Bacteriocin (Marcescin) typing of clinically isolated Serratia marcescens
Tohoku journal of experimental medicine
A study of bacteriocin (marcescin) typing was carried out by an agar cross streaking method (without any induction reagent) with 654 strains of Serratia marcescens recently isolated from clinical materials in Nagasaki University Hospital. In a complete checker-board experiment with 80 strains on bacteriocin production and sensitivity, 43 strains (54%) were productive, 74 (93%) were sensitive and 4 (5%) were negative. Immunity was confirmed in all strains. Eight out of 80 strains of Serratia
... ins of Serratia marcescens were selected as indicators in order to achieve the best differentiation of strains in bacteriocin typing, and 654 strains were classified into 30 types by bacteriocin production typing and into 49 types by bacteriocin sensitivity typing; the former showed more stable results than the latter in reproducibility. Bacteriocins produced by this method were considered to be high molecular, phage tail-like group A bacteriocins reported by Prinsloo (1966) . Bacteriocin production typing was more useful for classification and subdivision of strains than serotyping (0-group). Serratia marcescens; bacteriocin; bacteriocin typing Bacteriocins are bactericidal proteins which are synthesized by bacteria, and inhibit the growth of other strains of the same species or closely related species (Reeves 1965; Nomura 1967) . The bacteriocins produced by Serratia marcescens (S. marcescens) were first described by Fuller and Horton (1950) , and named marcescens. They reported that marcescins were polypeptides which inhibited the growth of Corynebacterium aliphtheriae and Staphylococcus aureus. Hamon and Peron (1961) reported the bactericidal activity of marcescins among the same species of S. marcescens. Prinsloo (1966) demonstrated in her study of bacteriocin activity of 139 strains of S. marcescens that marcescins include two types of bacteriocins; group A bacteriocins are mainly active against S. marcescens, some strains of Salmonella and Escherichia coli, and are resistant to trypsin, heat and chloroform; group B bacteriocins are inactive against S. marcenscens, but are active against Escheriehia coli, Aerobaeter aerogenes and Hafnia, and are sensitive to trypsin, heat and chloroform. Furthermore she divided group A bacteriocins into 8 groups.