Abstract
Background Phaffia rhodozyma is a potential industrial source for production of natural astaxanthin. The synthetic mechanism of astaxanthin in P. rhodozyma is complex and unclear that blocked its development. Results In this study, eight genes related to dicyclic and monocyclic pathway in three different strains of P. rhodozyma were analyzed, and the relationship between the expression and astaxanthin biosynthesis was explored. Among these genes, crtYB (R=0.75, P<0.05) and asy genes (R=0.74, P<0.05) showed the most closely correlation with astaxanthin biosynthesis. In order to further study exact relationship, crtYB and asy genes were knocked out by homologous recombination. After crtYB knock-out, astaxanthin was decreased to be under detected line. It suggested crtYB played a role in dicyclic and monocyclic pathway. Meanwhile, the asy gene was in dicyclic pathway of astaxanthin biosynthesis, and its knock-out would promote the astaxanthin biosynthesis in monocyclic pathway, resulting in a 25.04% increase in astaxanthin production. Conclusion The possible rate-limiting enzymes were asy gene and crtYB illustrated by analysis of regression. Knock-out of asy and crtYB gene was great helpful to understand the synthetic pathway of astaxanthin, and significant to the industrial application of producing astaxanthin.
Dynamic modelling of Haematococcus pluvialis photoinduction for astaxanthin production in both attached and suspended photobioreactors
