蛋白组学差异揭示黑曲霉（Aspergillus niger）高产柠檬酸的分子机制

黑曲霉（Aspergillus niger）YX-1217是一株典型的柠檬酸高产菌株，基于二维聚丙烯酰胺凝胶电泳（2-DE）对黑曲霉YX-1217 和退化菌株YX-1217G的胞外分泌蛋白进行比较，同时利用同位素标记相对和绝对定量（iTRAQ）技术比较了两株菌的胞内蛋白差 异，揭示黑曲霉YX-1217高产柠檬酸的分子机制。 结果显示，菌株黑曲霉YX-1217G的胞外蛋白数量和浓度均显著低于菌株黑曲霉 YX-1217（P＜0.05），通过质谱鉴定了6个黑曲霉YX-1217高表达蛋白；利用iTRAQ技术共鉴定到3 553个蛋白，将差异蛋白按照京都基 因与基因组百科全书（KEGG）代谢数据库进行分类，发现与柠檬酸生物合成相关的酶在菌株黑曲霉YX-1217中的表达量显著高于退 化菌株（P＜0.05），这些蛋白的高效表达是菌株黑曲霉YX-1217高产柠檬酸的原因之一，为开发柠檬酸或其他有机酸的高产菌株提供 新的思路和观点。

Molecular mechanism revealed by proteomic differences of Aspergillus niger with high yield citric acid

Aspergillus niger YX-1217 is a typical high citric-acid-producing strain. Based on the two proteomics techniques of two-dimensional polyacrylamide gel electrophoresis (2-DE) and isobaric tags for relative and absolute quantification (iTRAQ), the exocytosis proteins and intracellular proteins of A. niger YX-1217 and degenerative A. niger YX-1217G were compared and the differential proteins involved in citric acid production were analyzed, which revealed the mechanism of A. niger YX-1217 with citric acid production. The results showed that the amount and concentration of extracellular proteins of A. niger YX-1217G were significantly lower than that of A. niger YX-1217 (P＜0.05), and six overexpression proteins were identified by mass spectrometry. A total of 3 553 intracellular proteins were identified by iTRAQ technique. The differential proteins were classified according to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database and the results showed that the expression level of proteins involved in citric acid biosynthesis in strain A. niger YX-1217 was significantly higher than that in degenerative strain A. niger YX-1217G (P＜0.05). The high expression of these proteins was obviously one of the important reasons for the citric acid production of strain A. niger YX-1217, which would provide new ideas for the development of strains with high yield citric acid or other organic acids.