Co-production of yeast oil and b-carotene by biodiesel-based crude glycerol from polyurethane foam and bioactive ingredient synthesis

Abstract

Co-producing yeast oil (YO) and beta -carotene from biodiesel-derived crude glycerol (BCG) offers a promising approach for high-value bioproduct synthesis and sustainable waste valorization. This study aimed to: 1) investigate the effect of surfactant and osmotic pressure on YO and beta -carotene co-production by Rhodosporidium toruloides using BCG-based medium, 2) improve production efficiency through an integrated cell retention system, and 3) explore practical applications of polyurethane foam production and beta -carotene encapsulation.

The effects of various inducer on YO and beta -carotene co-production were systematically evaluated. R. toruloides cultivation was conducted using continuous fermentation integrated with cell retention (CF-CR) system to enhance production efficiency. The produced YO and beta -carotene were subsequently applied to manufacture polyurethane (PU) foam and encapsulated powder, respectively.

Results revealed that Tween 20 and ethephon significantly increased total yeast oil and total beta -carotene production, with their combined use yielding 2.0 and 2.6-fold increases, respectively, in bioreactor conditions compared to flask cultivation. The CF-CR process enhanced total biomass and total oil by 1.55 and 1.86-fold compared to continuous fermentation alone. The YO primarily consisted of C16 and C18 long-chain fatty acids. YO was successfully transformed into both rigid and semi-rigid PU foams. Additionally, the encapsulated beta -carotene extract exhibited notable antimicrobial activity and stability under light conditions.