Salinity is one of the most dangerous environmental limiting factors of the plant productivity. A wide range of adaptation strategies is required to overcome salinity stress. However, such strategies seem to be long drawn and cost-intensive. It has been confirmed in recent years that plant growth promoting endophytes (PGPEs) that have the ability to further build a symbiotic association with their host to improve host plant salt tolerance. In our investigation try to improve plant salt tolerance using different species of endophytic bacteria. From the total eight endophytic bacterial species were isolated from root, stem, and leaf of Carthamustinctorius (safflower) plant, two isolates were capable of using 1-aminocyclopropane-1-carboxylic acid (ACC) as a sole nitrogen source, and they are of positive results for (ACC) deaminase activity and indole-3-acetic acid (IAA) production. The bacterial isolates were identified using 16S ribosomal DNA technique as Bacillus cereus and Bacillus aerius and had accession numbers MG708176 and MG711593 respectively, by submitting their sequences in GenBank database. This study showed that the bacterial strains B. cereus and B. aerius are valuable biological plant growth promoters that could enhance salt tolerance in Safflower plants under 100, 200, and 300mMNaCl levels resulting in an increase in plant growth and ascorbate-glutathione redox cycle, in comparison with the non-inoculated controls. Our findings reported that the co-inoculation of the two selected endophytic bacteria strains were successfully isolated from Safflower seedlings significantly alleviated the harmful effects of salt stress, promoted plant growth and biomass yield.

T3SS is an important virulence factor of Pseudomonas aeruginosa and has a central role in the infection process. However, the functional regulation of the T3SS by environmental signals is poorly understood. In our lab, we use fluorescence microscopy to study protein kinetics in real-time in live cells. In P. aeruginosa, results have shown that T3SS appears as bright foci at the cell membrane with no specific arrangement. In addition, T3SS is tightly controlled as it appears under a limited time period with the highest intensity at 3 h then disappears. Surprisingly, only 2.5% of the all assembled T3SS in the population have detectable ExoS synthesis. While T3SS assembly and ExoS synthesis increased under high salt concentration, they unexpectedly were not affected by different cyclic di-GMP levels. On the other hand, T3SS itself has an effect on the cyclic di-GMP levels inside the cell. Data have shown that despite T3SS in P. aeruginosa and Yersinia enterocolitica belong to the same the group, the two systems differentiate greatly in activity and regulation. We can conclude that every T3SS is unique and thus further studies are needed to elucidate the functional regulation of each system to better help effective inhibitor design.

Background Reinforcement corrosion and the concrete strength reduction are critical problems that resulted from crack creation in concrete. Very expensive and hazardous technologies based on chemical materials have been provided for repairing the cracks. Recently, crack repair using bio-catalysis precipitating bacteria has been developed as a viable and ecofriendly alternative technique. The main target of this study was to select and identify bacterial isolates with high urease activity to use in filling the cracks by the precipitation of CaCO3. Results Two endospore-forming and alkali-resistant ureolytic bacteria were combined with concrete to tolerate the mechanical stresses generated by mixing. The two isolates designated as (B1 and B2) were selected and identified as Bacillus wiedmannii strain FSL W8-0169 and Bacillus paramycoides strain MCCC 1A04098, respectively, using 16SrDNA gene sequencing. Both bacterial species completely heal cracks in fully destructed concrete and significant enhancement in compressive strength was illustrated. The calcite filling of cracks and CaCO3 crystals that were screened using a scanning electron microscope may explain the crack healing and the enhancement in concrete strength. Conclusions Bacillus wiedmannii strain FSL W8-0169 and Bacillus paramycoides strain MCCC 1A04098 can be inserted with the concrete to improve the compressive strength and the self-healing of cracks. The two ureolytic bacterial strains can be used to protect water buildings from exposure to frequent cracks.

No abstract

Novel carrier units were evaluated for their bio-healing benefits in our study to increase the efficacy of concrete healing. Bacillus cereus MG708176, an alkali-tolerant, calcite precipitating, endospore-forming strain was added as a bio-healing agent after its immobilization on wood ash units. A spore concentration of [1.3 × 107 spore/cm3] combined with 2.5% w/w urea was added to cement. Beams of 40 × 40 × 160 mm were used and tested for completely damaged mortar specimens after 7, 14, and 28 days of water treatment. Using wood ash bacterial mortars, totally destructed specimens were fully healed in all time intervals. Positive changes in concrete mechanical properties in bacterial wood ash treatment that were 24.7, 18.9, and 28.6% force for compressive, flexural, and tensile strengths more than control. The micro-images of the Scanning Electron Microscope (SEM) showed the dense concrete structure via calcite, Bacillafilla, and ettringite formation. Our results have shown improvements in the concrete healing efficiency and the mechanical concrete properties by filling the concrete cracks using a calcite-producing bacterium that is immobilized on wood ash units.