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We evaluated symbiotic (rhizobia) and non‐symbiotic efficiency and the diversity of native communities of plant growth‐promoting rhizobacteria (PGPR) in soil samples from an area in recovery after iron mining (RA) and from adjacent phytophysiognomies (Ironstone Outcrops, Neotropical Savanna, Atlantic Forest) in the Quadrilátero Ferrífero region, MG, Brazil, in two climate seasons. Greenhouse experiments were conducted with siratro (Macroptilium atropurpureum) as a trap plant. The SPAD index in siratro was more effective in detecting the difference between the symbiotic efficiencies of the communities of PGPR than shoot dry matter, with readings of the SPAD index greater in RA. Genetic diversity, of 327 strains evaluated by partial sequencing of the 16S rRNA gene, showed 29 genera in the dry season and 19 in the rainy season, among these genera some recognized as nodulating and endophytes, and others potentially endophytes. Genera belonging to the phyla Acidobacteria, Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria were found. The nodule‐forming genera Bradyrhizobium and Rhizobium and the endophytic Paenibacillus were those of highest occurrence in both seasons and in all phytophysiognomies. The greater symbiotic efficiency and the high genetic diversity of the rhizobacterial community found in RA indicate that soil rehabilitation is effectively in process. As most of native legume species form symbiosis with Rhizobium and mainly Bradyrhizobium, these bacterial communities are an important source of potential inoculant strains, as well as, a relevant feature for the successful establishment of diverse legumes for revegetation purposes. [ABSTRACT FROM AUTHOR]

Leishmaniases are diseases with high epidemiological relevance and wide geographical distribution. In Brazil, Leishmania (Leishmania) amazonensis is related to the tegumentary form of leishmaniasis. The treatment for those diseases is problematic as the available drugs promote adverse effects in patients. Therefore, it is important to find new therapeutic targets. In this regard, one alternative is the study of biomolecules produced by endophytic microorganisms. In this study, the total extract produced by the endophytic Paenibacillus polymyxa RNC-D was used to evaluate the leishmanicidal, nitric oxide, and cytokines production using RAW 264.7 macrophages. The results showed that, in the leishmanicidal assay with L. amazonensis, EC50 values at the periods of 24 and 48 hours were 0.624 mg/mL and 0.547 mg/mL, respectively. Furthermore, the cells treated with the extract presented approximately 25% of infected cells with an average of 3 amastigotes/cell in the periods of 24 and 48 hours. Regarding the production of cytokines in RAW 264.7 macrophages infected/treated with the extract, a significant increase in TNF- α was observed at the periods of 24 and 48 hours in the treated cells. The concentrations of IFN- γ and IL-12 showed significant increase in 48 hours. A significant decrease in IL-4 was observed in all cells treated with the extract in 24 hours. It was observed in the treated cells that the NO production by RAW 264.7 macrophages increased between 48 and 72 hours. The endophytic Paenibacillus polymyxa RNC-D extract modulates the mediators of inflammation produced by RAW 264.7 macrophages promoting L. amazonensis death. The immunomodulatory effects might be a promising target to develop new immunotherapeutic and antileishmanial drugs. [ABSTRACT FROM AUTHOR]

The annual production of plastics has doubled over the past 15 years and, consequently, a large amount of plastic has accumulated in the environment generating ecological problems. In this study, a Paenibacillus sp. isolate was obtained from a landfill from Brazil and it presented the alkane hydroxylase gene (alkB). Weight loss of low-density polyethylene (LDPE) was measured and a significant difference in final weight compared to initial weight was assessed. Some chemical characteristics, such as bond scissions and formation of new functional groups [carboxylic acids (3300–2500 cm−1), esters (1210–1163 cm−1), and ethers (1075–1020 cm−1)], were detected by Fourier-transform infrared spectroscopy. Bacterial colonization on the plastic surface and physical changes, as formation of cracks and pits, was visualized by scanning electron microscopy. This isolate was susceptible to all the antimicrobials tested. Therefore, this isolate possesses great potential to degrade polyethylene and become an option for LDPE bioremediation. [ABSTRACT FROM AUTHOR]

