Avaliação da atividade antimicrobiana de ramnolipídeos sobre Listeria monocytogenes / Antimicrobial activity of rhamnolipids against Listeria monocytogenes

AUTOR(ES)

Luana Magalhães

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

16/02/2012

RESUMO

The rhamnolipids (RL) are biodegradable biosurfactants which have low toxicity and surface activity properties that can be useful for food processing industries. The objective of this study was to evaluate the susceptibility of Listeria monocytogenes with two rhamnolipids products: the rhamnolipid from P. aeruginosa LBI that was produced and purified in the Microbial Biotechnology Laboratory (RLMBL) and a commercial product (RL-Com - Jeneil Co.). Susceptibility tests were performed by the minimal inhibitory concentration (MIC) using the micro-broth dilution technique. The MIC values varied from 78.1 μg mL-1 to 2500 μg mL-1 and the 2500 μg mL-1 concentration was the predominant value . Among the 32 tested cultures, 68.7% were susceptible to RL-MBL and 90.6% to RL-Com. Results showed that the rhamnolipid activity was primarily bacteriostatic. The RL increases the membrane permeability of L. monocytogenes, however this effect was not directly related to its antimicrobial activity. The combined effect of nisin and RL-Com was evaluated against two wild-type isolates of L. monocytogenes, L12 more sensitive (MIC 156.2 μg mL-1) and L17 less sensitive (2500 μg mL-1). The FIC index for the isolates were 0.18 and 0.078 for L12 and L17 respectively, indicating a particular synergistic effect. The survival curve of isolates L12 and L17 showed that the combination between nisin and RL was bactericidal at lower concentration than for the individual antimicrobials. For L12 isolate 78.1 μg mL-1 of RL and 160 UI mL-1 of nisin eliminated the population after 30 min of incubation. The combination of 156.2 μg mL-1 of RL and 320 UI mL-1 of nisin reduced completely L17 population after 2 h of incubation. This work demonstrated the potential antimicrobial activity of rhamnolipids against L. monocytogenes, as well as the synergistic effect of this biosurfactant with nisin.

ASSUNTO(S)

antimicrobial activity atividade antimicrobiana listeria monocytogenes listeria monocytogenes nisin nisina ramnolipídeo rhamnolipids sinergismo synergistic effect

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