SUMMARY
Background: Mutation breeding is one of the most important routes to achieving high docosahexaenoic acid
(DHA) productivity using Schizochytrium. However, few selection strategies have been reported that aim to
generate a high DHA content in Schizochytrium lipids.
Results: First, culture temperature altered the butanol tolerance of Schizochytrium limacinum B4D1. Second, S.
limacinum E8 was obtained by selecting mutants with high butanol tolerance. This mutant exhibited a 17.97%
lower proportion of DHA than the parent strain S. limacinum B4D1. Third, a negative selection strategy was
designed in which S. limacinum F6, a mutant with poor butanol tolerance, was obtained. The proportion of
DHA in S. limacinum F6 was 11.22% higher than that of parent strain S. limacinum B4D1. Finally, the
performances of S. limacinum B4D1, E8 and F6 were compared. These three strains had different fatty acid
profiles, but there was no statistical difference in their biomasses and lipid yields.
Conclusion: It was feasible to identified the relative DHA content of S. limacinum mutants based on their butanol
tolerance.