Role of the outer membrane in the accumulation of quinolones bySerratia marcescens

Abstract

Accumulation of four quinolones by Serratia marcescens was measured fluorometrically. The passage of quinolones through the outer membrane was studied in both lipopolysaccharide-deficient and porin-deficient mutants. The lipopolysaccharide (LPS) layer formed a partially effective barrier for highly hydrophobic quinolones such as nalidixic acid. Quinolones with a low relative hydrophobicity coefficient seemed to pass preferentially through the water-filled Omp3 porin channels. Results were confirmed when Omp3 was cloned in a porin-defective Escherichia coli.

Prodigiosin and its potential applications

“…(Mekhael and Samira 2009). The antibacterial activity of prodigiosin (PG) was the result of the ability of prodigiosin to pass through the outer membrane and inhibiting target enzymes such as DNA gyrase and topoisomerase IV, which inhibited the cell growth (Berlanga et al 2000).…”

Bacterial polyhydroxyalkanoates-eco-friendly next generation plastic: Production, biocompatibility, biodegradation, physical properties and applications

“…Diversity among PHA-producing bacteria PHA producers have been reported to reside at various ecological niches which are naturally or accidently exposed to high organic matter or growth-limited conditions such as dairy wastes, hydrocarbon-contaminated sites, pulp and paper mill wastes, agricultural wastes, activated sludges of treatment plants, rhizosphere and industrial effluents (86). A wide range of taxonomically and physiologically different natural bacteria and some archae accumulate PHAs as storage reserve materials and deposit them as insoluble granules in the cytoplasm (10,11,69,70,83,84).…”

“…A wide range of taxonomically and physiologically different natural bacteria and some archae accumulate PHAs as storage reserve materials and deposit them as insoluble granules in the cytoplasm (10,11,69,70,83,84). After the discovery of PHB from the bacterium B. megaterium (18), over 300 different bacteria, including Gram-negative and -positive species, have been reported to accumulate various PHAs (11,28,83,86,87). To date, most PHA-producing bacteria were found to be Gram-negative.…”

“…PHAs are a class of polyesters of various hydroxycarboxylic acids, which are produced and accumulated by a large number of bacteria under unbalanced growth conditions as intracellular hydrophobic inclusions of carbon and energy storage compounds in the cytoplasm to levels as high as 90-97% of the cell dry weight (4)(5)(6)(7)(8)(9) or as an electron sink mechanism for redundant reducing power under the condition of limiting nutritional elements such as N, P, S, O or Mg in the presence of excess carbon source (10)(11)(12)(13). They are synthesized as byproducts not the major ones when there is no sufficient nutrient to promote their growth and do not play an essential role in development of the producing organisms, but convey survival in the biological community and environment, therefore, microbial PHAs are secondary metabolites (14).…”

Involvement of a Novel Efflux System in Biofilm-Specific Resistance to Antibiotics

“…Because the gene products encoded by the PA1874-1877 operon are predicted to function as a transporter, we wanted to determine whether the loss of the PA1874-1877 operon had an effect on the ability of the mutant to pump tobramycin out of the cells of the biofilm. Because the PA1874-1877 operon deletion showed no impairment in planktonic resistance, we devised a biofilm-specific accumulation bioassay that was adapted from other efflux/ accumulation assays used for planktonic cells (4,30). Biofilms of the wild type and PA1874-1877 knockout mutant were formed over 24 h and then exposed to tobramycin for 8 h. After exposure to tobramycin, the wells containing the biofilms were rinsed with phosphate-buffered saline to remove the external tobramycin, and the medium was replaced with a glycine lysis buffer.…”