Growth of marine bacteria in batch and continuous culture under carbon and nitrogen limitation
Growth of marine bacteria in batch and continuous culture under carbon and nitrogen limitation
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DOI：
10.4319/lo.2000.45.4.0789
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发表时间：
2000-06-01
影响因子：
4.5
通讯作者：
Dennett, MR
中科院分区：
文献类型：
--
作者：
Goldman, JC;Dennett, MR
在涉及海洋细菌自然组合的批量和连续培养实验的组合中，我们研究了改变碳和氮底物以及底物 C:N 比率 (C:N-S) 对细菌 C:N 比率 (C:N-B)、总生长效率 (GGE) 以及海洋细菌共代谢氨基酸和 NH4+ 的能力的影响。我们通过不同的葡萄糖、谷氨酸和 NH4+ 组合（在某些情况下使用氨基酸混合物和其他简单碳化合物）将 C:N-S 比率从 5:1（碳限制）更改为 30:1（氮限制）。我们发现 GGE 不受生长速率、C:N-S 比率或碳氮底物的不同组合的影响，平均约为 50%。然而，95% 置信区间高达 +/-20%，这表明实验误差可能是实验室研究中确定 GGE 时的常见问题，而在现场研究中进行此类估计时则是一个更为严重的问题。当碳限制生长时，C:N-B 比率在所有条件下都保持不变，约为 4.5:1（按原子计），但增加到类似于 7:1-9。在批量生长过程中达到稳定期时为 1，在连续培养中以非常低的生长速率达到 13:1。这些结果表明，C:N-B 比率作为确定细菌群体生理状态的诊断工具具有一定的价值，尽管对其普遍适用性存在一些担忧。最后，绝对没有证据表明 NH4+ 的吸收在氨基酸的存在下受到抑制。 NH4+ 吸收的关键是存在易于同化的碳源，以化学计量平衡氮吸收。这些发现对最近的建议有一定影响，即海洋细菌从生产性近海区域到贫营养性公海的 GGE 和氮偏好均存在梯度。
In a combination of batch and continuous culture experiments involving natural assemblages of marine bacteria we examined the impact of varying both the carbon and nitrogen substrates and the substrate C:N ratio (C:N-S) on the bacterial C:N ratio (C:N-B), the gross growth efficiency (GGE), and the ability of marine bacteria to cometabolize amino acids and NH4+. We varied the C:N-S ratio from 5 : 1 (carbon limitation) to 30 : 1 (nitrogen limitation) with varying combinations of glucose, glutamate, and NH4+ (and in some cases with an amino acid mixture and with other simple carbon compounds). We found that GGE was unaffected by growth rate, the C:N-S ratio, or different combinations of carbon and nitrogen substrates, averaging similar to 50%. However the 95% confidence interval was as high as +/-20%, suggesting that experimental error may be a common problem in determining GGE in laboratory studies and a far more serious problem in making such estimates in field studies. The C:N-B ratio was invariant at similar to 4.5:1 (by atoms) under all conditions when carbon was limiting growth, but increased to similar to 7 : 1-9. 1 when reaching the stationary phase during batch growth and up to 13 :1 at very low growth rates in continuous culture. These results indicate that the C:N-B ratio has some value as a diagnostic tool for determining the physiological state of bacterial populations, although there are some concerns about its general applicability. Finally, there was absolutely no evidence that NH4+ uptake was inhibited in the presence of amino acids. The key to NH4+ uptake is the presence of a readily assimilated carbon source to balance nitrogen uptake stoichiometrically. These findings have some bearing on the recent suggestions that gradients exist in both GGE and nitrogen preference of marine bacteria from productive inshore regions to the oligotrophic open ocean.