Alessandra Keiko Nakasone

Beneficial endophytic bacteria may confer advantages to their host plants and to the environment by pathogen control, while reducing pesticide use. The aim of this work was to determine the biochemical profile and antifungal activity of endophytic bacteria from black pepper roots against Fusarium solani f. sp. piperis , F. oxysporum , and Colletotrichum gloeosporioides , which cause fusariosis and anthracnose in black pepper. One hundred and sixty‐four endophyte bacteria strains isolated from black pepper roots were tested in vitro against three phytopathogenic fungi. Seven selected antagonistic strains were identified at the genus level by sequencing the 16S region of the ribosomal RNA. In addition, the production of lytic enzymes and siderophores was evaluated that may be related to the biocontrol of pathogenic microorganisms. The effect of ethyl acetate and ethanolic extracts of antagonistic strains on the germination of pathogen spores was evaluated. Strains C5.4, C5.9, T1.5, T4.1, T4.7, T6.2, and T6.4 showed antifungal activity with inhibition ranging from 30.27% to 61.42%, and were identified as species of the genus Burkholderia . The biochemical profile showed that strains produced lipase, esterase, protease, and siderophores, which may be related to their antifungal activity. The best results of antifungal activity were shown by the ethyl acetate extracts of strains C5.4, C5.9, T4.7, T6.2, T6.4, and T4.1, with percentages ranging from 4.71% to 51.89%. This study demonstrated that endophytic bacteria from black pepper have potential for the biocontrol of fungal diseases and can be further investigated to obtain a formulation for the control of pathogenic microorganisms associated with this crop.

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.

As principais doenças do maracujazeiro são causadas por microorganismos. O fungo Rhizoctonia solani Kuhn é um fungo fitopatogênico e na cultura do maracujá, este fungo é responsável pela queima foliar, causando sérios prejuízos ao seu cultivo. O presente trabalho teve como objetivo buscar extratos bioativos de fungos endofíticos de noni (Morinda citrifolia) contra Rhizoctonia solani Kuhn. Foram isolados 82 fungos endofíticos das folhas, frutos, caule e raiz de M. citrifolia e separados em 11 grupos, onde de um fungo de cada grupo foi obtidos seu extrato. No ensaio in vitro os extratos demonstraram boa atividade antifúngica. Os extratos mais ativos NF12, NF17, NR7 e NFrS2 foram analisados por HPLC o que evidenciou a presença de compostos das classes das azafilonas, terpenos, tricotecenos e compostos fenólicos como constituintes químicos majoritários nos extratos. Os dados demostram que extratos de fungos endofíticos podem representar uma nova abordagem para os problemas relacionados ao combate as doenças do maracujazeiro.

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.

The objective of this work was to evaluate the in vitro potential effect of extracts of amazonian bee propolis on the growth of Xanthomonas axonopodis pv. manihotis, causal agent of cassava bacteriosis. The propolis samples were collected in apiaries with hives inhabited by Apis mellifera L. (africanized) bees in the municipalities of Santa Izabel and Curuçá, in the state of Pará. The extracts were obtained from static maceration for 24 h with hexane solvents, ethyl acetate and 80% ethanol. The phenolic profiles of the samples were obtained by High Performance Liquid Chromatography/Diode Array Detection/Mass Spectrometry with Electrospray Ionization. The antibacterial activity was verified with the extracts in concentrations of 0.1; 0.2; 0.3 and 0.4%. The chemical analysis revealed the presence of kaempferol in the Santa Izabel-PA sample, gallic acid in the Curuçá-PA sample, and 3,4-dihydroxybenzoic in both samples. The 80% ethanolic extract of the bee propolis from Santa Izabel significantly reduced the growth of X. axonopodis pv. manihotis.

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.

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.

Biotransformations are reactions carried out by microorganisms that lead to changes in the structures of organic compounds, among the biotransformations there are bioreductions. Bioreductions are of great interest to the pharmaceutical and food industries, as they almost always lead to the formation of enantiomerically pure compounds. Thus, this work aimed to verify the ability of the fungus Lasiodiplodia pseudotheobromae in bioreduce α,β-unsaturated carbonyl compounds. Compounds (3E)-4-(2-methoxy-phenyl)-but-3-en-2-one (1), (1E, 4E)-1,5-diphenyl-pent-1,4-dien-3-one (2) and (1E, 4E)-1,5-bis-(2-methoxy-phenyl)-penta-1,4-dien-3-one (3) were used as substrates. The reactions were carried out on an orbital shaker for 8 days at room temperature. The products formed were characterized by analytical thin layer chromatography (ATLC), high performance liquid chromatography (HPLC) and hydrogen nuclear magnetic resonance (¹H NMR). For all products formed was observed reduction in double bonds C=C and C=O leading to the formation of the respective alcohols. This is the first report of biotransformation reactions using the fungus Lasiodiplodia pseudotheobromae.

No entanto, a cultura é acometida por diversos problemas fitossanitários que podem refletir na produtividade e no aumento dos custos de produção (⁶). Dentre os fitopatógenos, principalmente de origem fúngica, destaca-se o fungo Thielaviopsis paradoxa, agente etiológico da podridão basal da palma de óleo (¹, ²⁵).