Soybean is the most important oilseed in the world, cropped in 120–130 million hectares each year. The three most important soybean producers are Argentina, Brazil, and United States, where soybean crops are routinely inoculated with symbiotic N2-fixing Bradyrhizobium spp. This extended inoculation gave rise to soybean-nodulating allochthonous populations (SNAPs) that compete against new inoculant for nodulation, thus impairing yield responses. Competitiveness depends on intrinsic factors contributed by genotype, extrinsic ones determined by growth and environmental conditions, and strain persistence in the soil. To assess these factors in Argentinean SNAPs, we studied 58 isolates from five sites of the main soybean cropping area. BOX-A1R DNA fingerprint distributed these isolates in 10 clades that paralleled the pHs of their original soils. By contrast, reference Bradyrhizobium spp. strains, including those used as soybean-inoculants, were confined to a single clade. More detailed characterization of a subset of 11 SNAP-isolates revealed that five were Bradyrhizobium japonicum , two Bradyrhizobium elkanii , two Rhizobium radiobacter (formerly Agrobacterium tumefaciens), one Bradyrhizobium diazoefficiens , and one Paenibacillus glycanilyticus -which did not nodulate when inoculated alone, and therefore was excluded from further characterization. The remaining subset of 10 SNAP-isolates was used for deeper characterization. All SNAP-isolates were aluminum- and heat-tolerant, and most of them were glyphosate-tolerant. Meanwhile, inoculant strains tested were sensitive to aluminum and glyphosate. In addition, all SNAP-isolates were motile to different degrees. Only three SNAP-isolates were deficient for N2-fixation, and none was intrinsically more competitive than the inoculant strain. These results are in contrast to the general belief that rhizobia from soil populations evolved as intrinsically more competitive for nodulation and less N2-fixing effective than inoculants strains. Shoot:root ratios, both as dry biomass and as total N, were highly correlated with leaf ureide contents, and therefore may be easy indicators of N2-fixing performance, suggesting that highly effective N2-fixing and well-adapted strains may be readily selected from SNAPs. In addition, intrinsic competitiveness of the inoculants strains seems already optimized against SNAP strains, and therefore our efforts to improve nodules occupation by inoculated strains should focus on the optimization of extrinsic competitiveness factors, such as inoculant formulation and inoculation technology. [ABSTRACT FROM AUTHOR]

A new xylanolytic strain, Paenibacillus favisporus CC02-N2, was isolated from sugarcane plantation fields in Brazil. The strain had a xylan-degrading system with multiple enzymes, one of which, xylanase Xyn30A, was identified and characterized. The enzyme is a single-domain xylanase belonging to family 30 of the glycosyl hydrolases (GH30). Xyn30A shows high activity on glucuronoxylans, with a Vmax of 267.2 U mg-1, a Km of 4.0 mg/ml, and a kcat of 13,333 min-1 on beechwood xylan, but it does not hydrolyze arabinoxylans. The three-dimensional structure of Xyn30A consists of a common (β/α)8 barrel linked to a side-chain-associated β-structure, similar to previously characterized GH30 xylanases. The hydrolysis products from glucuronoxylan were methylglucuronic-acid-substituted xylooligomers (acidic xylooligosaccharides). The enzyme bound to insoluble xylan but not to crystalline cellulose. Our results suggest a specific role for Xyn30A in xylan biodegradation in natural habitats. The enzyme is a good candidate for the production of tailored xylooligosaccharides for use in the food industry and in the biotechnological transformation of biomass. [ABSTRACT FROM AUTHOR]

