Leaf-cutting ants live in an obligate symbiosis with a species, a basidiomycete that serves as a food source to the larvae and queen. The aim of this work was to isolate, identify and complete the phylogenetic study of species of . Macroscopic and microscopic features were used to identify the fungal symbiont of the ants. The ITS1-5.8S-ITS2 region was used as molecular marker for the molecular identification and to evaluate the phylogeny within the genus. One fungal symbiont associated with was isolated and identified as. The phylogeny of obtained using the ITS molecular marker revealed three well established monophyletic groups. It was possible to recognize one clade of associated with phylogenetically derived leaf-cutting ants ( and ). A second clade of free living forms of (non-cultivated), and a third clade of associated with phylogenetically basal genera of ants were also recognized. The clades corresponded to traditional taxonomic groups, and were differentiated by ecological habitats of different species.
Yerba mate (Ilex paraguariensis St. Hil.) is a species native to the subtropical regions of South America. Despite being an important crop for the region, there are few studies on the use of microorganisms to improve the growth of seedlings in the nursery stage. The objective of this study was to isolate spore-forming endophytic bacteria with plant growth promoting properties associated with yerba mate seedlings and determine their phytobeneficial effect under controlled laboratory conditions. Isolates were selected based on their sporulation capacity and evaluated for in vitro plant growth promoting properties (nitrogen fixation, phosphate solubilization, production of siderophores and synthesis of indolic compounds). Yerba mate seedlings were inoculated with the most promising isolates, which were identified via analyses of the sequence of their 16S rDNA gene as Bacillus circulans (12RS3) and Bacillus altitudinis (19RS3, T5S-T4). After 120 days plants showed higher root dry weight when inoculated with isolate 19RS3 and higher shoot dry weight with 19RS3 and T5S-T4. In conclusion, further studies to determine the ability of these isolates to adapt to the climatic conditions and to survive amidst the native soil microflora in yerba mate cultivated native soils, will be crucial for developing such strains as biofertilizer.
The bioconversion of lignocellulosic biomass into monomeric sugars is a key economic difficulty hindering the profitable use of plant biomass as energy. The production of cellulase is a main factor in the cellulose hydrolysis. Among the main cellulase producers are the filamentous fungi. Therefore, many efforts have been made in obtaining new microorganisms with high cellulase secretion capacity. The cellulase secretory capacity of 28 isolates of Trichoderma was qualitatively and quantitatively evaluated. The detection of cellulolytic fungi was correlated with both Congo red and the dinitrosalicylic acid reagent methods. Based on qualitatively assays, sixteen of the isolates revealed carboxymethyl cellulose degradation ability, where the Trichoderma POS7 isolate showed the highest increase in filter paper activity, endo-1,4-β-glucanases and β-glucosidases activities (p<0.05) in a short incubation time. This isolate was molecularly identified as Trichoderma koningiopsis, based on internal transcribed spacer sequences. Our results provide new information and reveal new microorganism in the hydrolysis of cellulose material. The phylogenetic analysis revealed close positioning of T. koningiopsis clade with T. viride, T. viridescens and T. petersenii clades in a closely related group, in concordance with the current taxonomic classification of Trichoderma genus.
Trichoderma koningiopsis strain POS7 produces significantly large amounts of cellulase enzymes in solid-state fermentation. The Illumina-based sequence analysis reveals an approximate genome size of 36.6 Mbp, with a G+C content of 48.82% for T. koningiopsis POS7. Based on ab initio prediction, 12,661 coding genes were annotated.
The production of yerba mate seedlings through seeds has several limitations, which can be overcome by ex vitro vegetative propagation techniques such as the mini-cuttings, in which it is usually necessary to use synthetic chemical fertilizers and fungicides. However, there is a tendency towards sustainable agriculture, using biofertilizers (growth-promoting bacteria) and biocontrollers (Trichoderma sp.). Therefore, the objectives of this work were to evaluate the effect of biofertilizers on the production of mini-cuttings from yerba mate mini-stumps; as well as the effect, of biocontrollers on survival and rooting capacity of mini-cuttings. Strains of Bacillus sp. and Trichoderma asperelloides of yerba mate were used under two radiation conditions. There was a positive relationship between the availability of radiation and the production of mini-cuttings and the rooting capacity. All the mini-stumps sprouted regardless of treatments. The largest production of viable mini-cuttings occurred in a situation of high radiation and fertilization; while the treatments with growth-promoting bacteria and high radiation had intermediate values. The mini-cuttings inoculated with Trichoderma asperelloides had higher rooting percentage, greater number and length of roots than the mini-cuttings treated with fungicide. Therefore, we demonstrated that the use of chemical products can be replaced by biological ones and achieves acceptable yields.
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