A large number of Gram-negative pat

A large number of Gram-negative pathogens produce N-acylhomoserine lactones (AHLs) as signal molecules for
quorum sensing (QS). This cell–cell communication system allows them to coordinate gene expression and
regulate virulence. Therefore, strategies to inhibit QS are promising for the control of infectious diseases. The aim
of the present study was to develop a high-throughput method for the isolation and identification of AHLdegrading
bacteria from environmental samples. Samples were cultured in a microtitre plate in a minimal
medium containing 1 mM N-(3-oxo-dodecanoyl)-L-homoserine lactone and 2 mM N-(3-oxo-hexanoyl)-Lhomoserine
lactone as the sole sources of carbon and nitrogen. Isolates growing on this minimal medium were
subcultured and identified by partial 16S rRNA gene sequencing. Subsequently, the AHL-degrading capacity of
each isolate was evaluated in the Pseudomonas aeruginosa QSIS2 biosensor assay, as such or after treatment with
heat or proteinase K. The 16 samples tested yielded a total of 59 isolates which are, either alone or as part of a
consortium, able to use AHL signalmolecules as sole sources of carbon and nitrogen. Follow-up experiments have
shown that in each sample there is at least one isolate with quorum quenching (QQ) activity, and that for all
samples combined, 41 isolates haveQQactivity. Furthermore, heat treatment did not fully inhibitQQactivity in all
isolates. In someisolates, QQactivitywas lost after proteinase K treatment,while others remained able to quench
QS. Therefore, it is likely that some isolates produce and secrete (a) heat-stable, lowmolecularweight inhibitory
compound(s).

Results (English) 2:

大量的革兰氏阴性菌产生的N-酰基高丝氨酸内酯（AHLs）作为信号分子
群体感应（QS）。这种细胞–细胞通讯系统使他们能够协调基因表达和调控的毒力
。因此，抑制QS是控制传染病的重要策略。目的
本研究开发的ahldegrading
细菌从环境样品中分离和鉴定的高通量方法。样品培养微孔板在最小的
中含有1毫米N（3-oxo-dodecanoyl）-高丝氨酸内酯和2毫米N-（3 -氧代-己酰基）- lhomoserine
内酯为唯一碳、氮源。在基本培养基上生长的菌株进行传代培养和鉴定
通过16S rRNA基因测序。随后，AHL降解能力的
各菌株的铜绿假单胞菌qsis2生物传感器检测评价，为等或与
热或蛋白酶K 16个样本中，共产生了59株，治疗后，无论是单独或作为一个
财团的一部分，能够使用AHL signalmolecules作为唯一的碳源和氮源。后续实验
表明各样品中至少有一个分离群体感应淬灭（QQ）的活性，并对所有
样品组合，41株haveqqactivity。此外，热处理并没有在所有的
完全inhibitqqactivity菌株。在someisolates，蛋白酶K处理后丢失qqactivitywas，而另一些仍然能够解渴
QS。因此，它是可能的，一些菌株产生和分泌（一）热稳定，低分子量的化合物抑制
（S）。