Resumen Algunas especies del género Trichoderma poseen la capacidad de parasitar hongos patógenos de plantas. Esta característica propicia un alto potencial de uso en el control de las enfermedades (antracnosis) causadas por hongos en el fruto de aguacate postcosecha. Por lo tanto, el objetivo de esta investigación fue el aislamiento e identificación de cepas nativas de Trichoderma de cultivos de aguacate con potencial antagonista in vivo e in vitro contra patógenos de este fruto. Las cepas fueron aisladas de raíz y suelo del huerto de aguacate en la localidad de Tanaxuri, Michoacán. Se obtuvieron seis cepas y se caracterizaron como TSONM1 (Trichoderma spp.), TRONM2 (Trichoderma spp.), TSONM3 (Trichoderma spp.), TSONM4 (Trichoderma spp.), TSONM5 (Trichoderma spp.) y TSONM6 (Trichoderma harzianum). Posteriormente, las cepas aisladas fueron confrontadas con Neofusicoccum parvum, Colletotrichum gloeosporioides, Diaporthe sp. y Phomopsis perseae observándose inhibiciones in vitro mayores al 80 %. Mientras que en la evaluación in vivo, la cepa TSONM6 (Trichoderma harzianum) presentó mayor actividad antagónica contra C. gloeosporioides, Diaporthe sp. y P. persea. Adicionalmente, los frutos de aguacate tratados con TSONM6, presentaron mínimos porcentajes (< 2 %) de pudrición de la pulpa y pedúnculo. Por lo tanto, Thichoderma harzianun podría ser una buena alternativa para el control biológico del aguacate en postcosecha.

Abstract Some species of the genus Trichoderma have the ability to parasitize fungal plant pathogens. This characteristic provides a high potential for use in the control of diseases (anthracnose) caused by fungi in post-harvest avocado fruit. Therefore, the objective of this research was the isolation and identification of native Trichoderma strains from avocado cultures with antagonistic potential in vivo and in vitro against pathogens of this fruit. The strains were isolated from the root and soil of the avocado in the town of Tanaxuri, Michoacán. Six strains were obtained and characterized as TSONM1 (Trichoderma spp.), TRONM2 (Trichoderma spp.), TSONM3 (Trichoderma spp.), TSONM4 (Trichoderma spp.), TSONM5 (Trichoderma spp.) and TSONM6 (Trichoderma harzianum). Subsequently, the isolated strains were confronted with Neofusicoccum parvum, Colletotrichum gloeosporioides, Diaporthe sp. and Phomopsis perseae, observing in vitro inhibitions greater than 80 %. In the in vivo evaluation, the TSONM6 strain (Trichoderma harzianum) showed greater antagonistic activity against C. gloeosporioides, Diaporthe sp. and P. persea. Additionally, the avocado fruits treated with TSONM6, presented minimum percentages (< 2 %) of pulp and peduncle rotting. Therefore, Thichoderma harzianun could be a good alternative for postharvest biological control of avocado.

Summary Currently, antibiotic resistance and indiscriminate use of chemical fungicides in agriculture need to be addressed. This research evaluated the inhibitory effect of aqueous, methanolic, acetonic and hexanic extracts from leaf and stem of Vitex mollis Kunth (Lamiaceae) against several bacteria (Escherichia coli, Micrococcus luteus, Salmonella enterica and Staphylococcus aureus) and species of Fusarium fungus (F. verticillioides, F. oxysporum, F. tapsinum and F. oxysporum f.sp. lycopersici), and determined their general chemical composition. The minimum inhibitory concentration (MIC) was determined by the micro-dilution technique for all extracts, except for the hexanic extract which did not show inhibition on the bacteria studied. S. enterica was the bacterium that showed the highest sensitivity to the methanolic extracts from stem (MIC = 28 µg mL-1), followed by M. luteus (MIC = 32 µg mL-1), S. aureus (MIC = 75 µg mL-1) and E. coli (MIC = 80 µg mL-1). The methanolic and aqueous extracts from the stem presented higher percentage of inhibition against different types of Fusarium evaluated by the agar dilution method. Extracts of V. mollis inhibited F. verticillioides between 62 and 91 % with 120 µg mL-1 of extract. The order of fungi species as inhibited by the extracts was F. verticillioides > F. oxysporum > F. tapsinum > F. oxysporum f.sp. lycopersici. The chemical composition of the species was determined by tests for phenols, tannins, flavonoids, triterpenes, alkaloids, coumarins and saponins. None of the extracts presented alkaloids and saponins. Phenols (37.1 mg EAG/g dry sample) and flavonoids (26.8 mg EQ/g dry sample) were the major compounds in the methanolic and aqueous extracts. In conclusion, small amounts of extracts are required to inhibit bacteria and Fusarium; hence, V. mollis can be considered a source of metabolites for this purpose and in agriculture as an alternative control within an integrated management of diseases.

