There are only a few reports available about the assimilation of hydrophobic substrates by microorganisms, however, it is well known that oleaginous microorganisms are capable of utilizing both hydrophilic and hydrophobic substrates and accumulate lipids via two different pathways namely de novo and ex novo lipid synthesis, respectively. In the present study, an oleaginous yeast, Cryptococcus curvatus, was investigated for its potentials to utilize a waste substrate of hydrophobic nature (waste cooking oil - WCO) and compared with its ability to utilize a hydrophilic carbon source (glucose). To facilitate the utilization of WCO by C. curvatus, the broth was sonicated to form a stable oil-in-water emulsion without adding any emulsifier, which was then compared with WCO samples without any ultrasound treatment (unsonicated) for the yeast cultivation. Ultrasonication reduces the size of hydrophobic substrates and improves their miscibility in an aqueous broth making them easily assimilated by oleaginous yeast. Under de novo lipid fermentation, the yeast synthesized 9.93 ± 0.84 g/L of cell dry weight and 5.23 ± 0.49 g/L lipids (lipid content of 52.66 ± 0.93 %) when cultivated on 40 g/L of glucose (C/N ratio of 40). The amount of cell dry weight, lipid concentration, and lipid content were considerably higher during the ex novo lipid synthesis. More specifically, the highest lipid content achieved was 70.13 ± 1.65 % w/w with a corresponding dry cell weight and lipid concentration of 18.62 ± 0.76 g/L and 13.06 ± 0.92 g/L respectively, when grown on 20 g/L sonicated WCO. The highest lipid concentration, however, was observed when the yeast was cultivated on 40 g/L sonicated WCO. Under these conditions, 20.34 g/L lipids were produced with a lipid content of 57.05% w/w. On the other hand, lipid production with unsonicated WCO was significant lower, reaching 11.16 ± 1.02 g/L (69.14 ± 1.34 % w/w of lipid content) and 12.21 ± 1.34 g/L (47.39 ± 1.67 % w/w of lipid content) for 20 g/L and 40 g/L of WCO, respectively. This underpins the significance of the sonication treatment, especially at elevated WCO concentrations, to improve the accessibility of the yeast to the WCO. Sonication treatment that was used in this study assisted the utilization of WCO without the need to add emulsifiers, thus reducing the need for chemicals and in turn has a positive impact on the production costs. The microbial lipids produced presented a different fatty acid composition compared to the WCO, making them more suitable for biodiesel production as suggested by the theoretical estimation of the biodiesel properties.

有仅由微生物几个可用的关于疏水性衬底的同化报告，但是，它是公知的是含油微生物通过两种不同的途径能够利用亲水性和疏水性基材和累加脂质即从头和Novo生产脂质合成，分别。在本研究中，研究了含油酵母曲霉隐球菌（Cryptococcus curvatus）的潜力，该潜力可利用疏水性的废底物（废食用油-WCO），并将其与利用亲水性碳源（葡萄糖）的能力进行比较。促进弯线虫对WCO的利用然后，对肉汤进行超声处理以形成稳定的水包油型乳化液，而无需添加任何乳化剂，然后将其与未经任何超声处理（未超声处理）的WCO样品进行比较，以进行酵母培养。超声处理减小了疏水性底物的尺寸，并改善了其在水性肉汤中的可混溶性，使它们易于被油质酵母吸收。在从头进行脂质发酵的情况下，在40 g / L葡萄糖上培养时，酵母合成了9.93±0.84 g / L的细胞干重和5.23±0.49 g / L的脂质（脂质含量为52.66±0.93％）。 40）。从头开始，细胞干重，脂质浓度和脂质含量明显更高脂质合成。更具体地说，当在20 g / L超声处理的WCO上生长时，达到的最高脂质含量为70.13±1.65％w / w，相应的干细胞重量和脂质浓度分别为18.62±0.76 g / L和13.06±0.92 g / L。 。但是，当酵母在40 g / L超声WCO中培养时，观察到最高脂质浓度。在这些条件下，产生了20.34 g / L的脂质，脂质含量为57.05％w / w。另一方面，使用未超声处理的WCO的脂质产量显着降低，达到11.16±1.02 g / L（69.14±1.34％w / w的脂质含量）和12.21±1.34 g / L（47.39±1.67％w / w的脂质）含量分别为20 g / L和40 g / L的WCO。这加强了超声处理的重要性，尤其是在WCO浓度升高的情况下，以改善酵母对WCO的可及性。这项研究中使用的超声处理无需添加乳化剂即可辅助WCO的利用，从而减少了对化学药品的需求，进而对生产成本产生了积极影响。与WCO相比，产生的微生物脂质呈现出不同的脂肪酸组成，这使它们更适合生物柴油的生产，这是根据生物柴油特性的理论估算得出的。