Especies de Trichoderma antagonistas a Lasiodiplodia pseudotheobromae causante de la muerte descendente del limón “persa” (Citrus latifolia)

AZUCENA LUCENA CUEVAS (2023)

En las zonas productoras de limón “Persa” del estado de Morelos, una de las enfermedades de mayor incidencia es la muerte descendente causada por el patógeno Lasiodiplodia spp. Actualmente el control biológico de fitopatógenos con microorganismos antagonistas representa una alternativa para el manejo de esta enfermedad. En el presente trabajo se evalúo in vitro la capacidad antagónica de cepas nativas de Trichoderma spp. hacia el patógeno Lasiodiplodia pseudotheobromae y su sensibilidad frente a dos fungicidas: benomilo y clorotalonil. Para el aislamiento de Trichoderma se colectaron muestras de suelo de cultivos de cítricos de Tepalcingo, Tlaltizapán y Villa de Ayala del estado de Morelos y el patógeno se aisló de plantas enfermas de limón “Persa”. Se calculó el porcentaje de inhibición del crecimiento (PIC) mediante la confrontación dual de Trichoderma hacia L. pseudotheobromae, y la concentración inhibitoria 50 (CI50) de las mejores cepas de Trichoderma frente a los dos fungicidas.

In the “Persa” lemon producing areas of the state of Morelos, one of the most common diseases is dieback caused by the pathogen Lasiodiplodia spp. Currently, the biological control of phytopathogens with antagonistic microorganisms represents an alternative for the management of this disease. In the present study, the antagonistic capacity of native strains of Trichoderma spp. towards the pathogen Lasiodiplodia psudotheobromae and its sensitivity towards two fungicides was evaluated in vitro: benomyl and chlorotalonil. For the isolation of Trichoderma, soils samples were collected from citrus crops of Tepalcingo, Tlaltizapan y Villa de Ayala in the state of Morelos and the pathogen was isolated from diseased “Persa” lemon plants. The percentage of growth inhibition (PGI) of Trichoderma towards L. pseudotheobromae and the inhibitory concentration (IC50) on the best Trichoderma strains against the two fungicides were evaluated.

Master thesis

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS cítricos, Trichoderma spp., Lasiodiplodia pseudotheobromae, clorotalonil, benomilo. citrus, Trichoderma spp., Lasiodiplodia pseudotheobromae, chlorothalonil, benomyl.

Screening of xylose utilizing and high lipid producing yeast strains as a potential candidate for industrial application

Linnea Qvirist RICARDO VAZQUEZ JUAREZ Thomas Andlid (2022)

"Background: Sustainable production of oil for food, feed, fuels and other lipid-based chemicals is essential to meet the demand of the increasing human population. Consequently, novel and sustainable resources such as lignocel- lulosic hydrolysates and processes involving these must be explored. In this paper we screened for naturally-occurring xylose utilizing oleaginous yeasts as cell factories for lipid production, since pentose sugar catabolism plays a major role in efcient utilization of lignocellulosic feedstocks. Glycerol utilization, which is also benefcial in yeast-based oil production as glycerol is a common by-product of biodiesel production, was investigated as well. Natural yeast isolates were studied for lipid accumulation on a variety of substrates, and the highest lipid accumulating strains were further investigated in shake fask cultivations and fermenter studies on xylose and hydrolysate. Results: By collecting leaves from exotic plants in greenhouses and selective cultivation on xylose, a high frequency of oleaginous yeasts was obtained (>40%). Diferent cultivation conditions lead to diferences in fatty acid contents and compositions, resulting in a set of strains that can be used to select candidate production strains for diferent purposes. In this study, the most prominent strains were identifed as Pseudozyma hubeiensis BOT-O and Rhodosporidium toruloides BOT-A2. The fatty acid levels per cell dry weight after cultivation in a nitrogen limited medium with either glucose, xylose or glycerol as carbon source, respectively, were 46.8, 43.2 and 38.9% for P. hubeiensis BOT-O, and 40.4, 27.3 and 42.1% for BOT-A2. Furthermore, BOT-A2 accumulated 45.1% fatty acids per cell dry weight in a natural plant hydrolysate, and P. hubeiensis BOT-O showed simultaneous glucose and xylose consumption with similar growth rates on both carbon sources. The fatty acid analysis demonstrated both long chain and poly-unsaturated fatty acids, depending on strain and medium. Conclusions: We found various natural yeast isolates with high lipid production capabilities and the ability to grow not only on glucose, but also xylose, glycerol and natural plant hydrolysate. R. toruloides BOT-A2 and P. hubeiensis BOT-O specifcally showed great potential as production strains with high levels of storage lipids and comparable growth to that on glucose on various other substrates, especially compared to currently used lipid production strains..."

Article

Microbial lipids, Oleaginous yeast, Lignocellulose, Pseudozyma hubeiensis, Rhodosporidium toruloides BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA MICROBIOLOGÍA MICROBIOLOGÍA MICROBIOLOGÍA

Phylogenetic relationships of Pseudo-nitzschia subpacifica (Bacillariophyceae) from the Mexican Pacific, and its production of domoic acid in culture

Sonia Quijano (2020)

Pseudo-nitzschia is a cosmopolitan genus, some species of which can produce domoic acid (DA), a neurotoxin responsible for the Amnesic Shellfish Poisoning (ASP). In this study, we identified P. subpacifica for the first time in Todos Santos Bay and Manzanillo Bay, in the Mexican Pacific using SEM and molecular methods. Isolates from Todos Santos Bay were cultivated under conditions of phosphate sufficiency and deficiency at 16°C and 22°C to evaluate the production of DA. This toxin was detected in the particulate (DAp) and dissolved (DAd) fractions of the cultures during the exponential and stationary phases of growth of the cultures. The highest DA concentration was detected during the exponential phase grown in cells maintained in P-deficient medium at 16°C (1.14 ± 0.08 ng mL-1 DAd and 4.71 ± 1.11 × 10−5 ng cell-1 of DAp). In P-sufficient cultures DA was higher in cells maintained at 16°C (0.25 ± 0.05 ng mL-1 DAd and 9.41 ± 1.23 × 10−7 ng cell-1 of DAp) than in cells cultured at 22°C. Therefore, we confirm that P. subpacifica can produce DA, especially under P-limited conditions that could be associated with extraordinary oceanographic events such as the 2013–2016 "Blob" in the northeastern Pacific Ocean. This event altered local oceanographic conditions and possibly generated the presence of potential harmful species in areas with economic importance on the Mexican Pacific coast. © 2020 Quijano-Scheggia et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Article

domoic acid, domoic acid, kainic acid, Article, cell growth, controlled study, diatom, Mexico, morphology, nonhuman, Pacific Ocean, phylogeny, plant cell, plant growth, Pseudo nitzschia, toxin analysis, cell culture technique, classification, diatom, CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO OCEANOGRAFÍA OCEANOGRAFÍA