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Deproteinized whey was used as a substrate for the production of lipids by cold‐adapted yeast Yarrowia lipolytica B9 under non‐sterile culture conditions. Undesired microbial contamination in non‐sterile whey medium could be prevented when appropriate culture parameters (inoculum size of 3 mL/100 mL, initial pH of 5.5 and incubation temperature of 15 °C) were selected. In contrast to additional nitrogen (ammonium sulfate) and phosphorus (potassium dihydrogen phosphate) sources, additional carbon source (lactose) increased lipid accumulation. Under optimized culture conditions, biomass and lipid concentrations of the yeast were found as 7.4 g/L and 4.29 g/L, respectively. Lipid content was determined as 58% of total cell biomass. Fatty acids of the yeast were oleic acid (18:1), cis‐10‐heptadecenoic acid (C17:1), palmitoleic acid (16:1) and palmitic acid (16:0). The yeast was found to contain no polyunsaturated fatty acids. The content of C16 and C18 fatty acids was found to be 91.98% of total lipids. Monounsaturated fatty acids accounted for 80.54% of total lipids. Due to rich monounsaturated fatty acid composition, biomass of Y. lipolytica B9 may be used as feedstock for biodiesel production, especially operating in winter conditions. This is the first report on the use of cheese whey as a lipid production substrate for cold‐adapted microorganisms including Y. lipolytica yeast. Besides, lipid production potential of Y. lipolytica under non‐sterile culture conditions was investigated for the first time in this study. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

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This study focused on investigating the effect of exogenously applied two quorum sensing molecules (tyrosol and farnesol) on the synthesis of bioactive metabolites (pigments, lactic acid, ethanol, and citric acid) in Monascus purpureus ATCC16365. None of the tested concentrations (62.5, 125, 250, and 500 µl/L) of farnesol affected the synthesis of metabolites as well as cell growth. As with farnesol application, none of the tested concentrations (3.45, 6.9, 13.8, and 27.6 mg/L) of tyrosol caused a significant change in the synthesis of lactic acid and citric acid as well as cell growth. Conversely, all of the tested concentrations of tyrosol increased pigment synthesis but reduced ethanol synthesis, compared with the control. Maximum increases (3.16‐, 2.68‐, and 2.87‐fold increase, respectively) in yellow, orange, and red pigment production were achieved, especially when 6.9‐mg/L tyrosol was added to the culture on day 3. On the contrary, 6.9‐mg/L tyrosol reduced the content of citrinin by approximately 51.5%. This is the first report on the effect of tyrosol and farnesol on the synthesis of Monascus metabolites. Due to potential properties, such as low price, nonhuman toxicity, promotion of pigment synthesis, and reduction in citrinin synthesis, tyrosol can be used as a novel inducer in the fermentative production of Monascus pigments.

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