Valorization of Crude Glycerol, Residue Deriving from Biodiesel- Production Process, with the Use of Wild-type New Isolated Yarrowia lipolytica Strains: Production of Metabolites with Pharmaceutical and Biotechnological Interest

Abstract

Background & Objective: Crude glycerol (Glol), used as substrate for screening eleven natural Yarrowia lipolytica strains in shake-flask experiments. Aim of this study was to assess the ability of the screened strains to produce biomass (dry cell weight; X), lipid (L), citric acid (Cit), mannitol (Man), arabitol (Ara) and erythritol (Ery), compounds presenting pharmaceutical and biotechnological interest, in glycerol-based nitrogen-limited media, in which initial glycerol concentration had been adjusted to 40 g/L. Methods: Citric acid may find use in biomedical engineering (i.e. drug delivery, tissue engineering, bioimaging, orthopedics, medical device coating, wound dressings). Polyols are considered as compounds with non-cariogenic and less calorigenic properties as also with low insulin-mediated response. Microbial lipids containing polyunsaturated fatty acids (PUFA) are medically and dietetically important (selective pharmaceutical and anticancer properties, aid fetal brain development, the sight function of the eye, hormonal balance and the cardio-vascular system, prevent reasons leading to type-2 diabetes, present healing and anti-inflammatory effects). Results: All strains presented satisfactory microbial growth (Xmax=5.34-6.26 g/L) and almost complete substrate uptake. The principal metabolic product was citric acid (Citmax=8.5-31.7 g/L). Production of cellular lipid reached the values of 0.33-0.84 g/L. Polyols were also synthesized as strain dependent compounds (Manmax=2.8-6.1 g/L, Aramax ~2.0 g/L, Erymax= 0.5-3.8 g/L). The selected Y. lipolytica strain ACA-DC 5029 presented satisfactory growth along with synthesis of citric acid and polyols, thus, was further grown on media presenting an increased concentration of Glol~75 g/L. Biomass, lipid and citric acid production presented significant enhancement (Xmax=11.80 g/L, Lmax=1.26 g/L, Citmax=30.8 g/L), but conversion yield of citric acid produced per glycerol consumed was decreased compared to screening trials. Erythritol secretion (Erymax=15.6 g/L) was highly favored, suggesting a shift of yeast metabolism from citric acid accumulation towards erythritol production. Maximum endopolysaccharides (IPS) concentration was 4.04 g/L with yield in dry weight 34.2 % w/w. Conclusion: Y. lipolytica strain ACA-YC 5029 can be considered as a satisfactory candidate grown in high concentrations of crude glycerol to produce added-value compounds that interest pharmaceutical and biotechnology industries.

Physiological Characterization of a Novel Wild-Type Yarrowia lipolytica Strain Grown on Glycerol: Effects of Cultivation Conditions and Mode on Polyols and Citric Acid Production

“…Total cellular lipids were converted into their corresponding FAMEs, and cellular fatty acid (FA) composition analysis was performed for the late growth phase in the case of the shake-flask cultures, and throughout the culture, for the fed-batch bioreactor experiment (Table 6). In general, FA composition of total lipids of the strain LMBF Y-46 presented important similarities with those reported for various other Y. lipolytica strains cultivated in batch flask and bioreactor cultures, during growth on glycerol or similarly metabolized compounds, under nitrogen limitation [8,16,18,19,21,22,38,40,49,53]. Specifically, the yeast lipids were mainly composed of the FAs oleic (C18:1), palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0) and linoleic (C18:2).…”

“…Moreover, it is interesting to indicate that the maximum volumetric productivity of CA (P CAmax ) achieved in the current batch culture (P CAmax calculated as P CAmax = CA max ∆t , where ∆t is the fermentation time in the batch or fed-batch culture requested to achieve this CA max value) was ≈0.65 g/L/h, being certainly comparable with the highest values reported by other wild-type or mutant Y. lipolytica strains cultivated in batch (0.52-0.85 g/L/h [55]), fed-batch (i.e., 0.40-0.93 g/L/h [56][57][58][59]), and continuous (between 0.70 and 1.30 g/L/h [60]) bioreactor operations (in the cited batch and fed-batch cultures, P CAmax was calculated as in the present study, whereas in the continuous cultures, P CA was calculated as P CA = CA • D, where CA was the concentration at the steady-state and D was the dilution rate imposed). It is noted that in the shake-flask citric acid production experiments, the achieved productivities (calculated as previously stated) are, in general, much lower (0.07-0.25 g/L/h) [8,19,23,40,49,53,61,62].…”

“…In most cases in the literature in which Y. lipolytica strains have grown under nitrogen limitation on glycerol-based media and medium pH remaining >4.5, this event normally favored the biosynthesis and secretion into the medium of citric acid. In contrast, relatively low quantities of polyols were simultaneously synthesized [8,23,40,46,48,49]. However, in agreement with the behavior of the strain LMBF Y-46 that mostly produced polyols instead of citrate, despite the maintenance of pH in values ranging between 4.5-6.1, in recent years, some reports have indicated similar physiological behaviors of other wild-type Y. lipolytica strains cultivated on slightly acidic conditions (medium pH between 4.5-6.5) with glycerol employed as the substrate, in which mostly polyols have been synthesized [15,16,18,36,37].…”

Sugar Alcohols and Organic Acids Synthesis in Yarrowia lipolytica: Where Are We?

“…This value is higher than those obtained in a glucose-based medium, suggested that OMW triggers CA synthesis and this waste stream could be used as a co-substrate for CA production. Using a mixture of OMW and crude glycerol, the strain ACA-DC 5029 produced CA with a resultant titer of 79 g/L and yield from glycerol of 0.46 g/g in 528 h [32]. For the Y. lipolytica strain ACA-YC 5031, addition of NaCl (%) in OMW-based media significantly increases CA production with titer and yield from glycerol of 54 g/L and 0.82 g/g, respectively [33].…”

Food and Feed Protein Preparations from Peas and Chickpeas: Production, Properties, Application

“…Микроорганизмы на определенных составах питательной среды обладают высокой скоростью роста и способностью синтезировать спектр питательных соединений: белков, липидов, углеводов, каротиноидов, витаминов и т. д. [51,52]. Биомасса микроорганизмов может использоваться в составе рационов сельскохозяйственных животных и птицы для повышения продуктивности, а в питании человека -для получения новых источников белков.…”