Transposable elements (TE), small mobile genetic elements unable to exist independently of the host genome, were initially believed to be exclusively deleterious genomic parasites. However, it is now clear that they play an important role as bacterial mutagenic agents, enabling the host to adapt to new environmental challenges and to colonize new niches. This review focuses on the impact of insertion sequences (IS), arguably the smallest TE, on bacterial genome plasticity and concomitant adaptability of phenotypic traits, including resistance to antibacterial agents, virulence, pathogenicity and catabolism. The direct consequence of IS transposition is the insertion of one DNA sequence into another. This event can result in gene inactivation as well as in modulation of neighbouring gene expression. The latter is usually mediated by de-repression or by the introduction of a complete or partial promoter located within the element. Furthermore, transcription and transposition of IS are affected by host factors and in some cases by environmental signals offering the host an adaptive strategy and promoting genetic variability to withstand the environmental challenges.

最初被认为是转座因子（TE），即不能独立于宿主基因组而存在的小型活动遗传元件，仅被认为是有害的基因组寄生虫。然而，现在清楚的是，它们作为细菌诱变剂发挥着重要作用，使宿主能够适应新的环境挑战并定居新的生态位。这项审查集中在插入序列（IS），可以说是最小的TE，对细菌基因组可塑性和表型性状的伴随适应性的影响，包括对抗菌剂的抵抗力，毒力，致病性和分解代谢。IS转座的直接结果是将一个DNA序列插入另一个DNA序列。此事件可能导致基因失活以及对邻近基因表达的调节。后者通常通过去阻抑或通过引入位于元件内的完全或部分启动子来介导。此外，IS的转录和转座受到宿主因素的影响，在某些情况下还受到环境信号的影响，这些信号为宿主提供了一种适应性策略，并促进了遗传变异性以应对环境的挑战。