Validation of the AquaCHROM™ ECC for the Detection and Enumeration of Coliforms and Escherichia coli in Water Samples: AOAC Performance Tested MethodSM 072202.

Background: The AquaCHROM™ ECC method from CHROMagar is intended for the detection and enumeration of Escherichia coli and coliform bacteria in 100 mL water samples after 18-24 h of incubation at 35-37°C.

Objective: To validate the AquaCHROM ECC method for qualitative and quantitative detection of E. coli and coliforms with different water matrixes.

Bacterial flagellins: mediators of pathogenicity and host immune responses in mucosa.

Flagella contribute to the virulence of pathogenic bacteria through chemotaxis, adhesion to and invasion of host surfaces. Flagellin is the structural protein that forms the major portion of flagellar filaments. Thus, flagellin consists of a conserved domain that is widespread in bacterial species and is dedicated to filament polymerization.

Membrane topology and mutational analysis of Escherichia coli CydDC, an ABC-type cysteine exporter required for cytochrome assembly.

Cytochrome bd is a respiratory quinol oxidase in Escherichia coli. Besides the structural genes (cydA and cydB) encoding the oxidase complex, the cydD and cydC genes, encoding an ABC-type transporter, are required for assembly of this oxidase. Recently, cysteine has been identified as a substrate (allocrite) that is transported from the cytoplasm by CydDC, but the mechanism of cysteine export to the periplasm and its role there remain unknown.

A novel haem compound accumulated in Escherichia coli overexpressing the cydDC operon, encoding an ABC-type transporter required for cytochrome assembly.

cydDC genes encode a heterodimeric ABC transporter required for assembly of the membrane-bound cytochrome bd quinol oxidase and periplasmic cytochromes. Here, we demonstrate that overexpression of functional cydDC genes on a multicopy plasmid results in elevated levels of cytochromes b and d, but most notably formation in anaerobically grown cells of a novel haem-containing component P-574. The pigment has a distinctive absorbance at 574-579 nm and 448 nm in reduced minus oxidised spectra and renders over-producing cells reddish in colour.

Nitric oxide releases intracellular zinc from prokaryotic metallothionein in Escherichia coli.

Nitric oxide (NO) has a broad spectrum of signalling and regulatory functions and multiple molecular targets. Recently, the intrabacterial toxicity of NO and mechanisms for NO resistance have been intensively investigated. Here we report for the first time that NO elicits release of zinc from a bacterial protein.

NO sensing by FNR: regulation of the Escherichia coli NO-detoxifying flavohaemoglobin, Hmp.

Nitric oxide (NO) is a signalling and defence molecule of major importance in biology. The flavohaemoglobin Hmp of Escherichia coli is involved in protective responses to NO. Because hmp gene transcription is repressed by the O(2)-responsive regulator FNR, we investigated whether FNR also senses NO.