| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1119-1 | ||||
Resumo:Tropaeolum majus L. is a versatile edible plant originating from Latin America that is currently explored due to its medicinal properties, usage in landscaping projects and as a key element for intercropping systems. In a previous study from our group, 236 endophytes were isolated from T. majus roots, whereas 101 strains showed more than 3 plant growth promoting (PGP) features in vitro. To select a PGP consortium using the endophytes previously isolated to offer sustainable alternatives for biofertilization, the present study aimed to (i) perform genome analysis of two endophytes (Bacillus sp. CAPE95 and Paenibacillus sp. CAPE238) using the whole genome sequencing technique to search for genes related to biofertilization; (ii) evaluate the in vivo PGP capacity of both endophytes through greenhouse experiments with T. majus seeds and seedlings; and (iii) analyze the impact of the inoculum of the consortium on the bacteriome of T. majus seedlings using 16S rRNA gene metabarcoding. The strains CAPE95 and CAPE238 selected in this study had previously shown more than 5 PGP traits and no antagonistic activity against each other. The total DNA from both strains was isolated and sequenced through Illumina NovaSeq6000. Raw reads quality control was performed using fastp, and Unicycler was used for genome assembly. Sequences were taxonomically classified using GTDB-Tk, while phylogenomic and metabolic annotations were performed using Anvi’o. The phylogenomic analysis indicated that the CAPE95 strain was closely related to Bacillus thuringiensis (ANI=98) and CAPE238 to Paenibacillus polymyxa (ANI=98.8). KEGG metabolic annotation showed the presence of pathways related to nutrient metabolism (nitrogen, phosphorus and sulfur) and biosynthesis of PGP substances (siderophores, phytohormones and antimicrobial substances) in both strains. For the in vivo experiments, CAPE95 and CAPE238 cells were resuspended in 1X PBS (107xCFU/mL) and mixed to compose the consortium. In the first experiment, T. majus seeds were inoculated with the consortium, and their germination taxa were calculated and compared to the control. The seeds treated with the consortium showed a tendency to germinate faster and had a higher germination index (69.44%) when compared to the control (56.48%). In the PGP experiment, carried out with 1-month-old seedlings, plant height and leaf diameters were significantly higher (p<0.05) in the plants treated with the consortium. Thirty days after inoculation, fifteen plants of each condition were harvested and processed for total root DNA isolation. The DNA was sequenced through Illumina NovaSeq600 for the 16S rRNA gene metabarcoding technique, and raw sequences were analyzed using Mothur. The plants treated with the consortium showed a higher richness (Chao1 index, p<0.001) and diversity (Shannon index, p<0.001) of species when compared to the control, while there were no significant differences observed in species abundance (Simpson index, p>0.05). The consortium showed great potential to be used as a biofertilizer and, in the future, we hope to expand the experiments to different plant species. Palavras-chave: Plant growth-promoting bacteria, 16S rRNA gene metabarcoding, whole genome sequencing, Bacillus thuringiensis, Paenibacillus polymyxa Agência de fomento:Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) | |||||