[Studies on the correlation between production of L-malic acid and some cytosolic enzymes in the L-malic acid producing strain Aspergillus sp. N1-14].
The cytosol enzymatic study in the case of high L-malic acid(LMA) production of Aspergillus sp. N1-14' was reported. The activities of 4 kind enzymes that catalyse the CO2 fixation reactions have been detected, which are pyruvate carboxylase(PC), phosphoenolpyruvate carboxlase (PEPC), phosphoenolpyurvate carboxykinase(PCK) and malic enzyme(ME). With the exception of ME, the linear correlation was found between activities of three carboxlases and the production rate of LMA. The activity of malate dehydrogenase(MDH) was at the level of 2-3 exponential higher than that of the other analysed enzymes, while the activity of succinate dehydrogenase(SDH) was much lower, and as a discrepancy, SDH was in a positive correlation to the content of LMA in fermenting slurry(r = 0.9252). It is shown that the accumulated LMA acted as an activator of SDH. Through dynamic study, it is found that, in contrast with the slow and even increase of biomass, the content of cytosol protein(Cp) sharply fluctuated mainly due to the changes of aeration conditions. The data of the linear correlation coefficients(r) of activities of cytosol enzymes to Cp(PC r = 0.9563, PEPC r = 0.7688, PCK r = 0.7300, MDH r = 0.3920, SDH r = -0.2086) exhibited an inner law of protein synthesis. Experiment of increasing the amount of spore inoculum resulted in increase of LMA and decrease of SA. After fermenting 120 h in a 5 L stirred fermentor, with 3-fold of original spore inoculum 105.88 g/L of LMA was achieved, the overall productivity was 0.883 g/(L.h), the converting rate of glucose to LMA was 78.43%. This result supports the exist of a inner law of protein synthesis in the early period of LMA fermentation by Aspergillus sp. N1-14'.
Zhou
X
X
Guangdong Institute of Microbiology, Guangzhou 510070.
Wu
Q
Q
Cai
Z
Z
Zhang
J
J
D001230:Aspergillus / Q000201:enzymology* / Q000378:metabolism; D005285:Fermentation; D008291:Malate Dehydrogenase / Q000378:metabolism; D008293:Malates / Q000378:metabolism*; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011766:Pyruvate Carboxylase / Q000378:metabolism; D013172:Spores, Fungal; D013385:Succinate Dehydrogenase / Q000378:metabolism
D008293:Malates; C030298:malic acid; D008291:Malate Dehydrogenase; D013385:Succinate Dehydrogenase; C069767:phosphoenolpyruvate carboxylase kinase; D017346:Protein Serine-Threonine Kinases; D010730:Phosphoenolpyruvate Carboxylase; D011766:Pyruvate Carboxylase