Co-expression of Exo-inulinase and Endo-inulinase Genes in the Oleaginous Yeast Yarrowia lipolytica for Efficient Single Cell Oil Production from Inulin

Abstract

Yarrowia lipolytica is a promising platform for the single cell oil (SCO) production. In this study, a transformant X+N8 in which exo- and endo-inulinase genes were co-expressed could produce an inulinase activity of 124.33 U/mL within 72 h. However, the inulinase activity of a transformant X2 carrying a single exo-inulinase gene was only 47.33 U/mL within 72 h. Moreover, the transformant X+N8 could accumulate 48.13% (w/w) SCO from inulin and the cell dry weight reached 13.63 g/L within 78 h, which were significantly higher than those of the transformant X2 (41.87% (w/w) and 11.23 g/L) under the same conditions. In addition, inulin hydrolysis and utilization of the transformant X+N8 were also more efficient than those of the transformant X2 during the fermentation process. These results demonstrated that the co-expression of the exo- and endo-inulinase genes significantly enhanced the SCO production from inulin due to the improvement of the inulinase activity and the synergistic action of exo- and endo-inulinase. Besides, over 95.01% of the fatty acids from the transformant X+N8 were C16-C18, especially C18:1 (53.10%), suggesting that the fatty acids could be used as feedstock for biodiesel production.

Efficient simultaneous production of extracellular polyol esters of fatty acids and intracellular lipids from inulin by a deep-sea yeast Rhodotorula paludigena P4R5

“…As shown in Table 1, it was found that over 88% of the intracellular fatty acids from the strain P4R5 were C 16:0 , C 18:0 , C 18:1 and C 18:2 , especially C 18:1 (35.93%). This composition was similar to those of the other oleaginous yeast lipids reported [22, 24, 25], and such yeast oils could be used as high-quality feedstock in biodiesel production that requires C 16 –C 18 fatty acids [26]. For extracellular PEFA, the GC/MS analysis indicated the presence of three major hydroxyl fatty acids of 3-OH-C 14:0 (4.40%), 3-OH-C 16:0 (70.51%) and 3-OH-C 18:0 (15.97%), in addition to a small amount of 2-hexadecenoic acid and 2-octadecenoic acid, which were probably resulted from the dehydration of the corresponding 3-hydroxyl fatty acids during the methyl esterification process (Table 1).…”

“…In addition to glucose, inulin also has received considerable attention as a renewable and competitive non-food biomass resource for microbial lipids production by oleaginous yeasts [20, 22]. For examples, the yeast strains R. toruloides 2F5 and Pichia guilliermondii Pcla22 could produce 70.36% and 60.6% (w/w) of lipid based on cell dry weight from inulin due to their native exo-inulinase genes, respectively [24, 25].…”

“…For the analysis of the fatty acid composition of PEFA and intracellular oil, the samples extracted above were transmethylated according to the reported procedure [22]. The fatty acid methyl esters (FAMEs) obtained were determined via gas chromatography/mass spectrometry (GC/MS) using an Agilent 7890A gas chromatograph interfaced with an Agilent 5975C mass-selective detector as previously reported [22].…”

“…Many efforts have concentrated on using industrial waste and raw biomass materials as low-cost carbon sources, such as molasses, whey, industrial fats, glycerol, cassava and lignocellulose [19]. In addition, inulin, a linear polysaccharide (β-2,1-linked d -fructose residues terminated by a glucose residue) presented as a storage carbohydrate in plants such as chicory, Jerusalem artichoke and dahlia, has also received attention as a renewable non-food biomass resource for the production of ethanol, pullulan, single cell oil, citric acid and other chemicals [20–22]. However, the utilization efficiency of inulin depends on the native or heterogenous inulinase activity of yeast strains.…”

Organic Wastes as Feedstocks for Non-Conventional Yeast-Based Bioprocesses

“…The accumulated lipids consisted mainly of C 16:0 , C 18:1 , and C 18:2 [98]. In another study, the exo-inulase gene from K. marxianus strain KM-0 and endo-inulinase gene from Aspergillus niger strain F4 were co-expressed in Y. lipolytica strain ACA-DC 50109 [99]. The enzymes secreted from the resulting transformant (X + N8) acted synergistically to hydrolyze 90% of the inulin, with the inulinase activity reaching 136.6 U/ml in the culture medium.…”