Year: 2019
Type: dissertation
Abstract: Lactic acid bacteria (LAB) are frequently used in fermentation processes and have been gaining attention in biopreservation approaches against fungal contaminations. Fungal contaminations can be responsible for health issues, and economic losses since several species produce toxic compounds named mycotoxins. Mycotoxins can cause several organs diseases and cancer. In this work, cell-free supernatant (CFS) of the Lactobacillus plantarum UM55 strain demonstrated the ability to reduce Aspergillus flavus growth by 32% and aflatoxin production by 91%. Additionally, this strain CFS and the CFS from strain Lactobacillus buchneri UTAD104 inhibited radial growth of Penicillium nordicum by 17% and Ochratoxin A (OTA) production by 60%. These inhibitions resulted from organic acids produced by LAB. CFS of L. plantarum UM55 contained lactic acid, phenyllactic acid (PLA), hydroxyphenyllactic acid (OH-PLA) and indole lactic acid (ILA), while CFS of L. buchneri UTAD104 had acetic acid, lactic acid, and PLA. These compounds were individually tested against A. flavus and P. nordicum, with all showing an inhibiting effect on fungal growth and mycotoxin production. PLA and acetic acid were the most effective inhibiting A. flavus and P. nordicum, respectively. When the inhibitory activity of LAB cells incorporated into an agar culture medium was tested, L. buchneri UTAD104 inhibited the production of OTA entirely in all conditions tested, with acetic acid being the main responsible for this effect. L. buchneri UTAD104 was further incorporated into edible films and coatings to prevent fungal contamination in cheese. Films containing the bacteria, maintained their physicochemical, mechanical and barrier properties when compared with control films. These films completely inhibited the growth of P. nordicum on the surface of cheese samples, resulting in the absence of OTA in the samples. Some LAB strains are definitely capable of controlling mycotoxigenic fungi. The antifungal ability of these strains is mainly due to the production of organic acids. LAB strains can be incorporated into edible films and coatings for the control of mycotoxigenic fungi in cheese products.
Author: Ana Guimarães
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: green
Awards: Centro de Engenharia Biológica da Universidade do Minho, G1489525204, G1516346500, G2905247347, G2916317827, G3268162410, G3286620597, BioTecNorte: Biotecnologia para o desenvolvimento sustentado da bioeconomia do Norte de Portugal, G4768249466, G6469001316, G7584003722, Inhibition of fungal growth and mycotoxin production by lactic acid bacteria, G8467349387, G96847669
OpenAlex ID: W3087169382