A case of acute bacterial cystitis caused by carbon dioxide-dependent Escherichia coli with a deletion mutation in the can.

A small-colony variant (SCV) of carbon dioxide-dependent Escherichia coli was isolated from a patient with acute bacterial cystitis. After the urine sample was inoculated on 5% sheep blood agar and incubated overnight at 35 °C in ambient air, no colony formation was observed. However, after overnight incubation at 35 °C in 5% CO2-enhanced ambient air, numerous colonies were obtained. We failed to characterize or identify the SCV isolate using the MicroScan WalkAway-40 System because the isolate did not grow in the system. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 16S rRNA sequencing were useful for identifying this SCV isolate. Genome sequencing analysis of the isolates revealed the presence of an 11-bp deletion mutation leading to premature translational truncation in the carbonic anhydrase gene, can, and the presence of 10 known antimicrobial resistance genes. The results of the antimicrobial susceptibility tests performed under CO2-enhanced ambient air were consistent with the presence of antimicrobial resistance genes. Our results also showed that Can is important to grow E. coli in ambient air, and that antimicrobial susceptibility testing of carbon dioxide-dependent SCVs should be performed in 5% CO2-enhanced ambient air. A revertant strain was obtained by passaging the SCV isolate, but the deletion mutation in can remained. To the best of our knowledge, this is the first case in Japan of acute bacterial cystitis caused by carbon dioxide-dependent E. coli with a deletion mutation in can.

Phytoremediation of shallow organically enriched marine sediments using benthic microalgae.

We examined whether replantation of benthic microalgae (BMA) can remediate shallow organically enriched sediment. Nitzschia sp., the dominant species in the tested area (Hiroshima Bay, Japan), was isolated and mass cultured, then replanted in the same area. Changes in the condition of the sediment were monitored for five months. During the study period, we observed an increase in redox potential (ORP) and a decrease in acid-volatile sulfide (AVS) in the experimental area, indicating that the sediment condition changed from reduced to oxic. Organic matter in the sediment, represented by chemical oxygen demand (COD), ignition loss (IL) and organic nitrogen (ON) decreased significantly, while inorganic nutrients (ammonia and phosphate) increased in the interstitial water. These changes imply that oxygen produced by the replanted BMA may have enhanced aerobic bacterial activity, accelerating the decomposition of organic matter. Thus, replantation of BMA shows potential as a novel and promising "phytoremediation" method for organically enriched sediment.