ROLE OF OXYGEN LIMITATION IN FORMATION OF POLY-BETA-HYDROXYBUTYRATE DURING BATCH AND CONTINUOUS CULTURE OF AZOTOBACTER-BEIJERINCKII
ROLE OF OXYGEN LIMITATION IN FORMATION OF POLY-BETA-HYDROXYBUTYRATE DURING BATCH AND CONTINUOUS CULTURE OF AZOTOBACTER-BEIJERINCKII
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DOI：
10.1042/bj1281193
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发表时间：
1972-01-01
影响因子：
4.1
通讯作者：
DAWES, EA
中科院分区：
文献类型：
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作者：
SENIOR, PJ;BEECH, GA;DAWES, EA
拜氏固氮菌在无氨葡萄糖-矿物盐培养基中分批培养和恒化培养中生长，受葡萄糖、氧气或分子氮供应的限制。在分批培养中，在指数生长快结束时形成聚-β-羟基丁酸酯，并累积至细胞干重的约74%。在恒化器培养中，氮限制的生物体中几乎没有聚β-羟基丁酸酯积累，但当氧限制时，观察到每摩尔葡萄糖的细胞产量大大增加，并且生物体含有高达其干重的50%的聚-β-羟基丁酸酯。在碳限制培养物中（D，稀释率=0.035-0.240h−1），生长产量范围为13.1至19.8g/mol葡萄糖，聚-β-羟基丁酸酯含量不超过干重的3.0%。在限氧培养物中（D=0.049–0.252h−1），生长产量范围为 48.4 至 70.1g/mol 葡萄糖，聚-β-羟基丁酸酯含量为干重的 19.6% 至 44.6%。在限氮培养物中（D=0.053–0.255h−1），生长产量范围为7.45至19.9g/mol葡萄糖，聚-β-羟基丁酸酯含量小于干重的1.5%。对限氮恒化器培养物突然施加氧限制会导致聚-β-羟基丁酸酯含量和细胞产量快速增加。对恒化培养物的测定表明，在限氧稳态（D=0.1h−1）期间，摄氧量下降至每毫克干重 100μl h−1。与葡萄糖限制培养物的 675 相比 (D=0.1h−1)。氮限制培养物的 CO2 产生值范围为每毫克干重 660 至 1055μl h−1。生长速率为 0.053–0.234h−1 时，碳限制培养物表现出每毫克干重 185 至 1328μl h−1 之间的 CO2 产量变化。增长率在 0.035 和 0.240h−1 之间。这些发现与葡萄糖生长过程中聚-β-羟基丁酸酯的形成、生长效率和生长产量相关进行了讨论。我们认为，聚-β-羟基丁酸酯是响应氧限制而产生的，它不仅代表碳和能量的储存，而且还是可以引导过量还原能力的电子接收器。
Azotobacter beijerinckiiwas grown in ammonia-free glucose–mineral salts media in batch culture and in chemostat cultures limited by the supply of glucose, oxygen or molecular nitrogen. In batch culture poly-β-hydroxybutyrate was formed towards the end of exponential growth and accumulated to about 74% of the cell dry weight. In chemostat cultures little poly-β-hydroxybutyrate accumulated in organisms that were nitrogen-limited, but when oxygen limited a much increased yield of cells per mol of glucose was observed, and the organisms contained up to 50% of their dry weight of poly-β-hydroxybutyrate. In carbon-limited cultures (D, the dilution rate,=0.035–0.240h−1), the growth yield ranged from 13.1 to 19.8g/mol of glucose and the poly-β-hydroxybutyrate content did not exceed 3.0% of the dry weight. In oxygen-limited cultures (D=0.049–0.252h−1) the growth yield ranged from 48.4 to 70.1g/mol of glucose and the poly-β-hydroxybutyrate content was between 19.6 and 44.6% of dry weight. In nitrogen-limited cultures (D=0.053–0.255h−1) the growth yield ranged from 7.45 to 19.9g/mol of glucose and the poly-β-hydroxybutyrate content was less than 1.5% of dry weight. The sudden imposition of oxygen limitation on a nitrogen-limited chemostat culture produced a rapid increase in poly-β-hydroxybutyrate content and cell yield. Determinations on chemostat cultures revealed that during oxygen-limited steady states (D=0.1h−1) the oxygen uptake decreased to 100μl h−1per mg dry wt. compared with 675 for a glucose-limited culture (D=0.1h−1). Nitrogen-limited cultures had CO2production valuesin situranging from 660 to 1055μl h−1per mg dry wt. at growth rates of 0.053–0.234h−1and carbon-limited cultures exhibited a variation of CO2production between 185 and 1328μl h−1per mg dry wt. at growth rates between 0.035 and 0.240h−1. These findings are discussed in relation to poly-β-hydroxybutyrate formation, growth efficiency and growth yield during growth on glucose. We suggest that poly-β-hydroxybutyrate is produced in response to oxygen limitation and represents not only a store of carbon and energy but also an electron sink into which excess of reducing power can be channelled.