RESUMO
ABSTRACT Arbuscular mycorrhizal fungi (AMF) have the potential to reduce the deleterious effect of soil-borne pathogens, but their ability for pathogen biocontrol may vary depending on the genotype of the plant, the pathogen, and the AMF interaction. Thus, the aim of this work was to evaluate the effect of the Mexican biofertilizer Rizofermic-UV based on a mix of AMF formulation against the common bean root rot caused by the pathogenic fungus Rhizoctonia solani Kühn 1858 (Teleomorph: Thanatephorus cucumeris). Additionally, the total phenolic content, individual phenolic acid (caffeic, ferulic, o-cumaric, p-cumaric, sinapic, and vanillic), and the flavonoid (catechin, kaempherol, quercetin, and rutin) profiles were analyzed. Our results show that the AMF biofertilization reduces the disease severity up to 68 %, and this was accompanied by a boost in total phenolic content in dual inoculation. Furthermore, a variation in the individual phenolic profiles caused by both AMF interaction and pathogen treatment alone were observed. In dual inoculations, vanillic acid was significantly different among treatments, suggesting it may contribute to the enhanced resistance of mycorrhizal roots to soil-borne pathogens. Further work is required to elucidate the exact role of these compounds in the bioprotection of arbuscular mycorrhizal to plant pathogens.
RESUMEN Los hongos micorrízicos arbusculares (AMF) tienen el potencial de reducir el efecto negativo de los patógenos en plantas, pero su capacidad para el biocontrol puede variar dependiendo del genotipo de la planta, el patógeno y AMF. Por lo tanto, el objetivo de este trabajo fue evaluar el efecto del biofertilizante mexicano Rizofermic-UV basado en una mezcla diversos AMF contra la pudrición de la raíz del frijol causada por el hongo patógeno Rhizoctonia solani Kühn 1858 (Teleomorfa: Thanatephorus cucumeris). Se evaluó también el contenido de fenoles totales, el de ácidos fenólicos individuales (cafeico, ferúlico, o-cumárico, p-cumárico, sinápico y vanílico) y los perfiles de flavonoides (catequina, kaempferol, quercetina y rutina). Nuestros resultados muestran que la biofertilización reduce la severidad hasta un 68 %, esto es acompañado por un aumento en el contenido de fenoles totales en la inoculación doble. Además, se observó una variación en los perfiles fenólicos individuales en la interacción con los AMF y en el tratamiento que contenía solo el patógeno. En las inoculaciones duales, el ácido vanílico fue significativamente diferente entre los tratamientos, lo que sugiere que puede contribuir a una mayor resistencia de las raíces micorrizadas a los patógenos transmitidos por el suelo. Se requiere trabajo adicional para dilucidar el papel exacto de estos compuestos en la bioprotección de las micorrizas arbusculares contra los patógenos de las plantas.
RESUMO
ABSTRACT: Two chemical treatments, five enzymatic (pectinase, lipase, hemicellulase, hemicellulose-cellulase or lipase-pectinase) and one microbiological (Bacillus subtilis) treatment were evaluated to obtain glucosamine hydrochloride (Gluc-HCl) from the chitin obtained from crab (Callinectes bellicosus) exoskeletons. Chemical treatments were referred as Method A (HCl hydrolysis during 75 min at 90°C) and Method B (HCl hydrolysis during 20 min and 14 h of rest). Glucosamine and, in some cases, N-acetyl-D-glucosamine were identified and quantified by HPLC. Treatments with the greater concentrations of Gluc-HCl in descending order were: lipase (94.4 mg/g), microbiological (45.7 mg/g), lipase-pectinase (22.9 mg/g), hemicellulase-cellulase (20.9 mg/g), hemicellulase (15.3 mg/g), pectinase (10.7 mg/g), Chemical A (7.3mg/g) and Chemical B (7.3mg/g). In terms of yield, the best treatments in descending order were: pectinase (94%), microbiological (94%), hemicellulase (92%), lipase (91%), Chemical B (88%), lipase-pectinase (88%), hemicellulase-cellulase (86%) and Chemical A (28.5%). The two most profound treatments were lipase and microbiological, so they are proposed as part of a viable method to produce Gluc-HCl from crab exoskeletons; they are ecofriendly procedures and could add value to the crab´s productive chain.
RESUMO: Dois tratamentos químicos, cinco enzimáticos (pectinase, lipase, hemicelulase, hemicelulose-celulase ou lipase-pectinase) e um microbiológico (Bacillus subtilis) foram avaliados para obter o cloridrato de glucosamina (Gluc-HCl) da quitina obtida a partir de exoesqueletos de caranguejo (Callinectes. Bellicosus). Os dois tratamentos químicos foram nomeados como método A (hidrólise de HCl para 75 min a 90 °C) e método B (hidrólise de HCl para 20 min e 14 h de repouso). A Glucosamina e, em alguns casos, N-acetil-D-glucosamina foram identificados e quantificados por HPLC. Os tratamentos em que as melhores concentrações de Glucosamina-HCl foram obtidas, em ordem decrescente: lipase (94,4 mg/g), microbiológica (45,7 mg/g), lipase-pectinase (22,9 mg/g), hemicelulase-celulase (20,9 mg/g), hemicelulase (15,3 mg/g), pectinase (10,7mg/g), Quïmica A (7,3 mg/g) e Quïmica B (7,3 mg/g). Em termos de produtividade, os melhores tratamentos em ordem decrescente foram: pectinase (94%), microbiológica (94%), hemicelulase (92%), lipase (91%), química B (88%), lipase-pectinase (88%), hemicelulase- celulase (86%) e produto químico A (28,5%). Os dois melhores tratamentos foram lipase e microbiológicos, propostos como método viável para obtenção de Gluc-HCl a partir de exoesqueletos de caranguejo; cumprem procedimentos ecologicamente corretos e podem agregar valor à cadeia produtiva do caranguejo.