In this chapter, the author discusses microbial spoilage as it can affect the brewing process, and the means of detecting it. He focuses on the potential of the rapid methods which have been developed years and in particular on one of the methods which has attracted most attention, Adenosine triphosphate (ATP) bioluminescence. AMP levels were generally ten times higher than ADP and ATP. Spoilage potential during the brewing process varies greatly from stage to stage. Bioluminescence was one of the methods used by D. S. Ryder et al. to investigate the relationship between yeast growth and glycolytic efficiency during fermentation. Coliform bacteria grow in wort if given sufficient time without competition from healthy brewing yeast, but the most common bacterial contaminants are the remarkable, well-named Obesumbacterium, which co-exists and competes with pitching yeast, and Acetobacter spp. Common antibodies are absorbed by treating with ale brewing strains.