RESUMEN

The objective of this study was to evaluate the antioxidant capacity by spectrophotometric methods, the in vitro and in vivo antifungal effect against Lasiodiplodia theobromae and the constitution of the essential oils (EO) of oregano and thyme in comparison with their commercial counterparts. The results showed by the EOs of extracted thyme (T-EO), commercial thyme (CT-EO), extracted oregano (O-EO) and commercial oregano (CO-EO), demonstrated antioxidant profiles with a radical neutralizing potential (DPPH•) of IC50: 1.11 ± 0.019; 1.08 ± 0.05; 40.56 ± 0.227 and 0.69 ± 0.004 mg/mL, respectively. They also revealed a ferric ion reducing capacity (FRAP) of 93.05 ± 0.52; 97.72 ± 0.42; 21.85 ± 0.57 and 117.24 ± 0.64 mg Eq Trolox/g. A reduction in ß-carotene degradation of 65.71 ± 0.04; 51.97 ± 0.66; 43.58 ± 1.56 and 57.46 ± 1.56 %. A total phenol content (Folin-Ciocalteu) of 132.97 ± 0.77; 141.89 ± 2.56; 152.04 ± 0.10 and 25.66 ± 0.40 mg EGA/g. Chemical characterization performed by gas chromatography mass spectrometry (GC-MS) showed that the respective major components of the samples were thymol (T-EO: 45.78 %), thymol (CT-EO: 43.57 %), alloaromadendrene (O-EO: 25.17 %) and carvacrol (CO-EO: 62.06 %). Regarding antifungal activity, it was evident that at the in vitro level, both commercial EOs had a MIC of 250 ppm while the extracted thyme EO had a MIC of 500 ppm; In vivo studies demonstrated that the application of thyme EO had a behavior similar to the synthetic fungicide, slowing down rot in bananas under storage conditions. Finally, partial least squares discriminant analysis (PLS-DA) and heat maps suggest p-cymene, carvacrol, linalool, eucalyptol, 4-terpineol, (z)-ß-terpineol, alkanhol, caryophyllene, ß-myrcene, d-limonene, α-terpinene, α-terpineol, d-α-pinene, camphene, caryophyllene oxide, δ-cadinene, terpinolene and thymol as relevant biomarkers associated with the assessed bioactive properties demonstrating the potential of extracted essential oils for the development of a botanical biofungicide.

RESUMEN

Ecuador is one of the world's leading producers of cacao beans, and Nacional x Trinitario cacao represents one of the most distinctive varieties due to its flavor and aroma characteristics. This study aimed to evaluate the effect of the starter culture isolated from microbial diversity during the spontaneous fermentation of Nacional x Trinitario cacao. A total of 249 microbial isolates were obtained from spontaneous culture, with Lactiplantibacillus (45 %), Saccharomyces (17 %), and Acetobacter (2 %) being the most relevant genera for fermentation. Tolerance tests were conducted to select microorganisms for the starter culture. Lactiplantibacillus plantarum exhibited the highest tolerance at pH 5 and 6 % ethanol and tolerated concentrations up to 15 % for glucose and fructose. Acetobacter pasteurianus grew at pH 2 and 6 % ethanol, tolerating high sugar concentrations of up to 15 % for glucose and 30 % for fructose, with growth observed in concentrations up to 5 % for lactic and acetic acid. Subsequently, a laboratory-scale fermentation was conducted with the formulated starter culture (SC) comprising S. cerevisiae, L. plantarum, and A. pasteurianus, which exhibited high tolerance to various stress conditions. The fermentation increased alcoholic compounds, including citrusy, fruity aromas, and floral notes such as 2-heptanol and phenylethyl alcohol, respectively 1.6-fold and 5.6-fold compared to the control. Moreover, the abundance of ketones 2-heptanone and 2-nonanone increased significantly, providing sweet green herbs and fruity woody aromas. Cacao fermented with this SC significantly enhanced the favorable aroma-producing metabolites characteristic of Fine-aroma cacao. These findings underscore the potential of tailored fermentation strategies to improve cacao product quality and sensory attributes, emphasizing the importance of ongoing research in optimizing fermentation processes for the cacao industry.

