Feasible microbial accumulation of triacylglycerides from crude glycerol

BACKGROUND: Crude glycerol, a by-product of the biodiesel production industry, was used to produce intracellular storage polymers for waste valorization. The enrichment of a mixed microbial culture (MMC) in microorganisms with the ability to accumulate intracellular polymers was performed in a sequencing batch reactor (SBR) submitted to feast–famine conditions. The effect of different carbon sources in the accumulation of biopolymers was investigated. RESULTS: A MMC enriched in yeast and bacteria was obtained using crude glycerol as feedstock. Accumulation experiments performed with crude glycerol, synthetic glycerol and synthetic methanol showed the feasibility of the MMC to produce different biopolymers. Triacylglyceride (TAG) accumulation up to 46 wt% in yeast cells was promoted by the presence of residual lipids in crude glycerol. However, bacteria from class Betaproteobacteria used glycerol mainly to accumulate 28 wt% of polyglucose (PG) and methanol as carbon source for cell growth. CONCLUSIONS: As waste valorization, a possible advantage which comes out of the present study is the use of open, non-sterile and non-defined systems to produce TAGs. These TAGs can potentially re-enter the biodiesel production process helping on the maximisation of the feedstock used in this process.