Serratia Marcescens usually grow in a temperature between 50C to 400C, and in pH level between 5 and 9. Most commonly, they grow on bread and make red spots appear on the bread. They can also grow in plant material, and the two extracellular proteases from serratia marcescens have been found to grow in whey too. However, there has been no evidence so far of this bacterium growing in glucose salt broth.