Are envelope stress responses essential for persistence to β-lactams in ?

Bacterial persistence to antibiotics defines the ability of small sub-populations of sensitive cells within an isogenic population to survive high doses of bactericidal antibiotics. Here, we investigated the importance of the five main envelope stress responses (ESRs) of in persistence to five bactericidal β-lactam antibiotics by combining classical time-kill curve experiments and single-cell analysis using time-lapse microscopy. We showed that the survival frequency of mutants for the Bae, Cpx, Psp, and Rcs systems treated with different β-lactams is comparable to that of the wild-type strain, indicating that these ESRs do not play a direct role in persistence to β-lactams.

Shear-enhanced sorting of ovoid and filamentous bacterial cells using pinch flow fractionation.

In this paper, we experimentally investigate the influence of the flow rate on the trajectory of ovoid and filamentous bacterial cells of in a low aspect ratio pinch flow fractionation device. To that aim, we vary the Reynolds number over two orders of magnitude, while monitoring the dynamics of the cells across our device. At low flow rates, filamentous cells adopt several rotational motions in the pinched segment, which are induced both by the shear rate and by their close interactions with the nearest wall.

Reassessing the Role of the Type II MqsRA Toxin-Antitoxin System in Stress Response and Biofilm Formation: Is Transcriptionally Uncoupled from .

Toxin-antitoxin (TA) systems are broadly distributed modules whose biological roles remain mostly unknown. The system is a noncanonical TA system in which the toxin and antitoxins genes are organized in operon but with the particularity that the toxin gene precedes that of the antitoxin. This system was shown to regulate global processes such as resistance to bile salts, motility, and biofilm formation.