Effect of Incubation Media on the Recovery of Escherichia coli K12 Heated at 52 0C

Abstract

37The exposure of exponentially grown Escherichia coli ~1 2 to 52 "C for 30 min in Tris/Mg2+ buffer resulted in a considerable loss of viability when plated on tryptone agar. When such heated bacteria were held at 37 "C for 2 h in tryptone broth before plating on tryptone agar, there was a significant increase in viability. Thus, heat damage was repaired in tryptone broth but not on tryptone agar. Recovery was greater in tryptone broth than in synthetic medium. In tryptone broth, recA or polA mutants also recovered but a lex mutant did not.As a result of heating, the sensitivity of bacteria to ultraviolet radiation (u.v.), to mitomycin C and to plating on high salt medium was enhanced. After incubation for 2 h in tryptone broth at 37 "C, the bacteria regained their resistance to U.V. and mitomycin C and tolerance to high salt medium. Recovery of viability required RNA and protein synthesis, whereas recovery of U.V. resistance did not require protein synthesis. Heating for 30 min inhibited the release of acid-soluble material from DNA in all strains of E. coli used.

Cryopreservation of Mycobacterium tuberculosis Complex Cells

“…When cells are exposed to stressful environments, e.g., cooling, heating, radiation, or desiccation, cellular functions may be impaired. It has been observed that for some cells, preincubation in broth or liquid medium for some time after exposure to the stress may help repair the injuries (1,8,15,23); however, others doubt its effectiveness (7). In the present work, preincubation did not improve the recovery of cryopreserved BCG cells from cryoinjury.…”

“…Common cryopreservation media, the effect of a cryoprotective agent (glycerol), and the cooling rate were studied. It has been suggested that transient incubation of cells in broth medium after exposure to stress environments, such as heating, freezing/thawing, or UV light, helps to repair the injury for some cell types (1,8,15,23). Therefore, the effect of transient incubation (preincubation) on cryopreserved BCG cells was also explored.…”

Heat Resistance in Liquids of Enterococcus spp., Listeria spp., Escherichia coli, Yersinia enterocolitica, Salmonella spp. and Campylobacterspp

“…Most Probable Number (MPN) techniques were applied in some investigations. Procedures for repair of heat-injured bacteria were studied by [1,127,116,157,158,63]. …”

Solar optics-based active panel for solar energy storage and disinfection of greywater

“…For example, the D 60 and Z values of E. coli were reported to range from 35 $ 42 s to 5.9 $ 6.1 C (95% confidence interval). [29][30][31][32][33][34][35][36][37][38] The D 60 and Z values of E. faecium ranged from 1.0 Â 10 3 $ 1.3 Â 10 3 s to 8.8 $ 11 C (95% confidence interval). [39][40][41][42][43][44][45][46] The effects of SOAP on water temperature and R D with respect to lens structure (e.g., hemispherical and semi cylindrical lens) are also investigated in Figure 3 temperature of the hemispherical lens at the focal point is higher than that of the semi cylindrical lens by about 8 C, the hemispherical lens shows about 3% higher R D in the case of E. faecium (Figure 3(c)).…”