Abstract: Several strains of bacilli, mainly species of the genera Bacillus and Paenibacillus, displaying important plant growth promoting (PGP) characteristics were isolated from seven distinct rice production zones of the Rio Grande do Sul State, Brazil. Of 296 isolates, 155 were from rhizospheric soil and 141 from bulk soil. In order to evaluate the diversity among the isolates of each bacterial population the Shannon index was used on a 70% similarity basis. Diversity indices varying from 2.27 to 5.51 were obtained. Using principal coordinate analysis (PCA) to correlate bacterial diversity with soil parameters, it was found that soil pH was the characteristic most closely related to bacilli diversity. The bacilli isolated were also analyzed for some PGP activities. Of those 296 isolates, 94 and 148 produced between 0.1 and 30μg of indole-3-acetic acid (IAA)ml−1 in vitro after 72 and 144h of incubation, respectively. Twenty-two isolates were able to solubilize phosphate and 32 isolates produced siderophores. Paenibacillus and Bacillus genera were the most prominent groups in the rhizosphere and soil populations analyzed. Paenibacillus borealis was the most frequent species in both locations. The isolate SVPR30, identified by 16S rRNA gene sequence analysis as a strain of Bacillus sp., was chosen for in vivo greenhouse experiments and proved to be very efficient in promoting a significant increase in the roots and shoot parts of rice plants. The identification and isolation of PGP bacilli from temperate and subtropical soils, which combine the ability to fix nitrogen with the production of substances capable to promote the plant growth, could significantly increase productivity of grain crops in Brazil. [Copyright &y& Elsevier]

Three facultatively anaerobic endospore-forming bacteria were isolated from the rhizosphere of sunflowers grown in fields of Rio Grande do Sul State, Brazil. The designated type strain P26E T was previously identified as a sunflower growth promoting bacterium and is able to fix nitrogen and to excrete ammonia. According to analyses of 16S rRNA gene sequences, P26E T presented similarity values above 98.8% in relation to Paenibacillus azotifigens NF2-4-5 T , Paenibacillus graminis RSA19 T , Paenibacillus jilunlii Be17 T , Paenibacillus salinicaeni LAM0A28 T , and Paenibacillus sonchi X19-5 T . Phylogenetic reconstructions based on 16S rRNA gene and core proteome data showed that the strains P26E T , P3E and P32E form a distinct clade, which did not include any type strain of the currently described Paenibacillus species. Also, genomic comparisons using average nucleotide identity (ANI), Orthologous ANI and in silico DNA-DNA hybridization revealed similarity ranges below the recommended thresholds when the three isolates from sunflower were compared to their close relatives. The DNA G + C content of strain P26E T was determined to be 49.4 mol%. The major cellular fatty acids are anteiso-C 15:0 and iso-C 15:0 , representing about 58 and 14% of the total fatty acids in P26E T , respectively. Based on different taxonomic genomic metrics, phylogeny, and phenotypic data, we propose that strain P26E T (= DSM 102269 = BR10509) represents a novel species within the genus Paenibacillus, for which the name Paenibacillus helianthi sp. nov. is proposed.

Paenibacillus riograndensis is a Gram-positive rhizobacterium which exhibits plant growth promoting activities. It was isolated from the rhizosphere of wheat grown in the state of Rio Grande do Sul, Brazil. Here we announce the complete genome sequence of P. riograndensis strain SBR5 T . The genome of P. riograndensis SBR5 T consists of a circular chromosome of 7,893,056 bps. The genome was finished and fully annotated, containing 6705 protein coding genes, 87 tRNAs and 27 rRNAs. The knowledge of the complete genome helped to explain why P. riograndensis SBR5 T can grow with the carbon sources arabinose and mannitol, but not myo -inositol, and to explain physiological features such as biotin auxotrophy and antibiotic resistances. The genome sequence will be valuable for functional genomics and ecological studies as well as for application of P. riograndensis SBR5 T as plant growth-promoting rhizobacterium. [ABSTRACT FROM AUTHOR]