PUFA

1. SINGLE CELL OIL
DR. ESTHER SHOBA R
ASSISTANT PROFESSOR
KRISTU JAYANTI COLLEGE
BANGALORE

2. INTRODUCTION
• Single cell oils (SCO) are the edible oils extracted from micro-
organisms-the single-celled entities that are at the bottom of the food
chain.
• Single celled entities are algae, bacteria, yeast .
• Lipids are produced by the organism from basic units like carbohydrates
for their cell metabolism & survival.
• THEY ARE THE Triglyceride fats generated by microorganisms.
• Lipid components are similar to those found in plant and animal
• These microbial oils can be used for a variety of production lines ranging
from edible oils and fats to biodiesel.

3. OLEAGINOUS MICROORGANISMS
• Although all microbes have the ability to produce some amount of lipids for their
structural components such as membranes, only a few of them are able to
accumulate lipid in amounts which are of commercial importance.
• Those microorganisms which have the ability to amass lipids more than
20% of their dry cell weight are characterised as oleaginous
microorganisms.
Oleaginous microorganisms fall within the groups of bacteria,
algae, yeasts and fungi, the properties and the compositions of the oils varying
on the species.
Among these, yeasts and fungi are the most efficient producers of oils.
• They produce a variety of oils that are structurally similar to plant oils.
• Moreover, they produce larger amounts of oils than other microbes and their
oils can be easily extracted.
• These characteristics are considered important in order permit an industrially

4. MICRO ALGAE
• Micro algae also produce up to 20-40% (w/w dry weight) lipid content and
their lipids include several polyunsaturated fatty acids of dietary significance.
• However, they require specific growth conditions such as warm temperature,
sunshine and clean water making them a not so suitable choice for industrial
applications.
• Furthermore, special recovery techniques are needed for the extraction of
algal oils, thus further restricting their use.
• However, micro algae are an excellent choice to be used in waste or sewage
treatment plants thereby permitting the production of oils simultaneously with
the bioremediation process.
• In addition, several researches have been carried out and been successful
on growing algae heterotrophically.

5. BACTERIA
• Bacteria, however, are not extensively used as oil producers.
• Though many species of bacteria do produce lipids, only a few of them accumulate
high enough amounts of extractable lipids.
• Some species of bacteria such as Mycobacterium, Corynebacterium and
Rhodococcus accumulate up to 30-40% of lipids but these lipids are hard to extract
and are associated with toxic or allergic factors, making them undesirable as edible
oil producers.
• However, there are on-going researches on using glycoloipids isolated form these
organisms as surfactant.
• Some bacteria, such as Arthrobacter AK 19 can store up to 80% of lipids as its
biomass.
• But this bacterium is slow growing, making its use in commercial applications
somewhat restricted.

10. PHYSIOLOGY OF MICROBIAL PRODUCTION
• Microorganisms produce and accumulate oils as an energy reserve.
• When the microorganisms are grown in a medium in which carbon is
plentiful but another essential nutrient is scarce, the cells rapidly grow and
proliferate until the limited nutrient is exhausted.
• Then the microbes stop dividing but continue to grow.
• Usually, in industrial fermentations nitrogen is the growth limiting nutrient.
• When all the nitrogen in the growth medium is used up, the cells cannot
create new cells since the protein and nucleic acid synthesis is stopped.
• But they continue to assimilate carbon and convert it into oils and fats.

11. • The amount and the nature of the accumulated lipids depend on the
type of microorganism and are genetically predetermined.
• ATP citrate lyase is the enzyme that is responsible for lipid
accumulation in larger quantities.
• The presence of this enzyme implies that the microorganism can stock
lipids more than 20% their biomass.

14. INDUSTRIAL PRODUCTION OF SINGLE CELL OILS
• In commercial manufacturing plants, oil rich biomass is produced by
fermentation of sugar rich media.
• These cells are then seperated by centrifugation.
• Then the oils are extracted by disrupting the cell walls in the presence of
a solvent such as hexane and evaporating the solvent by drying under
vacuum conditions.
• Finally, the extracted crude oil is refined through a series of steps
including neutralisation, degumming, bleaching and deodorisation.

15. THE ADVANTAGES AND DISADVANTAGES OF SINGLE
CELL OILS
• The synthesis of lipids by microorganisms has several advantages over the
production of plant or animal derived oils.
• Microbes have shorter life cycles than plants or animals, warranting a rapid
production.
• Unlike other sources, there is no requirement for farm lands and therefore the
effect of climatic factors on the production is insignificant.
• Moreover, microbial fermentation involves less labour and the scaling up the
production is easier than in other methods.
• On the other hand, the microbial synthesis of lipids is not as economical as the
plant oil production due to the high cost of the carbon sources and the
requirement of sophisticated extraction techniques.
• Furthermore, the oil yields which can be obtained by microorganisms are
comparatively lower than that with plants or animals.

16. • However, these organisms can be genetically engineered to utilise cheaper
substrates such as industrial wastes.
• Another more economical approach is modifying these organisms into producing
more value-added specialty fats and oils or products which can’t be extracted
through other sources.
• This will be more profitable than modifying plant oils into products of higher value
such as cocoa butter.
• An infant formula including a blend of single cell oils, namely arachidonic acid
(ARA) and docosahexaenoic acid (DHA) is currently available in Europe,
Australasia, Far East and USA.
• In addition, cocoa butter-like products are produced using several species of
yeasts such as Cryptococcus curvatus.
• Furthermore, many polyunsaturated fatty acids (PUFA) which have gained
interest as dietary supplements and nutraceuticles, are being synthesised using
microorganisms, mostly fungal and algal species.