José Ivo Baldani

A cana-de-açúcar (Saccharum L.) é uma Poaceae (gramínea) de grande importância na agricultura brasileira, com produtos derivados tais como: açúcar, etanol, metanol, biodiesel, biogás, bioplásticos e produção de energia. Com a pandemia do Corona vírus ou Covid-19 (SARS-CoV-19), e conseqüente aumento da demanda por álcool em gel no Brasil e no mundo, despertou-se grande interesse na busca pelo incremento de produtividade desta cultura, o que impulsionou o uso de fertilizantes nitrogenados para este fim. Como justificativa a necessidade de testar a ação fertilizante das demais estirpes presentes no banco de bactérias da Embrapa Agrobiologia, comparando com os estudos da estirpe CBAmC.O objetivo foi avaliar os efeitos fertilizantes de bactérias promotoras de crescimento (BPC) com sua inoculação na variedade de cana-de-açúcar RB 867515. Metodologia em blocos ao acaso, de cinco repetições. Oito tratamentos e uma cultivar Saccharum sp., RB867515.Todas as estirpes utilizadas foram obtidas a partir da cultura bacteriana da coleção CRB-Johanna Döbereiner (números BR), sendo as espécies pesquisadas: 1) Sphingomonas sp. DYAPIAC4409-BR14763; 2) Sphingomonas sp. JMAPRB9417-BR14740; 3) Mix. 3, Bacilus sp. Lmc 06, Bacilus sp. Lmc 21 e Bacilus sp. Lmc 44; 4) Azospirillum-7BSG5a2; 5) Herbaspirillum-MA30. E ainda, 6) Nitrospirillum amazonense CBAmC-BR11145, como objeto de comparação. Atualmente existe apenas uma bactéria (Nitrospirillum amazonense estirpe CBAmC) recomendada pelo MAPA para inoculação em cana-de-açúcar. Os resultados encontrados, estão descritos na Figura 1 e nas Tabelas 1,2,3,4 deste artigo.

Plant growth-promoting bacteria (PGPB) possessing 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity have the potential to enhance plant growth and development, particularly under adverse environmental conditions. This study aimed to identify bacterial strains with ACC deaminase activity able of mitigating the effects of water deficit stress and promoting the growth of Brachiaria genotypes. Bacterial strains isolated from Brachiaria genotypes were screened in vitro for ACC deaminase activity, and the presence of the acdS gene was confirmed via polymerase chain reaction (PCR) analysis. The bacterial isolates were screened for in vitro tolerance to water deficit stress, using 10% polyethylene glycol 8000 (PEG 8000) in association with B. ruziziensis and the effects of bacterial inoculation were assessed based on plant height and fresh biomass accumulation. Additionally, the association between endophytic bacterial strains and Brachiaria genotypes was evaluated using confocal laser microscope. The results showed that among the 213 strains tested, 32 demonstrate the ability to degrade ACC into α-ketobutyrate. ACC deaminase activity was detected in 17 strains, with values ranging from 1.98 to 102.52 μmol α-ketobutyrate mg^-1 protein h^-1. The presence of the acdS gene was confirmed in nine strains. The strains NRB142 (Paraburkholderia silvatlantica), NRB223 (Azospirillum melinis), and BR11790 (Herbaspirillum frisingense GSF30^T) exhibited the most significant promotion of plant development in B. ruziziensis under water deficit stress mediated by 10% PEG 8000. Confocal microscopy analysis revealed the rhizospheric and inner root colonization of B. ruziziensis and B. brizantha cv. Paiaguás by the NRB142 mCherry-labeled strain. This study showed no predominance of a specific group of bacterial strains in terms of ACC deaminase activity. However, a subset of strains demonstrated the ability to colonize Brachiaria plants and mitigate the negative effects of water deficit stress. This study highlights the potential of ACC deaminase-producing bacteria in alleviating water deficit stress in Brachiaria plants supporting their use as a promising strategy for improving plant resilience under drought conditions.

As bactérias endofíticas têm sido isoladas e estudadas via metodologias que utilizam meios de cultivo, já se sabe que a maioria dessas bactérias ainda não são cultiváveis e permanecem à disposição da pesquisa, afim de ser conhecido o seu potencial. Portanto é necessário a utilização estratégias independentes de cultivo para estudo das bactérias. Neste sentido, a metagenômica, e a experimentação agrícola, são as principais estratégias no estudo das bactérias endofíticas, e a identificação destas, permite uma análise da população microbiana, identificando suas interações com o hospedeiro. A cana-de-açúcar representa um excelente ecossistema para microrganismos e permite uma interação com diferentes comunidades microbianas, como: bactérias, archaea, fungos e protistas, etc. A variedade RB 867515 possui crescimento ereto e rápido, com despalha fácil. Os colmos possuem entrenós cilíndricos, de cor verde-arroxeados sob a palha, e roxo intenso. O objetivo deste, foi avaliar os efeitos da inoculação das bactérias promotora de crescimento BPC, estirpes obtidas da cultura bacteriana da Coleção CRB-Johanna Döbereiner (números BR), promovendo a inoculação em mudas pré-brotadas, cultivando-as 60 DAP, direto no solo. As espécies foram: 1) Sphingomonas sp. DYAPIAC4409-BR14763, 2) Sphingomonas sp. JMAPRB9417-BR14740, 3) Mix. 3, Bacilus sp. Lmc 06, Bacilus sp. Lmc 21 e Bacilus sp. Lmc 44, 4) Azospirillum-7BSG5a2, 5) Herbaspirillum-MA30, 7) Nitrospirillum amazonense CBAmC-BR11145, que é objeto de comparação da pesquisa. Apenas a bactéria (Nitrospirillum amazonense estirpe CBAmC) é recomendada pelo MAPA para inoculação em cana. A necessidade de testar bactérias do banco do laboratório da Embrapa Agrobiologia, faz-se necessário para dar continuidade a este trabalho. A metodologia do experimento, foi blocos ao acaso com 5 repetições, 8 tratamentos e uma cultivar (RB867515) de cana-de-açúcar (Saccharum sp.). Referencial teórico, estima-se que a contribuição da fixação biológica de nitrogênio FBN para a nutrição nitrogenada da cana-de-açúcar no Brasil, pode contribuir com pelo menos 40 kg ha-¹ de N (URQUIAGA et al., 2012). Os resultados encontrados, estão descritos na Figura 2 e na Figura 3 deste artigo.

