Coffee is considered a product of great importance in world trade. However, since 1960 the presence of mycotoxins has been detected in various foods, not just coffee. Mycotoxins, such as ochratoxin A (OTA), is associated with various neurotoxic, genotoxic, teratogenic disorders, among other disorders in animals and humans. In addition, the contaminated grains cause significant economic losses for the agricultural sector (932 million dollars / year). The main microorganisms that produce mycotoxins are fungi of the genus Aspergillus, Penicillium and Fusarium. Objective. With this background, the objective of this work is to determine the physicochemical and ecological interactions involved in the biocontrol of the Aspergillus carbonarius (considered as the largest producer of OTA in food) and the production of ochratoxin A in coffee beans, with the application of lactic acid bacteria "Lactobacillus plantarum" endemic of coffee pulp. Understanding the mode of action of L. plantarum and the influence of physicochemical factors on the bacterium-fungus interaction will generate biotechnological alternatives that allow making recommendations to prevent, control or eliminate ochratoxin A from coffee crops. Methods. For this purpose, using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), light field microscopy (LFM), Zeta potential (ZP), Fouriertransform infrared spectroscopy (FTIR), the physicochemical mechanisms in the cell-cell interaction are studied making surface characterizations such as roughness, topography, chemical composition, surface charge and hydrophobicity of both microorganisms, which could be involved in the adhesion between both microorganisms and their association with the biocontrol of A. carbonarius. Results. We determined that L. plantarum inhibits fungal (radial) development in solid medium above 50% for 5-6 days (fungistatic biocontrol). The maximum inhibition (84%) is reached on the fourth day, using bacterial inoculum of 5x10 4 cell/mL. In the co-cultures in liquid medium we observed the effect of biocontrol on the germination of fungal spores up to 72 h. On the other hand, the production of L-lactic acid, D-lactic acid, formic acid, acetic acid, propionic acid and ethanol was characterized by HPLC, as fermentation products of trehalose by L. plantarum, molecules suggested in literature regarding fungal biocontrol. Interaction studies (co-culture) showed bacterial ÍNDICE DE CONTENIDO 1.