Potential of chitosan from Mucor rouxxi UCP064 as alternative natural compound to inhibit Listeria monocytogenes

摘要

Listeria monocytogenes is widely distributed in nature and the infection listeriosis is recognized as a potential threat for human health because of its mortality rate. The objective of this study was to evaluate the growth profile and chitosan production by Mucor rouxxi UCP 064 grown in yam bean (Pachyrhizus erosus L. Urban) medium. It was also to assess the anti-L. monocytogenes efficacy of the obtained chitosan. Higher values of biomass of M. rouxxi (16.9 g.L^-1) and best yield of chitosan (62 mg.g^-1) were found after 48 h of cultivation. Residual glucose and nitrogen in the growth media were 4.1 and 0.02 g.L^-1 after 96 h, respectively. Obtained chitosan presented 85 % of degree of deacetylation and 2.60 x 10⁴ g.mol^-1 of viscosimetric molecular weight. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of chitosan against L. monocytogenes ATCC 7644 were, respectively, 2.5 and 5.0 mg.mL^-1. At 2.5 and 5.0 mg.mL^-1 chitosan caused cidal effect in a maximum time of 4 h. Bacterial count below 2 log cfu.mL^-1 were found from 2 h onwards and no recovery in bacterial growth was noted in the remainder period. These results show the biotechnological potential of yam bean medium for chitosan production by Mucor rouxxi and support the possible rational use of chitosan from fungi as natural antimicrobial to control L. monocytogenes.