ABSTRACT

N-acyl homoserine lactones (AHLs) based quorum sensing controls various phenotype expressions, including biofilm formation, hence its interruption is considered to be an ideal option for membrane biofouling control. Bead entrapped quorum quenching bacteria was reported to be an efficient approach for degradation of signal molecules in recent years. In the present study, we investigated the potential of quorum quenching (QQ) bacteria immobilised magnetic nanocomposite beads (IMN) in degradation of signalling molecule, n-hexanoyl homoserine lactone (C6-HSL). Three QQ bacteria, named Acinetobacter baumannii JYQ2, Pseudomonas nitroreducens JYQ3 and Pseudomonas JYQ4 isolated from dairy industry waste activated sludge (WAS) were immobilised in the magnetic nanocomposite (IMN) beads. The scanning electron microscopy (SEM) of the IMN beads has indicated the successful entrapment of QQ bacteria within the alginate matrix. The GC-MS analysis showed that all the QQ bacteria immobilised magnetic nanocomposite (IMN) beads degraded the signalling molecule, n-hexanoyl homoserine lactone (C6-HSL) within 72 h of incubation. The nanocomposite beads containing the QQ bacteria Pseudomonas JYQ4 showed the maximum degradation percentage of 97 ± 0.13% leaving a residual HSL of 0.7 mg/L. All the other isolates showed C6-HSL degradation percentage in the range of 87% to 95%. The data suggest the potential of C6-HSL degradation by QQ bacteria IMN beads. Hence, the study offers possibilities of controlling biofilm developed on the membrane surface during wastewater treatment processes.

摘要

基于 N-酰基高丝氨酸内酯 (AHL) 的群体感应控制各种表型表达，包括生物膜的形成，因此其中断被认为是控制膜生物污染的理想选择。近年来，据报道，珠包埋的群体猝灭细菌是降解信号分子的有效方法。在本研究中，我们研究了群体猝灭 (QQ) 细菌固定磁性纳米复合珠 (IMN) 在信号分子正己酰高丝氨酸内酯 (C6-HSL) 降解中的潜力。三种 QQ 细菌，分别命名为鲍曼不动杆菌JYQ2、Pseudomonas nitroreducens JYQ3 和Pseudomonas从乳业废活性污泥 (WAS) 中分离出来的 JYQ4 被固定在磁性纳米复合材料 (IMN) 珠子中。IMN 珠的扫描电子显微镜 (SEM) 表明 QQ 细菌成功地被困在藻酸盐基质中。GC-MS 分析表明，所有 QQ 细菌固定化磁性纳米复合材料 (IMN) 珠在孵育 72 小时内降解了信号分子正己酰基高丝氨酸内酯 (C6-HSL)。含有 QQ 细菌假单胞菌的纳米复合珠JYQ4 的最大降解百分比为 97 ± 0.13%，残留 HSL 为 0.7 mg/L。所有其他分离株的 C6-HSL 降解百分比在 87% 至 95% 范围内。数据表明 QQ 细菌 IMN 珠可能降解 C6-HSL。因此，该研究提供了在废水处理过程中控制膜表面形成的生物膜的可能性。