One of the most important objections to the expansion of the Manitoba livestock industry is the problem of odour from animal wastes. Bacteria ferment manure under anaerobic conditions to produce most of the objectionable odour compounds. Little is known about the microbiology of anaerobic bacteria in manure. Microbiological research has relied on conventional techniques such as growing the bacteria and measuring biochemical properties. Techniques that rely on growing bacteria underestimate the population and the diversity of species of microorganisms present in manure. Most bacterial species present in an environment such as manure cannot be grown. If we cannot culture these bacteria, we cannot measure their contributions to odour compound generation. To overcome this problem, new techniques from the field of molecular genetics have been applied in this study. For each sample, the DNA from all of the bacteria was isolated. The polymerase chain reaction (PCR) technique was applied to produce enough of a specific gene which every bacterium carries, the 16S rRNA gene. While every bacterium carries this gene, the precise sequence of nucleotides of the gene varies amongst different species and can be used to identify a particular bacterium. Nucleotides are the individual building blocks of all genes. Determining the nucleotide sequences is expensive so, in this study, a technique was first used to determine how many different 16S rRNA genes were present. Once this was accomplished, then the most abundant genes actually had their individual nucleotide sequences determined. The technique to indicate the number of different 16S rRNA genes present is called denaturing gradient gel electrophoresis. This technique is based on the principle that each different type of 16S rRNA gene a