AUTHOR=Choi Seong Seok , Seo Yong Bae , Nam Soo-Wan , Kim Gun-Do 

TITLE=Enhanced Production of Astaxanthin by Co-culture of Paracoccus haeundaensis and Lactic Acid Bacteria

JOURNAL=Frontiers in Marine Science

VOLUME=7

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2020.597553

DOI=10.3389/fmars.2020.597553

ISSN=2296-7745

ABSTRACT=<p>This study aimed to determine the increase in astaxanthin production from <italic>Paracoccus haeundaensis</italic> by optimizing the medium conditions and co-culturing with lactic acid bacteria. In order to select a suitable strain to co-culture with <italic>P. haeundaensis</italic>, several strains were co-cultured with <italic>P. haeundaensis</italic>. <italic>Lactobacillus fermentum</italic> was selected as the optimal strain. Further to optimize the astaxanthin production in the co-culture, various medium conditions were tested and the PMF medium developed in this study was selected as the optimum medium. For the co-culture under optimal conditions, the dried cell mass and astaxanthin concentration were 1.84 ± 0.09 g/L and 821.09 ± 30.98 μg/g-dried cell weight, respectively, which was 2.5 times higher than that of the <italic>P. haeundaensis</italic> strain in the Luria-Bertani broth medium. In order to confirm the transcription level of the carotenoid biosynthesis genes such as <italic>crtE, crtB, crtI, crtY, crtZ</italic>, and <italic>crtW</italic> of <italic>P. haeundaensis</italic> in the co-culture, real-time qPCR was performed. Among the six carotenoid biosynthesis genes, <italic>crtI, crtY</italic>, and <italic>crtZ</italic> showed a significant difference in relative RNA levels. The mass culture was performed using a 5 L jar fermenter and the astaxanthin concentration was the same as that at the laboratory scale. These results may be used as reference for co-culture and astaxanthin production in carotenoid biosynthesis microorganisms.</p>