inorganic phosphate fixation, [61][62][63] adaptation to temperature. [64,65] Substantial research is focused on gene engineering and selection of microalga for food and pigment production.…”

The phycosphere and its role in algal biofuel production

“…While this relationship benefits the bacteria, it can also benefit the algal cell via a mutualistic relationship (Kazamia et al, 2012;Zhou et al, 2016;Mugnai et al, 2023). Many algae require vitamin B12 to function properly, which is provided by bacteria in the phycosphere (Fuentes et al, 2016;Yao et al, 2019); different bacteria can provide a variety of vitamins including B1 and B7 (Lutzu and Turgut Dunford, 2018;Zhu et al, 2023). Bacteria present in the phycosphere can contribute to algal defense by releasing compounds that impede invasive species, such as the production of antibiotics and toxins (Kizhakkekalam and Chakraborty, 2020).…”