In situ recovery of the aroma compound perillene from stirred-tank cultured Pleurotus ostreatus using gas stripping and adsorption on polystyrene

Abstract

Supplementation of the key metabolite, alpha-(Z)-acaridiol, to stirred-tank cultured Pleurotus ostreatus was used to demonstrate that integrated in situ product recovery resulted in high conversion rates and quantitative separation of the target product perillene from the nutrient medium. The conversion of beta-myrcene by P. ostreatus was scaled-up from shake-flasks into a controlled, stirred tank bioreactor equipped with gas stripping and adsorption on a polystyrene fixed bed. The formation of the attractive flavour compound perillene was measured daily using standard controlled capillary gas chromatography. The formation of alpha-(Z)-acaridiol was the metabolic bottleneck of the conversion of beta-myrcene to perillene. Efficient in situ recovery of the volatile product enabled quantitative separation of the pure flavour compound. Appropriated bioprocessing, i.e. in situ separation of product, steadily shifted the metabolic equilibria and thus accomplished high conversion rate and pure product.

Short-Chain Flavor Ester Synthesis in Organic Media by an E. coli Whole-Cell Biocatalyst Expressing a Newly Characterized Heterologous Lipase

“…However, performing bioconversion with live cells presents some limitations, such as slow growth and substrate/product toxicity. As a result, yields are often very low (rarely above 1 g/L), an issue that can only be circumvented via elaborate in situ extraction techniques such as gas stripping [3], [8]. In some cases, however, de novo synthesis of relatively simple molecules is not a prerequisite, and taking advantage of pure or crude enzyme preparations to synthesize flavors can be much more efficient [9].…”

Bioprocess Engineering for Microbial Synthesis and Conversion of Isoprenoids

“…Stripping can effectively reduce the concentration of the isoprenoid product in the aqueous phase and avoid toxic effects on the biocatalyst. A straightforward way to remove isoprenoid volatile products from bioprocesses is their separation from bioreactor off-gas streams by adsorption to a solid-phase material such as activated carbon [105] or thermoplastics [45,64,68], or absorption into a hydrophobic liquid [4,5]. The receiving phase has a certain affinity and capacity for the product: that is, at certain product loadings breakthrough of product leading to product loss occurs if no technical countermeasures (gas sensor, change of reservoir) have been installed [64,105].…”

Biotechnology of flavours—the next generation

“…-in situ recovery of product, for example by gas stripping (Krings and Berger 2008), -two-phase systems to separate non-polar conversion chemistry from biology (Morrish et al 2008), -fed-batch of substrate to avoid cytotoxic concentrations of substrate and product (Etschmann and Schrader 2006), -specific reactor construction, such as membrane (Boontawan and Stuckey 2006), solid state (Longo and Sanroman 2006) or closed loop reactors, the latter to prevent volatile substrate from loss through the exhaust stream (Pescheck et al 2009), or -use of non-conventional media, such as organic solvents, ionic liquids or supercritical fluids (Cantone et al 2007). …”