Swimming and rafting of E.coli microcolonies at air–liquid interfaces

The dynamics of swimming microorganisms is strongly affected by solid-liquid and air-liquid interfaces. In this paper, we characterize the motion of both single bacteria and microcolonies at an air-liquid interface. Both of them follow circular trajectories. Single bacteria preferentially show a counter-clockwise motion, in agreement with previous experimental and theoretical findings. Instead, no preferential rotation direction is observed for microcolonies suggesting that their motion is due to a different physical mechanism. We propose a simple mechanical model where the microcolonies move like rafts constrained to the air-liquid interface. Finally, we observed that the microcolony growth is due to the aggregation of colliding single-swimmers, suggesting that the microcolony formation resembles a condensation process where the first nucleus originates by the collision between two single-swimmers. Implications of microcolony splitting and aggregation on biofilm growth and dispersion at air-liquid interface are discussed

Gut microbiota related to Giardia duodenalis, Entamoeba spp. and Blastocystis hominis infections in humans from Côte d'Ivoire.

INTRODUCTION: Literature data provide little information about protozoa infections and gut microbiota compositional shifts in humans. This preliminary study aimed to describe the fecal bacterial community composition of people from Côte d'Ivoire harboring Giardia duodenalis, Entamoeba spp., and Blastocystis hominis, in trying to discover possible alterations in their fecal microbiota structure related to the presence of such parasites. METHODOLOGY: Twenty fecal samples were collected from people inhabiting three different localities of Côte d'Ivoire for copromicroscopic analysis and molecular identification of G. duodenalis, Entamoeba spp., and B. hominis. Temporal temperature gradient gel electrophoresis (TTGE) was used to obtain a fingerprint of the overall bacterial community; quantitative polymerase chain reaction (qPCR) was used to define the relative abundances of selected bacterial species/group, and multivariate statistical analyses were employed to correlate all data. RESULTS: Cluster analysis revealed a significant separation of TTGE profiles into four clusters (p < 0.0001), with a marked difference for G. duodenalis-positive samples in relation to the others (p = 5.4×10-6). Interestingly, qPCR data showed how G. duodenalis-positive samples were related to a dysbiotic condition that favors potentially harmful species (such as Escherichia coli), while Entamoeba spp./B. hominis-positive subjects were linked to a eubiotic condition, as shown by a significantly higher Faecalibacterium prausnitzii-Escherichia coli ratio. CONCLUSIONS: This preliminary investigation demonstrates a differential fecal microbiota structure in subjects infected with G. duodenalis or Entamoeba spp./B. hominis, paving the way for using further next-generation DNA technologies to better understand host-parasite-bacteria interactions, aimed at identifying potential indicators of microbiota changes

Gut microbiota related to Giardia duodenalis, Entamoeba spp. and Blastocystis hominis infections in humans from Côte d'Ivoire

Introduction: Literature data provide little information about protozoa infections and gut microbiota compositional shifts in humans. This preliminary study aimed to describe the fecal bacterial community composition of people from Côte d’Ivoire harboring Giardia duodenalis, Entamoeba spp., and Blastocystis hominis, in trying to discover possible alterations in their fecal microbiota structure related to the presence of such parasites. Methodology: Twenty fecal samples were collected from people inhabiting three different localities of Côte d’Ivoire for copromicroscopic analysis and molecular identification of G. duodenalis, Entamoeba spp., and B. hominis. Temporal temperature gradient gel electrophoresis (TTGE) was used to obtain a fingerprint of the overall bacterial community; quantitative polymerase chain reaction (qPCR) was used to define the relative abundances of selected bacterial species/group, and multivariate statistical analyses were employed to correlate all data. Results: Cluster analysis revealed a significant separation of TTGE profiles into four clusters (p < 0.0001), with a marked difference for G. duodenalis-positive samples in relation to the others (p = 5.4×10-6 ). Interestingly, qPCR data showed how G. duodenalis-positive samples were related to a dysbiotic condition that favors potentially harmful species (such as Escherichia coli), while Entamoeba spp./B. hominis-positive subjects were linked to a eubiotic condition, as shown by a significantly higher Faecalibacterium prausnitzii-Escherichia coli ratio. Conclusions: This preliminary investigation demonstrates a differential fecal microbiota structure in subjects infected with G. duodenalis or Entamoeba spp./B. hominis, paving the way for using further next-generation DNA technologies to better understand host-parasite-bacteria interactions, aimed at identifying potential indicators of microbiota changes

A bacterial ratchet motor

Self-propelling bacteria are a dream of nano-technology. These unicellular organisms are not just capable of living and reproducing, but they can swim very efficiently, sense the environment and look for food, all packaged in a body measuring a few microns. Before such perfect machines could be artificially assembled, researchers are beginning to explore new ways to harness bacteria as propelling units for micro-devices. Proposed strategies require the careful task of aligning and binding bacterial cells on synthetic surfaces in order to have them work cooperatively. Here we show that asymmetric micro-gears can spontaneously rotate when immersed in an active bacterial bath. The propulsion mechanism is provided by the self assembly of motile Escherichia coli cells along the saw-toothed boundaries of a nano-fabricated rotor. Our results highlight the technological implications of active matter's ability to overcome the restrictions imposed by the second law of thermodynamics on equilibrium passive fluids.Comment: 4 pages, 3 figure

Structural variations of vaginal and endometrial microbiota. Hints on female infertility

