Modified PA3679 agar (MPA3679A) was formulated as a plating medium to provide improved recovery of Clostridium sporogenes Putrefactive Anaerobe (PA) 3679 spores. A comparative study of MPA3679A and two currently used plating media, Yeast extract agar (YEA), and Peptone trypticase agar (PTA), showed that MPA3679A was superior for the recovery of heat activated and heat stressed spores. Further, when this medium was altered for use as an inoculated pack subculture medium, recovery of severely heat stressed spores was superior to that in the previously recommended PA3679 agar, also known as T-Best.

The history of sulfide spoilage in canned foods is traced from its earliest reported occurrence in an Iowa cannery in 1919 through several outbreaks in the midwest and east in 1945. The taxonomy of the causative organism, beginning with the name, Clostridium nigrificans, proposed by Werkman and Weaver in 1927, and ending with Desulfotomaculum nigrificans introduced by Campbell and Postgate in 1965, is discussed. Mention is made of the kinds of canned foods that have been involved in sulfide spoilage, and the spoilage characteristics, such as appearance, odor, pH, etc. exhibited by spoiled product. The morphology, staining characteristics, and culturing methods are discussed. Methods of analysis of common canned food ingredients such as sugar, flour, starch and nonfat dry milk are presented. A brief account of the thermal resistance of the spores of D. nigrificans is also given. Ingredient and equipment contamination and spoilage prevention are discussed in detail.