“…Experimental phage A994 (derived from phage 85, Witte, Nguyen van Dip & Diinnhaupt, 1986) was used; the experimental procedure is described by Witte (1976). The transductants were selected on nutrient medium L4 containing cadmium sulphate (200 ,g/ml), chloramphenicol (10 jug/ml, erythromycin (2 ,ug/ml), gentamicin (1 jug/ml) and oxytetracycline (10 ,ug/ml).…”