The cadmium tolerance and bioaccumulation mechanism of <i>Tetratostichococcus</i> sp. P1: insight from transcriptomics analysis
Creators: name: Sahabudin, Eri
name: Kubo, Shohei
name: Yuzir, Muhamad Ali Muhammad
name: Othman, Nor’azizi
name: Akhir, Fazrena Nadia Md
name: Suzuki, Kengo
name: Yoneda, Kohei
name: Maeda, Yoshiaki
name: Suzuki, Iwane
name: Hara, Hirofumi
name: Iwamoto, Koji
Publisher: name: Taylor & Francis
Year: 2024
Subjects: subject: Biochemistry
subject: Microbiology
subject: FOS: Biological sciences
subject: Cell Biology
subject: Genetics
subject: Environmental Sciences not elsewhere classified
subject: Chemical Sciences not elsewhere classified
subject: Ecology
subject: Biological Sciences not elsewhere classified
subject: Inorganic Chemistry
subject: FOS: Chemical sciences
subject: Plant Biology

description: Cadmium (Cd) has become a severe issue in relatively low concentration and attracts expert attention due to its toxicity, accumulation, and biomagnification in living organisms. Cd does not have a biological role and causes serious health issues. Therefore, Cd pollutants should be reduced and removed from the environment. Microalgae have great potential for Cd absorption for waste treatment since they are more environmentally friendly than existing treatment methods and have strong metal sorption selectivity. This study evaluated the tolerance and ability of the microalga <i>Tetratostichococcus</i> sp. P1 to remove Cd ions under acidic conditions and reveal mechanisms based on transcriptomics analysis. The results showed that <i>Tetratostichococcus</i> sp. P1 had a high Cd tolerance that survived under the presence of Cd up to 100 µM, and IC<sub>50</sub>, the half-maximal inhibitory concentration value, was 57.0 μM, calculated from the change in growth rate based on the chlorophyll content. Long-term Cd exposure affected the algal morphology and photosynthetic pigments of the alga. <i>Tetratostichococcus</i> sp. P1 removed Cd with a maximum uptake of 1.55 mg g<sup>−1</sup> dry weight. Transcriptomic analysis revealed the upregulation of the expression of genes related to metal binding, such as metallothionein. Group A, Group B transporters and glutathione, were also found upregulated. While the downregulation of the genes were related to photosynthesis, mitochondria electron transport, ABC-2 transporter, polysaccharide metabolic process, and cell division. This research is the first study on heavy metal bioremediation using <i>Tetratostichococcus</i> sp. P1 and provides a new potential microalga strain for heavy metal removal in wastewater. <b>Abbreviations:</b>BP: Biological process; bZIP: Basic Leucine Zipper; CC: Cellular component; ccc1: Ca (II)-sensitive cross complementary 1; Cd: Cadmium; CDF: Cation diffusion facilitator; Chl: Chlorophyll; CTR: Cu TRansporter families; DAGs: Directed acyclic graphs; DEGs: Differentially expressed genes; DVR: Divinyl chlorophyllide, an 8-vinyl-reductase; FPN: FerroportinN; FTIR: Fourier transform infrared; FTR: Fe TRansporter; GO: Gene Ontology; IC50: Growth half maximal inhibitory concentration; ICP: Inductively coupled plasma; MF: molecular function; NRAMPs: Natural resistance-associated aacrophage proteins; OD: Optical density; RPKM: Reads Per Kilobase of Exon Per Million Reads Mapped; VIT1: Vacuolar iron transporter 1 families; ZIPs: Zrt-, Irt-like proteins.