Department of Biology, Faculty of Sciences, University of Isfahan, Azadi Sq., Daneshgah St., Isfahan, Islamic Republic of Iran.
Appl Biochem Biotechnol. 2012 Jan;166(1):1-12. doi: 10.1007/s12010-011-9397-6. Epub 2011 Oct 12.
To screen strains of halotolerant or halophile bacteria which are able to convert isoeugenol to vanillin, 36 different strains of bacteria isolated from the salty environments in Iran were investigated. During growth on isoeugenol, a moderately halotolerant Gram-negative coccobacil showed capability of converting isoeugenol to vanillin. Based on morphological, physiological, and phylogenetic studies, strain CSW4 was classified as a bacterium belonging to the genus Psychrobacter. The bioconversion products were confirmed by thin-layer chromatography, high-performance liquid chromatography, and spectral data obtained from UV/Vis spectroscopy, FTIR, and mass-spectroscopy. Using growing cells, vanillin reached its maximum level of 88.18 mg L(-1) after 24 h of reaction time in the presence of 1 g L(-1) isoeugenol, resulting in a molar yield of 10.2%. The use of resting cells led to the optimal yield of vanillin (16.4%) which was obtained after 18-h reaction using 1 g L(-1) isoeugenol and 3.1 g of dry weight of cells per liter harvested at the end of the exponential growth phase. To improve vanillin yield, the effect of substrate concentration on vanillin production under resting cells conditions was also investigated. Using 10 g L(-1) isoeugenol, the maximal vanillin concentration (1.28 g L(-1)) was achieved after a 48-h reaction, without further optimization. The present study brings the first evidence for biotransformation of isoeugenol to vanillin in the genus Psychrobacter.
为了筛选能够将异丁香酚转化为香草醛的耐盐或嗜盐细菌菌株，我们研究了从伊朗盐环境中分离得到的 36 株不同的细菌。在异丁香酚生长过程中，一株中度耐盐革兰氏阴性球杆菌表现出将异丁香酚转化为香草醛的能力。根据形态学、生理学和系统发育研究，CSW4 菌株被分类为属于Psychrobacter 属的细菌。通过薄层层析、高效液相色谱和从紫外/可见光谱、傅里叶变换红外光谱和质谱获得的光谱数据确认了生物转化产物。使用生长细胞，在 1 g/L 异丁香酚存在下反应 24 小时后，香草醛达到 88.18 mg/L 的最大水平，摩尔产率为 10.2%。使用静止细胞导致香草醛的最佳产量（16.4%），这是在 1 g/L 异丁香酚和 3.1 g/L 对数生长期结束时收获的细胞干重的条件下反应 18 小时获得的。为了提高香草醛的产量，还研究了静止细胞条件下底物浓度对香草醛生产的影响。使用 10 g/L 异丁香酚，在 48 小时反应后，达到了最大香草醛浓度（1.28 g/L），无需进一步优化。本研究首次证明了 Psychrobacter 属中异丁香酚向香草醛的生物转化。
