THE ROLE OF CARBON-DIOXIDE IN GLUCOSE-METABOLISM OF BACTEROIDES-FRAGILIS
THE ROLE OF CARBON-DIOXIDE IN GLUCOSE-METABOLISM OF BACTEROIDES-FRAGILIS
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DOI：
10.1007/bf00419476
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发表时间：
1983-01-01
影响因子：
2.8
通讯作者：
MACY, JM
中科院分区：
文献类型：
--
作者：
CASPARI, D;MACY, JM
在确定的矿物质培养基中，研究了CO2浓度对脆弱芽孢杆菌生长和葡萄糖发酵的影响。分批培养实验是在封闭的管子中进行的，二氧化碳浓度在10-100%之间(加入适量的碳酸氢盐以保持pH为6.7)。当CO2浓度高于30%CO2(最低有效CO2-HCO3-，25.5 mm)时，CO2对生长速率或细胞产量没有影响，而在20和10%CO2(有效CO2-HCO3-，分别为17和8.5 mm)时，这些参数略有下降。当CO2-HCO3-浓度低于10 mM时，细胞生长停滞期延长，最大生长速率和细胞产量下降。乙酸量减少，D-乳酸浓度增加。二氧化碳的净产量允许在添加的二氧化碳浓度极低的条件下生长。当脆弱芽孢杆菌在100%CO_2或100%N_2连续培养条件下生长时，稀释度影响醋酸酯、琥珀酸、丙酸、D-乳酸、L-苹果酸和甲酸的形成。在这两种条件下，降低稀释率都有利于丙酸酯和乙酸酯的生产。当有机体在100%的氮气中生长时，在所有稀释率下生成的丙酸量大于形成的琥珀酸量。除缓慢稀释速率外，当使用100%二氧化碳时情况正好相反。当氮气浓度为100%时，脆弱芽孢杆菌不能以高于0.154 h-1的稀释率生长。当气体气氛为100%CO2时，当稀释率超过0.38h-1时，微生物被冲出培养物。用脆弱芽孢杆菌的完整、通透性细胞对磷酸烯醇式丙酮酸(PEP)羧酸激酶(EC 4.1.1.49)的测定表明，随着CO2浓度的降低，比酶活性增加。讨论了脆弱芽孢杆菌适应低二氧化碳水平的机制。
The effect of CO2 concentration on growth and glucose fermentation of B. fragilis was studied in a defined mineral medium. Batch culture experiments were done in closed tubes containing CO2 concentrations ranging from 10-100% (with appropriate amounts of bicarbonate added to maintain the pH at 6.7). CO2 had no influence on growth rate or cell yield when the CO2 concentration was above 30% CO2 (minimum available CO2-HCO3-, 25.5 mM), whereas a slight decrease in these parameters was observed at 20 and 10% CO2 (available CO2-HCO3-, 17 and 8.5 mM, respectively). If CO2-HCO3- concentrations were below 10 mM, the lag phase lengthened and a decrease in maximal growth rate and cell yield were observed. The amount of acetate made decreased, while D-lactate concentration increased. A net production of CO2 allowed growth under conditions of extremely low concentrations of added CO2. When B. fragilis was grown in continuous culture with 100% CO2 or 100% N2, the dilution rate influenced the concentrations of acetate, succinate, propionate, D-lactate, L-malate and formate formed. Decreasing the dilution rate favored propionate and acetate production under both conditions. When the organism was grown with 100% N2, the amount of propionate formed was greater than the amount of succinate formed at all dilution rates. Except at slow dilution rates the reverse was true when 100% CO2 was used. B. fragilis was unable to grow at dilution rates faster than 0.154 h-1 when grown with 100% N2. If the gas atmosphere was 100% CO2 the organism was washed out of the culture when the dilution rate exceeded 0.38 h-1. Measurement of the phosphoenolpyruvate (PEP) carboxykinase (EC 4.1.1.49) with whole, permeabilized cells of B. fragilis showed an increase of specific enzyme activity with decreasing CO2 concentrations. The mechanisms used by B. fragilis to adjust to low levels of CO2 are discussed.