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Abstract:
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L-Glutamine amidohydrolase (L-glutaminase, EC 3.5.1.2) is a therapeutically
and industrially important enzyme. Because it is a potent antileukemic
agent and a flavor-enhancing agent used in the food industry, many
researchers have focused their attention on L-glutaminase. In this article, we
report the continuous production of extracellular L-glutaminase by the
marine fungus Beauveria bassiana BTMF S-10 in a packed-bed reactor. Parameters
influencing bead production and performance under batch mode were
optimized in the order-support (Na-alginate) concentration, concentration
of CaCl2 for bead preparation, curing time of beads, spore inoculum concentration,
activation time, initial pH of enzyme production medium, temperature
of incubation, and retention time. Parameters optimized under batch
mode for L-glutaminase production were incorporated into the continuous
production studies. Beads with 12 × 108 spores/g of beads were activated in
a solution of 1% glutamine in seawater for 15 h, and the activated beads were
packed into a packed-bed reactor. Enzyme production medium (pH 9.0) was
pumped through the bed, and the effluent was collected from the top of the
column. The effect of flow rate of the medium, substrate concentration, aeration,
and bed height on continuous production of L-glutaminase was studied.
Production was monitored for 5 h in each case, and the volumetric productivity
was calculated. Under the optimized conditions for continuous production,
the reactor gave a volumetric productivity of 4.048 U/(mL·h), which indicates
that continuous production of the enzyme by Ca-alginate-immobilizedspores is well suited for B. bassiana and results in a higher yield of enzyme
within a shorter time. The results indicate the scope of utilizing immobilized
B. bassiana for continuous commercial production of L-glutaminase |