A rapid luminescent‐phage based MPN method for the enumeration of Salmonella typhimurium in environmental samples

Materials such as soils, waters, sewage sludges and foods can contain low numbers of salmonellas. A most‐probable‐number (MPN) method that utilized a bioluminescent‐bacteriophage is described that allowed the specific determination of as few as one Salmonella typhimurium cell/100 ml of material within 24 h. The method was developed with soil, lake water and sewage sludge inoculated with Salm. typhimurium and had an efficiency of 100% when tested against a traditional MPN method. The protocol is rapid, sensitive, inexpensive, has a low operator time compared to the traditional MPN method, allows for the repair of injured cells and is amenable to automation.