Effects of temperature on cell growth and xanthan production in batch cultures of Xanthomonas campestris
Effects of temperature on cell growth and xanthan production in batch cultures of Xanthomonas campestris
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温度对野油菜黄单胞菌分批培养细胞生长和黄原胶产量的影响
DOI：
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发表时间：
1990
影响因子：
3.8
通讯作者：
Shangtian Yang
中科院分区：
文献类型：
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作者：
C. Shu;Shangtian Yang
对野油菜黄单胞菌NRRL B-1459在22~35℃不同温度下分批发酵黄原胶进行了研究。在24℃或更低的温度下，黄原胶的形成明显滞后于细胞的生长，类似于典型的次生代谢。然而，在27℃和更高的温度下，黄原胶的生物合成伴随着细胞的生长，从指数期开始一直持续到稳定期。细胞在35℃时生长非常缓慢，比生长率接近于零。在27~31℃温度范围内，比生长速率达到最大值0.26h−1，细胞产量从22℃时的0.53g/g葡萄糖降至33℃时的0.28g/g葡萄糖，而黄原胶产量从22℃时的54%提高到33℃时的90%。不同温度下产生的黄原胶的丙酮酸含量在1.9%~4.5%之间，最大值出现在27℃到30℃之间。这些结果表明，细胞生长的最适温度在24℃到27℃之间，而黄原胶形成的最适温度在30℃到33℃之间。对于单级分批发酵，黄原胶的最佳发酵温度取决于设计标准(即发酵速度、黄原胶产量和胶质量)。然而，建议采用两段发酵工艺，将温度从27℃升高到32℃，以分别优化每个阶段的细胞生长和黄原胶形成，从而提高黄原胶发酵的整体水平。
Batch xanthan fermentations by Xanthomonas campestris NRRL B‐1459 at various temperatures ranging between 22°C and 35°C were studied. At 24°C or lower, xanthan formation lagged significantly behind cell growth, resembling typical secondary metabolism. However, at 27°C and higher, xanthan biosynthesis followed cell growth from the beginning of the exponential phase and continued into the stationary phase. Cell growth at 35°C was very slow; the specific growth rate was near zero. The specific growth rate had a maximum value of 0.26 h−1 at temperatures between 27°C and 31°C. Cell yield decreased from 0.53 g/g glucose at 22°C to 0.28 g/g glucose at 33°C, whereas xanthan yield increased from 54% at 22°C to 90% at 33°C. The specific xanthan formation rate also increased with increasing temperature. The pyruvate content of xanthan produced at various temperatures ranged between 1.9% and 4.5%, with the maximum occurring between 27°C and 30°C. These results suggest that the optimal temperatures for cell growth are between 24°C and 27°C, whereas those for xanthan formation are between 30°C and 33°C. For single‐stage batch fermentation, the optimal temperature for xanthan fermentation is thus dependent on the design criteria (i. e., fermentation rate, xanthan yield, and gum qualities). However, a two‐stage fermentation process with temperature shift‐up from 27°C to 32°C is suggested to optimize both cell growth and xanthan formation, respectively, at each stage, and thus to improve overall xanthan fermentation.