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The shiitake culinary-medicinal mushroom Lentinus edodes is one of the most consumed species worldwide because it has nutritional, medicinal, and palatable properties. Its organoleptic characteristics contribute substantially to its high popularity. The pleasant aromas result from the presence of volatile compounds. The objective of the present work was to study the profiles of volatile constituents of fresh fruiting bodies of five strains of L. edodes. The volatile compounds were extracted by solid phase microextraction method and analyzed by gas chromatography and mass spectrometry. The aromatic profiles of the strains revealed variability. Both alcohols and sulfides were the most abundant volatile compounds. LE6 strain presented the highest number of volatile compounds with predominance of sulfides (dimethyl pentasulfide, s-tetrathiane) and for LE2, the aldehydes were the most representative chemical class with the main volatile being (E)-2-octen-1-al.

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Plant growth-promoting bacteria have been highlighted by their potential for application in plant production, allowing the reduction of the use of fertilizers and pesticides, which is due to the ability to stimulate the growth of plants by nitrogen-fixation and production of phytohormones, such as indole-3-acetic acid (IAA). The objective of this study was to verify the potential of plant growth promotion of 25 wild isolates from the Agricultural Microbiology Culture Collection of the Federal University of Lavras (CCMA-UFLA) through the evaluation of the biological nitrogen-fixation capacity and the production of IAA. In addition, the growth of three selected strains inoculated on roots of strawberry seedlings in greenhouse conditions was evaluated. The experiment was conducted in a completely randomized design (CRD), with an 8 × 2 factorial schemes involving eight combinations of bacteria: alone, in pairs and threes, plus the control without inoculation. Two fertilizer levels were used (0% and 50% of nitrogen), totaling 16 treatments with eight replicates each. After 75 days, variables such as root length, root dry weight, aerial part length, aerial part dry weight, leaf number, total dry mass and ultrastructural analysis of the inoculated and uninoculated roots, were evaluated. The results showed that the strawberry crop responded positively to inoculation with the three bacteria combined Azospirillum brasilense (Ab-V5) + Burkholderia cepacia (CCMA 0056) + Enterobacter cloacae (CCMA 1285) compared to the uninoculated controls. More expressive responses in terms of plant growth were observed in relation to the combined inoculation of the three bacterial strains plus fertilizer application with 50% of nitrogen.

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ABSTRACT Composting is the process of natural degradation of organic matter carried out by environmental microorganisms whose metabolic activities cause the mineralization and partial humification of substances in the pile. This compost can be beneficially applied to the soil as organic fertilizer in horticulture and agriculture. The number of studies involving microbial inoculants has been growing, and they aim to improve processes such as composting. However, the behavior of these inoculants and other microorganisms during the composting process have not yet been described. In this context, this work aimed to investigate the effects of using a microbial inoculum that can improve the composting process and to follow the bacterial population dynamics throughout the process using the high-resolution melt (HRM) technique. To do so, we analysed four compost piles inoculated with Bacillus cereus, Bacillus megaterium, B. cereus + B. megaterium and a control with no inoculum. The analyses were carried out using samples collected at different stages of the process (5th to 110th days). The results showed that the bacterial inocula influenced the process of composting, altering the breakdown of cellulose and hemicelluloses and causing alterations to the temperature and nitrogen levels throughout the composting process. The use of a universal primer (rDNA 16S) allowed to follow the microbial succession during the process. However, the design of a specific primer is necessary to follow the inoculum throughout the composting process with more accuracy.

