Gut microbiota of patients with Parkinson’s disease and healthy volunteers was analyzed by the method of high throughput 16S rRNA sequencing of bacterial genomes. In patients with Parkinson’s ...diseases, changes in the content of 9 genera and 15 species of microorganisms were revealed: reduced content of
Dorea
,
Bacteroides
,
Prevotella
,
Faecalibacterium
,
Bacteroides massiliensis
,
Stoquefichus massiliensis
,
Bacteroides coprocola
,
Blautia glucerasea
,
Dorea longicatena
,
Bacteroides dorei
,
Bacteroides plebeus
,
Prevotella copri
,
Coprococcus eutactus
, and
Ruminococcus callidus
, and increased content of
Christensenella
,
Catabacter
,
Lactobacillus
,
Oscillospira
,
Bifidobacterium
,
Christensenella minuta
,
Catabacter hongkongensis
,
Lactobacillus mucosae
,
Ruminococcus bromii
, and
Papillibacter cinnamivorans
. This microbiological pattern of gut microflora can trigger local inflammation followed by aggregation of α-synuclein and generation of Lewy bodies.
All bacteria produce secreted vesicles that carry out a variety of important biological functions. These extracellular vesicles can improve adaptation and survival by relieving bacterial stress and ...eliminating toxic compounds, as well as by facilitating membrane remodeling and ameliorating inhospitable environments. However, vesicle production comes with a price. It is energetically costly and, in the case of colonizing pathogens, it elicits host immune responses, which reduce bacterial viability. This raises an interesting paradox regarding why bacteria produce vesicles and begs the question as to whether the benefits of producing vesicles outweigh their costs. In this review, we discuss the various advantages and disadvantages associated with Gram‐negative and Gram‐positive bacterial vesicle production and offer perspective on the ultimate score. We also highlight questions needed to advance the field in determining the role for vesicles in bacterial survival, interkingdom communication, and virulence.
Why do bacteria produce vesicles? They facilitate nutrient acquisition, survival, and adaptation, but also elicit antagonistic host responses. Close examination reveals how vesicle production yields a net positive for bacteria.
Lactic acid bacteria Holzapfel, Wilhelm H; Wood, Brian J.B
2014., 2014, 2014-04-29
eBook
Lactic Acid Bacteria Biodiversity and Taxonomy Lactic Acid Bacteria Biodiversity and Taxonomy Edited by Wilhelm H. Holzapfel and Brian J.B. Wood The lactic acid bacteria (LAB) are a group of related ...microorganisms that are enormously important in the food and beverage industries. Generally regarded as safe for human consumption (and, in the case of probiotics, positively beneficial to human health), the LAB have been used for centuries, and continue to be used worldwide on an industrial scale, in food fermentation processes, including yoghurt, cheeses, fermented meats and vegetables, where they ferment carbohydrates in the foods, producing lactic acid and creating an environment unsuitable for the survival of food spoilage organisms and pathogens. The shelf life of the product is thereby extended, but of course these foods are also enjoyed around the world for their organoleptic qualities. They are also important to the brewing and winemaking industries, where they are often undesirable intruders but can in specific cases have desirable benefits. The LAB are also used in producing silage and other agricultural animal feeds. Clinically, they can improve the digestive health of young animals, and also have human medical applications. This book provides a much-needed and comprehensive account of the current knowledge of the LAB, covering the taxonomy and relevant biochemistry, physiology and molecular biology of these scientifically and commercially important microorganisms. It is directed to bringing together the current understanding concerning the organisms' remarkable diversity within a seemingly rather constrained compass. The genera now identified as proper members of the LAB are treated in dedicated chapters, and the species properly recognized as members of each genus are listed with detailed descriptions of their principal characteristics. Each genus and species is described using a standardized format, and the relative importance of each species in food, agricultural and medical applications is assessed. In addition, certain other bacterial groups (such as Bifidobacterium) often associated with the LAB are given in-depth coverage. The book will also contribute to a better understanding and appreciation of the role of LA B in the various ecosystems and ecological niches that they occupy. In summary, this volume gathers together information designed to enable the organisms' fullest industrial, nutritional and medical applications. Lactic Acid Bacteria: Biodiversity and Taxonomy is an essential reference for research scientists, biochemists and microbiologists working in the food and fermentation industries and in research institutions. Advanced students of food science and technology will also find it an indispensable guide to the subject. Also available from Wiley Blackwell The Chemistry of Food Jan Velisek ISBN 978-1-118-38384-1 Progress in Food Preservation Edited by Rajeev Bhat, Abd Karim Alias and Gopinadham Paliyath ISBN 978-0-470-65585-6
