A nivel mundial, la producción de jitomate y chile es de gran relevancia. Recientemente, en Israel y Jordania se notificó la presencia de un nuevo miembro del género Tobamovirus en plantaciones de jitomate, al cual se le llamó Tomato brown rugose fruit virus (ToBRFV). Los frutos de plantas infectadas manifiestan áreas amarillas, necróticas o de color marrón incluso rugosidades. En los municipios de Yurécuaro y Tanhuato, Michoacán, se han observado cultivos de jitomate y chile con síntomas similares a los antes mencionados por lo que, el objetivo del presente trabajo fue determinar si el ToBRFV se encuentra presente en estas localidades. Se colectó tejido foliar de jitomate con síntomas y se realizó RT-PCR con iniciadores que amplifican un segmento del ORF2 del genoma de este virus; además, se prepararon rejillas para su observación al microscopio electrónico de transmisión (MET). Se obtuvo el amplicón esperado y las secuencias tuvieron una similitud de 99 a 100 % con ToBRFV. Al MET se observaron partículas virales en forma de varilla rígida típicas de tobamovirus. Hasta donde sabemos este es el primer reporte de la presencia del ToBRFV asociado a plantas de jitomate y chile cultivados en México.

En la actualidad es de importancia estratégica contar con herramientas de diagnóstico rápido y preciso que permitan conocer si el material de interés está infectado con algún virus de importancia cuarentenaria o económica. Por tal motivo, en el presente trabajo se diseñó un par de oligonucleótidos específicos para la detección del ToBRFV por RT-PCR, considerando una región de la secuencia codificante de la RdRP localizada en el ORF1 y la metodología para detectarlo fue estandarizada. Adicionalmente, los amplicones fueron clonados y secuenciados, los productos fueron usados para predecir la relación evolutiva entre ToMMV, ToMV, TMV y ToBRFV por el método Maximum Likelihood. Los resultados indicaron que los oligonucleótidos diseñados en el presenté trabajo permiten la identificación de manera rápida y específica del ToBRFV.

The zygomycete fungus Lichtheimia ramosa H71D, isolated from sugarcane bagasse compost, was identified by applying phylogenetic analysis based on the DNA sequence of the Internal Transcribed Spacer (ITS), and subsequent secondary structure analysis of ITS2. L. ramosa H71D was able to grow over a wide range of temperatures (25–45 °C), manifesting optimal growth at 37 °C. A 64 kDa xylanase (named LrXynA) was purified from the culture supernatant of L. ramosa H71D grown on 2% carboxymethylcellulose (CMC), as the only carbon source. LrXynA displayed optimal activity at pH 6 and temperature of 65 °C. The enzyme retained more than 50% of its maximal activity over a broad range of pH values (4.5–7.5). Enzyme half-life (t½) times at 55, 65 and 75 °C were 80, 25, and 8 min, respectively. LrXynA showed higher affinity (k M of 2.87 mg/mL) and catalytic efficiency (k cat /k M of 0.651 mg s/mL) towards Beechwood xylan in comparison to other substrates such as Birchwood xylan, Oat-spelt xylan, CMC, Avicel and Solka floc. The predominant final products from LrXynA-mediated hydrolysis of Beechwood xylan were xylobiose and xylotriose, suggesting that the enzyme is an endo-β-1,4 xylanase. Scanning electron microscopy (SEM) imaging of sugar cane bagasse (SCB) treated with LrXynA, alone or in combination with commercial cellulases, showed a positive effect on the hydrolysis of SCB. To our knowledge, this is the first report focusing on the biochemical and functional characterization of an endo-β-1,4 xylanase from the thermotolerant and fast-growing fungus Lichtheimia ramosa.

A 32-fold increase in laccase activity production by the thermophilic biomass-degrading fungus T. terrestris Co3Bag1 was achieved when the microorganism was grown on a modified medium containing fructose, sodium nitrate, and copper. A 70 kDa laccase (TtLacA), produced under the above conditions, was purified, immobilized in copper alginate gel beads, and characterized. TtLacA, both free and immobilized enzymes, exhibited optimal activity at pH 3.0, at a temperature of 65 and 70 °C, respectively, although both displayed 70% of activity from 40 to 70 °C. Free and immobilized enzymes retained at least 80% of relative activity in the pH range from 3 to 4.6. Immobilized TtLacA manifested a 2.3-fold higher thermal stability than the free form of the enzyme at 60 and 70 °C. Immobilized TtLacA retained 95% initial activity for six consecutive reuse cycles at 60 °C, and also retained 86% of initial activity after 12 days of storage at 4 °C. Based on the biochemical features, thermophilic TtLacA may be an efficient enzyme for dye decolorization and other industrial applications at high temperatures or acidic conditions. This work represents the first report about the immobilization and biochemical characterization of a thermophilic laccase from a member of the genus Thielavia.

Strawberry (Fragaria × ananassa) and papaya (Carica papaya) are susceptible to fungal plant pathogens such as Botrytis cinerea and Colletotrichum spp., which are controlled mainly by chemical fungicides. However, their use causes adverse health effects. Therefore, the search for ecological alternatives is essential to reduce the impact of pesticides. This study aimed to identify Botrytis spp. and Colletotrichum spp. isolated from strawberries and papaya fruits with symptoms of grey mould and anthracnose disease and to evaluate the in vitro antifungal activity of different fatty acids on their mycelial growth. Phylogenetic analysis allowed the identification of Botrytis cinerea and Colletotrichum nymphaeae isolated from strawberry and C. siamense from papaya, which have been reported as pathogens of both crops. The in vitro antifungal index (AI) of the fatty acids was determined at concentrations of 100, 1000, and 2000 µM. Inhibition assays showed AIs of 100% for B. cinerea, C. nymphaeae, and C. siamense using decanoic acid (1000 and 2000 µM). Sodium octanoate (1000 and 2000 µM) and hexanoic acid (2000 µM) also inhibited C. nymphaeae with an AI of 100%. This is the first report on the antifungal effects of decanoic acid on three isolated fungi, as well as sodium octanoate and hexanoic acid, on C. nymphaeae. These results suggest that these molecules could potentially control diseases caused by these fungi in strawberry and papaya fruits.