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Low-cost lipid production by an oleaginous yeast cultured in non-sterile conditions using model waste resources.

Santamauro F, Whiffin FM, Scott RJ, Chuck CJ - Biotechnol Biofuels (2014)

Bottom Line: This approach resulted in yields of up to 40% lipid, which compares favourably with other oleaginous microbes.We also demonstrate that M. pulcherrima metabolises glycerol and a diverse range of other sugars, suggesting that heterogeneous biomass could provide a suitable carbon source.M. pulcherrima also grows well in a minimal media containing no yeast extract.

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Affiliation: Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK. R.J.Scott@bath.ac.uk.

ABSTRACT

Background: The yeast Metschnikowia pulcherrima, previously utilised as a biological control agent, was evaluated for its potential to produce lipids for biofuel production.

Results: Cultivation in low cost non-sterile conditions was achieved by exploiting its ability to grow at low temperature and pH and to produce natural antimicrobial compounds. Although not previously classified as oleaginous, a combination of low temperature and restricted nutrient availability triggered high levels of oil production in M. pulcherrima cultures. This regime was designed to trigger the sporulation process but prevent its completion to allow the accumulation of a subset of a normally transitional, but oil-rich, 'pulcherrima' cell type. This approach resulted in yields of up to 40% lipid, which compares favourably with other oleaginous microbes. We also demonstrate that M. pulcherrima metabolises glycerol and a diverse range of other sugars, suggesting that heterogeneous biomass could provide a suitable carbon source. M. pulcherrima also grows well in a minimal media containing no yeast extract. Finally, we demonstrate the potential of the yeast to produce lipids inexpensively on an industrial scale by culturing the yeast in a 500 L, open air, tank reactor without any significant contamination.

Conclusions: The production of antimicrobial compounds coupled to efficient growth at low temperature and pH enables culture of this oleaginous yeast in inexpensive, non-sterile conditions providing a potential route to economic biofuel production.

No MeSH data available.


Related in: MedlinePlus

Effect of glycerol concentration on the growth of a culture of M. pulcherrima, grown at 20°C over 15 days with a starting pH of 5.
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Figure 3: Effect of glycerol concentration on the growth of a culture of M. pulcherrima, grown at 20°C over 15 days with a starting pH of 5.

Mentions: The original screening, to promote lipid accumulation in M. pulcherrima utilised glycerol as a feedstock [26]. Glycerol is an important waste product derived from the biodiesel production process as an aqueous solution (approximately 65% wt/wt) contaminated with small amounts (below 5% wt/wt of each contaminant) of compounds such as methanol, catalyst and organic compounds. These contaminants have not been found to significantly affect the growth of other microorganisms compared to pure glycerol [31]. We therefore first tested the ability of M. pulcherrima to exclusively utilize 95% pure glycerol, a model waste resource, across a broad range of concentrations (1 to 25%). The biomass content increased steadily over the 15-day culture period irrespective of the glycerol concentration (Figure 3). The maximum biomass yield was achieved with a 9% glycerol concentration, which decreased only slightly at higher concentrations. Although we did not investigate the cause of this reduction, high glycerol content could inhibit oxygen uptake or create high osmotic pressures sufficient to inhibit culture growth. However, this effect was minor and our data therefore demonstrate that the yeast thrives on a wide range of glycerol concentrations. Significantly, biomass productivity was above 5 g/L and constant at glycerol concentrations between 5 and 9%, indicating that there is little benefit in biomass terms from almost doubling the glycerol concentration.


Low-cost lipid production by an oleaginous yeast cultured in non-sterile conditions using model waste resources.

Santamauro F, Whiffin FM, Scott RJ, Chuck CJ - Biotechnol Biofuels (2014)

Effect of glycerol concentration on the growth of a culture of M. pulcherrima, grown at 20°C over 15 days with a starting pH of 5.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016040&req=5

Figure 3: Effect of glycerol concentration on the growth of a culture of M. pulcherrima, grown at 20°C over 15 days with a starting pH of 5.
Mentions: The original screening, to promote lipid accumulation in M. pulcherrima utilised glycerol as a feedstock [26]. Glycerol is an important waste product derived from the biodiesel production process as an aqueous solution (approximately 65% wt/wt) contaminated with small amounts (below 5% wt/wt of each contaminant) of compounds such as methanol, catalyst and organic compounds. These contaminants have not been found to significantly affect the growth of other microorganisms compared to pure glycerol [31]. We therefore first tested the ability of M. pulcherrima to exclusively utilize 95% pure glycerol, a model waste resource, across a broad range of concentrations (1 to 25%). The biomass content increased steadily over the 15-day culture period irrespective of the glycerol concentration (Figure 3). The maximum biomass yield was achieved with a 9% glycerol concentration, which decreased only slightly at higher concentrations. Although we did not investigate the cause of this reduction, high glycerol content could inhibit oxygen uptake or create high osmotic pressures sufficient to inhibit culture growth. However, this effect was minor and our data therefore demonstrate that the yeast thrives on a wide range of glycerol concentrations. Significantly, biomass productivity was above 5 g/L and constant at glycerol concentrations between 5 and 9%, indicating that there is little benefit in biomass terms from almost doubling the glycerol concentration.

Bottom Line: This approach resulted in yields of up to 40% lipid, which compares favourably with other oleaginous microbes.We also demonstrate that M. pulcherrima metabolises glycerol and a diverse range of other sugars, suggesting that heterogeneous biomass could provide a suitable carbon source.M. pulcherrima also grows well in a minimal media containing no yeast extract.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK. R.J.Scott@bath.ac.uk.

ABSTRACT

Background: The yeast Metschnikowia pulcherrima, previously utilised as a biological control agent, was evaluated for its potential to produce lipids for biofuel production.

Results: Cultivation in low cost non-sterile conditions was achieved by exploiting its ability to grow at low temperature and pH and to produce natural antimicrobial compounds. Although not previously classified as oleaginous, a combination of low temperature and restricted nutrient availability triggered high levels of oil production in M. pulcherrima cultures. This regime was designed to trigger the sporulation process but prevent its completion to allow the accumulation of a subset of a normally transitional, but oil-rich, 'pulcherrima' cell type. This approach resulted in yields of up to 40% lipid, which compares favourably with other oleaginous microbes. We also demonstrate that M. pulcherrima metabolises glycerol and a diverse range of other sugars, suggesting that heterogeneous biomass could provide a suitable carbon source. M. pulcherrima also grows well in a minimal media containing no yeast extract. Finally, we demonstrate the potential of the yeast to produce lipids inexpensively on an industrial scale by culturing the yeast in a 500 L, open air, tank reactor without any significant contamination.

Conclusions: The production of antimicrobial compounds coupled to efficient growth at low temperature and pH enables culture of this oleaginous yeast in inexpensive, non-sterile conditions providing a potential route to economic biofuel production.

No MeSH data available.


Related in: MedlinePlus