Thomas L V, Wimpenny J W, Peters A C
School of Pure and Applied Biology, University of Wales College of Cardiff, UK.
Int J Food Microbiol. 1992 Jan-Feb;15(1-2):165-75. doi: 10.1016/0168-1605(92)90145-s.
Six Salmonella strains were grown on two-dimensional sodium chloride-pH and temperature-pH gradient plates. Using image analysis the results were expressed in the form of three-dimensional wire frame graphs. On the temperature-pH gradient plates the optimum growth range was 20-30 degrees C and the minimum pH for visible growth was ca. pH 4, except for strain S. typhimurium CRA63 which grew over a narrower temperature and pH range. On the NaCl-pH gradient plates (whose NaCl gradient began at 2.75% (w/v) NaCl) the maximum concentration of salt at which growth was visible varied from 3.9% to 6.0%, and the minimum pH at which growth was observed varied from pH 4.7 to 5.4 according to the strain used. The incorporation of 0.02% (w/v) sodium nitrite reduced the maximum salt concentration and increased the minimum pH at which the strains could grow. The strains were combined and used in a mixed inoculum on NaCl-pH gradient plates containing 6 different concentrations of NaNO2 incubated at 6 different temperatures. Comparison of the data from the mixed inoculum with data from individual strains showed that, apart from one case, the mixed inoculum represented the extremes of the growth domains of the individual strains. The effect of NaNO2 on the ability of the strains to grow at different pH, NaCl concentrations and temperatures, was more clearly shown by subtracting the data of plates containing NaNO2 from the data of plates without NaNO2.
将6株沙门氏菌菌株接种在二维氯化钠-pH值和温度-pH值梯度平板上培养。利用图像分析，结果以三维线框图的形式呈现。在温度-pH值梯度平板上，最佳生长温度范围为20-30℃，除鼠伤寒沙门氏菌CRA63菌株在较窄的温度和pH值范围内生长外，可见生长的最低pH值约为pH 4。在氯化钠-pH值梯度平板上（其氯化钠梯度从2.75%（w/v）氯化钠开始），可见生长的最大盐浓度在3.9%至6.0%之间变化，根据所用菌株的不同，观察到生长的最低pH值在pH 4.7至5.4之间变化。添加0.02%（w/v）亚硝酸钠可降低菌株生长的最大盐浓度，并提高菌株能够生长的最低pH值。将这些菌株混合，并以混合接种物的形式接种在含有6种不同浓度亚硝酸钠的氯化钠-pH值梯度平板上，在6个不同温度下培养。将混合接种物的数据与单个菌株的数据进行比较，结果表明，除了一种情况外，混合接种物代表了各个菌株生长域的极值。通过从不含亚硝酸钠的平板数据中减去含有亚硝酸钠的平板数据，更清楚地显示了亚硝酸钠对菌株在不同pH值、氯化钠浓度和温度下生长能力的影响。
