Performance evaluation of a new matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, ASTA MicroIDSys system, in bacterial identification against clinical isolates of anaerobic bacteria.

INTRODUCTION: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been introduced for bacterial identification. The ASTA MicroIDSys system (ASTA, Suwon, Korea) is a new MALDI-TOF MS system developed for species identification of microorganisms. We evaluated the performance of MicroIDSys against clinical isolates of anaerobic bacteria. MATERIAL AND METHODS: A total of 370 non-duplicated clinical isolates of anaerobic bacteria were tested in this study. Bacterial identification with MicroIDSys was performed with a direct smear method, and measured spectra were analyzed using respective software. The results of MicroIDSys were compared with the results of Bruker Biotyper and 16S rRNA sequencing. RESULTS: The overall agreement rates for the 370 clinical isolates (34 genera and 99 species) were 95.4% (353/370) at the genus level and 91.6% (n = 340) at the species level. Only 17 isolates were incorrectly identified at the genus level: five misidentifications and 12 unidentifications. The MicroIDSys system exhibited excellent performance in the identification of clinically relevant bacterial species. Most of the Bacteroides isolates (98.0%, 99/101) and all of the Clostridium difficile (100%, n = 11), Clostridium perfringens (100%, n = 10), Finegoldia magna (100%, n = 11), and Parvimonas micra (100%, n = 10) isolates were correctly identified at the species level. CONCLUSION: The MicroIDSys system proved useful in the identification of anaerobic bacteria, especially clinically relevant species. This system could be of use in clinical microbiology laboratories as a primary tool for identifying anaerobic bacteria.

Pyrolytic remediation of crude oil-contaminated soil.

Deterioration of our terrestrial environment due to decreasing soil quality brought on by crude oil spills and leakages is a major issue. In this study, soil samples were prepared by mixing clay (bentonite) and sand contaminated with 5 and 10 wt% crude oil (in order to study the effect of oil concentration), and weathered in a laboratory to simulate actual contaminated soil. Volatilization of light oil was inhibited in clay rich-soil, resulting in higher contamination after weathering. The efficiency of the pyrolytic treatment was evaluated by comparing the weight change and n-hexane extractable material (HEM) content of the soil samples. The working temperature influenced pyrolysis efficiency more than the reaction time. A residual amount of 0.29-0.61 wt% (below the soil pollution standard) was observed in the samples with high clay content and pollution level (by pyrolysis for 30 min at 400 °C). Infrared analysis of treated soil samples showed a reduction in alkyl functionality (CH), confirming a decrease in hydrophobicity and an improvement in water holding capacity (WHC). Seed germination and plant growth were relatively better in the pyrolyzed soil. The field applicability of the pyrolytic treatment process was confirmed at laboratory and pilot scale, as well as by treating soil samples collected from actual polluted sites.