Effect of Organochlorine Pesticides on Growth and Biological Activities of Bacterial Species Important to the Dairy Food Industry

Abstract

Three growth patterns (no effect, slight inhibition, or complete inhibition) were observed when bacterial species common to the dairy-food industry were grown in media containing 50 or 100 ppm DDT, dieldrin, or endrin. The pattern obtained appeared to depend on species and type and concentration of pesticide. All pesticides studied had a greater inhibitory effect on gram positive species than they had on gram negative species when grown in broth. Acid production by lactic acid bacteria was inhibited in broth plus 5 ppm chlordane or heptachlor but unaffected in skimmilk plus up to 100 ppm of these pesticides. Generation times for gram negative species grown in broth plus 10 ppm chlordane or heptachlor were similar to those obtained in controls. Growth of gram positive species was inhibited in broth plus 10 ppm of these pesticides but unaffected in skimmilk containing similar pesticide concentrations. Generation times for several gram negative species were increased by 10 ppm heptachlor in skimmilk.