RESUMO
In Argentina, periurban agriculture is performed by farmers with inadequate training in the use of pesticides and chemical fertilizers, developing horticulture with serious soil deterioration. The aim of this work was to monitor bacterial diversity of a horticultural soil (S) and a reference soil (R) as quality index for the design of future restoration strategies. As crops changed together with the agrochemical applications, sample collection was before harvest for strawberries, post-harvest for red peppers, pre-harvest broccoli crop and of a resting soil in treatment with poultry litter as a fertilizing amendment. Bacterial diversity was analysed by the use of high throughput sequencing of the V1-V3 region of the 16S rRNA gene. Analysis of R soils seemed relatively constant in time, enriched in Alphaproteobacteria and Acidobacteria consistent with a reference to soil health. The effect of the intensive use of S soils was proved by differences in Chloroflexi, Bacteroidetes and Proteobacteria relative abundances. The main evidence of the alteration of S soils was the increase in Bacteroidetes and Betaproteobacteria. A weak recuperation trend of S soil microbiota was registered during a post-harvest inactive period. A strong influence of the soil use routine-consisting in high crop rotation and short time-rest cycles-on microbial community structure was verified. These results indicate the microbiota perturbation, caused by the intense use of periurban agriculture soils and will contribute for further actions to improve environment quality.
Assuntos
Microbiota , Solo , Agricultura , Argentina , Indicadores de Qualidade em Assistência à Saúde , RNA Ribossômico 16S/genética , Microbiologia do SoloRESUMO
Fungal endophytes are important sources of bioactive secondary metabolites. The genus Xylaria Hill (ex Schrank, 1789, Xylariaceae) comprises various endophytic species associated to both vascular and non vascular plants. The secondary metabolites produced by Xylaria species include a variety of volatile and non-volatile compounds. Examples of the former are sesquiterpenoids, esters, and alcohols, among others; and of the latter we find terpenoids, cytochalasins, mellein, alkaloids, polyketides, and aromatic compounds. Some of these metabolites have shown potential activity as herbicides, fungicides, and insecticides; others possess antibacterial, antimalarial, and antifungal activities, or α-glucosidase inhibitory activity. Thus metabolites from Xylaria are promising compounds for applications in agriculture for plague control as biopesticides, and biocontrol agents; and in medicine, for example as drugs for the treatment of infectious and non-infectious diseases. This review seeks to show the great value of the secondary metabolites of Xylaria, particularly in the agriculture and medicine fields.