Description of a novel extremophile green algae, Chlamydomonas pacifica, and its potential as a biotechnology host

Abstract

We present the comprehensive characterization of a newly identified microalga, Chlamydomonas pacifica, originally isolated from a soil sample in San Diego, CA, USA. This species showcases remarkable biological versatility, including a broad pH range tolerance (6-11.5), high thermal tolerance (up to 42 degree celsius), and salinity resilience (up to 2% NaCl). Its amenability to genetic manipulation and sexual reproduction via mating, particularly between the two opposing strains CC-5697 & CC-5699, now publicly available through the Chlamydomonas Resource Center, underscores its potential as a biotechnological chassis. The biological assessment of C. pacifica, revealed versatile metabolic capabilities, including diverse nitrogen assimilation capability, phototaxis, and motility. Genomic and transcriptomic analyses identified 17,829 genes within a 121 Mb genome, featuring a slightly lower GC content (61%) than the model organism Chlamydomonas reinhardtii. The codon usage of C. pacifica closely mirrors that of C. reinhardtii, indicating a conserved genetic architecture that supports a trend in codon preference with minor variations. Phylogenetic analyses position C. pacifica within the core-Reinhardtinia clade yet distinct from known Volvocales species. Through metabolomic and lipidomic profiling, we observed a high carbohydrate content, approximately 30% of the dry cell weight (DCW), suggesting a substantial capacity for bioplastic precursor production. The lipidomic data revealed an abundance of triacylglycerols (TAGs), promising for biofuel applications and lipids for health-related benefits. Our investigation lays the groundwork for exploiting C. pacifica in biotechnological applications, spanning from biofuel generation to synthesizing biodegradable plastics, positioning it as a versatile host for future bioengineering endeavors.