| Poly (γ-glutamic acid) (γ-PGA) is an unusual anionic, water-solubleand high viscous polymer in which glutamate is polymerized by amidelinkages between a-amino andγ-carboxylic acid groups. For its excellentcharacters, potential applications ofγ-PGA have been of interest in the pastfew years in a broad range of industrial fields. It has been used asthickeners, humectant and drug carrier.Bacillus subtilis ZJUTZY, which was aγ-PGA producer, was isolatedfrom natto. And the optimum condition for producingγ-PGA was studiedthrough with immobilized Bacillus subtilis ZJUTZY. The betterimmobilizing material was calcium-alginate and the optimum conditionwas as follows: temperature 30℃, initial pH7, rotation speed 200 rpm,inoculum size 12%,beads to liquid 1:3, and CaCl2 concentration 4%.We improved the method of mearing the yield ofγ-PGA by two steps.One is adding a meaturement of the concentration of glutamic acid in the deposit and the other is the confirmation of the dosage of NaOH in the stepof neutralization. Then we found that the highest yield ofγ-PGA was11.02 g/L when the culture time reached 30 hours.Two pairs of degenerate primers was designed to be used to amplifythe partial fragment of pgsB from Bacillus subtilis ZJUTZY according tothe conservative regions of pgsB and the sequence of pgsB from Bacillussubtilis ZJU-7. A DNA band of 817bp was obtained when the latter one wasused. The DNA fragment had 99% identity with the pgsB from manyBacillus subtilis. Based on these results, it was confirmed that partial ofpgsB gene was successfully cloned from the Bacillus subtilis ZJUTZY.
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