Anaerobic sporeformers and their significance with respect to milk and dairy products

• Reviewed sources of Clostridium spores on dairy farms
• Reviewed factors influencing the presence of anaerobic sporeformers in dairy products
• Epidemiology of foodborne illness caused by dairy associated Clostridium spp.
• Emphasises the threat posed by Clostridium botulinum to the dairy industry
• Discusses the taxonomic distribution of dairy associated Clostridium spp.

Sporeforming bacteria are a significant concern for the international dairy industry. Spores present in milk survive heat treatments and can persist during downstream processing. If they are present in sufficient numbers in dairy products they can cause spoilage or lead to illness as a result of toxin production. While many reviews have highlighted the threat posed by spores of aerobic bacteria to the dairy industry, few have focused on problems caused by the array of different species of anaerobic sporeformers (Clostridium and related genera) that can be found in milk. This is despite of the fact that members of these bacteria are found throughout the dairy farm environment, and can be toxigenic, neurotoxigenic or spoilage bacteria. This makes the possible presence of Clostridium and related spores in bulk tank milk (BTM) important from both a financial and a public health perspective. In this review dairy associated anaerobic sporefromers are assessed from a number of perspectives. This includes the taxonomy of this group of bacteria, the important subgroup of this genus the “sulphite reducing clostridia” (SRC), how these bacteria are detected in milk products, the epidemiological data regarding pathogenic species and strains within the SRC group as well as the influence of farming practices on the presence of SRC in BTM.