Simultaneous Production of Hydrophobic Bioactive Compounds from Biomass of Purple Non-sulfur Bacterium Cereibacter sphaeroides

Abstract

This paper presents a method for simultaneous extraction and separation of a number of valuable biologically active compounds (bacteriochlorophyll a, carotenoids, ubiquinone, fatty acids and lipids) from the biomass of purple non-sulfur bacteria using Cereibacter sphaeroides as an example. The hexane:isopropanol extraction method was demonstrated to isolate the most complete range of hydrophobic compounds and to preserve the stability of bacteriochlorophyll a to air oxygen and diffused light. Preliminary cell disruption did not significantly improve the extraction quality. It was also found that the use of low-pressure column chromatography did not provide the separation of the carotenoid fraction from the coenzyme Q10. Losses of target substances in this case amounted to 74 and 70% for bacteriochlorophyll a and carotenoids, respectively, relative to their content in the biomass. The HPLC method was applied for the separation and qualitative and quantitative determination of the carotenoid content in bacterial biomass. Losses of target substances in this case were also strongly reduced to 40 and 14% for bacteriochlorophyll a and carotenoids, respectively. The developed method of complex production of hydrophobic compounds using biomass of C. sphaeroides grown in fed-batch mode under chemoheterotrophic conditions allowed to obtain 4.4 mg of bacteriochlorophyll a, 1.5 mg of carotenoids and 2.1 mg of coenzyme Q10 per 1 g of dry biomass. The possibilities of further utilization of the residual biomass and supernatant are considered.