Illicium verum, commonly known as star anise, represents one of the notable botanical species and is recognized for its rich reservoir of diverse bioactive compounds. Beyond its culinary application ...as a spice, this plant has been extensively utilized in traditional medicine. Given the contemporary emphasis on incorporating natural resources into food production, particularly essential oils, to enhance sensory attributes and extend shelf life, our study seeks to elucidate the chemical composition and evaluate the antibacterial (in vitro, in situ) and insecticidal properties of Illicium verum essential oil (IVEO). Also, microbiological analyses of pumpkin sous vide treated with IVEO after inoculation of Salmonella enterica were evaluated after 1 and 7 days of study. GC/MS analysis revealed a significantly high amount of (E)-anethole (88.4%) in the investigated EO. The disc diffusion method shows that the antibacterial activity of the IVEO ranged from 5.33 (Streptococcus constellatus) to 10.33 mm (Citrobacter freundii). The lowest minimal inhibition concentration was found against E. coli and the minimum biofilm inhibition concertation was found against S. enterica. In the vapor phase, the best antimicrobial activity was found against E. coli in the pears model and against S. sonei in the beetroot model. The application of the sous vide method in combination with IVEO application decreased the number of microbial counts and eliminated the growth of S. enterica. The most isolated microbiota identified from the sous vide pumpkin were Bacillus amyloliquefaciens, B. cereus, B. licheniformis, and Ralstonia picketii. Modifications to the protein composition of biofilm-forming bacteria S. enterica were suggested by the MALDI TOF MS instigations. The IVEO showed insecticidal potential against Harmonia axyridis. Thanks to the properties of IVEO, our results suggest it can be used in the food industry as a natural supplement to extend the shelf life of foods and as a natural insecticide.
The bactericidal effect of various types of photoirradiated polyphenols against Gram-positive and -negative bacteria was evaluated in relation to the mode of action. Gram-positive bacteria ...(Enterococcus faecalis, Staphylococcus aureus, and Streptococcus mutans) and Gram-negative bacteria (Aggregatibacter actinomycetemcomitans, Escherichia coli, and Pseudomonas aeruginosa) suspended in a 1 mg/mL polyphenol aqueous solution (caffeic acid, gallic acid, chlorogenic acid, epigallocatechin, epigallocatechin gallate, and proanthocyanidin) were exposed to LED light (wavelength, 400 nm; irradiance, 260 mW/cm(2)) for 5 or 10 min. Caffeic acid and chlorogenic acid exerted the highest bactericidal activity followed by gallic acid and proanthocyanidin against both Gram-positive and -negative bacteria. It was also demonstrated that the disinfection treatment induced oxidative damage of bacterial DNA, which suggests that polyphenols are incorporated into bacterial cells. The present study suggests that blue light irradiation of polyphenols could be a novel disinfection treatment.
Host responses to infection encompass many processes in addition to activation of the immune system, including metabolic adaptations, stress responses, tissue repair, and other reactions. The ...response to bacterial infection in Drosophila melanogaster has been classically described in studies that focused on the immune response elicited by a small set of largely avirulent microbes. Thus, we have surprisingly limited knowledge of responses to infection that are outside the canonical immune response, of how the response to pathogenic infection differs from that to avirulent bacteria, or even of how generic the response to various microbes is and what regulates that core response. In this study, we addressed these questions by profiling the D. melanogaster transcriptomic response to 10 bacteria that span the spectrum of virulence. We found that each bacterium triggers a unique transcriptional response, with distinct genes making up to one third of the response elicited by highly virulent bacteria. We also identified a core set of 252 genes that are differentially expressed in response to the majority of bacteria tested. Among these, we determined that the transcription factor CrebA is a novel regulator of infection tolerance. Knock-down of CrebA significantly increased mortality from microbial infection without any concomitant change in bacterial number. Upon infection, CrebA is upregulated by both the Toll and Imd pathways in the fat body, where it is required to induce the expression of secretory pathway genes. Loss of CrebA during infection triggered endoplasmic reticulum (ER) stress and activated the unfolded protein response (UPR), which contributed to infection-induced mortality. Altogether, our study reveals essential features of the response to bacterial infection and elucidates the function of a novel regulator of infection tolerance.
Surfaces of prokaryotic cells play a significant role in the adsorption of metals from aqueous solution and the formation of authigenic minerals (Konhauser 2006). Although most studies focus on the ...cell wall, it is known that many bacteria synthesise an extracellular layer of polysaccharides and proteins, including what are known as sheaths. It has been shown that the cyanobacterium
Calothrix
sp. produces as sheath which is neutrally charged at circumneutral pH values, and it was hypothesized that such a sheath might allow the cyanobacterium to survive in geothermal settings with high silicification rates (Phoenix et al. 2002). Specifically, the dominance of hydroxyl sites on
Calothrix
’s sheath surface facilitates hydrogen bonding with aqueous silica species, inducing the precipitation of amorphous silica on the sheath and thus protecting the underlying cell (Phoenix et al. 2002).
