Degradation of aromatic compounds and lignin by marine protist Thraustochytrium striatum

This paper aimed at studying a novel high biomass strain (HBS) of marine protist, Thraustochytrium striatum, for lignin valorization to lipids and carotenoids. In the screening of 15 aromatic compounds, T. striatum HBS can utilize most compounds while achieving the best growth on 3,4-dihydroxybenzoic acid (3,4-DHBA) and 4hydroxybenzoic acid (4-HBA). The maximum cell mass concentration reached 2-3 g/L under 5 g/L of 3,4DHBA or 2 g/L of 4-HBA, which was comparable to that under equivalent concentration of glucose. The longchain fatty acids content was 13 % and 7 % with 3,4-DHBA and 4-HBA, respectively. The adoption of fedbatch fermentation mode improved the degradation of carbon source and prevented the inhibitory effect caused by overloading of aromatic compounds. Both final cellular fatty acids and carotenoids contents were doubled in the fermentation of 3,4-DHBA. T. striatum HBS exhibited limited lignin depolymerization (similar to 24 %) ability on technical lignins.

Automated summary

This paper investigated a novel high biomass strain of marine protist Thraustochytrium striatum for lignin valorization to lipids and carotenoids. The strain demonstrated the ability to utilize various aromatic compounds and achieved optimal growth on 3,4-dihydroxybenzoic acid and 4-hydroxybenzoic acid. Adoption of fed-batch fermentation mode improved the degradation of carbon source and enhanced the production of cellular fatty acids and carotenoids.