Production of lipase from aspergillus niger USM E15 using palm kernel cake as substrate and the enzyme application in terpene ester synthesis
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Date
2009-04
Authors
Pandian Kumar, Subbalaxmi
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Abstract
The objective of the study is to produce lipase from an indigenous isolate on
solid state fermentation for terpene ester synthesis. From the total 100 isolates
screened, isolate USM E15 which was identified as Aspergillus niger was
selected as a potential producer of lipase. Optimizations of physical and chemical
parameters were carried out in Erlenmeyer flask and tray system to enhance the
maximum growth and lipase production. The optimum conditions for 250 ml
flask system were 10 g of 0.5 mm palm kernel cake, 70% of (v/w) moisture
content, (0.5%) w/w of olive oil, (0.5%) w/w of molasses, (0.5%) w/w of
peptone, 1 ml inoculum with spore size 1x106 spore/ml, was cultivated for 72 hr
at room temperature (28 ± 3)°C. The maximum lipase activity achieved was 44.5
± 1.95 U/g substrate with the growth of 1.66 ± 0.09 mg glucosamine/g substrate.
The cultivation of Aspergillus niger USM E 15 was also carried out in tray system
of size 297 mm x 200 mm x 60 mm containing 100 g of substrate (Palm kernel
cake), 70% of moisture content, 0.5% (w/w) of olive oil, 1% (w/w) of molasses,
0.5% (w/w) of peptone and inoculum with spore size 1x107 spores/ml cultivated
at room temperature (28 ± 3)°C for 72 hr. The maximum lipase activity obtained
was 39.75 ± 0.27 U/g substrate and growth of 1.32 ± 0.01 mg glucosamine/g
substrate. Characterization of the enzyme shows that the optimum pH was 5.5.
The lipase from Aspergillus niger USM E 15 is stable at pH range from pH 4.5 to
8.0 respectively. The optimum temperature was 37°C. The lipase was stable at
temperature up to 40°C. The presence of metal ions does not show any effect. At
the final concentration of 1 mM EDT A, the lipase was inhibited by 16%. The
lipase also exhibited specificity towards the C-18:1 fatty acids and triolein was
the best substrate. Surfactants such as Tween 20, Tween 40, Tween 60 and Triton
X-100 also inhibited the lipase activity. The lipase is a 1, 3 positional specific.
The SSF material was used for the synthesis of terpene esters. The optimum
conditions for geranyl butyrate synthesis were geraniol (500 mM) butyric acid
(250 mM) at the ratio of 1:0.5, SSF material 0.75 g, molecular sieve pellets 0.75
g in 10 ml n-hexane as solvent. The maximum degree of esterification after
optimization obtained was 91.5 ± 1.5%.
Description
Keywords
Aspergillus niger USM E15 , Using palm kernel , Terpene ester synthesis