ESTUDOS DA ATIVIDADE ANTIMICROBIANA DA ESPÉCIE Plantago major L.: UMA REVISÃO INTEGRATIVA

Introdução: A Plantago major L. é popularmente conhecida como tanchagem pertence à família Plantaginacea. Tem estrutura perene com folhas rosetadas, as flores e folhas jovens são comestíveis. Utilizada na medicina popular para o tratamento de lesões na pele, gengivite, abcessos, dor de dente. Possui grande variedade de bioativos como alcalóides, terpenos, flavonóides, vitaminas. A sua atividade funcional é relacionada a presença desses compostos químicos.(1) Objetivos: Realizar um levantamento bibliográfico para identificar a atividade antimicrobiana de P. major. Métodos: Trata-se de uma revisão bibliográfica do tipo integrativa realizada por busca nas bases de dados Pubmed, SciELO e BVS, trabalhos indexados no período de 2016 a 2021. Foram utilizados para busca dos artigos os seguintes descritores “Plantago major” e “antimicrobial”. Como critério de inclusão foram pesquisados artigos em inglês, espanhol e português, disponíveis na íntegra, estudos com informações referentes ao uso da espécie como agente antimicrobiano. Os critérios de exclusão foram os artigos duplicados, revisões bibliográficas. Resultados: Foram encontrados 18 artigos, após realizar uma análise criteriosa do material, foram incluídos na revisão 6 trabalhos. Um dos trabalhos sugeriu a utilização de extrato de P. major como enxaguante bucal para o tratamento de mucosite oral.(2) Em outro estudo a aplicação do extrato de P. major mostrou atividade antibacteriana contra Pseudomonas tolaasii, resultando um maior diâmetro inibitório. Também apresentou inibição de crescimento contra Pseudomonas aeruginosa utilizando a técnica de disco, com o aparecimento de halos de inibição de crescimento maiores que 1 cm. No ensaio de citotoxicidade, o grau de hemólise foi classificado como baixo (5%), logo, indicando a segurança no uso da tanchagem(3) Utilizando sementes de P. major aplicadas em nanoparticulas apresentou atividade aceitável contra Micrococcus luteus, Escherichia coli e Penicillium digitatum. Além desses patógenos, outro estudo evidenciou que o extrato etanólico (75%;100%) de tanchagem apresentou efeito antibacteriano in vitro contra Porphyromonas gingivalis, apresentando halos de inibição.(4) Também foi obtido resultados contra Cândida albicans, aplicando extrato de P. major, com aucubina e baicaleína, atuando na hidrofobicidade de C. albicans, demonstrando eficácia como antifúngico, sugerindo ser um potencial promissor para infecções relacionadas ao biofilme por C. Albicans.(5) Conclusões: A partir desses resultados é possível identificar a possibilidade do uso de Plantago major para fins terapêuticos, fitoterápicos ou nutricionais sendo necessário realizar mais estudos quanto a sua atividade antimicrobiana além de testes quanto à sua toxicidade.

Characterization, Pathogenicity, Phylogeny, and Comparative Genomic Analysis of Pseudomonas tolaasii Strains Isolated from Various Mushrooms in China

Since 2016, devastating bacterial blotch affecting the fruiting bodies of Agaricus bisporus, Cordyceps militaris, Flammulina filiformis, and Pleurotus ostreatus in China has caused severe economic losses. We isolated 102 bacterial strains and characterized them polyphasically. We identified the causal agent as Pseudomonas tolaasii and confirmed the pathogenicity of the strains. A host range test further confirmed the pathogen’s ability to infect multiple hosts. This is the first report in China of bacterial blotch in C. militaris caused by P. tolaasii. Whole-genome sequences were generated for three strains: Pt11 (6.48 Mb), Pt51 (6.63 Mb), and Pt53 (6.80 Mb), and pangenome analysis was performed with 13 other publicly accessible P. tolaasii genomes to determine their genetic diversity, virulence, antibiotic resistance, and mobile genetic elements. The pangenome of P. tolaasii is open, and many more gene families are likely to emerge with further genome sequencing. Multilocus sequence analysis using the sequences of four common housekeeping genes (glns, gyrB, rpoB, and rpoD) showed high genetic variability among the P. tolaasii strains, with 115 strains clustered into a monophyletic group. The P. tolaasii strains possess various genes for secretion systems, virulence factors, carbohydrate-active enzymes, toxins, secondary metabolites, and antimicrobial resistance genes that are associated with pathogenesis and adapted to different environments. The myriad of insertion sequences, integrons, prophages, and genome islands encoded in the strains may contribute to genome plasticity, virulence, and antibiotic resistance. These findings advance understanding of the determinants of virulence, which can be targeted for the effective control of bacterial blotch disease.

