化学论文翻译

After enriched P. aeruginosa suspension was in SCDLP broth for 18–24 hat 37C, cultures were picked up at the interface of pellicle andmedium and inoculated on an acetamide agar plate for 24 h at 37C.P. aeruginosa grew well on it, and the medium around the colonies turnedto pink slightly. Other bacterium could not grow on it.RESULTS AND DISCUSSIONDevelopment of Modified Acetamide BrothCulture medium developed for selective detection of P. aeruginosa byMSPQC should meet the following requirements: first, it should providenecessarily nutrition for the growth of P. aeruginosa; second, otherbacterial must not be able to grow in it; third, the properties of mediumshould be suitable for MSPQC measurement. For SPQC, the frequencyshift (DF) shows linear relationship with the conductance change (DG)(Shen et al. 1993a, 1993b):DF ¼ KDG ð1Þwhere DG<<G0 and G0 is the initial conductance of the culture medium.DF¼FiF0, and K is a constant. G0 must be in the sensitive range ofMSPQC. The sensitive response range of G0 was from 352.18 to1034.26 mS (He et al. 2006).Traditional acetamide medium meets the first two requirements.P. aeruginosa can grow very well in this medium, and other bacterialcannot. But it is not suitable for MSPQC measurement. Here a modifiedacetamide broth, suitable for MSPQC measurement, was proposed. Thecomposition of new developed acetamide broth was acetamide (2 g=L),monopotassium phosphate (0.4 g=L), sodium chloride (0.2 g=L),magnesium sulfate (0.1 g=L), sodium molibdate (0.05 g=L), and ironsulfate (0.005 g=L). The conductivity of this medium was 731 mS,perfectly meeting the requirement of the sensitive range of MSPQC,so the medium was suitable for MSPQC measurement.Selective Detection of P. aeruginosa by MSPQCThe detection was based on the following fact: during the growingprocess of P. aeruginosa in acetamide medium, it released ammonia62 F. He et al.Downloaded By: [CAS Consortium] At: 03:09 20 April 2009and acetic acid as shown in the following chemical equation (Noel andHolt 1984):CH3CONH2 ! CH3COOH þ NH3 ð2ÞThe conductivity of the medium increased because the conductivity ofammonia and acetic acid is much larger than that of acetamide. Thischange was recorded by the MSPQC system. For other microorganisms,no growth occurred in this medium.The typical frequency curve of bacterium detected by SPQC is shownin Fig. 2.Oscillating frequency varied slowly at the first flat stage because thebacterium adjusted itself to new culture. After a few hours, bacteriumcame into an exponential growth stage, and oscillating frequency startedto decrease rapidly. Finally, when the growth of bacterium reachedsaturation, frequency arrived at the second flat stage. DF was thedifference between two flats, resulting from metabolism of bacterium.