Oleaginous yeast Yarrowia lipolytica culture with synthetic and food waste-derived volatile fatty acids for lipid production

Abstract

BackgroundThe sustainability of microbial lipids production from traditional carbon sources, such as glucose or glycerol, is problematic given the high price of raw materials. Considerable efforts have been directed to minimize the cost and find new alternative carbon sources. Volatile fatty acids (VFAs) are especially attractive raw materials, because they can be produced from a variety of organic wastes fermentation. Therefore, the use of volatile fatty acids as carbon sources seems to be a feasible strategy for cost-effective microbial lipid production.ResultsLipid accumulation in Y. lipolytica using synthetic and food waste-derived VFAs as substrates was systematically compared and evaluated in batch cultures. The highest lipid content obtained with acetic, butyric, and propionic acids reached 31.62 ± 0.91, 28.36 ± 0.74, and 28.91 ± 0.66%, respectively. High concentrations of VFA inhibited cell growth in the following order: butyric acid > propionic acid > acetic acid. Within a 30-day experimental period, Y. lipolytica could adapt up to 20 g/L acetic acid, whereas the corresponding concentration of propionic acid and butyric acid were 10 and 5 g/L, respectively. Cultures on a VFA mixture showed that the utilization of different types of VFA by Y. lipolytica was not synchronized but rather performed in a step-wise manner. Although yeast fermentation is an exothermic process, and the addition of VFA will directly affect the pH of the system by increasing environmental acidity, cultures at a cultivation temperature of 38 °C and uncontrolled pH demonstrated that Y. lipolytica had high tolerance in the high temperature and acidic environment when a low concentration (2.5 g/L) of either synthetic or food waste-derived VFA was used. However, batch cultures fed with food fermentate yielded lower lipid content (18.23 ± 1.12%) and lipid productivity (0.12 ± 0.02 g/L/day). The lipid composition obtained with synthetic and food waste-derived VFA was similar to commercial biodiesel feedstock.ConclusionsThis work demonstrated the feasibility of utilizing synthetic and food waste-derived VFA for lipid production by Y. lipolytica. The good adaptability of Y. lipolytica to the high temperature and acidic environment further illustrated its considerable potential for practical application.

Volatile fatty acids as novel building blocks for oil‐based chemistry via oleaginous yeast fermentation

“…When VFAs are used as a carbon source, the inhibitory effect of high acid concentration (up to 5 g/L) on yeast growth is well known (Fei et al, ; Fontanille et al, ; Huang et al, ; Liu, Yuan, Liu, & Huang, ). In this sense, several studies have concluded that the toxic effect on yeast increases with increasing VFA chain length (Gao et al, ; Liu, Yuan, Liu, & Huang, ). However, J. Liu et al () reported higher biomass and lipid yields (1.6 and 0.4 g/g C, respectively) from 5 g/L of butyric acid than from acetic or propionic acids in C. curvatus .…”

“…Besides this, in the ex novo pathway, the microbial lipids produced contain lower quantities of TAGs and somehow higher quantities of FFAs as compared with lipid produced through de novo process (Papanikolaou & Aggelis, ). There are some examples related to the microorganism's growth with hydrophobic and hydrophilic materials as cosubstrates (Beopoulos et al, ; Fontanille, Kumar, Christophe, Nouaille, & Larroche, ; Gao, Li, Zhou, Cheng, & Zheng, ) indicating possible simultaneous ex novo and de novo lipid biosynthesis pathways.…”

“…In terms of fermentation conditions, temperatures ranging from 25°C to 28°C are commonly used in lipid production by OY as temperatures higher than 30 °C hamper microbial growth and lipid accumulation (Fei et al, ; Gao et al, ). pH also has a crucial effect on OY lipid accumulation when VFAs are used as carbon source because it can influence the acid form (protonated/desprotonated) in solution and acid transport inside the cell (Béligon et al, ; Fei et al, ; J. Liu et al, ).…”

Screening a genomic library for genes involved in propionate tolerance in Yarrowia lipolytica

“…As a result, there is a growing interest in using volatile FAs (VFAs) as carbon sources for lipid production (Beopoulos et al, ; Fei et al, ; Qiao et al, ). VFAs can be obtained from agro‐industrial waste and several types of biodegradable organic waste (Papanikolaou, Galiotou‐Panayotou, Fakas, Komaitis, & Aggelis, ); in theory, they should have higher conversion efficiencies than sugar‐based carbon sources because of the shorter metabolic pathways involved (Gao, Li, Zhou, Cheng, & Zheng, ).…”

“…Propionate, one of the most common VFAs, can be used by Yarrowia lipolytica as its sole carbon source in lipid production (Fontanille, Kumar, Christophe, Nouaille, & Larroche, ; Kolouchová, Schreiberová, Sigler, Masák, & Řezanka, ; Gao et al, ). Recently, Y .…”