Department of Bacterial Genetics, Institute of Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
Int J Mol Sci. 2019 Apr 24;20(8):2015. doi: 10.3390/ijms20082015.
sp. DAB_AL32B, originating from Spitsbergen island (Arctic), carries the large plasmid pP32BP2 (54,438 bp). Analysis of the pP32BP2 nucleotide sequence revealed the presence of three predicted phenotypic modules that comprise nearly 30% of the plasmid genome. These modules appear to be involved in fimbriae synthesis via the chaperone-usher pathway (FIM module) and the aerobic and anaerobic metabolism of carnitine (CAR and CAI modules, respectively). The FIM module was found to be functional in diverse hosts since it facilitated the attachment of bacterial cells to abiotic surfaces, enhancing biofilm formation. The CAI module did not show measurable activity in any of the tested strains. Interestingly, the CAR module enabled the enzymatic breakdown of carnitine, but this led to the formation of the toxic by-product trimethylamine, which inhibited bacterial growth. Thus, on the one hand, pP32BP2 can enhance biofilm formation, a highly advantageous feature in cold environments, while on the other, it may prevent bacterial growth under certain environmental conditions. The detrimental effect of harboring pP32BP2 (and its CAR module) seems to be conditional, since this replicon may also confer the ability to use carnitine as an alternative carbon source, although a pathway to utilize trimethylamine is most probably necessary to make this beneficial. Therefore, the phenotype determined by this CAR-containing plasmid depends on the metabolic background of the host strain.
sp. DAB_AL32B，源自斯匹次卑尔根岛（北极地区），携带大型质粒 pP32BP2（54438bp）。对 pP32BP2 核苷酸序列的分析表明，存在三个预测的表型模块，占质粒基因组的近 30%。这些模块似乎参与了通过伴侣-usher 途径（FIM 模块）合成菌毛和肉碱的有氧和无氧代谢（分别为 CAR 和 CAI 模块）。FIM 模块在不同宿主中具有功能，因为它促进了细菌细胞附着在无生命表面上，增强了生物膜的形成。CAI 模块在所有测试的菌株中均未显示出可测量的活性。有趣的是，CAR 模块使肉碱的酶促分解成为可能，但这导致了有毒副产物三甲胺的形成，从而抑制了细菌的生长。因此，一方面，pP32BP2 可以增强生物膜的形成，这在寒冷环境中是一个非常有利的特征，另一方面，它可能会在某些环境条件下阻止细菌的生长。携带 pP32BP2（及其 CAR 模块）的不利影响似乎是有条件的，因为该复制子还可能赋予利用肉碱作为替代碳源的能力，尽管很可能需要一种利用三甲胺的途径来使这种能力有益。因此，这种含 CAR 质粒决定的表型取决于宿主菌株的代谢背景。
