A. Amanatidou et al., Superoxide dismutase plays an important role in the survival of Lactobacillus sake upon exposure to elevated oxygen, ARCH MICROB, 176(1-2), 2001, pp. 79-88
In this study, the responses of two Lactobacillus sake strains to elevated
oxygen concentrations at 8 degreesC were investigated. L. sake DSM 6333 (L.
sake(sens)), unlike L. sake NCFB 2813 (L. sake(ins)), showed a low growth
rate in the presence of 90% O-2 and a rapid loss in viability shortly after
entry into stationary phase. The steady-state cytosolic superoxide radical
(O-2(-)) concentration in L. sake(sens) was 0.134 muM and in the oxygen-in
sensitive mutant LSUV4 it was 0.013 muM. The nine- to ten-fold decrease in
the rate of O-2(-) elimination in L. sakesens indicates the significance of
the O-2(-) -scavenging system in protecting against elevated O-2. The supe
roxide dismutase (SOD) activity was 10- to 20-fold higher in L. sake ins th
an in L. sake(sens), depending on the growth phase. An oxygen-insensitive m
utant of L. sake,ens, designated as strain LSUV4, had a ten-fold higher SOD
activity than the wild-type strain, which likely restored its oxygen toler
ance. Damage to proteins in L. sake(sens), was evidenced by the increased p
rotein carbonyl content and reduced activities of the [Fe-S]-cluster-contai
ning enzymes fumarase and fumarate reductase. This study forms a physiologi
cal basis for understanding the significance of elevated oxygen stress as a
n additional method for inhibition of microbial growth in relation to food
preservation.