Efficient Expression of an Acidic Endo-polygalacturonase from Aspergillus niger and Its Application in Juice Production.
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY(2017)
摘要
An endo-polygalacturonase gene (pga-zj5a) was cloned by reverse transcription from cDNAs synthesized from Aspergillus niger ZJS total RNA. The open reading frame of pga-zjSa was 1089 base pairs encoding 362 amino acids. Pga-zj5a lacking a signal peptide sequence was successfully amplified using A. niger ZJS cDNA as the template and was ligated into the pPIC9 vector. The resulting plasmid was transformed into competent cells of Pichia pastoris GS115 for heterologous expression. The polygalacturonase showed a maximum activity level of 10436 U/mL in the culture supernatant from a 3 L fermenter. Assays of enzymatic properties showed that the optimal pH and temperature of the recombinant PGA-ZJ5A were 4.5 and 40 degrees C, respectively. PGA-ZJ5A was effective in pear juice clarification, increased the volume of pear juice by 41.8%, and improved its light transmittance 3-fold.
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关键词
endo-polygalacturonase,Aspergillus niger,Pichia pastoris,juice production
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