Searching for antibacterial agents producing microorganisms and evaluation of their properties

Abstract

Lactic acid bacteria and yeast with a wide range of antimicrobial activity can be an effective tool dealing with pathogenic and food spoilage bacteria. Depending on the environment, microorganisms adapt, resulting in different strains that can produce antibacterial substances with different properties. Such substances are bacteriocins and killer toxins [1, 2]. Bacteriocins and killer toxins are important in food industry because microorganisms which produce them are non-pathogenic and normally colonize the human body [3]. The aim of this work is to find lactic acid bacteria and yeast which have antibacterial activity in local raw bioproducts, such as sour milk, whey, bee bread and cottage cheese. All isolated lactic acid bacteria were preliminary identified based on their staining by Gram and catalase test. Morphology (cell form) of yeast colonies were determined using optical microscope. The antibacterial activity of all isolated microorganisms using S. aureus, E. coli, M. luteus and P. vulgaris strains was determined by agar well diffusion method [4]. Seven lactic acid bacteria and five yeast strains, isolated from bioproducts, showed different kind of antibacterial activity against all tested pathogenic bacteria strains. The stability of bacteriocins and killer toxins depending on temperature and pH were also estimated. Detailed results of the work will be presented during the conference.