RESUMO A compostagem é um processo de degradação natural da matéria orgânica realizado por microrganismos presentes no ambiente, levando a mineralização e humificação parcial das substâncias presentes na pilha, esse composto formado pode ser beneficamente aplicado ao solo como fertilizante orgânico na horticultura e agricultura. O número de estudos envolvendo inoculantes microbianos é crescente, os quais tem por objetivo a otimização de processos de compostagem. Contudo, o comportamento desses inoculantes e da microbiota ao longo do processo não tem sido caracterizado. Nesse contexto, este trabalho foi realizado com o objetivo de avaliar o efeito da utilização de um inóculo bacteriano que promova melhorias no processo de compostagem, bem como o de acompanhar a dinâmica populacional bacteriana ao longo de todo o processo através da técnica de High Resolution Melt (HRM). Para isso foram analisados quatro pilhas de compostagem inoculadas com Bacillus cereus, Bacillus megaterium, B. cereus + B. megaterium e o controle sem adição de inóculo. Foram realizadas análises químicas e moleculares (HRM) das amostras coletadas em diferentes períodos da compostagem (5º ao 110º dias). Os resultados mostraram que os inóculos bacterianos influenciaram no processo de compostagem com alteração na degradação de celulose, hemicelulose bem como alteração da temperatura e níveis de nitrogênio ao longo da compostagem. A utilização de um primer universal (rDNA 16S) permitiu acompanhar a sucessão bacteriana ao longo do processo, nos tratamentos. Contudo a construção de um primer específico é necessário para acompanhar de maneira mais precisa o inóculo durante o desenvolvimento da compostagem.

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The composition and genetic diversity of fungal populations during phase II of compost production for the cultivation of Agaricus subrufescens was determined using culture-dependent and -independent methods on days 3, 6, 10, 12, and 14 of phase II composting. The isolates were morphologically characterized and subsequently analyzed using repetitive extragenic palindromic sequences (rep-PCR), and the intergenic region was sequenced to genetically identify the isolates. Changes on in the filamentous fungi population were analyzed using denaturing gradient gel electrophoresis (DGGE), and the resulting bands were sequenced. The population did not significantly change from day 3 to 10 (2.55 x 10(5) -6 x 10(5) CFU g(-1)), and maximum counts on day 14 of phase II composting (6.92 log CFU g(-1)). In the morphological characterization, Scytalidium thermophilum, Thermomyces lanuginosus, and Thermomyces ibadanensis were the most abundant identified species. The 26 most abundant isolates identified by morphological analysis were characterized using rep-PCR. A significant amount of genetic diversity was detected among the isolates of all three studied species. Based on the DGGE analysis, the diversity of the fungi was reduced during phase II composting, and S. thermophilum was the predominant species identified throughout the entire process. Thus, this study presents the first report of the involvement of T. ibadanensis in the production of compost for Agaricus mushroom cultivation.

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This study used a multiphasic approach, characterized by the simultaneous use of culture-dependent and culture-independent methods, to investigate endophytic bacterial communities in strawberry (Fragaria ananassa) fruit. A total of 92 bacterial endophytes were isolated and initially grouped by their repetitive extragenic palindromic (rep)-PCR banding pattern and biochemical features. Phylogenetic analysis of the 16S rRNA gene sequences of 45 representatives showed that the isolates belonged to the species Bacillus subtilis (eight isolates), Bacillus sp. (seven isolates), Enterobacter sp. (seven isolates), Enterobacter ludwigii (six isolates), Lactobacillus plantarum (six isolates), Pseudomonas sp. (five isolates), Pantoea punctata (three isolates), and Curtobacterium citreum (three isolates). Nucleic acids were extracted from the strawberry fruit and subjected to 16S rRNA gene directed polymerase chain reaction denaturing gradient gel electrophoresis (16S rRNA PCR-DGGE). The species B. subtilis, Enterobacter sp., and Pseudomonas sp. were detected both by isolation and DGGE. The DGGE fingerprints of total bacterial DNA did not exhibit bands corresponding to several of the representative species isolated in the extinction dilution (L. plantarum, C. citreum, and P. punctata). In contrast, bands in the DGGE profile that were identified as relatives of Arthrobacter sp. and one uncultivable Erythrobacter sp. were not recovered by cultivation techniques. After isolation, the nitrogen fixation ability and the in vitro production of indole-3-acetic acid (IAA) equivalents and siderophores were evaluated. A high percentage of isolates were found to possess the ability to produce siderophores and IAA equivalents; however, only a few isolates belonging to the genera Pseudomonas and Enterobacter showed the ability to fix nitrogen. Plant growth promotion was evaluated under greenhouse conditions and revealed the ability of the Bacillus strains to enhance the number of leaves, shoot length, root dry weight, and shoot dry weight. The activity of the bacterial isolate identified as B. subtilis NA-108 exerted the greatest influence on strawberry growth and showed a 42.8% increase in number of leaves, 15.26% for high shoot, 43.5% increase in root dry weight, and a 77% increase in shoot dry weight when compared with untreated controls.

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