scholarly journals Bdellovibrio and like organisms bacterial predators are not equally distributed in peri-alpine lakes

2017 ◽  
Author(s):  
Benoit Paix ◽  
Stéphan Jacquet
Keyword(s):  
Single Species ◽  
Ecosystem Processes ◽  
Alpine Lakes ◽  
Gram Negative Bacteria ◽  
Prokaryotic Community ◽  
Abundance Distribution ◽  
Near Surface ◽  
Gram Negative ◽  
Different Depths ◽  
First Time

Microbes drive a variety of ecosystem processes and services but still many of them remain largely unexplored because of our lack of knowledge on both diversity and functionality of some potentially key microbiological compartments. This is typically the case with and within the group of bacterial predators collectively known as Bdellovibrio and like organisms (BALOs). Here we report for the first time the abundance, distribution and diversity of the three main families of these natural and obligatory predators of gram negative bacteria in three peri-alpine lakes (e.g. lakes Annecy, Bourget and Geneva) at different depths (surface vs. 45 or 50 m) and along a few months (from August 2015 to January 2016). We show that, using PCR-DGGE and cloning-sequencing approaches, the diversity appeared relatively low and very specific to fresh waters or even of the lakes themselves. While the Peredibacteraceae family was represented mainly by a single species (i.e. Peredibacter starii), it could constitute up to 7% of the total bacterial cell abundances. Comparati vel y, the abundances of the two other families (referred to as Bdellovibrionaceae and Bacteriovaracaceae) were significantly lower. More interestingly, the distribution in the water column was very different between the three groups suggesting various life strategies/niches for each of them: Peredibactereacea dominated near surface while the Bdellovibrionaceae and the Bacteriovaracaceae were more abundant at depth. All in all, our results suggest that these bacterial predators are likely to play a significant role in mortality, carbon fluxes and prokaryotic community structure in lakes.

scholarly journals Diversity, Dynamics, and Distribution ofBdellovibrioand Like Organisms in Perialpine Lakes

2019 ◽  
Vol 85 (6) ◽  
Author(s):  
Benoit Paix ◽  
Jade A. Ezzedine ◽  
Stéphan Jacquet
Keyword(s):  
Denaturing Gradient Gel Electrophoresis ◽  
Single Species ◽  
Abundance Distribution ◽  
Near Surface ◽  
Content Type ◽  
Perialpine Lakes ◽  
Gradient Gel Electrophoresis ◽  
Different Depths ◽  
Diversity Dynamics ◽  
Quantitative Importance

ABSTRACTMicrobes drive a variety of ecosystem processes and services, but many of them remain largely unexplored because of a lack of knowledge on both the diversity and functionality of some potentially crucial microbiological compartments. This is the case with and within the group of bacterial predators collectively known asBdellovibrioand like organisms (BALOs). Here, we report the abundance, distribution, and diversity of three families of these obligate predatory Gram-negative bacteria in three perialpine lakes (Lakes Annecy, Bourget, and Geneva). The study was conducted at different depths (near-surface versus 45 or 50 m) from August 2015 to January 2016. Using PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and cloning-sequencing approaches, we show that the diversity of BALOs is relatively low and very specific to freshwaters or even the lakes themselves. While thePeredibacteraceaefamily was represented mainly by a single species (Peredibacter starrii), it could represent up to 7% of the total bacterial cell abundances. Comparatively, the abundances of the two other families (BdellovibrionaceaeandBacteriovoracaceae) were significantly lower. In addition, the distributions in the water column were very different between the three groups, suggesting various life strategies/niches, as follows:Peredibacteraceaedominated near the surface, whileBdellovibrionaceaeandBacteriovoracaceaewere more abundant at greater depths. Statistical analyses revealed that BALOs seem mainly to be driven by depth and temperature. Finally, this original study was also the opportunity to design new quantitative PCR (qPCR) primers forPeredibacteraceaequantification.IMPORTANCEThis study highlights the abundance, distribution, and diversity of a poorly known microbial compartment in natural aquatic ecosystems, theBdellovibrioand like organisms (BALOs). These obligate bacterial predators of other bacteria may have an important functional role. This study shows the relative quantitative importance of the three main families of this group, with the design of a new primer pair, and their diversity. While both the diversity and the abundances of these BALOs were globally low, it is noteworthy that the abundance of thePeredibacteraceaecould reach important values.

