Cao Xinhua, Qi Yueling, Xu Chen, Yang Yuyi, Wang Jun
Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Appl Microbiol Biotechnol. 2017 Apr;101(8):3463-3472. doi: 10.1007/s00253-016-8087-2. Epub 2017 Jan 9.
Shewanella oneidensis MR-1 degrades various azo dyes under microaerophilic and anaerobic conditions, but this process is inhibited under aerobic conditions. The mechanisms underlying azo dye biodegradation and inhibition remain unknown. Therefore, we investigated metabolic and transcriptional changes in strain MR-1, which was cultured under different conditions, to elucidate these mechanisms. At the transcriptional level, genes involved in certain metabolic processes, particularly the tricarboxylic acid (TCA) cycle, amino acid biodegradation, and the electron transfer system, were significantly altered (M ≧ 2, p > 0.8 ) in the presence of methyl orange (MO). Moreover, a high concentration of dissolved oxygen heavily impacted the expression levels of genes involved in fatty acid biodegradation. Metabolome analysis revealed significant alteration (p < 0.05) in the concentrations of nine metabolites when strain MR-1 was cultured under aerobic conditions; the majority of these metabolites were closely associated with amino acid metabolism and DNA replication. Accordingly, we propose a possible pathway for MO biodegradation and discuss the most likely causes of biodegradation inhibition due to dissolved oxygen.
嗜铁素还原地杆菌MR-1在微需氧和厌氧条件下可降解多种偶氮染料，但该过程在有氧条件下会受到抑制。偶氮染料生物降解及抑制作用的潜在机制尚不清楚。因此，我们研究了在不同条件下培养的MR-1菌株的代谢和转录变化，以阐明这些机制。在转录水平上，在甲基橙（MO）存在的情况下，参与某些代谢过程的基因，特别是三羧酸（TCA）循环、氨基酸生物降解和电子传递系统的基因发生了显著变化（M≧2，p>0.8）。此外，高浓度的溶解氧严重影响了参与脂肪酸生物降解的基因的表达水平。代谢组分析显示，当MR-1菌株在有氧条件下培养时，9种代谢物的浓度发生了显著变化（p<0.05）；这些代谢物中的大多数与氨基酸代谢和DNA复制密切相关。据此，我们提出了一种可能的MO生物降解途径，并讨论了溶解氧导致生物降解抑制的最可能原因。
