Production of coenzyme Q10 by purple non-sulfur bacteria: Current development and future prospect

Coenzyme Q10 (CoQ10) is extensively used in the fields of medicine, cosmetics, food, and health care due to its function as an adenosine triphosphate (ATP) synthesis promoter and antioxidant. In recent years, the market demand (about 988-1369 tons/year) and application potential of CoQ10 have expanded, so it is necessary to enhance CoQ10 production. Microbial synthesis has gradually become a promising and commercially viable CoQ10 production method because of microorganisms have a high CoQ10 content, they are widely available, and they are inexpensive to grow. Among the microorganisms able to produce CoQ10, purple non-sulfur bacteria (PNSB) are desirable and preferred because of their ability of resource recovery with high yield from wastewater and the great potential of scaling up. In this review, the pros and cons of CoQ10 production methods are described and compared. The advantages of CoQ10 production from PNSB are detailed and illustrated. The influence factors and corresponding regulation strategies are summarized to effectively increase CoQ10 production from PNSB. Based on production cost benefits and environmental sustainability profiles, a novel, costeffective, and environmental-friendly conversion route for CoQ10 production from non-toxic wastewater by using PNSB is proposed. By using this novel route, the nutrients from wastewater are converted into PNSB biomass, which contains various value-added products (CoQ10, carotenoids, bacteriochlorophyll, 5-aminolevulinic acid, and protein), carbohydrates and metal elements. The cost of light, medium provisions, and temperature control can be reduced or saved. In addition, no fermentation residual broth was produced, and clean water can be obtained. Moreover, existing problems, such as the purity of CoQ10 products derived from wastewaters and the CoQ10 extraction method are analyzed. The perspectives of future research are also proposed to promote the development of CoQ10 production using PNSB.