The noncommensal bacterium Methylococcus capsulatus (Bath) ameliorates dextran sulfate (Sodium Salt)-Induced Ulcerative Colitis by influencing mechanisms essential for maintenance of the colonic barrier function.

Dietary inclusion of a bacterial meal has recently been shown to efficiently abolish soybean meal-induced enteritis in Atlantic salmon. The objective of this study was to investigate whether inclusion of this bacterial meal in the diet could abrogate disease development in a murine model of epithelial injury and colitis and thus possibly have therapeutic potential in human inflammatory bowel disease. C57BL/6N mice were fed ad libitum a control diet or an experimental diet containing 254 g/kg of body weight BioProtein, a bacterial meal consisting of Methylococcus capsulatus (Bath), together with the heterogenic bacteria Ralstonia sp., Brevibacillus agri, and Aneurinibacillus sp. At day 8, colitis was induced by 3.5% dextran sulfate sodium (DSS) ad libitum in the drinking water for 6 days. Symptoms of DSS treatment were less profound after prophylactic treatment with the diet containing the BioProtein. Colitis-associated parameters such as reduced body weight, colon shortening, and epithelial damage also showed significant improvement. Levels of acute-phase reactants, proteins whose plasma concentrations increase in response to inflammation, and neutrophil infiltration were reduced. On the other, increased epithelial cell proliferation and enhanced mucin 2 (Muc2) transcription indicated improved integrity of the colonic epithelial layer. BioProtein mainly consists of Methylococcus capsulatus (Bath) (88%). The results that we obtained when using a bacterial meal consisting of M. capsulatus (Bath) were similar to those obtained when using BioProtein in the DSS model. Our results show that a bacterial meal of the noncommensal bacterium M. capsulatus (Bath) has the potential to attenuate DSS-induced colitis in mice by enhancing colonic barrier function, as judged by increased epithelial proliferation and increased Muc2 transcription.

Draft genome sequence of the methane-oxidizing bacterium Methylococcus capsulatus (Texas).

Methanotrophic bacteria perform major roles in global carbon cycles via their unique enzymatic activities that enable the oxidation of one-carbon compounds, most notably methane. Here we describe the annotated draft genome sequence of the aerobic methanotroph Methylococcus capsulatus (Texas), a type strain originally isolated from sewer sludge.

Surface display of N-terminally anchored invasin by Lactobacillus plantarum activates NF-κB in monocytes.

The probiotic lactic acid bacterium Lactobacillus plantarum is a potential delivery vehicle for mucosal vaccines because of its generally regarded as safe (GRAS) status and ability to persist at the mucosal surfaces of the human intestine. However, the inherent immunogenicity of vaccine antigens is in many cases insufficient to elicit an efficient immune response, implying that additional adjuvants are needed to enhance the antigen immunogenicity. The goal of the present study was to increase the proinflammatory properties of L. plantarum by expressing a long (D1 to D5 [D1-D5]) and a short (D4-D5) version of the extracellular domain of invasin from the human pathogen Yersinia pseudotuberculosis. To display these proteins on the bacterial surface, four different N-terminal anchoring motifs from L. plantarum were used, comprising two different lipoprotein anchors, a transmembrane signal peptide anchor, and a LysM-type anchor. All these anchors mediated surface display of invasin, and several of the engineered strains were potent activators of NF-κB when interacting with monocytes in cell culture. The most distinct NF-κB responses were obtained with constructs in which the complete invasin extracellular domain was fused to a lipoanchor. The proinflammatory L. plantarum strains constructed here represent promising mucosal delivery vehicles for vaccine antigens.