Carotenoids are widely distributed and structurally diverse, which have significant roles in the photosynthesis of plants. As a precursor of vitamin A, carotenoids are also antioxidants that reduce various chronic diseases, which are beneficial for human health. Currently, the existing studies concerned the biological roles of APETALA2 (AP2)/ethylene-responsive factor (ERF) genes originated from higher plants. The AP2 superfamily of the transcriptional regulator was identified in higher plants, which was related to growth, development, carotenoid metabolism, and responses to various stresses. However, the regulatory mechanisms of the AP2-modulating carotenoid metabolism have not been reported in microalgae, which remain to be elucidated. Dunaliella parva AP2 (i.e., DpAP2), an important transcription factor, promotes carotenoid accumulation by binding to the promoter of target gene. Here, we identified an important AP2/ERF transcription factor, DpAP2, which could promote carotenoid accumulation by binding to the promoter of target gene. To demonstrate the function of DpAP2, the interacting proteins were identified by the yeast two-hybrid system. The results showed that DpAP2 could interact with three proteins with different activities (DNA-binding transcription factor activity, protein kinase activity, and alpha-D-phosphohexomutase activity); these proteins may be associated with multiple biological processes. This paper laid a good foundation for a deep understanding of the regulatory mechanisms of DpAP2 and genetic engineering breeding in D. parva.

WRINKLED1 (WRI1) is an important transcription factor controlling lipid biosynthesis. To elucidate the function of Dunaliella parva WRI1-like (WRI1-like) (i. e., DpWRI1-like), the targets of DpWRI1-like were identified by chromatin immunoprecipitation sequencing. The results showed that DpWRI1-like regulated many target genes involved in carbohydrate metabolism, lipid metabolism, photosynthesis, and transcription factor. It was proposed that DpWRI1-like participated in a regulatory network controlling lipid biosynthesis. This work laid a good foundation for a deep understanding of the regulatory mechanism of DpWRI1-like in D. parva.

A gene encoding phzR was isolated from a phenazine-producing bacterium Pseudomonas aeruginosa 2016NX1. This paper provided the full-length cDNA encoding phzR (GenBank Accession no., MW143078). The cDNA of the phzR contained an open reading frame (ORF) of 714 bp. The potential regulatory elements were predicted in the phzR promoter region. The deduced amino acid sequence of P. aeruginosa phzR showed significant homology to the known phzRs from different organisms. Gene overexpression analysis showed that the phenazine content was improved (44.39%) in comparison to wild-type 2016NX1.

No abstract

Growth inhibition of chromium (Cr), cadmium (Cd) and lead (Pb) to fresh water microalga Chlorella vulgaris (C. vulgaris) FACHB-8 was examined. These results demonstrated that the concentration level (EC50 value) of three heavy metals (Cr, Cd and Pb) could be utilized as an indicator for evaluating the toxicities of Cr, Cd and Pb for microalga growth. The EC50 values of Cr for C. vulgaris were 0.22, 0.07 and 0.04 mg/L at 24, 48 and 72 h based on Algorithm 2 (%Ir, percent inhibition in average specific growth rate), respectively. The EC50 values of Cd for C. vulgaris were 2.76, 1.08 and 0.93 mg/L at 24, 48 and 72 h based on Algorithm 2, respectively. The EC50 values of Pb for C. vulgaris were 73.21, 65.02 and 48.38 mg/L at 24, 48 and 72 h based on Algorithm 2, respectively. The results laid a good foundation for the application of C. vulgaris in the water quality monitoring.