الفهرس 
Asparaginase, importance and application in food and medicineOnly 14 pages are availabe for public view
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Abstract
Thirty-six of L-asparaginase producing bacteria were isolated from
soil at Fayoum Governorate. The bacterial isolates were screened for their L-
asparaginase activity on modified-M9 agar medium which supplemented with
0.017 % Bromothmol blue, the diameter of the blue greenish zones (mm) indicate
activity of each isolate was measurements. Bacterial isolates which showed
excellent activity on modified-M9 solid media were further used for the
production of L-asparaginase through the fermentation experiments and the
determination of their productivity after 24 hrs. in the submerged culture. In
generally, the enzyme yield obtained in the fermentation medium were
corresponding to the enzyme level recorded by the diameter of hydrolysis zone
on modified-M9 agar medium. According to the result from the fermentation
experiments, isolates No.15, No. 28 and No. 32 which gave the highest
enzymatic yield were identified. The three isolates were identified based on
morphological characteristic and 16s rRNAgene sequencing analysis, isolates
No. 15 was identified as Brevundimonas olei, isolate No. 28 , No. 32 were
identified as Bacillus subtitles and Bacillus cereus respectively.
The cultures namely Brevundimonas olei No.(15),Bacillus subtilis
No.(28 ) and Bacillus cereus No.(32) which were found potent to be the most
L-aspaginase isolates from soil at Fayoum Governorate, has been used in this
investigation. It was identified according to morphological characteristics by
Senath et al., 1986). Identification was further confirmed by sequencing of the
16S rRNA. Results showed that, the highest enzyme activity was obtained at pH
8.0 for Brevundimonas olei No.15 at incubation temperature 30 0 C. Low level of
L- asparaginase production by Bacillus subtilis No.28 occur at pH 7.0 at
incubation temperature 30 0 C, reached its maximum level at pH 9.0 at incubation
temperature 40 0 C. Also, the effect of different carbon sources on enzyme
production were studied i.e. dextrose, sucrose, Fructose, Lactose and Mannitol
at the concentration of (0.5%) at various incubation period 24, 48 and 72 hrs.
Results that, indicated that, Brevundimonas olei No.15 gave the highest enzyme
yield being (444.8 IU/ml.) after 24 hrs. fermentation period using mannitol as a
sole carbon source followed by dextrose (391.0 IU/ml.), lactose (390.0 IU/ml.)
, sucrose (386.2 IU/ml.) and fructose (379.3 IU/ml.) respectively. Orange and
potato peels were selected as a carbon source for production of L-asparaginase.
Therefore, orange or potato peels were added to the modified M9 broth medium
and substituted glucose. Generally results showed that, potato peels gave the
highest L-asparaginase yield than orange peel for all investigation bacteria
strains.