The RNA polymerase gene specificity factor sigma 54 is required for homogeneous non-planktonic growth of uropathogenic Escherichia coli

The canonical function of a bacterial sigma factor is to determine the gene specificity of the RNA polymerase (RNAP). In several diverse bacterial species, the sigma 54 factor uniquely confers distinct functional and regulatory properties on the RNAP. A hallmark feature of the sigma 54-RNAP is the obligatory requirement for an activator ATPase to allow transcription initiation. The genes that rely upon sigma 54 for their transcription have a wide range of different functions suggesting that the repertoire of functions performed by genes, directly or indirectly affected by sigma 54, is not yet exhaustive. By comparing the non-planktonic growth properties of prototypical enteropathogenic, uropathogenic and non-pathogenic Escherichia coli strains devoid of sigma 54, we uncovered sigma 54 as a determinant of homogenous non-planktonic growth specifically in the uropathogenic strain. Notably, bacteria devoid of individual activator ATPases of the sigma 54-RNAP do not phenocopy the sigma 54 mutant strain. It seems that sigma 54's role as a determinant of homogenous non-planktonic growth represents a putative non-canonical function of sigma 54 in regulating genetic information flow.

Filtered mud improves sugarcane growth and modifies the functional abundance and structure of soil microbial populations

Background Exploring high-quality organic amendments has been a focus of sustainable agriculture. Filtered mud (FM), a sugar factory waste derived from sugarcane stems, could be an alternative organic amendment for sugarcane production. However, the effects of its application proportions on soil fertility, nutrient cycling, structure of soil bacterial and fungal communities, and the growth of sugarcane in clay-loam soils remain unexplored. Methods Three application proportions of FM: (FM1-(FM: Soil at 1:4), FM2-(FM: Soil at 2:3), and FM3-(FM: Soil at 3:2)) were evaluated on sugarcane growth and soil nutrient cycling. High throughput sequencing was also employed to explore soil microbial dynamics. Results We observed that FM generally increased the soil’s nutritional properties while improving NO3− retention compared to the control, resulting in increased growth parameters of sugarcane. Specifically, FM1 increased the concentration of NH4+−N, the N fraction preferably taken up by sugarcane, which was associated with an increase in the plant height, and more improved growth properties, among other treatments. An increase in the proportion of FM also increased the activity of soil nutrient cycling enzymes; urease, phosphatase, and β-glucosidase. High throughput sequencing revealed that FM reduced the diversity of soil bacteria while having insignificant effects on fungal diversity. Although increasing FM rates reduced the relative abundance of the phyla Proteobacteria, its class members, the Gammaproteobacteria and Betaproteobacteria containing some N-cycling related genera, were stimulated. Also, FM stimulated the abundance of beneficial and lignocellulose degrading organisms. These included the bacterial phyla Actinobacteria, Bacteroidetes, Acidobacteria, Chloroflexi, and the fungal phylum Ascomycota. The distribution of the soil microbial community under FM rates was regulated by the changes in soil pH and the availability of soil nutrients. Since FM1 showed more promise in improving the growth properties of sugarcane, it could be more economical and sustainable for sugarcane production in clay-loam soils.

Antibiotic treatment impaired growth of tobacco in vitro shoots is associated with oxidative injury and reduced microbiome diversity

Plant in vitro cultures initiated from surface-sterilized explants often harbor complex microbial community. Antibiotics are commonly used to decontaminate plant tissue culture or during genetic transformation, however, the effect of antibiotic treatment on the diversity of indigenous microbial population and consequences for performance of the tissue culture are not completely understood. Therefore, the aim of this study was to assess the effect of antibiotic treatment on the growth and stress level of tobacco (Nicotiana tabacum L.) in vitro shoots as well as the composition of plant-associated microbiome. The study revealed that shoot cultivation on medium supplemented with 250 mg L−1 timentin resulted in 29 ± 4% reduced biomass accumulation and 1.2–1.6 fold higher level of oxidative stress injury compared to control. Moreover, the growth properties of shoots were only partially restored after transfer to medium without antibiotic. Shoot microbiome analysis using multi-variable region-based 16S rRNA sequencing revealed abundant microbial community in the control tobacco shoots, including bacteria from 59 families, however, it was largely dominated by Mycobacteriaceae. The antibiotic treatment resulted in a decline of species richness (the number of families was reduced 4.5-fold) and increased domination by the Mycobacteriaceae family. The results imply that the diversity of plant-associated microbiome might represent a significant factor contributing to the efficient propagation of in vitro tissue culture.

