Biological and Genomic Characterization of Two Astaxanthin-Producing Paracoccus marcusii Isolates as a Potential...

Area of Science:

• Microbiology
• Biotechnology
• Biochemistry

Background:

• Astaxanthin (AST), a carotenoid pigment, possesses significant antioxidant, anti-inflammatory, and antibacterial properties.
• AST is valuable in aquaculture, nutraceutical, and cosmetic industries.
• Paracoccus spp. are known for substantial astaxanthin production yields.

Purpose of the Study:

• To biochemically and genomically characterize two Paracoccus isolates (GCUPA1 and GCUPA3).
• To evaluate their potential as microbial sources of natural carotenoids, particularly astaxanthin.
• To assess their suitability as cell factories for sustainable astaxanthin production.

Main Methods:

• 16S rRNA gene sequencing for bacterial identification.
• Spectroscopic and chromatographic analyses for carotenoid identification.
• Genome sequencing and phylogenetic analysis to identify carotenoid biosynthetic gene clusters (BGCs).
• Antioxidant activity assay using ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)).

Main Results:

• Two red-orange pigmented strains, identified as P. marcusii GCUPA1 and GCUPA3, were isolated.
• Astaxanthin was confirmed as the predominant carotenoid in both strains.
• Extracted pigments demonstrated significant antioxidant activity.
• Complete genome sequences revealed intact carotenoid BGCs (crtWZYIBE) essential for astaxanthin synthesis.
• High nucleotide identity was observed within the BGCs of both strains.

Conclusions:

• P. marcusii GCUPA1 and GCUPA3 are promising candidates for sustainable astaxanthin production.
• These strains possess the genetic machinery for efficient astaxanthin biosynthesis.
• They offer potential advantages in processing efficiency and production economics over existing microbial systems.