Search results for "gram-negative bacteria"

Effects of dietary administration of fenugreek seeds, alone or in combination with probiotics, on growth performance parameters, humoral immune respo…

2016

The use of immunostimulants is considered a promising preventive practice that may help to maintain animal welfare and a healthy environment, while increasing production and providing higher profits. The purpose of this study was to evaluate the effects on gilthead seabream (Sparus aurata L.) of the dietary administration of fenugreek (Trigonella foenum graecum) seeds, alone or combined with one of the following probiotic strains: Bacillus licheniformis (TSB27), Lactobacillus plantarum or Bacillus subtilis (B46). Gilthead seabream were fed a control or one of the supplemented diets for 3 weeks. The effects of these supplemented diets on growth performance parameters and the humoral immune r…

In vitro cytokine profile revealed differences from dorsal and ventral skin susceptibility to pathogen-probiotic interaction in gilthead seabream

2016

Skin is the first barrier of defense on fish, which is crucial to protection against different stressors, including pathogens. Skin samples obtained from dorsal and ventral part of Sparus aurata specimens were incubated with Photobacterium damselae subsp. piscicida (a pathogen for this fish species), with Shewanella putrefaciens Pdp11 (a probiotic bacteria isolated from healthy gilthead seabream skin) or with both bacteria. The gene expression profile of nine cytokines (il1b, tnfa, il6, il7, il8, il15, il18, il10 and tgfb) was studied by qPCR in all the skin samples. The present findings revealed different patterns of cytokine profile in dorsal and ventral skin of gilthead seabream, which c…

Antimicrobial and Insecticidal: Cyclic Lipopeptides and Hydrogen Cyanide Produced by Plant-Beneficial Pseudomonas Strains CHA0, CMR12a, and PCL1391 C…

2017

Particular groups of plant-beneficial fluorescent pseudomonads are not only root colonizers that provide plant disease suppression, but in addition are able to infect and kill insect larvae. The mechanisms by which the bacteria manage to infest this alternative host, to overcome its immune system, and to ultimately kill the insect are still largely unknown. However, the investigation of the few virulence factors discovered so far, points to a highly multifactorial nature of insecticidal activity. Antimicrobial compounds produced by fluorescent pseudomonads are effective weapons against a vast diversity of organisms such as fungi, oomycetes, nematodes, and protozoa. Here, we investigated whe…

Amplified fragment length polymorphism (AFLP) and biochemical typing of Photobacterium damselae subsp. damselae.

2002

Aims: The aim of the present study was to characterize subspecifically Photobacterium damselae subsp. damselae strains isolated from cultured Sparus aurata and Dicentrarchus labrax by means of phenotypic and molecular typing techniques (amplified fragment length polymorphism, AFLP). Methods and Results: Seventy-one strains of P. damselae subsp. damselae were isolated from 38 cultured fishes at different fish farms located on the Mediterranean coast near Valencia, Spain. Most fish studied were asymptomatic and some were recovered during infectious outbreaks. Phenotypic characterization revealed a considerable degree of variability within the subspecies, including some characters, such as pro…

New Vocabulary for Bacterial Communication

2019

Abstract Quorum sensing (QS) is widely accepted as a procedure that bacteria use to converse. However, prevailing thinking places acyl homoserine lactones (AHLs) at the forefront of this communication pathway in Gram‐negative bacteria. With the advent of high‐throughput genomics and the subsequent influx of bacterial genomes, bioinformatics analysis has determined that the genes encoding AHL biosynthesis, originally discovered to be indispensable for QS (LuxI‐like proteins and homologues), are often absent in QS‐capable bacteria. Instead, the sensing protein (LuxR‐like proteins) is present with an apparent inability to produce any outgoing AHL signal. Recently, several signals for these Lux…

Response of soil bacteria to Hg (II) in relation to soil characteristics and cell location

2006

The response of indigenous bacterial communities to the addition of inorganic mercury (50 μM of Hg(II)) was compared over a 30 day period in four soils of contrasting properties. Hg(II) impact was estimated by following population dynamics of viable heterotrophic bacteria (VH) and mercury resistant bacteria (HgR) by indirect enumeration in unfractionated soil and in the inner and outer parts of soil aggregates obtained by successive washings. Numbers of VH bacteria in unfractionated soils were not affected by mercury in any of the studied soils, whereas an increase in resistant bacteria was observed in all of them. The lag phase before the increase of HgR bacteria and the magnitude of the e…

Phospholipid distribution in the cytoplasmic membrane of Gram-negative bacteria is highly asymmetric, dynamic, and cell shape-dependent

2020

The cell shape of Gram-negative bacteria is maintained metabolically by asymmetric lipid distribution in biogenic plasma membrane.

2015

Bacterial infections remain a serious health concern, in particular causing life-threatening infections of hospitalized and immunocompromised patients. The situation is exacerbated by the rise in antibacterial drug resistance, and new treatments are urgently sought. In this endeavour, accurate structures of molecular targets can support early-stage drug discovery. Here, crystal structures, in three distinct forms, of recombinantPseudomonas aeruginosaβ-ketoacyl-(acyl-carrier-protein) synthase II (FabF) are presented. This enzyme, which is involved in fatty-acid biosynthesis, has been validated by genetic and chemical means as an antibiotic target in Gram-positive bacteria and represents a po…

Evidence for Direct Binding of the First Component of Complement, C1, to Outer Membrane Proteins from Salmonella minnesota

1985

The outer membrane of gram-negative bacteria consists of a tight lattice of lipopolysaccharides (LPS), phospholipids, and proteins. It has been shown in E. coli and S. typhimurium that LPS molecules are exclusively localized in the outer layer of the outer membrane (Muhlradt and Golecki 1975; Smit et al. 1975; Funatura and Nikaido 1980). Localization of proteins in the outer membrane is also indicated by the fact that various major outer membrane proteins in association with LPS, serve as receptors for phages (Datta et al. 1977; Mu-TOH et al. 1978; Henning and Jann 1979; Yu and Mizushima 1982) and colicins (Kadner et al. 1979; Konisky 1979).

The role of Components of the Outer Membrane of Gram-Negative Bacteria in the Serum-Bactericidal Effect

1982

Abstract Effective killing-capacity of normal human and guinea pig sera depended on Ca ++ , C1q, C2 and C4. Fixation- and transfer-tests revealed that C1 and C1q were bound more tightly to the serum-sensitive R-forms of Salmonella strains than to the serum-resistant S-forms. Since all experiments were done in the absence of antibodies these findings provide evidence that the antibody-independent C1-binding is one of the initial reactions of the serum-mediated killing. This reaction seems to be influenced by the sugar-portion of the lipopolysaccharide (LPs) of the outer membrane: C1-binding to the bacteria occurs with higher affinity the shorter the LPS-molecule. This indicates that other ou…