RESUMEN

Biosurfactants (BS) are amphiphilic molecules that align at the interface reducing the surface tension. BS production is developed as an alternative to synthetic surfactants because they are biodegradable, with low toxicity and high specificity. BS are versatile, and this research proposes using a biosurfactant crude extract (BCE) as part of cleaning products. This paper reported the BCE production from Bacillus subtilis DS03 using a medium with molasses. The BCE product was characterized by different physical and chemical tests under a wide pH range, high temperatures, and emulsifying properties showing successful results. The water surface tension of 72 mN/m was reduced to 34 mN/m with BCE, achieving a critical micelle concentration at 24.66 ppm. BCE was also applied to polystyrene surface as pre-treatment to avoid microbial biofilm development, showing inhibition in more than 90% of Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes above 2000 ppm BCE. The test continued using BCE as post-treatment to remove biofilms, reporting a significant reduction of 50.10% Escherichia coli, 55.77% Staphylococcus aureus, and 59.44% Listeria monocytogenes in a concentration higher than 250 ppm BCE. Finally, a comparison experiment was performed between sodium lauryl ether sulfate (SLES) and BCE (included in commercial formulation), reporting an efficient reduction with the mixtures. The results suggested that BCE is a promising ingredient for cleaning formulations with applications in industrial food applications.

RESUMEN

ABSTRACT The adaptability of endophytic fungi to their hosts, the ecological benefits that it provides and the various antagonistic mechanisms against pests make them an alternative for the biological control of diseases. The potential of 17 strains of foliar endophytic fungi (FEF) obtained from healthy Theobroma cacao tissue as candidates for the biological control of Moniliophthora roreri (MR) and M. perniciosa (MP) was determined. We evaluated: i) mycoparasitism of FEF against colonies of Moniliophthora spp., ii) the effects of crude metabolites of FEF on the pathogens' growth, and iii) the ability to recolonize healthy leaves of the host by leaf assays. Three strains of Lasiodiplodia theobromae were the most promising: Ec098, Ec151 and Ec157. These strains inhibited the growth of MR and MP, both in the confrontation of the colonies and by their metabolites and, additionally, recolonized the host between 80-100 % of the time. Other strains showed outstanding values i n one indicator, and not desirable in others. For example, Ec035 (L. theobromae) showed the highest levels of mycoparasitism against both pathogens in the interaction of the colonies, and the second best for its metabolites, but could not reinfect the host. Strain Ec059 (Xylaria feejeensis) reinfected 100 %, but did not show desirable attributes of antagonism. On the other hand, the metabolites of Ec107 (Colletotrichum gloeosporioides s.l.) inhibited MR by 60 %, but also stimulated the growth of MP. No strain achieved all desirable characteristics for a biological control agent.

RESUMEN La adaptabilidad de los hongos endófitos a sus hospedantes, los beneficios ecológicos que le brinda y los diversos mecanismos antagónicos contra plagas que poseen los convierten en una alternativa para el control biológico de enfermedades. Se determinó el potencial de 17 cepas de hongos endofíticos foliares (FEF) obtenidas de tejido sano de Theobroma cacao como candidatas para el control biológico de Moniliophthora roreri (MR) y M. perniciosa (MP). Se evaluaron: i) el micoparasitismo de los FEF frente a colonias de Moniliophthora spp., ii) la acción de los metabolitos crudos de los FEF en el crecimiento, y iii) la habilidad para recolonizar hojas sanas del hospedante mediante ensayos de hojas sueltas. Tres cepas de Lasiodiplodia theobromae fueron las más promisorias: Ec098, Ec151 and Ec157. Estas cepas inhibieron el crecimiento de MR y MP, tanto en el enfrentamiento de las colonias como mediante sus metabolitos y, adicionalmente, recolonizaron el hospedante entre el 80-100 % de las veces. Otras cepas mostraron valores destacados en un indicador, y no deseables en otros. Por ejemplo, la Ec035 (L. theobromae) mostró los niveles más altos de micoparasitismo contra ambos patógenos en la interacción de las colonias, y el segundo mejor por sus metabolitos, pero no pudo reinfectar el hospedante. La cepa Ec059 (Xylaria feejeensis) reinfectó 100 %, pero no mostró los atributos deseados de antagonismo. Por su parte, los metabolitos de Ec107 (Colletotrichum gloeosporioides s.l.) inhibieron a MR en un 60 %, pero también estimularon el crecimiento de MP. Ninguna cepa logró todas las características deseables para un agente de control biológico.