Biodegradation of ferulic acid by a newly isolated strain of Cupriavidus sp. B-8

As a major component of lignin and abundantly existing in softwood and hardwood, ferulic acid has been used as a lignin-related compound for lignin biodegradation study. Biodegradation of ferulic acid by Cupriavidus sp. B-8, a newly isolated strain, was studied. This strain is able to utilize a wide range of lignin-related aromatic compounds as the sole carbon and energy source, including guaiacol, veratric acid, vanillic acid, cinnamic acid, p-coumaric acid, ferulic acid, and sinapic acid. In addition, the effects of different concentrations of ferulic acid on growth of Cupriavidus sp. B-8 were studied. The growth of Cupriavidus sp. B-8 is better under the condition of lower concentration. High-performance liquid chromatography （HPLC） analysis reveals that above 95% of ferulic acid is degraded within 12 h by Cupriavidus sp. B-8. Based on identification of biodegradation intermediates and further metabolites, the biodegradation pathway of ferulic acid by Cupriavidus sp. B-8 was proposed. Ferulic acid is initially converted to 4-vinylguaiacol, and further oxidized to vanillic acid and protocatechuic acid.

胞外聚合物对细菌还原去除水中Cr(Ⅵ)的作用

为了阐明胞外聚合物(EPS)在Cu^(2+)强化Cupriavidus basilensis B-8(简称“B-8”)还原去除水中Cr(Ⅵ)发挥的作用,通过考察不同Cu^(2+)质量浓度作用下EPS的产量,并借助傅里叶变换红外光谱和三维荧光光谱分析EPS的化学组成和结构。结果表明,当有Cu^(2+)存在时,B-8可分泌更多的EPS,其中溶解态EPS中的多糖和蛋白质量比最高分别可达124.66 mg/g干细胞和2790.87 mg/g干细胞,结合态EPS中的多糖和蛋白质量比最高分别可达41.66 mg/g干细胞和228.21 mg/g干细胞。EPS的增加有利于B-8对水中Cr(Ⅵ)的还原去除。对B-8分泌的溶解态EPS化学组成结构表征发现Cu^(2+)的添加虽提高了B-8分泌的EPS总量,但并未改变EPS的化学组成。另外,还发现Cu^(2+)会与EPS中的芳香类蛋白结合,从而使EPS蛋白质量比降低。这也会促进B-8分泌更多的EPS包裹在细菌的外部,对细菌起到保护,减弱Cr(Ⅵ)等有毒物质对细胞的毒害作用,不但保证了细菌的良好生长,而且保证了细菌对Cr(Ⅵ)还原作用的充分发挥,最终可促进B-8达到较好的Cr(Ⅵ)还原去除效果。