Abstract: The present invention provides methods of preparing extracts of material fermented with Paenibacillus sp., preferably Paenibacillus elgii ourofinensis. The extracts exhibit antimicrobial activity and may be used in the treatment or prophylaxis of infections in animals or plants or as a growth promoter in animals intended for slaughter for human consumption. The invention provides new peptides derived from the fractions of the fermentation of Paenibacillus elgii ourofinensis extract, prepared for example, by n-butanol extraction of the Paenibacillus fermentation broth. The extract may optionally be dried and/or mixed with other components such as appropriate nutritional components to form an animal feed, additional therapeutic adjuvants, or pharmaceutically or agriculturally acceptable carriers. The invention is also related to the isolation of this strain of Paenibacillus, including fermentation in a medium such as corn steep liquor and selection of catalase negative bacteria.