%0 Journal Article %A Geoffroy, Christiane %A Gaillard, Jean-Louis %A Alouf, Oseph E. %A Berche, Patrick %T Production of Thiol-dependent Haemolysins by Listeria monocytogenes and Related Species %D 1989 %J Microbiology, %V 135 %N 3 %P 481-487 %@ 1465-2080 %R https://doi.org/10.1099/00221287-135-3-481 %I Microbiology Society, %X Twenty-six strains belonging to the five main species of the genus Listeria were examined for production of thiol-dependent exotoxins. All strains of L. monocytogenes cultured in charcoal-treated broth secreted a haemolytic factor at a level ranging from 200 to 800 haemolytic units (HU) ml-1, except for the strain EGD (1500 HU ml−1) and the type strain CIP 82110T (10 HU ml−1). The haemolytic activity reached a maximum level by 8–10 h and then rapidly declined as soon as bacterial exponential growth ceased. The titres of haemolytic activity were markedly reduced when bacteria were grown in charcoal-untreated broth. The haemolytic factor produced by L. monocytogenes strains was characterized as listeriolysin O (M r about 60000), a member of the group of thiol-dependent exotoxins. Strains of Listeria ivanovii also produced high levels of thiol-dependent exotoxin (about 2500 HU ml−1), in both charcoal-treated and untreated broth. Small amounts of haemolytic factor (about 9–30 HU ml−1) were also produced by Listeria seeligeri in charcoal-treated broth. The haemolysin produced by L. seeligeri was identified for the first time as a thiol-dependent exotoxin of M r about 60000, antigenically related to listeriolysin O. As expected, we failed to detect thiol-dependent exotoxin in the two nonhaemolytic species, Listeria innocua and Listeria welshimeri. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-135-3-481