 A few decades ago, "Bacillus mesentericus" (rope), was a serious problem, but today's improved sanitary practices in the bakery, combined with rapid turnover of the finished product, have virtually eliminated this form of spoilage.Calcium propionate and sodium propionate are effective against both "B. mesentericus" rope and mold.Metabolism of propionate begins with its conversion to propionyl coenzyme A (propionyl-CoA), the usual first step in the metabolism of carboxylic acids.