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In vitro inhibition of Aspergillus carbonarius growth and reduction of ochratoxin A (OTA) contents using Lactobacillus plantarum strains isolated from coffee cherries

Beugre G.C., Kedjebo K.B.D., Kouame M.K.J., Durand N., Fontana A., Guehi T.S.. 2021. In : 28th Conference of Association for the Science and Information on Coffee - Books of abstracts. Montpellier : ASIC, p. 121. Conference of Association for the Science and Information on Coffee (ASIC 2021). 28, 2021-06-28/2021-07-01, Montpellier (France).

RATIONALE - Coffee is one of the main agricultural crops in the world. Raw coffee cherries can contain the mycotoxin ochratoxin A (OTA). OTA is produced by several species of Aspergillus and Penicillium. International coffee organizations pay more and more an attention on statutory limits for OTA in Coffee products (FAO, 2006). OTA contents need to be reduced in coffee cherries to as low as technologically control of mycotoxin by avoiding fungal growth and OTA production. METHODS - Identification of lactic bacteria (LAB) and Aspergillus carbonarius strains isolated from Ivorian coffee cherries were carried out using microbiological and molecular methods. Study of effect of cells and supernatant of liquid culture of L. plantarum strains were investigated on the growth of ochratoxinogenic A. carbonarius strain using various confrontation tests in vitro. Then, the best potential fungal growth inhibitor and OTA content reducing strains were inoculated with coffee cherries during post-harvest processing on farm. Fungal growth was measured by weighing the biomass during the incubation and at the end of coffee cherries drying. Samples of OTA contents reduction experiments were analysed by HPLC-FLD method (Sueck et al., 2019). RESULTS - Five OTA-producing A. carbonarius strains were detected. Sixteen isolates of LAB including 12 Lactobacillus plantarum strains, 2 Weissella confusa strains, 1 L. pentosus strain and 1 W. paramesenteroides strain. Ten strains of LAB showed potential activity with rates (17.3-79.1 %) against fungal growth and capacities to reduce OTA contents (6-96 %). Among these LAB, 7 strains of L. plantarum showed highest antifungal activities. Cells of LAB strains had highest inhibitory effect on fungal growth and reduction of OTA contents. On the farm, only the inoculation of L. plantarum D12 with coffee cherries result in reduction of OTA content without inhibition of fungal growth. CONCLUSION & PERSPECTIVES - The inoculation of specific L. plantarum with the coffee cherries on the farm results in decrease of OTA level without inhibition of fungal growth. Using L. plantarum D12 strain could allow to control and reduce to as low as biotechnologically promising and excellent way in coffee cherries and probably in other foodstuff. The further study may be performed on the comprehension of OTA reduction mechanism.

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