College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
Bioresour Technol. 2014 Mar;156:335-41. doi: 10.1016/j.biortech.2013.12.118. Epub 2014 Jan 7.
To better understand the mechanisms for microcystin-LR (MCLR) biodegradation, the linkage between MCLR-biodegradation kinetics and functional gene expression dynamics was originally investigated with Novosphingobium sp. THN1 as inoculum under various nutrient conditions. Along biodegradation, mlrA gene expression, coupled with mlrD, presented similar trend but was regulated differentially among different conditions. Good positive correlation was observed between MCLR degraded and induction ratios of functional genes until 42h at respective condition. Compared to those under nutrient-free condition, the stimulated or decelerated biodegradation with dipotassium phosphate (DP) or ammonium chloride (AC) (both at 100mg L(-1)) was related to higher or lower up-regulation in mlr gene expression, suggesting that divergent mlr gene expression was one of the reasons for different effects of DP or AC on degradation. However, stimulated degradation with sodium nitrate (100mg L(-1)) might involve other mechanisms where mlr expression was not the decisive prerequisite to govern MCLR-biodegradation.
为了更好地理解微囊藻毒素-LR（MCLR）生物降解的机制，本研究以新鞘氨醇单胞菌 THN1 为接种物，在不同营养条件下，最初研究了 MCLR 生物降解动力学与功能基因表达动力学之间的联系。在生物降解过程中，mlrA 基因表达与 mlrD 相关联，呈现出相似的趋势，但在不同条件下受到不同的调控。在各自的条件下，MCLR 降解与功能基因诱导率之间存在良好的正相关关系，直到 42 小时。与无营养条件相比，添加磷酸二氢钾（DP）或氯化铵（AC）（均为 100mg/L）会刺激或减缓生物降解，这与 mlr 基因表达的更高或更低的上调有关，表明不同 DP 或 AC 对降解的影响不同，可能与 mlr 基因表达的不同有关。然而，添加硝酸钠（100mg/L）刺激生物降解可能涉及其他机制，mlr 表达不是控制 MCLR 生物降解的决定性前提。