Resumen Actualmente existe la necesidad de hacer frente al problema de la resistencia a los antibióticos y al uso indiscriminado de fungicidas químicos en la agricultura. El objetivo de este trabajo fue evaluar el efecto inhibitorio de extractos acuosos, metanólicos, acetónicos y hexánicos de hoja y tallo de Vitex mollis Kunth (Lamiaceae) contra diferentes bacterias (Escherichia coli, Micrococcus luteus, Salmonella enterica y Staphylococcus aureus) y especies del hongo Fusarium (F. verticillioides, F. oxysporum, F tapsinum y F. oxysporum f.sp. lycopersici) de importancia en la salud y en la agricultura, así como determinar su composición química general. Se determinaron las concentraciones inhibitorias mínimas (CIM) de todos los extractos por la técnica de microdilución, excepto del hexánico, que no presentó inhibición en las bacterias estudiadas. S. enterica fue la bacteria que mostró mayor sensibilidad al extracto metanólico de tallo (CIM = 28 µg mL-1), le siguieron M. luteus (CIM = 32 µg mL-1), S. aureus (CIM = 75 µg mL-1) y E. coli (CIM = 80 µg mL-1). Los extractos metanólicos y acuosos de tallo presentaron mayor porcentaje de inhibición contra los diferentes tipos de Fusarium evaluados por el método de dilución en agar. Los extractos de V. mollis inhibieron a F. verticillioides entre 62 y 91 % con 120 µg mL-1 de extracto. El orden de las especies de hongos inhibidas por los extractos fue: F. verticillioides > F. oxysporum > F. tapsinum > F. oxysporum f.sp. lycopersici. La composición química de las especies se determinó mediante pruebas para fenoles, taninos, flavonoides, triterpenos, alcaloides, cumarinas y saponinas. Ninguno de los extractos presentó alcaloides y saponinas. Los fenoles (37.1 mg EAG/g muestra seca) y flavonoides (26.8 mg EQ/g muestra seca) fueron los compuestos mayoritarios en los extractos metanólicos y acuosos. En conclusión, se requieren cantidades muy pequeñas de extracto para la inhibición de bacterias y de Fusarium; por lo tanto, V. mollis puede ser considerada una fuente de metabolitos para este fin y en la agricultura como control alternativo dentro de un manejo integrado de enfermedades.

Abstract The aim of this study was evaluated the biofilm formation by Staphylococcus aureus 4E and Salmonella spp. under mono and dual-species biofilms, onto stainless steel 316 (SS) and polypropylene B (PP), and their sensitivity to cetrimonium bromide, peracetic acid and sodium hypochlorite. The biofilms were developed by immersion of the surfaces in TSB by 10 d at 37 °C. The results showed that in monospecies biofilms the type of surface not affected the cellular density (p > 0.05). However, in dual-species biofilms on PP the adhesion of Salmonella spp. was favored, 7.61 ± 0.13 Log10 CFU/cm2, compared with monospecies biofilms onto the same surface, 5.91 ± 0.44 Log10 CFU/cm2 (p < 0.05). The mono and dual-species biofilms were subjected to disinfection treatments; and the most effective disinfectant was peracetic acid (3500 ppm), reducing by more than 5 Log10 CFU/cm2, while the least effective was cetrimonium bromide. In addition, S. aureus 4E and Salmonella spp. were more resistant to the disinfectants in mono than in dual-species biofilms (p < 0.05). Therefore, the interspecies interactions between S. aureus 4E and Salmonella spp. had a negative effect on the antimicrobial resistance of each microorganism, compared with the monospecies biofilms.