scholarly journals The antimicrobial potential of cannabidiol

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mark A. T. Blaskovich ◽  
Angela M. Kavanagh ◽  
Alysha G. Elliott ◽  
Bing Zhang ◽  
Soumya Ramu ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Modern Medicine ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
New Class ◽  
Clostridioides Difficile ◽  
Excellent Activity ◽  
Induce Resistance ◽  
First Time

AbstractAntimicrobial resistance threatens the viability of modern medicine, which is largely dependent on the successful prevention and treatment of bacterial infections. Unfortunately, there are few new therapeutics in the clinical pipeline, particularly for Gram-negative bacteria. We now present a detailed evaluation of the antimicrobial activity of cannabidiol, the main non-psychoactive component of cannabis. We confirm previous reports of Gram-positive activity and expand the breadth of pathogens tested, including highly resistant Staphylococcus aureus, Streptococcus pneumoniae, and Clostridioides difficile. Our results demonstrate that cannabidiol has excellent activity against biofilms, little propensity to induce resistance, and topical in vivo efficacy. Multiple mode-of-action studies point to membrane disruption as cannabidiol’s primary mechanism. More importantly, we now report for the first time that cannabidiol can selectively kill a subset of Gram-negative bacteria that includes the ‘urgent threat’ pathogen Neisseria gonorrhoeae. Structure-activity relationship studies demonstrate the potential to advance cannabidiol analogs as a much-needed new class of antibiotics.

Ultrastructural studies of Chlamydia psittaci 6BC variant strains. I. Ultrastructure of the surface layers of egg-passaged 6BC strain

1973 ◽  
Vol 19 (8) ◽  
pp. 887-894
Author(s):  
Linda Poffenroth ◽  
J. W. Costerton ◽  
Nonna Kordová ◽  
John C. Wilt
Keyword(s):  
Chick Embryo ◽  
Microscopic Examination ◽  
Electron Microscopic Examination ◽  
Chlamydia Psittaci ◽  
Gram Negative Bacteria ◽  
Surface Layers ◽  
Electron Microscopic ◽  
Gram Negative ◽  
Ultrastructural Studies ◽  
First Time

Electron microscopic examination of a semipurified Chlamydia psittaci 6BC strain attenuated in chick embryo yolk sac revealed for the first time two morphologically distinct small elementary bodies which differ both in the ultrastructure of their surface layers and in their buoyant densities in sucrose gradients. Also, the morphology of the surface layers of the larger reticulate forms in cell-free systems is described for the first time. Many points of difference between the surface envelopes and internal structure of chlamydial particles and those of Gram-negative bacteria are discussed.

scholarly journals Shadowing the Actions of a Predator: Backlit Fluorescent Microscopy Reveals Synchronous Nonbinary Septation of Predatory Bdellovibrio inside Prey and Exit through Discrete Bdelloplast Pores

2010 ◽  
Vol 192 (24) ◽  
pp. 6329-6335 ◽  
Author(s):  
A. K. Fenton ◽  
M. Kanna ◽  
R. D. Woods ◽  
S.-I. Aizawa ◽  
R. E. Sockett
Keyword(s):  
Cell Division ◽  
Outer Membrane ◽  
Fluorescent Microscopy ◽  
Gram Negative Bacteria ◽  
Bacterial Cell Division ◽  
Prey Cell ◽  
Gram Negative ◽  
A Genome ◽  
Predatory Bacteria ◽  
First Time

