Westfälische Wilhelms-Universität Münster, Institut für Molekulare Mikrobiologie und Biotechnologie, Corrensstrasse 3, 48149, Münster, Germany.
Appl Microbiol Biotechnol. 2015 Feb;99(4):1557-70. doi: 10.1007/s00253-014-6316-0. Epub 2014 Dec 31.
Natural genetic competence enables bacteria to take in and establish exogenously supplied DNA and thus constitutes a valuable tool for strain improvement. Extensively studied in the Gram-positive model organism Bacillus subtilis genetic competence has indeed proven successful for genetic manipulation aiming at enhancement of handling, yield, and biosafety. The majority of Bacilli, particularly those relevant for industrial application, do not or only poorly develop genetic competence, although rather homologous DNA-uptake machineries are routinely encoded. Establishing the competent state solely due to high cell densities (quorum sensing dependency) appears to be restricted to the model organism, in which the small signalling peptide ComS initiates the regulatory pathway that ultimately leads to the expression of all genes necessary for reaching the competent state. Agreeing with the lack of a functional ComS peptide, competence-mediated transformation of other Bacilli depends on nutrient exhaustion rather than cell density. Genetically, competent strains of the model organism B. subtilis, cultivated for a long time and selected for laboratory purposes, display probably not least to such selection a point mutation in the promoter of a regulatory gene that favors competence development whereas the wild-type progenitor only poorly displays genetic competence. Consistent with competence being a matter of deregulation, all strains of Bacillus licheniformis displaying efficient DNA uptake were found to carry mutations in regulator genes, which are responsible for their genetic competence. Thus, strain-specific genetic equipment and regulation as well as the proven role of domestication for the well-established laboratory strains ought to be considered when attempting to broaden the applicability of competence as a genetic tool for strains other than the model organism.
天然遗传转化能力使细菌能够摄取和建立外源供应的 DNA，因此构成了改良菌株的有价值的工具。在革兰氏阳性模式生物枯草芽孢杆菌中广泛研究的遗传转化能力确实已被证明在遗传操作方面取得了成功，旨在提高处理能力、产量和生物安全性。大多数芽孢杆菌，特别是那些与工业应用相关的芽孢杆菌，要么不具备或仅表现出较差的遗传转化能力，尽管它们通常编码相当同源的 DNA 摄取机制。仅由于细胞密度高（群体感应依赖性）而建立转化能力似乎仅限于模式生物，在该生物中，小信号肽 ComS 启动调节途径，最终导致表达达到转化能力所需的所有基因。与缺乏功能性 ComS 肽一致，其他芽孢杆菌的转化能力依赖于营养物质的耗尽而不是细胞密度。在遗传上，经过长时间培养和为实验室目的选择的枯草芽孢杆菌转化能力菌株，可能至少由于选择，在调节基因的启动子中发生了点突变，这有利于转化能力的发展，而野生型前体仅表现出较差的转化能力。与转化能力是一种去调节的情况一致，所有表现出有效 DNA 摄取能力的地衣芽孢杆菌菌株都发现携带负责其转化能力的调节剂基因的突变。因此，当试图拓宽转化能力作为除模式生物以外的菌株的遗传工具的适用性时，应该考虑菌株特异性的遗传设备和调节以及为既定实验室菌株所证明的驯化作用。
