Optimization of carotenoids extraction from Rhodobacter sphaeroides

The comparison of the three methods ultrasonic assisting, grinding and HCl assisting on carotenoids extraction yield from Rhodobacter sphaeroides (R. sphaeroides) was carried out. The HCl-assisted extraction was found to be the most effective. And then, based on HCl-assisted extraction method, the effect of temperature, solvent–solid ratio and duration on the yield of carotenoids extracted from R. sphaeroides was investigated using single factor and Box–Behnken experimental design. The optimal conditions for HCl-assisted extraction of carotenoids from R. sphaeroides were found to be: temperature 30 °C, solvent–solid ratio 40 ml/g, duration 40 min. The first two extractions were enough to approximately exhaust the entire content of carotenoids in R. sphaeroides.