Search results for "GRAM-NEGATIVE BACTERIA"
showing 10 items of 118 documents
Putative evolutionary origin of plasmids carrying the genes involved in leucine biosynthesis in Buchnera aphidicola (endosymbiont of aphids)
1997
An 8.5-kb plasmid encoding genes (leuABCD) involved in leucine biosynthesis and a small plasmid of 1.74 kb of yet unknown function were found in the intracellular symbiont, Buchnera aphidicola, of two divergent aphid species, Thelaxes suberi and Tetraneura caerulescens, respectively. The leuABCD-carrying plasmid (pBTs1) was amplified from total aphid DNA by inverse long PCR, using outwardly oriented oligonucleotide primers specific to leuA. The resulting 8.2-kb PCR fragment as well as the 1.74-kb plasmid (pBTc1) were cloned and sequenced. pBTs1 differed from a previously described B. aphidicola plasmid (pRPE) of the aphid Rhopalosiphum padi by the presence of a small heat shock gene (ibp) a…
Antibiotic susceptibility of cocultures in polymicrobial infections such as peri-implantitis or periodontitis: an in vitro model.
2011
Although polymicrobial infections, such as peri-implantitis or periodontitis, were postulated in the literature to be caused by synergistic effects of bacteria, these effects remain unclear looking at antibiotic susceptibility. The aim of this study is to compare the antibiotic susceptibilities of pure cultures and definite cocultures.Laboratory strains of Aggregatibacter actinomycetemcomitans (Aa) (previously Actinobacillus actinomycetemcomitans), Capnocytophaga ochracea (Co), and Parvimonas micra (Pm) (previously Peptostreptococcus micros) were cultivated under anaerobic conditions, and their susceptibilities to 10 antibiotics (benzylpenicillin G, ampicillin, amoxicillin, ampicillin/sulba…
Reliable fluorescence technique to detect the antibiotic colistin, a possible environmental threat due to its overuse.
2022
AbstractColistin, considered a drug of last resort as it is effective towards multidrug-resistant Gram-negative bacterial infections. Oral administration of colistin in the poultry industry is a common practice, not only to prevent and reduce bacterial infections, but also as a rapid-growth promoter. Long-term exposure to any antibiotic will eventually lead to the development of bacterial resistance towards all antibiotics through various mechanisms in the physiological system and environment. Chicken is the most consumed source of animal protein for humans throughout the world. In addition, the manure of poultry, containing traces of the used antibiotics, is being used in farming. Exposure…
Plasmid-mediated QnrS2 determinant from a clinical Aeromonas veronii isolate.
2008
The main objective of this study was to determine the prevalence of the Qnr determinants in clinical and environmental Aeromonas spp. A total of 52 Aeromonas sp. isolates identified by biochemical methods (5), 25 isolated from natural waters (1) and 27 isolated from clinical samples from hospitals in Valencia, Spain, were tested for quinolone resistance by the disk diffusion method (4) (nalidixic acid, 30 μg; oxolinic acid, 2 μg; flumequine, 30 μg; ciprofloxacin, 5 μg; and levofloxacin, 5 μg). Among the studied isolates, 27 showed resistance to nalidixic acid and susceptibility to ciprofloxacin, 24 isolates were susceptible to both nalidixic acid and ciprofloxacin, and only 1, the A. veroni…
Antibacterial and antioxidant activities in Sideritis italica (Miller) Greuter et Burdet essential oils
2006
Sideritis italica (Miller) Greuter et Burdet is a widespread Lamiacea in the Mediterranean region used in traditional medicine. Essential oils were antibacterial against nine ATCC and as many clinically isolated Gram-positive and Gram-negative bacterial strains. Antibacterial activity was also found against Helicobacter pylori: a dose-dependant inhibition was shown between 5 and 25 microg/ml. The antibacterial activity of the oils was expressed as MICs (minimum inhibitory concentrations) and MBCs (minimum bactericidal concentrations). At a concentration between 3.9 and 250 microg/ml the oils showed a significant antibacterial effect against both Gram-negative and Gram-positive bacteria. In …
Reply to Z Weizman.
2013
Discovery and molecular characterization of a plasmid localized in Buchnera sp. bacterial endosymbiont of the aphid Rhopalosiphum padi
1995
We have identified and completely sequenced a novel plasmid isolated from the aphid Rhopalosiphum padi. Evidence which suggests that the plasmid occurs localized within the bacterial endosymbionts is presented. The plasmid contains the four genes that constitute the entire leucine operon. This fact makes it really unique since most plasmids are dispensable and lack genes that encode essential anabolic functions. Four more phloem-feeding aphid species also seem to contain homologous plasmids. Although further work is necessary, we hypothesize that this plasmid has appeared during the evolution of the symbiotic association between the aphid and the bacterial endosymbiont. The fact that this p…
Complete Genome Sequence of Acidaminococcus intestini RYC-MR95, a Gram-Negative Bacterium from the Phylum Firmicutes
2011
ABSTRACT Acidaminococcus intestini belongs to the family Acidaminococcaceae , order Selenomonadales , class Negativicutes , phylum Firmicutes . Negativicutes show the double-membrane system of Gram-negative bacteria, although their chromosomal backbone is closely related to that of Gram-positive bacteria of the phylum Firmicutes . The complete genome of a clinical A. intestini strain is here presented.
Isolation and partial characterization of antagonistic peptides produced by Paenibacillus sp. strain B2 isolated from the sorghum mycorrhizosphere.
2005
ABSTRACT Paenibacillus sp. strain B2, isolated from the mycorrhizosphere of sorghum colonized by Glomus mosseae , produces an antagonistic factor. This factor has a broad spectrum of activity against gram-positive and gram-negative bacteria and also against fungi. The antagonistic factor was isolated from the bacterial culture medium and purified by cation-exchange, reverse-phase, and size exclusion chromatography. The purified factor could be separated into three active compounds following characterization by amino acid analysis and by combined reverse-phase chromatography and mass spectrometry (liquid chromatography-mass spectrometry and mass spectrometry-mass spectrometry). The first com…
Chemical composition and antibacterial activity of essential oil of Pulicaria odora L.
2004
The chemical composition of the volatile oil constituent from Pulicaria odora L. roots has been analyzed by GC/MS. Twenty-seven components were identified, being thymol (47.83%) and its derivative isobutyrate (30.05%) the main constituents in the oil. Furthermore, the oil was tested against seven bacteria at different concentrations. Results showed that the oil exhibited a significant antibacterial activity.