Pilot-scale production of phylloquinone (vitamin K1) using a bubble column photo-bioreactor

Abstract

Phylloquinone (vitamin K1) is an essential nutrient for both humans and animals; it plays a key role in blood coagulation amongst other processes. In this work we describe the scale-up of a biosynthetic process for phylloquinone production using the cyanobacterium Anabaena cylindrica. A 50 L bubble column photo-bioreactor was used to cultivate A. cylindrica and the effects of a wide range of operating conditions including superficial velocities (0.67–6.7 cm s−1), day lengths (12–24 h), sparger designs and medium compositions were examined. The column design and superficial velocity had minimal impact on phylloquinone production, while changes to the medium composition and day length had large impacts. By varying these factors we were able to achieve final phylloquinone titres of the order 280 μg L−1 and productivities of 40 μg L−1 day−1, which are approximately double the values previously obtained. The biomass produced has clear applications in human and animal nutrition as its phylloquinone concentration was approximately 330 μg g−1 (dry basis); this being ten times higher than rich dietary sources. Conclusions regarding the effect of photo-bioreactor design and operating conditions can be applied to the production of phylloquinone, as well as the scale-up of cyanobacterial cultures more broadly.