ABSTRACT The Bdellovibrio are miniature “living antibiotic” predatory bacteria which invade, reseal, and digest other larger Gram-negative bacteria, including pathogens. Nutrients for the replication of Bdellovibrio bacteria come entirely from the digestion of the single invaded bacterium, now called a bdelloplast, which is bound by the original prey outer membrane. Bdellovibrio bacteria are efficient digesters of prey cells, yielding on average 4 to 6 progeny from digestion of a single prey cell of a genome size similar to that of the Bdellovibrio cell itself. The developmental intrabacterial cycle of Bdellovibrio is largely unknown and has never been visualized “live.” Using the latest motorized xy stage with a very defined z-axis control and engineered periplasmically fluorescent prey allows, for the first time, accurate return and visualization without prey bleaching of developing Bdellovibrio cells using solely the inner resources of a prey cell over several hours. We show that Bdellovibrio bacteria do not follow the familiar pattern of bacterial cell division by binary fission. Instead, they septate synchronously to produce both odd and even numbers of progeny, even when two separate Bdellovibrio cells have invaded and develop within a single prey bacterium, producing two different amounts of progeny. Evolution of this novel septation pattern, allowing odd progeny yields, allows optimal use of the finite prey cell resources to produce maximal replicated, predatory bacteria. When replication is complete, Bdellovibrio cells exit the exhausted prey and are seen leaving via discrete pores rather than by breakdown of the entire outer membrane of the prey.

Fusobacterium nucleatum, the first Gram-negative bacterium demonstrated to produce polyglutamate

2009 ◽  
Vol 55 (5) ◽  
pp. 627-632 ◽  
Author(s):  
Thomas Candela ◽  
Marie Moya ◽  
Michel Haustant ◽  
Agnès Fouet
Keyword(s):  
In Silico Analysis ◽  
Fusobacterium Nucleatum ◽  
Gram Negative Bacteria ◽  
Negative Bacterium ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
The Third ◽  
Gram Negative Organisms ◽  
First Time

Poly-γ-glutamate has been described in many Gram-positive organisms. When anchored to the surface, it is a capsule and as such a virulence factor. Based on sequence similarities, few Gram-negative organisms have been suggested to synthesize poly-γ-glutamate. For the first time, a Gram-negative bacterium, Fusobacterium nucleatum , is shown to produce and secrete poly-γ-glutamate. Putative poly-γ-glutamate-synthesizing genes from Gram-negative organisms have been compared with their Gram-positive homologs by in silico analysis, i.e., gene sequence and phylogenetic analysis. Clusters of three instead of four genes were highlighted by our screen. The products of the first two genes display similarity with their Gram-positive equivalents, yet the sequences from the Gram-negative organisms can be distinguished from those of the Gram-positives. Interestingly, the sequence of the predicted product of the third gene is conserved among Gram-negative bacteria but displays no similarity to that of either the third or fourth gene of the Gram-positive operons. It is suggested that, like for Gram-positive bacteria, poly-γ-glutamate has a role in virulence for pathogens and one in survival for other Gram-negative bacteria.

scholarly journals Antiadherent and Antibiofilm Activity ofHumulus lupulusL. Derived Products: New Pharmacological Properties

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Marcin Rozalski ◽  
Bartlomiej Micota ◽  
Beata Sadowska ◽  
Anna Stochmal ◽  
Dariusz Jedrejek ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Culture Medium ◽  
Antimicrobial Properties ◽  
Antibiofilm Activity ◽  
Pharmacological Properties ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Abiotic Surfaces ◽  
First Time ◽  
Plant Compounds

New antimicrobial properties of products derived fromHumulus lupulusL. such as antiadherent and antibiofilm activities were evaluated. The growth of gram-positive but not gram-negative bacteria was inhibited to different extents by these compounds. An extract of hop cones containing 51% xanthohumol was slightly less active againstS. aureusstrains (MIC range 31.2–125.0 μg/mL) than pure xanthohumol (MIC range 15.6–62.5 μg/mL). The spent hop extract, free of xanthohumol, exhibited lower but still relevant activity (MIC range 1-2 mg/mL). There were positive coactions of hop cone, spent hop extracts, and xanthohumol with oxacillin against MSSA and with linezolid against MSSA and MRSA. Plant compounds in the culture medium at sub-MIC concentrations decreased the adhesion ofStaphylococcito abiotic surfaces, which in turn caused inhibition of biofilm formation. The rate of mature biofilm eradication by these products was significant. The spent hop extract at MIC reduced biofilm viability by 42.8%, the hop cone extract by 74.8%, and pure xanthohumol by 86.5%. When the hop cone extract or xanthohumol concentration was increased, almost complete biofilm eradication was achieved (97–99%). This study reveals the potent antibiofilm activity of hop-derived compounds for the first time.

