We hypothesize that sweet potato genotypes can influence the bacterial communities related to phosphate mineralization and nitrogen fixation in the rhizosphere. Tuberous roots of field-grown sweet potato from genotypes IPB-149, IPB-052, and IPB-137 were sampled three and six months after planting. The total community DNA was extracted from the rhizosphere and analyzed by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) and quantitative real-time PCR (qPCR), based on the alkaline phosphatase coding gene (alp gene) and on the nitrogenase coding gene (nifH gene). The cluster analysis based on DGGE showed that plant age slightly influenced the bacterial community related to phosphate mineralization in the rhizosphere of IPB-137, although it did not affect the bacterial community related to nitrogen fixation. The statistical analysis of DGGE fingerprints (Permutation test, p ≤ 0.05) showed that nitrogen-fixing bacterial community of IPB-052 statistically differed from genotypes IPB-149 and IPB-137 after six months of planting. The bacterial community of IPB-137 rhizosphere analyzed by alp gene also showed significant differences when compared to IPB-149 in both sampling times (p ≤ 0.05). In addition, alp gene copy numbers significantly increased in abundance in the rhizosphere of IPB-137 after six months of planting. Therefore, plant genotype should be considered in the biofertilization of sweet potato.

Euterpe oleracea Mart., also known for its fruit açaí, is a palm native to the Amazon region. The state of Pará, Brazil, accounts for over 90% of açaí production. Demand for the fruit in national and international markets is increasing; however, climate change and diseases such as anthracnose, caused by the fungus Colletotrichum sp., lead to decreased production. To meet demand, measures such as expanding cultivation in upland areas are often adopted, requiring substantial economic investments, particularly in irrigation. Therefore, the aim of this study was to evaluate the potential of açaí rhizobacteria in promoting plant growth (PGPR). Rhizospheric soil samples from floodplain and upland açaí plantations were collected during rainy and dry seasons. Bacterial strains were isolated using the serial dilution method, and subsequent assays evaluated their ability to promote plant growth. Soil analyses indicated that the sampling period influenced the physicochemical properties of both areas, with increases observed during winter for most soil components like organic matter and C/N ratio. A total of 177 bacterial strains were isolated from rhizospheres of açaí trees cultivated in floodplain and upland areas across dry and rainy seasons. Among these strains, 24% produced IAA, 18% synthesized ACC deaminase, 11% mineralized organic phosphate, and 9% solubilized inorganic phosphate, among other characteristics. Interestingly, 88% inhibited the growth of phytopathogenic fungi of the genera Curvularia and Colletotrichum. Analysis under simulated water stress using Polyethylene Glycol 6000 revealed that 23% of the strains exhibited tolerance. Two strains were identified as Bacillus proteolyticus (PP218346) and Priestia aryabhattai (PP218347). Inoculation with these strains increased the speed and percentage of açaí seed germination. When inoculated in consortium, 85% of seeds germinated under severe stress, compared to only 10% in the control treatment. Therefore, these bacteria show potential for use as biofertilizers, enhancing the initial development of açaí plants and contributing to sustainable agricultural practices.

This chapter will address the main omics approaches used in studies involving the genus Corynebacterium, Gram-positive microorganisms that can be isolated from many diverse environments. Currently, the genus Corynebacterium has more than 130 highly diversified species, many of which present medical, veterinary and biotechnological importance, such as C. diphtheriae, C. pseudotuberculosis, C. ulcerans and C. glutamicum. Due to the wide application in these fields, several omics methodologies are used to better elucidate the species belonging to this genus, such as genomics, transcriptomics and proteomics. The genomic era has contributed to the development of more advanced and complex approaches that enable the increase of generated data, and consequently the advance on the structural, functional and dynamic knowledge of biological systems.

The hypothesis that cultivating açaí in agroforestry systems (AFS) can recruit beneficial microorganisms to its rhizosphere was tested in this study. For this purpose, rhizospheric soil samples were collected from an AFS area. The colony-forming unit (CFU) counts of the soil samples were 3.5 × 10⁶ CFU/g, with no statistically significant differences between the plants (p < 0.05). Regarding PGPR characteristics, of the 44 isolated strains, 18% produced siderophores, 9% mineralized organic phosphate, 15% solubilized inorganic phosphate, and 7% produced indole-3-acetic acid (IAA) and antimicrobial substances. Strains AP4-03, AP1-33, and AP2-36 were affiliated with the genus Bacillus sp. and produced IAA at 1.45, 1.35, and 2.02 µg/mL, respectively. Furthermore, these strains were able to inhibit the growth of the fungus Pestalotiopsis by 69%, 67%, and 71%, respectively. Regarding the antifungal activity of bacterial extracts, inhibition zones of 23 mm (AP-03), 20 mm (AP-33), and 18 mm (AP-36), with 96% and 92% inhibition at 50 mg/mL (AP4-03 and AP1-33) and 100% inhibition at 41 mg/mL (AP2-36), were observed. Considering seedling germination, açaí palms inoculated with the strain AP1-33 statistically differed from the controls in terms of root length and hypocotyl length. Furthermore, treatments inoculated with the strain AP2-36 or all strains in the consortium differed when only the hypocotyl length was compared to the control. Thus, the analyzed strains showed potential to improve the initial development of açaí plants.

We report here the draft genome sequence of Corynebacterium pseudotuberculosis PA05, isolated from an ovine host in Pará State, Brazil. C. pseudotuberculosis is an etiological agent of diseases with veterinary and medical importance. The genome contains 2,435,137 bp, a G+C content of 52.2%, 2,295 coding sequences, five pseudogenes, 53 tRNAs, and six rRNAs.

Buffalo milk stands out for its nutritional qualities and is mainly produced in Brazil in the Amazon region, particularly in the Marajó Archipelago, State of Pará. In this context, the milk microbiome is an intriguing and underexplored research topic. This study tested the hypothesis that the buffalo milk microbiome could share taxa with faeces, pasture soil and calf spittle. A possible correlation between generations was also explored. Samples of milk, faeces, spittle and pasture soil were analysed using a 16S rRNA metabarcoding approach, revealing significant phylogenetic and ecological differences among matrices. Beta‐diversity analysis showed clustering between milk samples from heifers and cows, as well as proximity between soil and buffalo samples (milk and faeces). Relative abundance analysis identified shared taxa between buffaloes and their calves, though no clustering was observed between generations. A total of 15 bacterial families were found across all matrices, with Staphylococcaceae , Planococcaceae and Enterobacteriaceae being the most prominent. The milk microbiota was similar among animals of different ages. The grouping pattern varied depending on the animal and matrix, but not on the maternal relationship. Despite compositional differences, the shared taxa reinforce the idea of interaction among the studied microbial communities.