Novel, automated, semi-industrial modular photobioreactor system for cultivation of demanding microalgae that produce fine chemicals—The next story of H. pluvialis and astaxanthin

Recently, there has been increased interest in the use of microorganisms in the production of pharmaceuticals, nutraceuticals and energy supply products, which is due to their rapid growth rate and ability to biosynthesize fine chemicals or biotransform specific xenobiotics. To achieve the desired scale of production and optimization of microbial cultures, it is necessary to design bioreactors that enable process automation, control of working parameters, reduction of microbial and chemical contaminations, and culture independence of climate conditions. In response to this need, an original, modular airlift-type photobioreactor system was designed and manufactured. This novel semitechnical system, with a total volume of 1000 dm3, was operated via computer control, which enabled the creation of time profiles of red, blue and white LED illumination and of carbon dioxide and air dosing. The quality and usefulness of the developed system was demonstrated via the case study, namely two-stage cultivation of the microalgae Haematococcus pluvialis—a species commonly used in the production of natural astaxanthin. The experimentally developed procedure ensures a repeatable and efficient biomass multiplication process and the maintenance of a light- and chemical-mediated effective stress mechanism that allows the production of up to 3.2% natural astaxanthin in terms of dry biomass.