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Background/AimsThis study aimed to investigate the microRNA (miRNA) expression profiles in peripheral blood mononuclear cell (PBMC) of hepatitis B virus (HBV)-infected patients with different clinical manifestations and to analyze the function of miR-197.MethodsPBMC miRNA expression profiles in 51 healthy controls, 70 chronic asymptomatic carriers, 107 chronic hepatitis B patients, and 76 HBV-related acute on chronic liver failure patients were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). miR-197 mimic and inhibitor were transfected in THP-1 cells. qRT-PCR and ELISA for interleukin (IL)-18 mRNA and protein levels were performed, respectively.ResultsThe microarray analysis revealed that 17 PBMC miRNA expression profiles (12 miRNAs downregulated and five miRNAs upregulated) differed significantly in HBV-induced liver disease patients presenting with various symptoms. The qRT-PCR results suggested that the PBMC miR-197 levels regularly decreased as the severity of liver disease symptoms became aggravated. IL-18, a key regulator in inflammation and immunity, was inversely correlated with miR-197 levels. Bioinformatic analysis indicated that IL-18 was a target of miR-197. Exogenous expression of miR-197 could significantly repress IL-18 expression at both the mRNA and protein levels in THP-1 cells.ConclusionsWe concluded that multiple PBMC miRNAs had differential expression profiles during HBV infection and that miR-197 may play an important role in the reactivation of liver inflammation by targeting IL-18.

Microbes can enter into healthy plants as endophytes and confer beneficial functions. The entry of commensal microbes into plants involves penetrating plant defense. Most mechanisms about overcoming plant defense are focused on adapted pathogens, while the mechanism involved in beneficial endophyte evades plant defense to achieve harmonious commensalism is unclear. Here, we discover a mechanism that an endophyte bacterium Bacillus subtilis BSn5 reduce to stimulate the plant defensive response by producing lantibiotic subtilomycin to bind self-produced flagellin. Subtilomycin bind with flagellin and affect flg22-induced plant defense, by which means promotes the endophytic colonization in A. thaliana. Subtilomycin also promotes the BSn5 colonization in a distinct plant, Amorphophallus konjac, where the BSn5 was isolated. Our investigation shows more independent subtilomycin/-like producers are isolated from distinct plants. Our work unveils a common strategy that is used for bacterial endophytic colonization.

Lantibiotics are antimicrobial peptides with potential applications as the next generation of antimicrobials in the food industry and/or the pharmaceutical industry. Nisin has successfully been used as a food preservative for over 40 years, but its major drawback is its limited stability under neutral and alkaline pH conditions. To identify alternatives with better biochemical properties, we screened more than 100 strains of the Bacillus cereus group. Three novel lantibiotics, ticins A1 (4,062.98 Da), A3 (4,048.96 Da), and A4 (4,063.02 Da), which were highly thermostable (121°C for 30 min) and extremely pH tolerant (pH 2.0 to 9.0), were identified in Bacillus thuringiensis BMB3201. They all showed potent antimicrobial activities against all tested Gram-positive bacteria and greater activities than those of nisin A against Bacillus cereus and Listeria monocytogenes, two important foodborne pathogens. These three novel lantibiotics, with their extremely stable properties and potent antimicrobial activities, have the potential for use as biopreservatives. Bacteriocins are ribosomally synthesized antimicrobial peptides produced by various bacteria that are active against other bacteria either of the same species (narrow spectrum) or across genera (broad spectrum) (1). They are classified into two groups: posttranslationally modified bacteriocins and unmodified or cyclic bacteriocins (2). Lantibiotics (lanthipeptides) are the best-characterized modified bacteriocins, and their modifications include the formation of meso-lanthionine and 3-methyllanthionine residues, as well as dehydrated amino acids (Dha and Dhb) (3). Lanthionine (Lan) consists of two alanine residues cross-linked via a thioether linkage; 3-methyllanthionine (MeLan) contains one additional methyl group. Lanthipeptides are classified into four classes depending on their biosynthetic enzymes. For class I lanthipeptides, dehydration is carried out by a LanB dehydratase, and cyclization is catalyzed by a LanC cyclase. Class II lanthipeptides are modified by LanM lanthionine synthetases, which have an N-terminal dehydration domain and a C-terminal cyclization domain. For class III and IV lanthipeptides, the dehydration and cyclization reactions are catalyzed by multifunctional enzymes (RamC/LabKC or LanL).In the past decade, research on bacteriocins or lantibiotics has focused primarily on lactic acid bacteria (LAB), primarily because of their potential applications as preservatives in the food industry and/or as viable alternatives to antibiotics in medicine (2, 4). These bacteriocins also have several desirable properties that make them suitable for food preservation, as follows: (i) they are generally recognized as safe (GRAS), (ii) they are nontoxic to eukaryotic cells, (iii) they can be inactivated by digestive proteases, (iv) they are pH and heat tolerant, (v) they have a relatively broad antimicrobial spectrum against many Gram-positive foodborne pathogenic and spoilage bacteria, (vi) they show a bactericidal mode of action and no cross-resistance w...

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