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Bacillus spp. produce a wide range of secondary metabolites, including antibiotics, which have been well studied for their antibacterial properties but less so as signaling molecules. Previous results indicated that the lipopeptide bacillomycin D is a signal that promotes biofilm development of Bacillus velezensis SQR9. However, the mechanism behind this signaling is still unknown. Here, we show that bacillomycin D promotes biofilm development by promoting the acquisition of iron. Bacillomycin D promotes the transcription of the iron ABC transporter FeuABC by binding to its transcription factor, Btr. These actions increase intracellular iron concentration and activate the KinB-Spo0A-SinI-SinR-dependent synthesis of biofilm matrix components. We demonstrate that this strategy is beneficial for biofilm development and competition with the Pseudomonas fluorescens PF-5. Our results unravel an antibiotic-dependent signaling mechanism that links iron acquisition to biofilm development and ecological competition. • Increasing intracellular iron concentrations serves as a cue for biofilm development • Bacillomycin D controls transcription of the specific iron transport gene feuABC • Bacillomycin D directly binds to the iron transport regulator Btr • Bacillomycin D modulates biofilm formation through the KinB-Spo0A-SinI-SinR pathway Natural lipopeptides are known antibiotics produced by Bacillus spp. Xu et al. demonstrate that the lipopeptide antibiotic bacillomycin D is involved in biofilm formation by promoting the acquisition of iron. Versatile functions of bacillomycin D in B. velezensis contribute to the microbe's ability to compete in its ecosystem. [ABSTRACT FROM AUTHOR]

The phase redundancy and freedom of the five-phase permanent magnet motor (FPPMM) enhance the reliability of the motor system. However, the temperature rise and torque reduction issues of the motor during open-circuit fault operation need to be further studied. In order to study the temperature distribution characteristics and the output capability of the motor under fault operation subject to temperature rise constraints, a 3-D global temperature field model containing a complex heat dissipation structure has been established. And the equal-amplitude temperature rise constraint current control method is proposed under open-circuit fault-tolerant operation to improve its output capability. The temperature distribution of the motor during steady state operation under rated operating conditions is analyzed with emphasis. Based on this, the temperature field changes of the motor during single-phase and two-phase open-circuit fault-tolerant operation are investigated. Then, the proposed equal-amplitude temperature rise constrained current method is introduced in detail to ensure the safe operation of the motor. An experimental platform is built, which verifies the accuracy of the temperature field calculation, as well as the correctness of equal-amplitude temperature rise constrained current method. [ABSTRACT FROM AUTHOR]

The nonlinearity of sinusoidal doubly salient electro-magnetic machine (SDSEM) leads to the fuzzy optimization range of its design parameters. And there is a conflict problem in multiple optimization objectives. Therefore, the multi-objective optimization of SDSEM with two different excitation modes is carried out based on the Gray-Fuzzy-Taguchi method. Firstly, the proposed sinusoidal method of square wave back electromotive force (EMF) phase modulation is introduced. And the key parameters to improve the symmetry and sinusoidal degree of the back EMF waveform are pointed out. Then, the sensitivity of key parameters is analyzed and the signal-to-noise (S/N) ratio is calculated by Taguchi orthogonal test. Secondly, the S/N ratio is linearly normalized by grey correlation analysis. Then, fuzzy reasoning is used to synthesize multiple performance indexes of the motor into a multiple performance characteristics index (MPCI) value, and the optimal scheme is obtained. Finally, the optimized SDSEM with concentrated magneto-motive forces (SDSEM-CF) and SDSEM with distributed magneto-motive forces (SDSEM-DF) are simulated and compared. The SDSEM-DF prototype is developed and verified by experiments. The results show that the no-load back EMF of the prototype has a good sinusoidal degree. Based on vector control, the sinusoidal drive of DSEM is realized without increasing the control complexity, which greatly reduces the torque ripple of the flux reluctance motor. [ABSTRACT FROM AUTHOR]

Harnessing the power of beneficial microbes in the rhizosphere to improve crop performance is a key goal of sustainable agriculture. However, the precise management of rhizosphere microbes for crop growth and health remains challenging because we lack a comprehensive understanding of the plant–rhizomicrobiome relationship. In this review, we discuss the latest research progress on root colonisation by representative beneficial microbes (e.g. Bacillus spp. and Pseudomonas spp.). We also highlight the bidirectional chemical communication between microbes and plant roots for precise functional control of beneficial microbes in the rhizosphere, as well as advances in understanding how beneficial microbes overcome the immune system of plants. Finally, we propose future research objectives that will help us better understand the complex network of plant–microbe interactions. • The three-step root colonisation of chemotaxis, attachment and biofilm were concluded. • The bidirectional chemical communication between microbes and root was summarized. • A two-step strategy was proposed to control the beneficial rhizosphere microbes. [ABSTRACT FROM AUTHOR]

The rhizosphere microbiome plays a key role in plant nutrient provision. However, the impacts of the vertically transmitted seed microbiome on the assembly of the rhizosphere microbiome and consequently on the functional traits remain unclear. Here, to assess the role of seed-borne beneficial microbes on the assembly of rhizosphere microbiome, we conducted a guest-soil cultivation study using two maize cultivars and their corresponding native soils with different available nutrient contents. The assembly of the rhizosphere bacterial and fungal communities was assessed by amplicon DNA sequencing. Our results demonstrated that the soil microbiome dominates the assembly of the rhizosphere microbiome. A seed-borne beneficial bacterium, Burkholderia gladioli , was able to colonize the rhizosphere in great relative abundance, which significantly altered the assembly of the rhizosphere microbiome. Genome analysis demonstrated that this seed-borne beneficial bacterial species may contain extracellular phosphatase-encoding genes, and gene quantification confirmed their existence, suggesting the possible compensation of phosphate solubilizing function. This functional compensation, which is probably a response to the low concentration of soil available phosphorus, may consequently promote phosphorus acquisition of the host plant. Overall, this study provides new insights into our understanding of the assembly of the rhizosphere microbiome, suggesting that the seed microbiome serves as a functional compensation reservoir to enhance the fitness of progeny plants and highlighting the necessity to consider the seed microbiome during plant breeding. ●Plant seeds possess beneficial microbial storage as a functional compensation reservoir. ●Seed-borne bacteria contribute to the composition of the rhizosphere microbiome. ●A seed-borne P solubilizing bacterium improves rhizospheric function in low P soil. [ABSTRACT FROM AUTHOR]