Cheng Cheng, Wang Junqing, Wang Tengfei, Yang Xiaohui, Wang Ruiming
College of Biological Engineering, Qilu University of Technology, Jinan 250353, Shandong, China.
Sheng Wu Gong Cheng Xue Bao. 2017 Feb 25;33(2):237-246. doi: 10.13345/j.cjb.160278.
Candida tropicalis uses alkanes and fatty acids to produce long chain dicarboxylic acids. However, the yield can be affected by β-oxidation in peroxisomes. Pxa1p was a membrane protein of Saccharomyces cerevisiae peroxisomes. Pxa1p and Pxa2p form a dimer that is involved in transporting of long chain fatty acids into peroxisomes, but the similar transporting system of Candida tropicalis has not yet been reported. In this study, a ctpxa1 gene deletion strain named C. tropicalis 1798-pxa1 was constructed by homologous single exchange method using PCR fragment. The expression of ctpxa1 gene in C. tropicalis 1798, C. tropicalis 1798-pxa1 was detected by semi-quantitative RT-PCR, and the ratio of gray value was 2.03, implying that the expression of ctpxa1 in C. tropicalis 1798-pxa1 was weakened. After 144 h fermentation, the dodecanedioic acid production of C. tropicalis 1798-pxa1 was increased 94.3% than the former strain, the maximum yield was 10.3 g/L.
热带假丝酵母利用烷烃和脂肪酸生产长链二元羧酸。然而，其产量会受到过氧化物酶体中β-氧化的影响。Pxa1p是酿酒酵母过氧化物酶体的一种膜蛋白。Pxa1p和Pxa2p形成二聚体，参与长链脂肪酸转运进入过氧化物酶体，但热带假丝酵母类似的转运系统尚未见报道。本研究利用PCR片段通过同源单交换法构建了一株ctpxa1基因缺失菌株，命名为热带假丝酵母1798-pxa1。采用半定量RT-PCR检测ctpxa1基因在热带假丝酵母1798、热带假丝酵母1798-pxa1中的表达，灰度值比值为2.03，表明ctpxa1在热带假丝酵母1798-pxa1中的表达减弱。发酵144 h后，热带假丝酵母1798-pxa1的十二烷二酸产量比原菌株提高了94.3%，最高产量为10.3 g/L。
