%0 Journal Article
%T CaCO3 Stimulates α-ketoglutarate Accumulation During Pyruvate Fermentation by Torulopsis glabrata<br>碳酸钙促进丙酮酸发酵过程中α-酮戊二酸的形成
%A LIU Li-Ming
%A LI Yin
%A DU Guo-Cheng CHEN Jian
%A <br>刘立明
%A 李寅
%A 堵国成
%A 陈坚
%J 生物工程学报
%D 2003
%I 
%X A large amount of alpha-ketoglutarate (alpha-KG) (6.8 g/L) was accumulated in flask culture when CaCO3 was used as a buffering agent in the production of pyruvate by multi-vitamin auxotrophic yeast Torulopsis glabrata CCTCC M202019. In a 5 L jar-fermentor, less alpha-KG (1.3 g/L) was produced when NaOH was used to adjust the pH, while more alpha-KG (11.5 g/L) detected when CaCO3 was used as the buffer. In the latter case, the molar carbon ratio of pyruvate to alpha-KG (C(PYR)/ CalphaKG) was similar to that obtained in flask culture, suggesting the accumulation of alpha-ketoglutarate was related to the addition of CaCO3. Furthermore, it was found that: (1) delaying the addition time of CaCO3 decreased the a-ketoglutarate formation but increased C(PYR)/ C(alphaKG); and (2) under vitamin limitation conditions increasing the concentration of CaCO3 led to an increased a-KG accumulation at the expenses of pyruvate. To study which ions in CaCO3 was responsible for the accumulation of alpha-KG, the effects of different pH buffers on the a-KG accumulation were studied. The level of alpha-KG was found to correlate with the levels of both Ca2+ and CO3(2-), with Ca2+ played a dominant role and CO3(2-) played a minor role. To find out which pathway was responsible for the accumulation of alpha-KG, the effects of biotin and thiamine on alpha-KG accumulation was investigated. The increase in biotin concentration led to an increase in alpha-KG accumulation and a decrease in C(PYR)/ C(alpha-KG), while the levels of alpha-KG and C(PYR)/C(alphaKG) were not affected by thiamine concentration. The activity of pyruvate carboxylase was increased as much as 40% when the medium was supplemented with Ca2+ . On the other hand, the activity of the pyruvate dehydrogenase complex was unaffected by the presence of Ca2+. To conclude, the higher level of a-KG was caused by higher activity of pyruvate carboxylase stimulated by Ca2+, with CO3(2-) served as the substrate of the reaction.
%K 光滑球拟酵母，α-酮戊二酸，碳酸钙，丙酮酸羧化酶，丙酮酸，发酵
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=90BA3D13E7F3BC869AC96FB3DA594E3FE34FBF7B8BC0E591&jid=A66E90C274451689E69F6F0291467824&aid=48A9E75993CC03BF&yid=D43C4A19B2EE3C0A&vid=2A8D03AD8076A2E3&iid=B31275AF3241DB2D&sid=04EA291949415E08&eid=762CFFBBDED11937&journal_id=1000-3061&journal_name=生物工程学报&referenced_num=8&reference_num=10