Comparative analysis of biofilm characterization of probiotic Escherichia coli.

Biofilms are thought to play a vital role in the beneficial effects of probiotic bacteria. However, the structure and function of probiotic biofilms are poorly understood. In this work, biofilms of Escherichia coli (E. coli) Nissle 1917 were investigated and compared with those of pathogenic and opportunistic strains (E. coli MG1655, O157:H7) using crystal violet assay, confocal laser scanning microscopy, scanning electron microscopy and FTIR microspectroscopy. The study revealed significant differences in the morphological structure, chemical composition, and spatial heterogeneity of the biofilm formed by the probiotic E. coli strain. In particular, the probiotic biofilm can secrete unique phospholipid components into the extracellular matrix. These findings provide new information on the morphology, architecture and chemical heterogeneity of probiotic biofilms. This information may help us to understand the beneficial effects of probiotics for various applications.

Analysis of the complete genome sequence of Paenibacillus sp. lzh-N1 reveals its antagonistic ability.

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.

IL-12 Contributes to the Development of Asthma by Targeting HIF-1α/NLRP3 Pathway through Runx3.

INTRODUCTION: The aim of the study was to determine the role and mechanism of runt-related transcription factor 3 (Runx3) in the development of asthma. METHODS: An asthma mouse model was constructed and validated by hematoxylin-eosin analysis of lung tissue and noninvasive enhanced pause (Penh) evaluation of airway hyperresponsiveness. Then, the levels of Runx3 and interleukin (IL)-12 in peripheral blood and lung tissue were detected by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. By use Runx3+/- mice, the effect of Runx3 downregulation on ovalbumin (OVA)-induced asthma was investigated. After stimulated by different doses of IL-12, the expressions of Runx3, hypoxia inducible factor-1α (HIF-1α), and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) in BEAS-2B cells were tested through Western blot and immunofluorescence. Subsequently, BEAS-2B cells treated with 20 ng/mL IL-12 were divided into control, Runx3 overexpression negative control, Runx3 overexpression, HIF-1α inhibitor, and Runx3 overexpression + HIF-1α agonist groups. The Western blot, immunofluorescence, and ELISA indicators were tested repeatedly. RESULTS: The increased number of inflammatory cells and Penh value confirmed the success of the asthma mouse model. IL-12 expression was significantly increased, and Runx3 was reduced in asthma mice compared with wild-type mice. Meanwhile, the level of immunoglobulin E (IgE) in serum, cytokines in bronchoalveolar lavage fluid, and IL-12, HIF-1α, NLRP3 in the lung were significantly elevated in Runx3+/- mice. With the increase of IL-12 concentration, Runx3 protein expression decreased, while HIF-1α and NLRP3 expression increased. Further mechanistic studies suggest that Runx3 ameliorates IL-12-induced BEAS-2B injury by inhibiting HIF-1α/NLRP3 pathway. CONCLUSION: These results suggested that IL-12 contributes to the development of asthma by targeting HIF-1α/NLRP3 pathway through Runx3, thus providing a novel strategy for asthma therapy.