Highly-efficient lipid production from hydrolysate of Radix paeoniae alba residue by oleaginous yeast Cutaneotrichosporon oleaginosum

Valorization of herbal extraction residues (HERs) into value-added products is pivotal for the sustainability of Chinese medicine industry. Here, seven different enzymatic hydrolysates of dilute acid pretreated HERs were evaluated for lipid production by Cutaneotrichosporon oleaginosum. Among them, the highest sugar yield via hydrolysis and the maximum lipid production were obtained from Radix paeoniae alba residue (RPAR). More interestingly, high proportion of sugar polymers was disintegrated into fermentable sugars during the pretreatment step, allowing a cheap non-enzymatic route for producing sugars from RPAR. A repeated dilute acid pretreatment gained a high sugar concentration of 241.6 g/L through reusing the pretreatment liquor (PL) for four times. Biomass, lipid concentration, and lipid content achieved 49.5 g/L, 35.7 g/L and 72.2 %, respectively, using fed-batch culture of PL. The biodiesel parameters indicated lipids produced from HERs were suitable for biodiesel production. This study offers a cost-effective way to upgrade the HERs waste into micro-biodiesel.

Enzymatic in situ saccharification of herbal extraction residue by a medicinal herbal-tolerant cellulase

Herbel-tolerant strains exhibit considerable environmental and commercial values not only due to their harmless treatment of herbal-extraction residues (HERs) but also because of their use in preparing high-quality cellulase cocktails. In this study, three typical HERs were evaluated for enzymatic in situ saccharification performance. A HERs-tolerance fungus, identified as Penicillium oxalicum G2, can grow in 1.5% (w/v) Radix isatidis residues (RIR), thereby exhibiting the highest FPase (2.2 U/mL), carboxymethyl cellulase (13.3 U/mL), and β-glucosidase (4.6 U/mL) activities. The most effective production of cellulase cocktail was achieved via orthogonal experiment in a system with pH 6.0, 30 °C, and 96 h. Cellulase cocktail from P. oxalicum G2 can directly saccharify the extraction RIR, thereby achieving a maximum reducing sugar yield of 7.2 mg/mL, which is 1.7-fold higher than those of commercial cellulases. Results illustrate the potential of P. oxalicum G2 for enzymatic in situ saccharification.