rational evaluation of antimicrobial properties of lactobacilli isolates against some pathogenic microorganisms: a new method comparing the susceptibility of indicator microorganisms

background: lactobacilli are known as a valuable sourceof antimicrobial compounds and have a high potential of use infood biopreservation against food related microorganisms.objectives: antimicrobial potency of 63 dairy lactobacilliisolates against four highly important food-related microorganismswere evaluated. in addition, a new way in data organization wasintroduced, which led to a more informative and rationalcomparison of indicator microorganisms' susceptibilities to a setof compounds. correlation of ph and antimicrobial propertieswas investigated. methods: microbroth dilution assay wasused to evaluate indicator microorganisms' susceptibility tolactobacilli cfcs (cell free culture supernatant). results wereorganized by both the conventional way - demonstrating theminimum inhibitory and lethal concentrations of cfcs - and anew suggested method, representing comparative effectivenessof each cfcs specimen against indicator microorganisms ofcomparison interest. results: susceptibilities of tested strainswere in the following order: escherichia colio157:h7 > listeriamonocytogenes > aspergillus parasiticus> candida parapsilosis.despite the high susceptibility of l. monocytogenes, it showedthe highest resistance to death among the tested microorganisms.eefficiency of lactobacilli cfcs in killing the tested strainsshowed the following susceptibility order: e. coli o157:h7 > a.parasiticus> c. parapsilosis> l. monocytogenes. antimicrobialproperty was in correlation with the ph value of cfcs. ph hada pronounced impact on susceptibilities of c. parapsilosisand e.coli in ph values of concentrated cfcs lower than 4 and 4.5,respectively. conclusions: potency of lactobacilli isolates ingrowth inhibition of the indicator microorganisms was foundpromising, and the suggested data organization method providedadditional information, leading to more precise comparison ofindicator microorganisms.