Evaluating H2O2 in Living Bacteria by Ratiometric Fluorescent Probe

2022 ◽  
Vol 905 ◽  
pp. 210-217
Author(s):  
Qian Qian Chen
Keyword(s):  
Fluorescent Probe ◽  
Living Cells ◽  
Gram Negative Bacteria ◽  
Signal Molecule ◽  
Gram Negative ◽  
Key Factor ◽  
Live Bacteria ◽  
First Time ◽  
Living Bacteria ◽  
Ratiometric Fluorescent Probe

Hydrogen peroxide (H2O2) is a significant signal molecule in physiological and pathological processes. Levels of H2O2 in bacteria are proved to be a key factor in immune response. To sum up, detection of H2O2 levels in living bacteria is remarkable for further study of its physiological and pathological effects. Herein, we propose a novel ratiometric fluorescent probe (Nahp) to detect H2O2 in living cells and bacteria. In addition, based on boronate, Nahp has satisfactory selectivity and sensitivity toward H2O2 (LOD = 0.158 μM). Furthermore, with excellent detection performance to H2O2, Nahp is successfully used for fluorescent bioimaging of H2O2 and measuring H2O2 accumulation in bacteria. Most importantly, the probe was also used to image H2O2 in three Gram-negative bacteria, clearly revealing for the first time significant differences in H2O2 expression levels in live bacteria.

Composition and Antimicrobial Activity of the Essential Oil of a Wild Kiwi

2011 ◽  
Vol 322 ◽  
pp. 160-163
Author(s):  
Yin Lu ◽  
Hong Chen
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Antimicrobial Activity ◽  
Fungal Species ◽  
Gram Negative Bacteria ◽  
Significant Activity ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Leaf Oil ◽  
First Time

A medicinal wild kiwi in China, Actinidia valvata Dunn, has been well known for its activities against leprosy and cancers. The compositions and the antimicrobial activity of its leaf oil were reported for the first time. The oil obtained by hydrodistillation and analyzed by GC and GC-MS, was characterized by the high content of monoterpenes. Linalool (48.14%) is the major component identified, followed by 1,2-dimethyl-lindoline (7.94%), linolenic acid methylester (6.57%) and (E)-phytol (5.29%). The antimicrobial activity of the oil was evaluated against four bacterial and three fungal species. The results showed that it exhibited a mild antibacterial activity against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), a significant activity against Gram-negative bacteria (Escherichia coli), and no activity on Pseudomonas aeruginosa. The test fungi were more sensitive to the oil, with a MIC range of 0.78~1.56 μL/mL than bacteria in the range which were significantly higher from 0.78 to 25.50 μL/mL.

scholarly journals The ω Subunit Governs RNA Polymerase Stability and Transcriptional Specificity in Staphylococcus aureus

2016 ◽  
Vol 199 (2) ◽  
Author(s):  
Andy Weiss ◽  
Brittney D. Moore ◽  
Miguel H. J. Tremblay ◽  
Dale Chaput ◽  
Astrid Kremer ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Rna Polymerase ◽  
Gram Negative Bacteria ◽  
Sequencing Analysis ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Successful Infection ◽  
Transcriptional Changes ◽  
First Time

