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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 the initial pH on the growth of the M. pulcherrima culture grown at 20°C over 15 days (a) and the final pH of the cultures (b).
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Figure 2: Effect of the initial pH on the growth of the M. pulcherrima culture grown at 20°C over 15 days (a) and the final pH of the cultures (b).

Mentions: One of the main factors in maintaining a monoculture is the ability of M. pulcherrima to grow at low pH. In the literature, M. pulcherrima is reported to grow optimally at pH between 5.0 and 7.5, but has been shown to grow at pH as low as 3.0 [22,30]. Under the conditions used in this study M. pulcherrima grew well between pH 3.0 and pH 6.0, though the maximum biomass was observed at an initial pH of 5.0 (Figure 2a). To ensure that the conditions were capable of supporting significant lipid accumulation, a semi-quantitative assay was used. For this samples were collected at regular intervals, stained with the fluorescent dye Bodipy 493/503 and analysed by flow cytometry. Biomass production was only reduced slightly at pH 4.0. Even at pH 3.0, around 85% of the biomass was produced compared to that at pH 5.0. Irrespective of the starting pH, or change in pH during the culture period, biomass productivity remained above 5 g/L. Irrespective of the starting pH, M. pulcherrima acidified the environment, resulting in a pH slightly above 2 (Figure 2b). While presumably too low for optimal biomass production, this would further insure that the cultures remain sterile and that no bacteria could outcompete the yeast.


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 the initial pH on the growth of the M. pulcherrima culture grown at 20°C over 15 days (a) and the final pH of the cultures (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Effect of the initial pH on the growth of the M. pulcherrima culture grown at 20°C over 15 days (a) and the final pH of the cultures (b).
Mentions: One of the main factors in maintaining a monoculture is the ability of M. pulcherrima to grow at low pH. In the literature, M. pulcherrima is reported to grow optimally at pH between 5.0 and 7.5, but has been shown to grow at pH as low as 3.0 [22,30]. Under the conditions used in this study M. pulcherrima grew well between pH 3.0 and pH 6.0, though the maximum biomass was observed at an initial pH of 5.0 (Figure 2a). To ensure that the conditions were capable of supporting significant lipid accumulation, a semi-quantitative assay was used. For this samples were collected at regular intervals, stained with the fluorescent dye Bodipy 493/503 and analysed by flow cytometry. Biomass production was only reduced slightly at pH 4.0. Even at pH 3.0, around 85% of the biomass was produced compared to that at pH 5.0. Irrespective of the starting pH, or change in pH during the culture period, biomass productivity remained above 5 g/L. Irrespective of the starting pH, M. pulcherrima acidified the environment, resulting in a pH slightly above 2 (Figure 2b). While presumably too low for optimal biomass production, this would further insure that the cultures remain sterile and that no bacteria could outcompete the yeast.

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