Laboratory-Scale Biodegradation of Fuel Oil No. 6 in Contaminated Soils by Autochthonous Bacteria

In order to evaluate the degradation of fuel oil no. 6 (FO6) in contaminated soil, laboratory-scale bioreactors were set up to study biostimulation, bioaugmentation, and natural attenuation processes. A solution of fertilizers was added in biostimulation and biouagmentation (0.03% N, 0.01% P). To the bioaugmentation process, an enrichment culture of indigenous hydrocarbon-degrading microorganisms was also added once a week. Total aerobic and hydrocarbon-degrading microorganisms were determined by plate count, and total petroleum hydrocarbon (TPH) concentration was determined gravimetrically (EPA method 9071b) every 15 days. After 1 year of study, degradation rate was higher for biostimulation (0.19 g TPH/day), followed by natural attenuation (0.18 g TPH/day) and bioaugmentation (0.16 g TPH/day). TPH showed a change in composition of hydrocarbons, attributed to microbiological activity. Microbial counts of hydrocarbon-degrading microorganisms were on the range of 4–6 log CFU/g soil. Preliminary bacterial identification corresponded to Pseudomonas, Rhodococcus, Actinomyces, and Bacillus strains; randomly amplified polymorphic DNA (RAPD); and denaturing gradient gel electrophoresis (DGGE) analysis demonstrated a large microbial diversity. From the degradation rates, it can be predicted that such limits will be achieved by increasing further 107–117 days of the treatments. Results demonstrated to be efficient on the restoration of contaminated soil, being an alternative to treat soils contaminated with heavy hydrocarbons

Seguridad alimentaria: la continua lucha contra las enfermedades de los cultivos

El instinto del ser humano es la búsqueda de alimentos y la conservación de los mismos a través del almacenamiento de frutos, granos y semillas para garantizar su alimentación en periodos de escasez. En este documento se abordan temas relacionados con los riesgos que tiene la producción de alimentos en campo por causa de fitopatógenos, algunos ejemplos históricos, estudios de diagnóstico y una propuesta a favor de la soberanía alimentaria. Las epifitias han mermado la producción en México y en el mundo provocando grandes catástrofes. Las hambrunas de Irlanda y Bengala son los hechos más devastadores para la humanidad, debido a que provocaron la muerte de más de tres millones de personas. Enfermedades causadas por patógenos emergentes se están presentando en la actualidad, amenazando la producción de alimentos y los rendimientos por unidad de superficie. Para combatirlos, es necesario un diagnóstico preciso mediante el uso de técnicas moleculares, la medición de la magnitud del daño, entre otras variables epidemiológicas, aunada a la aplicación de medidas fitosanitarias adecuadas. Con el propósito de asegurar el abasto de alimento para todos los mexicanos, en este trabajo se propone que instancias gubernamentales e instituciones de investigación realicen esfuerzos conjuntos, dirigidos al diseño de políticas fitosanitarias y a la investigación sobre patógenos de importancia económica. Este tipo de patógenos representan la mayor amenaza para nuestros cultivos, aunado al riesgo de su introducción debido a las importaciones. Además se propone implementar programas de gobierno permanentes para financiar la investigación sobre patógenos reglamentados

Exploring Microbial Rhizosphere Communities in Asymptomatic and Symptomatic Apple Trees Using Amplicon Sequencing and Shotgun Metagenomics

The rhizosphere is a dynamic and highly interactive habitat where diverse microbial communities are established, and it plays crucial roles in plant health and disease dynamics. In this study, microbial communities and functional profiles in the rhizosphere of both asymptomatic and symptomatic apple trees were investigated through amplicon sequencing and shotgun metagenomics. The research was conducted at a location in the municipality of Cuauhtemoc, Chihuahua State, Mexico, and a total of 22 samples were collected, comprising 12 for amplicon sequencing and 10 for shotgun metagenomic sequencing. Symptomatic trees were identified based on reddish branches and internal necrosis in the trunk and root, while asymptomatic trees exhibited a healthy physiology. The findings showed that the dominant bacterial phyla included Proteobacteria, Actinobacteria, and Bacteroidetes, with prevalent genera such as Streptomyces, Pseudomonas, and Rhodanobacter. The fungal communities featured Ascomycota, Mortierellomycota, and Basidiomycota, which were dominated by Fusarium, Penicillium, and Mortierella. In the fungal communities, Mortierellomycota, notably abundant in asymptomatic trees, holds potential as a biocontrol agent, as seen in other studies on the suppression of Fusarium wilt disease. The application of shotgun metagenomic sequencing revealed significant differences in alpha and beta diversities in bacterial communities, suggesting a health-dependent change in species composition and abundance. Functional profile analysis highlighted enzymatic activities associated with lipid synthesis/degradation, amino acid biosynthesis, carbohydrate metabolism, and nucleotide synthesis, which have been documented to participate in symbiotic relationships between plants. These insights not only contribute to understanding the dynamics of rhizosphere microbial activity but also provide valuable perspectives on the potential application of microbial communities for tree health and implications for the management of apple orchards