Overexpression of a G-protein coupled receptor-like gene affects encystment of Acanthamoeba castellanii

Acanthamoeba castellanii is an amphizoic free-living amoeba as it can be found in humans and in the environment. This amoeba represents an important reservoir of pathogenic microorganisms. Persistence of A. castellanii in the environment or in humans is allowed by the ability of the vegetative form to differentiate under cysts when surrounding conditions are unfavorable. In this study, we investigate the role of the ACA1_383450 gene during encystment of A. castellanii. This gene encodes a putative G-protein coupled receptor, which shares homology with human GPR107 and murine GPR108. Expression of the ACA1_383450 gene is transiently repressed at the early phase of encystment and its overexpression affects encystment of A. castellanii. This study reveals a new Acanthamoeba gene which could affect the encystment process.

Biofilm formation capacity of Bacillus cereus on silicone, polyethylene terephthalate, Teflon, and aluminium food contact materials

Biofilms on food contact materials represent public health issues because they are resistant to cleaning and disinfection. This study aims to assess the Bacillus cereus biofilm formation capacity on silicone, polyethylene terephthalate, Teflon, and aluminium food contact materials. The biofilm biomass was analysed with the crystal violet assay method. We used the standard strain B. cereus CCM 2010, wild strain B. cereus 100 and spores of those two strains. The results show that both the vegetative form the bacteria and it spores form large amounts of biofilm on silicone, followed by polyethylene terephthalate, Teflon, and aluminium. More detailed analysis has shown that spores form more biomass on all materials in comparison to the vegetative form and that the standard strains form low levels of biofilm in contrast to the wild strains. Selecting proper material with the lowest biofilm formation potential can prevent or reduce food contamination and consequently increase food safety.

STUDY OF THE MASS-SPECTORS’ FEATURES OF SPORES AND VEGETATIVE FORMS OF BACILLUS ANTHRACIS BY THE METHOD OF TIME OF FLIGHT MASS-SPECTROMETRY

Aim. Investigation of the features of the protein profiles of the spore and vegetative form of the anthrax microbe by the MALDI-TOF MS method using the resources of the Mass-Up program and the package for the statistical software with open source code R. Materials and methods. Spores and vegetative forms of 32 strains of B. anthracis from the collection of microorganisms of the Stavropol Research Institute for Plague Control, including 8 strains isolated from an outbreak of anthrax in Yamal in 2016. Protein profiling was carried out on the Microflex MALDI-TOF mass spectrometer «Bruker Daltonics». Results. The alternative bioinformational-statistical approach used to analyze the MALDI-TOF mass spectra of the causative agent of anthrax made it possible to differentiate the spores and vegetative forms of the microbe based on the identification of the corresponding groups of biomarkers. Conclusion. A comparison of vegetative and spore cells of typical and atypical strains of anthrax causative agent on the basis of MALDI-TOF MS data was made. It has been experimentally confirmed that the protein profiles of cultures of Bacillus anthracis of the spore and vegetative form differ significantly, and this difference can be used to search for potential markers of each of the forms.

A new species of Bulbophyllum (Orchidaceae; Epidendroideae; Dendrobiinae) from Yunnan, China

Bulbophyllum Thouars (1822: 3) is one of the largest orchid genera, including more than 1900 species widely distributed from tropical America, Africa, Madagascar, and mainland Asia to Australasia (Lindley 1830, Pearce & Cribb 2002, Seidenfaden 1979, 1992, Chen et al. 2009, Pridgeon et al. 2014). The species possess a wide range of vegetative form and floral structure (Bose et al. 1980). There are about 103 species (33 endemic) in 18 sections in China (Chen et al. 2009).

Clostridium difficile

Clostridium difficile is a Gram-positive spore-forming anaerobic bacillus found in the environment. Its spores are part of the colonic flora in about 2 to 3% of healthy adults, with colonization rates increasing during hospitalization to 20 to 40%. Disease occurs when the organism shifts to its replicating vegetative form with toxin (A and B) production, this typically happening when there is inhibition of the competing colonic flora by antibiotics. ...

Vegetative Clostridium difficile Survives in Room Air on Moist Surfaces and in Gastric Contents with Reduced Acidity: a Potential Mechanism To Explain the Association between Proton Pump Inhibitors and C. difficile-Associated Diarrhea?

ABSTRACT Proton pump inhibitors (PPIs) have been identified as a risk factor for Clostridium difficile-associated diarrhea (CDAD), though the mechanism is unclear because gastric acid does not kill C. difficile spores. We hypothesized that the vegetative form of C. difficile, which is killed by acid, could contribute to disease pathogenesis if it survives in room air and in gastric contents with elevated pH. We compared the numbers of C. difficile spores and vegetative cells in stools of patients prior to and during the treatment of CDAD. We assessed the survival of vegetative cells on moist or dry surfaces in room air versus anaerobic conditions and in human gastric contents, in pH-adjusted gastric contents, and in gastric contents from individuals receiving PPI therapy. Stool samples obtained from patients prior to the initiation of antibiotic treatment for C. difficile contained ∼10-fold more vegetative cells than spores. On dry surfaces, vegetative C. difficile cells died rapidly, whereas they remained viable for up to 6 h on moist surfaces in room air. Vegetative C. difficile cells had only marginal survival in gastric contents at low pH; adjustment to a pH of >5 resulted in survival similar to that in the phosphate-buffered saline control. The survival of vegetative C. difficile in gastric contents obtained from patients receiving PPIs was also increased at a pH of >5. The ability of the vegetative form of C. difficile to survive on moist surfaces and in gastric contents with an elevated pH suggests a potential mechanism by which PPI therapy could increase the risk of acquiring C. difficile.

Murine Macrophages Kill the Vegetative Form of Bacillus anthracis

ABSTRACT Anti-protective antigen antibody was reported to enhance macrophage killing of ingested Bacillus anthracis spores, but it was unclear whether the antibody-mediated macrophage killing mechanism was directed against the spore itself or the vegetative form emerging from the ingested and germinating spore. To address this question, we compared the killing of germination-proficient (gp) and germination-deficient (ΔgerH) Sterne 34F2 strain spores by murine peritoneal macrophages. While macrophages similarly ingested both spores, only gp Sterne was killed at 5 h (0.37 log kill). Pretreatment of macrophages with gamma interferon (IFN-γ) or opsonization with immunoglobulin G (IgG) isolated from a subject immunized with an anthrax vaccine enhanced the killing of Sterne to 0.49 and 0.73 log, respectively, but the combination of IFN-γ and IgG was no better than either treatment alone. Under no condition was there killing of ΔgerH spores. To examine the ability of the exosporium to protect spores from macrophages, we compared the macrophage-mediated killing of nonsonicated (exosporium+) and sonicated (exosporium−) Sterne 34F2 spores. More sonicated spores than nonsonicated spores were killed at 5 h (0.98 versus 0.37 log kill, respectively). Pretreatment with IFN-γ increased the sonicated spore killing to 1.39 log. However, the opsonization with IgG was no better than no treatment or pretreatment with IFN-γ. We conclude that macrophages appear unable to kill the spore form of B. anthracis and that the exosporium may play a role in the protection of spores from macrophages.