Mechanical loading is an essential factor for bone formation. A previous study indicated that mechanical tensile strain of 2500 microstrain (με) at 0.5 Hz for 8 h promoted osteogenesis and corresponding mechanoresponsive microRNAs (miRs) were identified in osteoblasts. However, in osteocytes, it has not been identified which miRs respond to the mechanical strain, and it is not fully understood how the mechanoresponsive miRs regulate osteoblast differentiation. Mouse MLO-Y4 osteocytes were applied to the same mechanical tensile strain in vitro. Using molecular and biochemical methods, IGF-1 (insulin-like growth factor-1), PGE2 (prostaglandin E2), OPG (osteoprotegerin) and NOS (nitric oxide synthase) activities of the cells were assayed. MiR microarray and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays were applied to select and validate differentially expressed miRs, and the target genes of these miRs were then predicted. MC3T3-E1 osteoblasts were stimulated by the mechanical tensile strain, and the miR-29b-3p expression was detected with miR microarray and RT-qPCR. Additionally, the effect of miR-29b-3p on IFG-1 secretion of osteocytes and the influence of conditioned medium of osteocytes transfected with miR-29b-3p on osteoblast differentiation were investigated. The mechanical strain increased secretions of IGF-1 and PGE2, elevated OPG expression and NOS activities, and resulted in altered expression of the ten miRs, and possible target genes for these differentially expressed miRs were revealed through bioinformatics. Among the ten miRs, miR-29b-3p were down-regulated, and miR-29b-3p overexpression decreased the IGF-1 secretion of osteocytes. The mechanical strain did not change expression of osteoblasts’ miR-29b-3p. In addition, the conditioned medium of mechanically strained osteocytes promoted osteoblast differentiation, and the conditioned medium of osteocytes transfected with miR-29b-3p mimic inhibited osteoblast differentiation. In osteocytes (but not osteoblasts), miR-29b-3p was responsive to the mechanical tensile strain and regulated osteoblast differentiation via regulating IGF-1 secretion of mechanically strained osteocytes.

Background: Plant diseases caused by pathogenic fungi are devastating. However, commonly used fungicides are harmful to the environment, and some are becoming ineffective due to fungal resistance. Therefore, eco-friendly biological methods to control pathogenic fungi are urgently needed. Results: In this study, a strain, Paenibacillus sp. lzh-N1, that could inhibit the growth of the pathogenic fungus Mycosphaerella sentina (Fr) Schrorter was isolated from the rhizosphere soil of pear trees, and the complete genome sequence of the strain was obtained, annotated, and analyzed to reveal the genetic foundation of its antagonistic ability. The entire genome of this strain contained a circular chromosome of 5,641,488 bp with a GC content of 45.50%. The results of species identification show that the strain belongs to the same species as P. polymyxa Sb3-1 and P. polymyxa CJX518. Sixteen secondary metabolic biosynthetic gene clusters were predicted by antiSMASH, including those of the antifungal peptides fusaricidin B and paenilarvins. In addition, biofilm formation-related genes containing two potential gene clusters for cyclic lactone autoinducer, a gene encoding S-ribosylhomocysteine lyase (LuxS), and three genes encoding exopolysaccharide biosynthesis protein were identified. Conclusions: Antifungal peptides and glucanase biosynthesized by Paenibacillus sp. lzh-N1 may be responsible for its antagonistic effect. Moreover, quorum sensing systems may influence the biocontrol activity of this strain directly or indirectly.

Plant diseases significantly and persistently impair product quality and yield across the globe. Employing antagonistic microorganisms represents an environmentally friendly and cost-effective approach to pathogen management. In this study, Bacillus velezensis Lzh-5 was explored to understand the molecular underpinnings of its antagonistic activity and plant growth-promoting properties. We present the basic genomic profile of B. velezensis Lzh-5. Whole-genome analysis revealed that Lzh-5 possesses a 4,015,817 bp circular chromosome with a GC content of 46.0%, and an 8,933 bp circular plasmid with a GC content of 40.5%. A total of 3,998 genes were predicted, of which 3,881 (97.07%) are coding DNA sequences (CDSs). Through phylogenomic and comparative genomic analyses, strain Lzh-5 was confirmed as B. velezensis. The Lzh-5 genome harbors genes for cell wall-degrading enzymes. Additionally, 13 gene clusters responsible for secondary metabolite production were identified. Notably, a unique cluster (cluster 2) coding for an unknown compound was found exclusively in strain Lzh-5. Genes associated with plant growth enhancement, such as those involved in chemotaxis, motility, biofilm formation, phytohormone production, nitrogen fixation, phosphate solubilization, glycine betaine biosynthesis, and acetoin and 2,3-butanediol synthesis, were also identified. The basic characteristics of strain Lzh-5 genome were delineated through whole-genome sequencing. Our analysis indicates that the Lzh-5 genome encompasses various genes that promote plant growth, induce systemic resistance, and antagonize pathogens. Compared to other strains, several unique gene clusters in Lzh-5 may contribute to the discovery of novel bioactive compounds and offer a broader antagonistic spectrum. This investigation elucidates the antifungal and plant growth-promoting mechanisms of B. velezensis Lzh-5 at a genetic level, providing a theoretical foundation for further application in agricultural production.

Cyanobacterial blooming is an increasing environmental issue all over the world. Algicidal bacteria are potential tools for the control of algal blooms. The algicidal activity in many bacteria exhibits quorum-sensing (QS) dynamics and the regulatory mechanism of this activity in these bacteria is unclear. In this study, combining genomic sequencing and genome editing, we have identified that the primary quorum-sensing system in the isolated algicidal strain Shewanella xiamenensis Lzh-2 is the LuxS/AI-2 signaling pathway. Disruption of the QS system through recombination deletion of the LuxS gene led to a loss of algicides production and algicidal activity. Restoration of the LuxS gene in the deletion mutant compensated the QS system and recovered the algicidal activity. Consequently, we proved that Lzh-2 regulates the algicidal activity through LuxS/AI-2 quorum-sensing system.

Pseudomonas chlororaphis Lzh-T5 is a plant growth-promoting rhizobacterium (PGPR) with antimicrobial activity isolated from tomato rhizosphere in the city of Dezhou, Shandong Province, China. Here, the draft genome sequence of P. chlororaphis Lzh-T5 is reported, and several functional genes related to antifungal antibiotics and siderophore biosynthesis have been found in the genome.

Harmful cyanobacterial blooms (HABs), primarily composed of toxic cyanobacteria like Microcystis aeruginosa, pose a significant threat to aquatic ecosystems and human health. Algicidal bacteria had emerged as a promising strategy for HAB control due to their safety and efficacy. In this study, the algicidal bacterium Streptomyces violaceorubidus lzh-14, isolated from Cha Lake in Dezhou, China, exhibited strong algicidal activity against M. aeruginosa. When bacterial culture was added to algal cultures at a final volume ratio of 10% (v/v), the algicidal activity reached 94.5% ± 1.8% after 72 h. Moreover, S. violaceorubidus lzh-14 showed varying degrees of algicidal activity against other tested cyanobacterial species. Microscopic observation revealed that M. aeruginosa cells treated with lzh-14 became deformed and ruptured, resulting in the leakage of cellular contents. The algicidal substance extracted from S. violaceorubidus lzh-14 demonstrated strong stability under varying temperatures and pH conditions. Based on these findings, algicidal powder was preliminarily developed. This study confirms that S. violaceorubidus lzh-14 and its active substance have potential as effective biocontrol agents against HABs.