ABSTRACT Staphylococcus aureus is a major human pathogen that causes infection in a wide variety of sites within the human body. Its ability to adapt to the human host and to produce a successful infection requires precise orchestration of gene expression. While DNA-dependent RNA polymerase (RNAP) is generally well characterized, the roles of several small accessory subunits within the complex have yet to be fully explored. This is particularly true for the omega (ω or RpoZ) subunit, which has been extensively studied in Gram-negative bacteria but largely neglected in Gram-positive counterparts. In Escherichia coli, it has been shown that ppGpp binding, and thus control of the stringent response, is facilitated by ω. Interestingly, key residues that facilitate ppGpp binding by ω are not conserved in S. aureus, and consequently, survival under starvation conditions is unaffected by rpoZ deletion. Further to this, ω-lacking strains of S. aureus display structural changes in the RNAP complex, which result from increased degradation and misfolding of the β′ subunit, alterations in δ and σ factor abundance, and a general dissociation of RNAP in the absence of ω. Through RNA sequencing analysis we detected a variety of transcriptional changes in the rpoZ-deficient strain, presumably as a response to the negative effects of ω depletion on the transcription machinery. These transcriptional changes translated to an impaired ability of the rpoZ mutant to resist stress and to fully form a biofilm. Collectively, our data underline, for the first time, the importance of ω for RNAP stability, function, and cellular physiology in S. aureus. IMPORTANCE In order for bacteria to adjust to changing environments, such as within the host, the transcriptional process must be tightly controlled. Transcription is carried out by DNA-dependent RNA polymerase (RNAP). In addition to its major subunits (α2ββ′) a fifth, smaller subunit, ω, is present in all forms of life. Although this small subunit is well studied in eukaryotes and Gram-negative bacteria, only limited information is available for Gram-positive and pathogenic species. In this study, we investigated the structural and functional importance of ω, revealing key roles in subunit folding/stability, complex assembly, and maintenance of transcriptional integrity. Collectively, our data underline, for the first time, the importance of ω for RNAP function and cellular harmony in S. aureus.

scholarly journals Antimicrobial and Antioxidant Activities of Plants from Northeast of Mexico

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Ricardo Salazar-Aranda ◽  
Luis Alejandro Pérez-López ◽  
Joel López-Arroyo ◽  
Blanca Alicia Alanís-Garza ◽  
Noemí Waksman de Torres
Keyword(s):  
Antioxidant Activity ◽  
Inhibitory Concentration ◽  
Antioxidant Activities ◽  
Scientific Information ◽  
Gram Negative Bacteria ◽  
Bacterial Strains ◽  
Time Activity ◽  
Gram Negative ◽  
Cyperus Alternifolius ◽  
First Time

Traditional medicine has a key role in health care worldwide. Obtaining scientific information about the efficacy and safety of the plants from our region is one of the goals of our research group. In this report, 17 plants were selected and collected in different localities from northeast Mexico. The dried plants were separated into leaves, flowers, fruit, stems, roots and bark. Each part was extracted with methanol, and 39 crude extracts were prepared. The extracts were tested for their antimicrobial activity using three Gram-negative bacterial strains (Pseudomonas aeruginosa,Klebsiella pneumoniaeandAcinetobacter baumannii), three Gram-positive bacterial strains (Enterococcus faecalisand twoStaphylococcus aureusstrains), and seven clinically isolated yeasts (Candida albicans,C. krusei,C. tropicalis,C. parapsilosisandC. glabrata); their antioxidant activity was tested using a DPPH free radical assay. No activity against Gram-negative bacteria was observed with any extract up to the maximum concentration tested, 1000 μg ml−1. We report here for the first time activity ofCeanothus coeruleusagainstS. aureus(flowers, minimal inhibitory concentration (MIC) 125 μg ml−1),C. glabrata(MICs 31.25 μg ml−1) andC. parapsilosis(MICs between 31.25 and 125 μg ml−1);Chrysanctinia mexicanaagainstC. glabrata(MICs 31.25μg ml−1);Colubrina greggiiagainstE. faecalis(MICs 250 μg ml−1) andCordia boissieriagainstC. glabrata(MIC 125μg ml−1). Furthermore, this is the first report about antioxidant activity of extracts fromCeanothus coeruleus,Chrysanctinia mexicana,Colubrina greggiiandCyperus alternifolius. Some correlation could exist between antioxidant activity and antiyeast activity against yeasts in the speciesCeanothus coeruleus,Schinus molle,Colubrina greggiiandCordia boissieri.

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