Biotransformations are reactions mediated by microorganisms, such as fungi. These bioreactions have high chemo- and stereoselectivity on organic substrates and can be applied in the search for new bioactive compounds. In this study, acanthoic acid (AA) was biotransformed using the fungus Xylaria sp., giving the novel compound 3β,7β-dihydroxyacanthoic acid (S1). Both the AA and the product S1 were tested against Gram-positive and Gram-negative bacteria. To identify and validate possible biological targets as enzymes or proteins involved in the activity observed in vitro, we used the molecular docking method. Hydroxylation at the C-3 and C-7 positions of the biotransformation product enhanced its activity against Escherichia coli as well as its binding affinity and interactions with superoxide dismutase 1 (SOD1; PDB ID 4A7G). Based on our results, the SOD1 enzyme was suggested to be a possible target for the antioxidant activity of product S1.

Bacterial spot, which is the main disease occurring in passion fruit trees, is caused by the bacterium Xanthomonas axonopodis pv. passiflorae, leading to large annual losses in passion fruit crops. This study aims to find extracts and/or bioactive compounds of endophytic fungi of noni (Morinda citrifolia) to treat bacterial spot in passion fruit trees. Nine fungi isolated from a specimen of M. citrifolia from the Brazilian Amazon are studied. The fungus Guignardia mangiferae NF17 shows the best inhibition results and is selected for the isolation of its secondary metabolites by chromatography techniques. The isolated compounds Sydowinol (S1) and Sydowinin A (S2) are identified by nuclear magnetic resonance (NMR). Compounds S1 and S2, as well as the acetonitrile extract from the biomass of G. mangiferae NF17, are tested against four strains of X. axonopodis pv. passiflorae obtained from plants infected by bacterial spot, and which inhibited bacterial growth up to the lowest concentration tested (3.125 µg/mL). This study reports, for the first time, the antibacterial activity against X. axonopodis pv. passiflorae by the compounds Sydowinol and Sydowinin A. Compounds S1 and S2 are reported for the first time for the genus Gignardia.

O objetivo deste trabalho foi determinar a capacidade de isolados de bactérias endofíticas em promover o crescimento de plantas de pimenta-do-reino. As bactérias endofíticas foram inoculadas em mudas de pimenta-do-reino por imersão em suspensão bacteriana na concentração de 108 UFC mL-1 por 5 minutos. Plantas do tratamento controle foram imersas em água destilada estéril. Em seguida, as mudas foram plantadas em vasos contendo fibra de coco estéril. Para avaliar a promoção de crescimento das plantas foram medidas a altura, o diâmetro do caule e a massa seca. Os isolados C5.11, C6.2, T2.2 e C1.4 promoveram crescimento de plantas de pimenta-do-reino, com aumento na altura de 26,82, 27,37, 35,55 e 37,99%, respectivamente, na massa seca, aumento em valores de 10,13, 3,92, 6,25 e 10,17%, respectivamente, e em relação ao crescimento em diâmetro do caule, o isolado C5.11 promoveu aumento de 33,66% na taxa de crescimento em relação ao tratamento controle. No presente estudo, os isolados C6.2, T2.2, C5.11 e C1.4 promoveram crescimento de plantas de pimenta-do-reino, com o aumento na altura e massa seca das plantas em comparação ao tratamento controle.

The yellow passionfruit (Passiflora edulis Sims f. flavicarcarpa Deg.) is important culture in Brazilian Amazon agriculture, especially in the state of Pará. But its cultivation has been suffering the reduction of its areas and productivity due the diseases caused by bacteria, where chemical control, sometimes does not present the expected results. The propolis of Africanized bees (Apis mellifera L.) is an important natural antibiotic for the control of undesirable microorganisms of plants and animals. The present work aimed at the in vitro study of the antibiotic activity of different propolis extracts of Africanized bees from two different locations in the state of Pará in the agent that causes the passionfruit bacterial blight (Xanthomonas axonopodis pv. passiflorae). A factorial analysis of three factors was performed: origin X solvent X concentration. It was verified that the concentrations of 0.5% were statistically superior to the others, with average growth inhibition power of 86%, and the propolis extract from an apiary in Santa Izabel do Pará, Pará, Brazil, obtained in ethanol at 80%, was statistically different and superior for the inhibitory effect of the growth of colony forming units (CFU) of X. axonopodis pv. passiflorae.

The objective of this work was to investigate three endophytic bacterial strains as to their ability to promote the growth and rooting of black pepper stem cuttings, as well as to determine the mechanisms involved in the promoting activity through molecular methods. The strains were identified by 16S sequencing as belonging to the genera Bacillus, Priestia, and Lysinibacillus. They were characterized for the production of indoleacetic acid (IAA), phosphate solubilization, and siderophore production. In two assays, the roots of the cuttings were immersed in bacterial suspensions to evaluate growth promotion through plant height, stem diameter, and root and shoot dry mass. The Bacillus sp. C1.4 and Priestia sp. T2.2 strains were able to produce siderophores, whereas Priestia sp. T2.2 and Lysinibacillus sp. C5.11 produced IAA. In addition, Priestia sp. T2.2 significantly increased plant height and dry mass, whereas Lysinibacillus sp. C5.11 significantly increased root dry mass. Therefore, Priestia sp. T2.2 and Lysinibacillus sp. C5.11 are able to promote the growth and rooting of black pepper stem cuttings, respectively. This growth promotion is linked directly to the production of IAA and siderophores.