Increasing incidents of microbial disease caused by antibiotic-resistant organisms has necessitated the search for new classes of effective life-saving antimicrobials. Classically, antibiotic producing organisms have come from the soil and more recently, marine environments. Common isolates from these sources include bacteria from the Streptomycetaceae or Cyanobacteriaceae families and mold species such as Penicillium. However, the beneficial microbiota of the intestines of animals may prove to be a novel source of producers since there may be organisms present that produce antibiotics as a mechanism to decrease microbial competitors in their habitat. Additionally, since the antibiotic producers are part of the beneficial microbiota of animals, the antibiotics produced should be non-toxic to animals. Thus we looked in the intestines of deep cold freshwater fish for novel producers. We report here a highly successful search for novel bacterial producers from the gastro-intestinal tracts of three species of fish caught at a depth of 150 meters in Lake Superior. We show that the intestines of three fish species; Myoxocephalus thompsonii (deepwater sculpin), Cottus cognatus (slimy sculpin), and Cottus ricei (spoonhead sculpin); harbor bacteria that produce antibiotics. Most isolates produced antibiotics that killed both gram-negative and gram-positive bacterial pathogens. Some isolates exhibited anti-fungal activity. Surprisingly, most of the isolates are members of the Pseudomonadaceae family. We are now characterizing the products further.