Seed bio-priming with phosphate solubilizing bacteria strains to improve rice (Oryza sativa L. var. FARO 44) growth under ferruginous ultisol conditions

The research investigated the possibility of phosphate solubilizing bacteria (PSB) with plant growthpromoting (PGP) capabilities to improve growth properties of rice plant under ferruginous ultisol (FU) condition through bio-priming strategy. The PSB with PGP properties used in this research were Bacillus cereus strain GGBSU-1, Proteus mirabilis strain TL14-1 and Klebsiella variicola strain AUH-KAM-9 that were previously isolated and characterized following the 16S rRNA gene sequencing. Biosafety analysis of the PSB isolates was conducted using blood agar. The rice seeds were then bio-primed with the PSBs at 3, 12 and 24 hours priming durations and then sown in a composite FU soil sample. Differences in germination bioassay involving SEM, morphology, physiology and biomass parameters were investigated for 15 weeks after bio-priming. The composite FU soil used in the study had high pH, low bioavailable phosphorus, low water holding capacity and high iron levels which has led to a low growth properties of rice seeds without bio-priming in FU soil. Germination parameters was better in seeds bio-primed with the PSBs, especially at 12h priming duration as against seeds without priming. SEM showed more bacterial colonization in the PSB bioprimed seeds. Seed bio-priming of rice seed with Bacillus cereus strain GGBSU-1, Proteus mirabilis strain TL14-1 and Klebsiella variicola strain AUH-KAM-9 under FU soil condition significantly improved seed microbiome, rhizocolonization and soil nutrient properties, thereby enhancing growth properties of the rice plant. This suggest the ability of PSB to solubilize and mineralize soil phosphate and improve its availability and soil property for optimum plant usage in phosphate stressed and iron toxic soils.

Rhizo-inoculation of phosphate solubilizing bacteria strains to improve rice (Oryza sativa L. var. FARO 44) growth under ferruginous ultisol conditions.

Background The research investigated the possibility of phosphate solubilizing bacteria (PSB) with plant growth-promoting (PGP) capabilities to improve growth properties of rice plant under ferruginous ultisol (FU) condition through rhizo-inoculation strategy. The PSB with PGP properties used in this research were Bacillus cereus strain GGBSU-1, Proteus mirabilis strain TL14-1 and Klebsiella variicola strain AUH-KAM-9 that were previously isolated and characterized following the 16S rRNA gene sequencing. The rice seeds were sown in a composite FU soil sample and a humus soil (control) and then rhizo-inoculated along the root region of the growing rice seedling at 16 days after sowing. The rice plant was studied for differences in morphological, physiological and biomass parameters for 16 weeks after rhizo-inoculation. Results The composite FU soil used in the study had high pH, low bioavailable phosphorus, low water holding capacity and high iron levels which has led to a low growth properties of rice seeds sown in FU soil without rhizo-inoculation. After rhizo-inoculation, a significant increase in morphological, biomass and physiological parameters were observed in the rice plant grown in the FU soil as against the control and the rice plant in FU soil without inoculation except for terpenoid which is usually known to signify biotic stress and as part of plant defense mechanism. Generally, Bacillus cereus strain GGBSU-1 showed higher improvement compared to other PSBs used in the present study. This is due to a more improved growth properties observed. Conclusion Rhizo-inoculation of rice seedling with Bacillus cereus strain GGBSU-1, Proteus mirabilis strain TL14-1 and Klebsiella variicola strain AUH-KAM-9 under FU soil condition significantly improved growth properties of the rice plant. This suggest the ability of PSB to solubilize and mineralize soil phosphate and improve its availability for plant use in phosphate stressed soil, thereby improving plant growth properties.