Leptothrix cholodnii
is a sheathed, iron and manganese-oxidizing bacterium that frequently inhabits minerals seeps, where Fe
2+
and Mn
2+
discharge into oxygenated surface waters (Spring et al. 1996). As a result, the sheath becomes encrusted with Fe(III) and Mn(IV) oxyhydroxides while the underlying cells are protected from mineralization (Emerson and Ghiorse 1992, Emerson et al. 2010). However, unlike
Calothrix, Leptothrix’
s sheath composition suggests that it might behave differently at circumneutral pH (Emerson and Ghiorse 1993). To investigate the surface reactivity of
Leptothrix
's sheath and cell wall we analyzed isolated sheaths, sheathless cells, and intact filaments of
L. cholodnii
SP-6. We studied these components using potentiometric titration, zeta-potential, Cd-adsorption, and Fourier transform infrared (FTIR) spectroscopy to elucidate changes in surface charge between the cell wall and sheath. For the isolated sheaths and intact filaments, titration data were fit using a two-site protonation model, resulting in the following pKa values: 6.05 (±0.29) and 9.34 (±0.11); and 7.77 (±0.17) and 10.50 (±0.20), respectively. For the sheathless cells, the best fit was obtained by using a three-site protonation model, resulting in the following pKa values: 5.40 (±0.59), 8.11 (±1.64) and 10.73 (±0.45). Total proton-active site concentrations were lower in isolated sheaths compared to intact filaments. Additionally, at circumneutral pH, net negative charge was lower for sheathless cells compared to intact filaments and isolated sheaths (Fig. 1). This information agrees with the Cd adsorption behaviour found for the three materials (Fig. 2). Thus, our preliminary results suggest that
Leptothrix
’s sheath
is less reactive than the intact filaments at circumneutral pH, leading us to hypothesize that the outermost layer would sequester relatively lower amounts of cations, including Mn
2+
, from solution and potentially would protect the underlaying cell from deleterious mineralization. In addition to that, the less reactive sheath’s surface would also contribute to cell attachment, which is important for a species commonly found in streams (Phoenix et al. 2002, Emerson et al. 2010).
Noble metal-based nanomaterials have shown promise as potential enzyme mimetics, but the facet effect and underlying molecular mechanisms are largely unknown. Herein, with a combined experimental and ...theoretical approach, we unveil that palladium (Pd) nanocrystals exhibit facet-dependent oxidase and peroxidase-like activities that endow them with excellent antibacterial properties via generation of reactive oxygen species. The antibacterial efficiency of Pd nanocrystals against Gram-positive bacteria is consistent with the extent of their enzyme-like activity, that is {100}-faceted Pd cubes with higher activities kill bacteria more effectively than {111}-faceted Pd octahedrons. Surprisingly, a reverse trend of antibacterial activity is observed against Gram-negative bacteria, with Pd octahedrons displaying stronger penetration into bacterial membranes than Pd nanocubes, thereby exerting higher antibacterial activity than the latter. Our findings provide a deeper understanding of facet-dependent enzyme-like activities and might advance the development of noble metal-based nanomaterials with both enhanced and targeted antibacterial activities.
Summary
Type IV secretion systems (T4SSs) are versatile multiprotein nanomachines spanning the entire cell envelope in Gram‐negative and Gram‐positive bacteria. They play important roles through the ...contact‐dependent secretion of effector molecules into eukaryotic hosts and conjugative transfer of mobile DNA elements as well as contact‐independent exchange of DNA with the extracellular milieu. In the last few years, many details on the molecular mechanisms of T4SSs have been elucidated. Exciting structures of T4SS complexes from Escherichia coli plasmids R388 and pKM101, Helicobacter pylori and Legionella pneumophila have been solved. The structure of the F‐pilus was also reported and surprisingly revealed a filament composed of pilin subunits in 1:1 stoichiometry with phospholipid molecules. Many new T4SSs have been identified and characterized, underscoring the structural and functional diversity of this secretion superfamily. Complex regulatory circuits also have been shown to control T4SS machine production in response to host cell physiological status or a quorum of bacterial recipient cells in the vicinity. Here, we summarize recent advances in our knowledge of ‘paradigmatic’ and emerging systems, and further explore how new basic insights are aiding in the design of strategies aimed at suppressing T4SS functions in bacterial infections and spread of antimicrobial resistances.
Type IV secretion systems (T4SSs) are highly sophisticated nanomachines in the cell envelope of many bacteria. They exhibit crucial roles during infection of humans by the secretion of effector proteins, conjugative transfer of DNA and exchange of DNA with the extracellular environment. In this MicroReview, we summarize recent progress on T4SS composition, assembly and structure and highlight how basic understanding of their functions is aiding in the design of novel strategies for antimicrobial therapies.
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