Identification and Characterization of Oleaginous Yeast Isolated from Kefir and Its Ability to Accumulate Intracellular Fats in Deproteinated Potato Wastewater with Different Carbon Sources

Abstract

The search for efficient oleaginous microorganisms, which can be an alternative to fossil fuels and biofuels obtained from oilseed crops, has been going on for many years. The suitability of microorganisms in this regard is determined by their ability to biosynthesize lipids with preferred fatty acid profile along with the concurrent utilization of energy-rich industrial waste. In this study, we isolated, characterized, and identified kefir yeast strains using molecular biology techniques. The yeast isolates identified were Candida inconspicua, Debaryomyces hansenii, Kluyveromyces marxianus, Kazachstania unispora, and Zygotorulaspora florentina. We showed that deproteinated potato wastewater, a starch processing industry waste, supplemented with various carbon sources, including lactose and glycerol, is a suitable medium for the growth of yeast, which allows an accumulation of over 20% of lipid substances in its cells. Fatty acid composition primarily depended on the yeast strain and the carbon source used, and, based on our results, most of the strains met the criteria required for the production of biodiesel. In particular, this concerns a significant share of saturated fatty acids, such as C16:0 and C18:0, and unsaturated fatty acids, such as C18:1 and C18:2. The highest efficiency in lipid biosynthesis exceeded 6.3 g L−1. Kazachstania unispora was able to accumulate the high amount of palmitoleic acid.

Deproteinated Potato Wastewater as a Sustainable Nitrogen Source in Trichosporon domesticum Yeast Lipids Biosynthesis—a Concept of Valorization of Wastewater from Starch Industry

“…After 24-h culture in YPD (yeast extract 10 g L −1 , peptone 20 g L −1 , glucose 20 g L −1 ) medium, yeast biomass (2 mL) was centrifuged at 716×g and 4°C for 10 min. DNA from the yeast biomass was isolated following the protocol described by Gientka et al (2017). The internal transcribed spacer (ITS) region was amplified from yeast ribosomal DNA by PCR using primers ITS1 (5′-TCC GTA GGT GAA CCT GCG G-3′) and ITS4 (5′-TCC TCC GCT TAT TGA TAT GC-3′) (White et al 1990).…”

“…The high C18:1/C18:0 ratios (3.52-3.83) compared with the C16:1/C16:0 ratios (0.03-0.08) during T. domesticum PCM 2960 incubation with DPW may suggest important Δ9 desaturase activity that has a better affinity for fatty acids with 18 carbon atoms than for those with 16 carbon atoms. Makri et al (2010) and Gientka et al (2017) demonstrated a high activity of Δ9 desaturase during the exponential phase of yeast growth. The high levels of C18:1/ C18:0 in Trichosporon lipids on the final culturing day should be explained by the further multiplication of cells.…”

“…Determination of fatty acid methyl esters was conducted using a gas chromatography technique coupled with a flame ionization detector (GC-FID TRACE 1300, Thermo Scientific) after prior acid methylation to methyl esters. Methylation and chromatographic procedures were conducted according to Gientka et al (2017), and the identification of methyl esters was carried out on the basis of retention times of standards present in the mixture (GLC 461 Nu-Chek Prep., Inc., USA).…”

“…In our previous research, we demonstrated that the use of DPW for the cultivation of Candida and Rhodotorula yeast and for obtaining valuable metabolites, such as β-glucans, proteins, lipids, and carotenoids, is possible. DPW is a good source of available forms of nitrogen, and it is also a source of phosphorus, potassium, magnesium, and other micronutrients necessary for the growth of yeast (Bzducha-Wróbel et al 2015;Gientka et al 2017;Kot et al 2017).…”

Deproteinated potato wastewater as a low-cost nitrogen substrate for very high yeast biomass quantities: starting point for scaled-up applications

“…Analysis of the potato wastewater obtained from the process line after the deproteinization stage indicated containing nitrogen and other elements and can be a source of biogenic elements for yeast growth [7,11,17]. Potato wastewater is also a good source of vitamins B 1 , B 2 , B 6 , B 3 /PP, and C, which positively affects the growth of yeast [18].…”