Production of gamma-decalactone by the psychrophilic yeast Rhodotorula aurantiaca A19

(1)

Production of y-decalactone

by the psychrophilic yeast

Rhodotorula aurantiaca

A 19

Université

de liège

L-I __ ••••

Mohamed Alchihab,Frank Delvigne,Jean-Marc Aldric,Jacqueline Destain, Philippe Thonart

Centre Wallon de Biologie Industrielle (CWBI), ULg GxABT, Unité de Bio-industries, Passage des Déportés 2, B-5030 Gembloux,

Belgique.

Ob

j

ectives

The aim of this study was the production of y-decalactone by a psychrophilic yeast in different scales of bioreactor and the extraction of the lactone from broth culture by adsorption on Macronet resins.

Materials and methods:

The influence of substrate (olive oil, castor oil and ricinoleic acid) on the production of y-decalactone by

R. aurantiaca

was firstly studied in a shake-flask cultures. The addition of gum tragacanth to the fermentation medium was also tested to avoid toxicity of the lactone.The production of y-decalactone was realised in 20- and 100-L bioreactors.

The lactone was then extracted of culture broth using 3 Macronet resins (MN-100,MN-102and MN202).

Results:

Experiment

1 _

Effect of substrate on the production of

y-decalactone by

R. aurantiaca.

Preliminary experiments were done to compare the production of y-decalactone by

R. aurantiaca

using pure ricinoleic acid (2%), castor oil (2%) and olive oil (2%) in shake-flask cultures. No difference was observed in y-decalactone production with castor oil and ricinoleic acid. The production of y-decalactone was around 5.2 glL after 10 days of culture. ln the same conditions, no traces of lactones were detected by using olive oil as substrate of bioconversion.

Experiment

2.

Effect of gum tragacanth on the production of

y-decalactone by

R

.

aurantlaca

Experiment 3. Production of y-decalactone by

R

.

aurantiaca

in

20-and 100-L bioreactors.

7

0

₆

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ni

E

5 E

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0

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0

1

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cu

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5 E

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ni

;:

₂

c

0

1

0

1

---gamma10 ....•...MS

.

..-2

3

4

Time (Days)

5

6

7

---gamma10 ....•...MS

B

---"---1

2

3

4

5

6

7

Time (Days)

Figure 2.Production of y-decalactone by

R

.

aurantiaca

in 20- and 100-L

bioreactors

Experiment 4. Extraction of v-decalactone produced by

R

.

aurantiaca

from culture broth.

7

~

100

6

~

:J

_••

:

§5

n

1:

₈₀

ni CI>

n n

~

g

4 C"

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u CI)

₆₀

.!!! 3 .0 cu

• ..

u 0

.

g

2 tI) CIl

>

-"

40 "

1:

cu

o

1 1 1 .L....--J.._...L..._..._J. 1 1 1 1 1----,

"

CIl

20

Control 1 2 3 4 .0

• ..

0 Gumtragacanthconcentration(glL) tI)

"

0

<C

Figure 1.Effect of gum tragacanth on the production of y-decalactone

by

R

.

aurantiaca

The gum tragacanth had a significant effect on the lactone production. The yield was up 30 % on the control with 3 glL of the gum.

o

Adsorbed 0 Desorbed

--3ô

--

r

-l

-

i

-

--3ô-

-

r

-

r

-

+

-MN-202

MN-100

MN-102

Figure 3. Extraction of y-decalactone produced by

R

.

aurantiaca

by adsorption on Macronet resins

The adsorption of y-decalactone on the resins Macronet is a good technique to extract lactone from the culture broth. The resins can be reused without lost of efficacity.