The Effect of Different Levels of Nitrogen, Phosphorous and Potassium in Some Growth Properties of Rosa Damascena Mill L.

The experiment was conducted on cuttings of Rosa damascena mill L. During the period from mid-March of 2014 until the end of 2015 before the period of formation of flowers for picking at the College of Agriculture/University of Karbala According to the design of complete random sectors, The research included a global experiment with three different factors of the first chemical fertilizer nitrogen fertilization and three levels (0, 0.5 and 1 gm N. Kg -1 soil) and fertilization with the element phosphorus with three levels (0, 15 and 30 mg P2O5. Kg -1 soil) and three levels of Potassium (0, 100 and 200 mg K2O. Kg -1 soil). The results showed that the single effect of the fertilization treatment with nitrogen, phosphorous, and potassium resulted in a significant increase in the characteristic of plant height and number of leaves, and the fertilization treatment with nitrogen and phosphorus component separately resulted in the production of seedlings that were characterized by a high dry green weight compared to the comparison treatment. The data of the bilateral overlap between nitrogen and phosphorous indicate the presence of significant differences, as the treatment with nitrogen component gave a concentration of (0.5 and 1 g. Kg-1) overlapping with the component of phosphorus concentration (30 mg. Kg-1) with the highest significant rate of (39.66 cm). The treatment of the triple interference between nitrogen, phosphorous, and potassium gave a significant effect on all the studied traits.

In-Vitro Selection of Ceftazidime/Avibactam Resistance in OXA-48-Like-Expressing Klebsiella pneumoniae: In-Vitro and In-Vivo Fitness, Genetic Basis and Activities of β-Lactam Plus Novel β-Lactamase Inhibitor or β-Lactam Enhancer Combinations

Ceftazidime/avibactam uniquely demonstrates activity against both KPC and OXA-48-like carbapenemase-expressing Enterobacterales. Clinical resistance to ceftazidime/avibactam in KPC-producers was foreseen in in-vitro resistance studies. Herein, we assessed the resistance selection propensity of ceftazidime/avibactam in K. pneumoniae expressing OXA-48-like β-lactamases (n = 10), employing serial transfer approach. Ceftazidime/avibactam MICs (0.25–4 mg/L) increased to 16–256 mg/L after 15 daily-sequential transfers. The whole genome sequence analysis of terminal mutants showed modifications in proteins linked to efflux (AcrB/AcrD/EmrA/Mdt), outer membrane permeability (OmpK36) and/or stress response pathways (CpxA/EnvZ/RpoE). In-vitro growth properties of all the ceftazidime/avibactam-selected mutants were comparable to their respective parents and they retained the ability to cause pulmonary infection in neutropenic mice. Against these mutants, we explored the activities of various combinations of β-lactams (ceftazidime or cefepime) with structurally diverse β-lactamase inhibitors or a β-lactam enhancer, zidebactam. Zidebactam, in combination with either cefepime or ceftazidime, overcame ceftazidime/avibactam resistance (MIC range 0.5–8 mg/L), while cefepime/avibactam was the second best (MIC: 0.5–16 mg/L) in yielding lower MICs. The present work revealed the possibility of ceftazidime/avibactam resistance in OXA-48-like K. pneumoniae through mutations in proteins involved in efflux and/or porins without concomitant fitness cost mandating astute monitoring of ceftazidime/avibactam resistance among OXA-48 genotypes.

Growth, Properties, and Applications of Branched Carbon Nanostructures

Nanomaterials featuring branched carbon nanotubes (b-CNTs), nanofibers (b-CNFs), or other types of carbon nanostructures (CNSs) are of great interest due to their outstanding mechanical and electronic properties. They are promising components of nanodevices for a wide variety of advanced applications spanning from batteries and fuel cells to conductive-tissue regeneration in medicine. In this concise review, we describe the methods to produce branched CNSs, with particular emphasis on the most widely used b-CNTs, the experimental and theoretical studies on their properties, and the wide range of demonstrated and proposed applications, highlighting the branching structural features that ultimately allow for enhanced performance relative to traditional, unbranched CNSs.