Effect of sodium hypochlorite (NaClO) sanitizer-induced stress on growth kinetics and morphological changes in Escherichia coli and Bacillus cereus spores

(+)-Terpinen-4-ol Inhibits Bacillus cereus Biofilm Formation by Upregulating the Interspecies Quorum Sensing Signals Diketopiperazines and Diffusing Signaling Factors

“…Spore Formation and Germination Assay. B. cereus spores were prepared and collected using previously reported procedures 37 with some modifications. For the spore formation assay, B. cereus ATCC 14579 was cultivated in manganese sulfate nutrient medium at 30 °C for 72 h in the absence and presence of (+)-terpinen-4-ol (3 or 6 μmol/mL).…”

“…The B. cereus cell morphology was observed using TEM (JEM-2100PLUS, JEOL, Japan) according to previously reported procedures with some modifications. , B. cereus ATCC 14579 was cultured in manganese sulfate nutrient medium at 30 °C for 1 week. Then, each sample of bacterial culture was centrifuged at 1500 × g for 5 min, and the precipitate was resuspended in 0.5% (v/v) glutaraldehyde.…”

A phenotypic screening bioassay forEscherichia colistress and antibiotic responses based on Fourier‐transform infrared (FTIR) spectroscopy and multivariate analysis

“…The following stress agents were evaluated, since these challenge bacteria with a wide range of stresses, thereby providing a broad variety of responses: 10% (v/v) ethanol (Sigma-Aldrich, St. Louis, MO); 8% (w/v) NaCl (Merck); 80 ppm sodium hypochlorite (VWR, Lisboa, Portugal); 2 mol l À1 hydrochloric acid solution (Sigma-Aldrich) corresponding to a final pH of 2Á00; and a 0Á5 mol l À1 sodium hydroxide solution (Fluka, Diegem, Belgium) corresponding to a final pH of 10Á66. These concentrations are adequate to study E. coli stress responses since they are insufficient to induce cell death, as confirmed by cell viability assays in other studies (Foster and Richard 2004;Sharma and Beuchat 2004;Kwak et al 2014;Kim and Rhee 2016;Cao et al 2017). Moreover, each stress agent had a paired control sample, where the stress agent was replaced with distilled sterile water.…”

“…Bacterial responses to stressful events encompass a wide variety of adaptations, many of which have been described for E. coli , including those following exposure to: sodium hypochlorite, a strong oxidizer that up‐regulates over 380 genes and induces faster post‐exposure recovery cell growth (Wang et al ; Kwak et al ); ethanol, which disrupts the membrane and cell wall integrity, reducing O 2 levels and ATP production, as well as fostering DNA damage and a six orders of magnitude increase of protein expression (Soufi et al ; Cao et al ); sodium chloride, which increases water efflux, thereby affecting morphology and reducing maximum growth, ultimately resulting in extensive cell damage and loss of integrity (Hajmeer et al ; Kim and Rhee ; Lee and Kang ,, ; Omotoyinbo and Omotoyinbo ); and acidic environments that activate mechanisms to counteract the pH imbalance (Richard and Foster ; Foster ; Foster and Richard ; Kanjee and Houry ). Fewer studies have discussed alkaline stress responses in E. coli , nonetheless two heat shock proteins and the rpoS gene have been shown to take part in the alkaline stress response (Saito and Kobayashi ; Sharma and Beuchat ), and other propositions have been put forward for other lactic acid bacteria (Nyanga‐Koumou et al ).…”