Molecular Mechanism of Modified Clay Controlling the Brown Tide Organism <i>Aureococcus anophagefferens</i> Revealed by Transcriptome Analysis

The
data and experiences in mitigating harmful algal blooms (HABs)
by modified clay (MC) show that a bloom does not continue after the
dispersal of the MC, even though the density of the residual cells
in the water is still high, at 20–30% of the initial cell density.
This interesting phenomenon indicates that in addition to flocculation,
MC has an additional control mechanism. Here, transcriptome sequencing
technology was used to study the molecular mechanism of MC in controlling
HABs. In residual cells treated with MC, the photosynthetic light
reaction was the most affected physiological process. Some genes related
to the light harvesting complex, photosystem (PS) I and PS II, were
significantly up-regulated (p < 0.05), and several
transcripts increased by as much as 6-fold. In contrast, genes associated
with the dark reaction did not significantly change. In addition to
genes associated with photosynthesis, numerous genes related to energy
metabolism, stress adaptation, cytoskeletal functioning, and cell
division also responded to MC treatment. These results indicated that
following treatment with MC, the normal physiological processes of
algal cells were disrupted, which inhibited cell proliferation and
growth. Thus, these findings provide scientific proof that HABs are
controlled by MC.