Fusarium wilt is one of main phytopathology attacking tomato (Solanum lycopersicum L.) plantations in Brazil. Plant rhizosphere and endophytic beneficial microorganism are well known as plant growth promoters and biocontrol agents. The present study aims to evaluate the potential of different Bacillus strains as biocontrol agent to Fusarium oxysporum f. sp. lycopersici Race 3 strains; and also as plant growth promoting bacteria on Solanum lycopersicum cv Perinha. Different in vitro and greenhouse experiments were carried out to evaluate the direct and indirect bacterial-fungus antagonism, and they inoculation effects on plant traits. In vitro direct, metabolites, and volatile antagonism analysis demonstrated that B. toyonensis BR 10491(FORT 02) presented a broad antagonism to all tested race 3 FOL strains while B. megaterium BR 10466 (FORT 12), B. aryabhattai BR 10494 (FORT 25), B. stratosphericus BR 10438 (FORT 29) and B. cereus BR 10493 (FORT 113.1) strains showed significant antagonistic activity for at least two applied methods. Greenhouse pot experiments demonstrated a significant BCA effect of FORT 113.1 and FORT 02 against FOL Race 3 Fus 1302 strain during different tomato development stages (seedling, vegetative, and reproductive). Bacillus cereus (FORT 113.1) showed significantly higher shoot and height fresh weight, Chlorophyll a and Chlorophyll b content, stomata conductance, water use efficiency, and also a lower xylem infection percentage during vegetative and reproductive stages. Antioxidant enzymatic components analysis demonstrated a synergic effect of Fusarium and Bacillus inoculation, leading to a higher superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activity. In conclusion, the results suggest that strain FORT113.1 could be considered as a good candidate for production of new biofungicide with high potential to augment the existing biocontrol strategies.

As agricultural practices become more sustainable, adopting more sustainable practices will become even more relevant. Searching for alternatives to chemical compounds has been the focus of numerous studies, and bacteriocins are tools with intrinsic biotechnological potential for controlling plant diseases. We continued to explore the biotechnological activity of the bacteriocin Gluconacin from Gluconacetobacter diazotrophicus, PAL5 strain, by investigating this protein’s antagonism against important tomato phytopathogens and demonstrating its effectiveness in reducing bacterial spots caused by Xanthomonas perforans. In addition to this pathogen, the bacteriocin Gluconacin demonstrated bactericidal activity in vitro against Ralstonia solanacearum and Pseudomonas syringae pv. tomato, agents that cause bacterial wilt and bacterial spots, respectively. Bacterial spot control tests showed that Gluconacin reduced disease severity by more than 66%, highlighting the biotechnological value of this peptide in ecologically correct formulations.

Gluconacetobacter diazotrophicus has been the focus of several studies aiming to understand the mechanisms behind this endophytic diazotrophic bacterium. The present study is the first global analysis of the early transcriptional response of exponentially growing G. diazotrophicus to iron, an essential cofactor for many enzymes involved in various metabolic pathways. RNA-seq, targeted gene mutagenesis and computational motif discovery tools were used to define the G. diazotrophicusfur regulon. The data analysis showed that genes encoding functions related to iron homeostasis were significantly upregulated in response to iron limitations. Certain genes involved in secondary metabolism were overexpressed under iron-limited conditions. In contrast, it was observed that the expression of genes involved in Fe-S cluster biosynthesis, flagellar biosynthesis and type IV secretion systems were downregulated in an iron-depleted culture medium. Our results support a model that controls transcription in G. diazotrophicus by fur function. The G. diazotrophicusfur protein was able to complement an E. colifur mutant. These results provide new insights into the effects of iron on the metabolism of G. diazotrophicus, as well as demonstrate the essentiality of this micronutrient for the main characteristics of plant growth promotion by G. diazotrophicus.

Anais do Workshop do PPG-Fitotecnia (2763-5767) - Análise Do Efeito Do Líquido Apoplástico Da Cana-De-Açúcar Em Gluconacetobacter Diazotrophicus Pal5 Usando Como Ferramenta A Proteômica Quantitativa