Heat-induced blebbing and vesiculation of the outer membrane of Escherichia coli

Abstract

Thermal damage to the outer membrane of Escherichia coli W3110 was studied. When E. coli cells were heated at 55°C in 50 mM Tris-hydrochloride buffer at pH 8.0, surface blebs were formed on the cell envelope, mainly at the septa of dividing cells. Membrane lipids were released from the cells during the heating period, and part of the released lipids formed vesicle-like structures from the membrane. This vesicle fraction had a lipopolysaccharide to phospholipid ratio similar to that of the outer membrane of intact cells, whereas it had a lower content of protein than the isolated outer membrane. After heating bacterial cells at 55°C for 30 min, the resulting leakage from the cells of a periplasmic enzyme, alkaline phosphatase, amounted to 52% of the total activity, whereas no release of a cytoplasmic enzyme, glucose-6-phosphate dehydrogenase, was detected. The results obtained suggest that surface blebs formed by heat treatment almost completely consist of the outer membrane and that the blebs may be gradually released from the cell surface into the heating menstruum to partially form vesicles.

Temperature shock, injury and transient sensitivity to nisin in Gram negatives

“…This is presumably due to the temporary appearance of phospholipid in the OM ®lling the void space (Nikaido and Vaara 1985). The release of LPS by heating has been reported previously (Katsui et al 1982;Tsuchido et al 1985) but not as a result of freeze/thawing, though conformational alteration and structural damage of LPS in the heptose region have been described (Ray et al 1976;Kempler and Ray 1978).…”

“…In particular, a variety of changes can occur in the outer membrane, including morphological and structural changes, involving blebs and vesiculation, and damage or release of lipopolysaccharides. These changes can alter the permeability barrier, causing ef¯ux of periplasmic enzymes, and sensitivity to hydrophobic compounds, dyes and surfactants (Ray et al 1976;Kempler and Ray 1978;Katsui et al 1982;Tsuchido et al 1985). Such injury can be temporary, with bacteria having the capacity to recover or repair subsequently.…”

Sensitivity of Sublethally Injured Gram‐negative Bacteria to Pediocin P

“…In particular, a variety of changes can occur in the OM, including morphological and structural changes involving blebs, vesiculation and damage or release of lipopolysaccharides (LPS). These changes can alter the permeability barrier, causing efflux of periplasmic enzymes and sensitivity to hydrophobic compounds, dyes and surfactants (Ray et al 1976;Kempler and Ray 1978;Katsui et al 1982). Stressed and sublethally injured bacteria are more susceptible to the bactericidal action of bacteriocins because of impaired cell wall barriers.…”

The recovery of heat-stressed Escherichia coli in lake water microcosms

“…Several possible targets for thermal inactivation of bacteria, such as DNA, RNA, protein and membranes, have been proposed (Iandolo and Ordal 1966;Woodcock and Grigg 1972;Tomlins and Ordal 1976;Welker 1976). Rogers (1971) showed that proteins and lipopolysaccharide were lost from the outer membrane of heated Gram-negative bacteria and Katsui et al (1982) showed that parts of the lipid A region were also lost. Evidence for damage to the substrate transport function of membranes due to heat treatment in Escherichia coli has been presented by Gray (1978).…”

“…Escherichia coli and Listeriu monocytugenes subjected to heat shock at 50°C and 71°C respectively became more sensitive to inhibitory compounds such that counts on selective media were lower than plate counts on non-selective nutrient agar plates (Stiles et al 1973 ;Mossel and van Netten 1984;Sorqvist 1993). Starved cells also show a lower count on selective media (Bissonnette et al 1975) suggesting that this response could be due to the loss of membrane integrity upon heating and starvation (Hitchener and Egan 1977 ;Katsui et al 1982).…”