Sulfur amino acids status controls selenium methylation in Pseudomonas tolaasii: Identification of a novel metabolite from promiscuous enzyme reactions

Selenium (Se) deficiency affects many millions of people worldwide, and the volatilization of methylated Se species to the atmosphere may prevent Se from entering the food chain. Despite the extent of Se deficiency, little is known about fluxes in volatile Se species and their temporal and spatial variation in the environment, giving rise to uncertainty in atmospheric transport models. To systematically determine fluxes, one can rely on laboratory microcosm experiments to quantify Se volatilization in different conditions. Here, it is demonstrated that the sulfur (S) status of bacteria crucially determines the amount of Se volatilized. Solid phase microextraction gas chromatography mass spectrometry showed that Pseudomonas tolaasii efficiently and rapidly (92% in 18h) volatilized Se to dimethyldiselenide and dimethylselenylsulfide through promiscuous enzymatic reactions with the S metabolism. However, when the cells were supplemented with cystine (but not methionine), a major proportion of the Se (∼48%) was channelled to thus far unknown, non-volatile Se compounds at the expense of the previously formed dimethyldiselenide and dimethylselenylsulfide (accounting for < 4% of total Se). Ion chromatography and solid phase extraction were used to isolate unknowns, and electrospray ionization ion trap mass spectrometry, electrospray ionization quadrupole time-of-flight mass spectrometry and microprobe nuclear magnetic resonance spectrometry were used to identify the major unknown as a novel Se metabolite, 2-hydroxy-3-(methylselanyl)propanoic acid. Environmental S concentrations often exceed Se concentrations by orders of magnitude. This suggests that in fact S status may be a major control on selenium fluxes to the atmosphere. Importance Volatilization from soil to the atmosphere is a major driver for Se deficiency. "Bottom up" models for atmospheric Se transport are based on laboratory experiments quantifying volatile Se compounds. The high Se and low S concentrations in such studies poorly represent the environment. Here, we show that S amino acid status has in fact a decisive effect on the production of volatile Se species in Pseudomonas tolaasii. When the strain was supplemented with S amino acids, a major proportion of the Se was channelled to thus far unknown, non-volatile Se compounds at the expense of volatile compounds. This hierarchical control of the microbial S amino acid status on Se cycling has been thus far neglected. Understanding these interactions – if occurring in the environment- will help to improve atmospheric Se models and thus predict drivers of Se deficiency.

Insights into detoxification of tolaasins, the toxins behind mushroom bacterial blotch, by Microbacterium foliorum NBRC 103072T

Tolaasins are lipodepsipeptides secreted by Pseudomonas tolaasii, the causal agent of brown blotch disease of mushrooms, and are the toxins that cause the brown spots. We previously reported that Microbacterium foliorum NBRC 103072T is an effective tolaasin-detoxifying bacterium. In this study, we aimed to characterize the tolaasin-detoxification process of M. foliorum NBRC 103072T. The tolaasin-detoxification by M. foliorum NBRC 103072T was carried out by hydrolyzation of tolaasins at two specific sites in the peptide moiety of tolaasins by its cells, and the resulting fragments were released from bacterial cells. The tolaasin-hydrolyzing activity can be extracted by neutral detergent solution from M. foliorum NBRC 103072T cells. Moreover, tolaasin-adsorption to the bacterial cells occurred prior to hydrolyzation of tolaasins, which might contribute to the effective tolaasin-detoxification by M. foliorum NBRC 103072T. It is notable that the tolaasin-degradation process by M. foliorum NBRC 103072T is carried out by hydrolyzation at specific sites in the peptide moiety of lipopeptide by bacterial cells as a novel biological degradation process of cyclic lipopeptides.

Exogenous Fe2+ alleviated the toxicity of CuO nanoparticles on Pseudomonas tolaasii Y-11 under different nitrogen sources

Extensive use of CuO nanoparticles (CuO-NPs ) inevitably leads to their accumulation in wastewater and toxicity to microorganisms that effectively treat nitrogen pollution. Due to the effects of different mediums, the sources of CuO-NPs-induced toxicity to microorganisms and methods to mitigating the toxicity are still unclear. In this study, CuO-NPs were found to impact the nitrate reduction of Pseudomonas tolaasii Y-11 mainly through the action of NPs themselves while inhibiting the ammonium transformation of strain Y-11 through releasing Cu2+. As the content of CuO-NPs increased from 0 to 20 mg/L, the removal efficiency of NO3− and NH4+ decreased from 42.29% and 29.83% to 2.05% and 2.33%, respectively. Exogenous Fe2+ significantly promoted the aggregation of CuO-NPs, reduced the possibility of contact with bacteria, and slowed down the damage of CuO-NPs to strain Y-11. When 0.01 mol/L Fe2+ was added to 0, 1, 5, 10 and 20 mg/L CuO-NPs treatment, the removal efficiencies of NO3- were 69.77%, 88.93%, 80.51%, 36.17% and 2.47%, respectively; the removal efficiencies of NH4+ were 55.95%, 96.71%, 38.11%, 20.71% and 7.43%, respectively. This study provides a method for mitigating the toxicity of CuO-NPs on functional microorganisms.