Microbiota are microorganismal communities colonizing human tissues exposed to the external environment, including the urogenital tract. The bacterial composition of the vaginal microbiota has been established and is partially related to obstetric outcome, while the uterine microbiota, considered to be a sterile environment for years, is now the focus of more extensive studies and debates. The characterization of the microbiota contained in the reproductive tract (RT) of asymptomatic and infertile women, could define a specific RT microbiota associated with implantation failure. In this pilot study, 34 women undergoing personalized hormonal stimulation were recruited and the biological samples of each patient, vaginal fluid, and endometrial biopsy, were collected immediately prior to oocyte-pick up, and sequenced. Women were subsequently divided into groups according to fertilization outcome. Analysis of the 16s rRNA V4-V5 region revealed a significant difference between vaginal and endometrial microbiota. The vaginal microbiota of pregnant women corroborated previous data, exhibiting a lactobacilli-dominant habitat compared to non-pregnant cases, while the endometrial bacterial colonization was characterized by a polymicrobial ecosystem in which lactobacilli were exclusively detected in the group that displayed unsuccessful in vitro fertilization. Overall, these preliminary results revisit our knowledge of the genitourinary microbiota, and highlight a putative relationship between vaginal/endometrial microbiota and reproductive success

Serum albumin and osmolality inhibit Bdellovibrio bacteriovorus predation in human serum

We evaluated the bactericidal activity of Bdellovibrio bacteriovorus, strain HD100, within blood sera against bacterial strains commonly associated with bacteremic infections, including E. coli, Klebsiella pneumoniae and Salmonella enterica. Tests show that B. bacteriovorus HD100 is not susceptible to serum complement or its bactericidal activity. After a two hour exposure to human sera, the prey populations decreased 15- to 7,300-fold due to the serum complement activity while, in contrast, the B. bacteriovorus HD100 population showed a loss of only 33%. Dot blot analyses showed that this is not due to the absence of antibodies against this predator. Predation in human serum was inhibited, though, by both the osmolality and serum albumin. The activity of B. bacteriovorus HD100 showed a sharp transition between 200 and 250 mOsm/kg, and was progressively reduced as the osmolality increased. Serum albumin also acted to inhibit predation by binding to and coating the predatory cells. This was confirmed via dot blot analyses and confocal microscopy. The results from both the osmolality and serum albumin tests were incorporated into a numerical model describing bacterial predation of pathogens. In conclusion, both of these factors inhibit predation and, as such, they limit its effectiveness against pathogenic prey located within sera

Investigating the Responses of Human Epithelial Cells to Predatory Bacteria

One beguiling alternative to antibiotics for treating multi-drug resistant infections are Bdellovibrio-and-like-organisms (BALOs), predatory bacteria known to attack human pathogens. Consequently, in this study, the responses from four cell lines (three human and one mouse) were characterized during an exposure to different predatory bacteria, Bdellovibrio bacteriovorus HD100, Bacteriovorus BY1 and Bacteriovorax stolpii EB1. TNF-alpha levels were induced in Raw 264.7 mouse macrophage cultures with each predator, but paled in comparison to those obtained with E. coli. This was true even though the latter strain was added at an 11.1-fold lower concentration (p &lt; 0.01). Likewise, E. coli led to a significant (54%) loss in the Raw 264.7 murine macrophage viability while the predatory strains had no impact. Tests with various epithelial cells, including NuLi-1 airway, Caco2, HT29 and T84 colorectal cells, gave similar results, with E. coli inducing IL-8 production. The viabilities of the NuLi-1 and Caco-2 cells were slightly reduced (8%) when exposed to the predators, while T84 viability remained steady. In no cases did the predatory bacteria induce actin rearrangement. These results clearly demonstrate the gentle natures of predatory bacteria and their impacts on human cells.ope

Gut microbiota related to Giardia duodenalis, Entamoeba spp. and Blastocystis hominis infections in humans from Côte d'Ivoire

Introduction: Literature data provide little information about protozoa infections and gut microbiota compositional shifts in humans. This preliminary study aimed to describe the fecal bacterial community composition of people from Côte d’Ivoire harboring Giardia duodenalis, Entamoeba spp., and Blastocystis hominis, in trying to discover possible alterations in their fecal microbiota structure related to the presence of such parasites. Methodology: Twenty fecal samples were collected from people inhabiting three different localities of Côte d’Ivoire for copromicroscopic analysis and molecular identification of G. duodenalis, Entamoeba spp., and B. hominis. Temporal temperature gradient gel electrophoresis (TTGE) was used to obtain a fingerprint of the overall bacterial community; quantitative polymerase chain reaction (qPCR) was used to define the relative abundances of selected bacterial species/group, and multivariate statistical analyses were employed to correlate all data. Results: Cluster analysis revealed a significant separation of TTGE profiles into four clusters (p < 0.0001), with a marked difference for G. duodenalis-positive samples in relation to the others (p = 5.4×10-6 ). Interestingly, qPCR data showed how G. duodenalis-positive samples were related to a dysbiotic condition that favors potentially harmful species (such as Escherichia coli), while Entamoeba spp./B. hominis-positive subjects were linked to a eubiotic condition, as shown by a significantly higher Faecalibacterium prausnitzii-Escherichia coli ratio. Conclusions: This preliminary investigation demonstrates a differential fecal microbiota structure in subjects infected with G. duodenalis or Entamoeba spp./B. hominis, paving the way for using further next-generation DNA technologies to better understand host-parasite-bacteria interactions, aimed at identifying potential indicators of microbiota changes