Nakagawa Tomoyuki, Yamada Kaichiro, Fujimura Shuki, Ito Takashi, Miyaji Tatsuro, Tomizuka Noboru
Department of Food Science and Technology, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri, Hokkaido 099-2493, Japan.
Microbiology (Reading). 2005 Jun;151(Pt 6):2047-2052. doi: 10.1099/mic.0.27895-0.
The methylotrophic yeast Pichia methanolica was able to grow on pectic compounds, pectin and polygalacturonate, as sole carbon sources. Under the growth conditions used, P. methanolica exhibited increased levels of pectin methylesterase, and pectin-depolymerizing and methanol-metabolizing enzyme activities. On the other hand, P. methanolica has two alcohol oxidase (AOD) genes, MOD1 and MOD2. On growth on pectin, the P. methanolica mod1Delta and mod1Deltamod2Delta strains showed a severe defect in the growth yield, although the mod2Delta strain could grow on polygalacturonate to the same extent as the wild-type strain. The expression of MOD1 was detected in pectin-grown cells, but the MOD2-gene expression detected by pectin was much lower than that of MOD1. Moreover, pectin could induce peroxisome proliferation in P. methanolica, like methanol and oleic acid. These findings showed that P. methanolica was able to utilize the methylester moiety of pectin by means of methanol-metabolic enzymes in peroxisomes, and that the functional AOD subunit for pectin utilization was Mod1p in P. methanolica.
甲基营养型酵母甲醇毕赤酵母能够以果胶化合物、果胶和聚半乳糖醛酸作为唯一碳源生长。在所使用的生长条件下，甲醇毕赤酵母表现出果胶甲酯酶、果胶解聚酶和甲醇代谢酶活性水平升高。另一方面，甲醇毕赤酵母有两个醇氧化酶（AOD）基因，即MOD1和MOD2。在果胶上生长时，甲醇毕赤酵母mod1Δ和mod1Δmod2Δ菌株在生长产量上表现出严重缺陷，尽管mod2Δ菌株在聚半乳糖醛酸上的生长程度与野生型菌株相同。在果胶培养的细胞中检测到MOD1的表达，但果胶检测到的MOD2基因表达远低于MOD1。此外，果胶能够像甲醇和油酸一样诱导甲醇毕赤酵母中的过氧化物酶体增殖。这些发现表明，甲醇毕赤酵母能够通过过氧化物酶体中的甲醇代谢酶利用果胶的甲酯部分，并且甲醇毕赤酵母中用于利用果胶的功能性AOD亚基是Mod1p。
