Laboratory of Molecular Epidemiology, Federal University of Uberlandia, Uberlandia, Brazil.
Biotechnology Institute, Federal University of Uberlandia, Uberlandia, Brazil.
Front Cell Infect Microbiol. 2023 Mar 28;13:1122450. doi: 10.3389/fcimb.2023.1122450. eCollection 2023.
Despite being considered fragile and fastidious, is the most prevalent cause of foodborne bacterial gastroenteritis, and chicken meat is considered the main vehicle of transmission to humans. This agent can survive adverse conditions in the form of biofilms, but extreme stress (nutritional, oxidative and thermal) promotes the acquisition of a state called viable but not culturable (VBNC). The emergence of this pathogen worldwide and the recent international requirements in its control instigated us to qualitatively and quantitatively estimate the time required for the acquisition of the VBNC form in 27 strains of , characterize morphological aspects, determine its adaptive and invasive potential and perform comparative metabolomic evaluation. Extreme stress promoted the complete acquisition of the VBNC form in a mean time of 26 days. Starting from an average initial count of 7.8 log CFU/mL, the first four days determined the greatest average reduction of the culturable form of 3.2 log CFU/mL. The scanning and transmission image analyses showed a transition from the typical viable form (VT) to the VBNC form, with initial acquisition of the straight rod shape, followed by loss of the flagella and subdivision into two to 11 imperfect cocci arranged in a chain and rich in cellular content, until their individual release. RT-PCR identified the presence of and transcripts in the 27 cultivable strains, a character maintained in the VBNC form only for and in 59.3% (16/27) of the VBNC strains for the gene. The average inoculation of 1.8 log CFU/mL of VBNC into primary chicken embryo hepatocyte cells promoted the occurrence of apoptosis processes significantly after 24 hours of contact by one of the strains tested. In VBNC, we detected higher expression of metabolites linked to protective and adaptation mechanisms and of volatile organic precursor compounds indicative of metabolism interruption. The oscillations in the time of acquisition of the VBNC form together with the presence of transcripts for and , the identification of cell lysis and metabolites that ensure the maintenance of the pathogen alert to the fact that VBNC remains virulent and adapted to stress, which makes evident the potential danger of this latent form, which is not detectable by official methodologies.
尽管被认为脆弱且挑剔， 却是食源性细菌胃肠炎最普遍的原因，而鸡肉被认为是传播给人类的主要媒介。这种病原体可以以生物膜的形式在不利条件下存活，但极端压力（营养、氧化和热）会促进其获得一种称为存活但不可培养（VBNC）的状态。该病原体在全球范围内的出现以及最近对其控制的国际要求促使我们定性和定量估计 27 株 获得 VBNC 形式所需的时间，表征形态方面，确定其适应和侵袭潜力，并进行比较代谢组学评估。极端压力在 26 天内完全促进了 VBNC 形式的获得。从平均初始计数 7.8 log CFU/mL 开始，前四天确定了可培养形式的最大平均减少 3.2 log CFU/mL。扫描和传输图像分析显示，从典型的存活形式 (VT) 到 VBNC 形式的转变，最初获得直杆形状，随后失去鞭毛并分裂成两个至 11 个不完美的球菌，排列成链状并富含细胞内容物，直到它们单独释放。RT-PCR 在 27 株可培养 中鉴定出 和 转录本的存在，该特征仅在 VBNC 形式中保持，仅对于 和在 59.3%（16/27）的 VBNC 株中保持 基因。将 1.8 log CFU/mL 的 VBNC 平均接种到原代鸡胚肝细胞中，在接触后 24 小时内显著促进了一种测试菌株引起的细胞凋亡过程。在 VBNC 中，我们检测到与保护和适应机制相关的代谢物以及挥发性有机前体化合物的表达水平升高，这些化合物表明代谢中断。获得 VBNC 形式的时间波动以及 和 的转录本的存在、细胞裂解的鉴定和维持病原体警觉的代谢物，这表明 VBNC 仍然具有毒力并适应压力，这突显了这种潜在形式的潜在危险，这种形式无法通过官方方法检测到。
