食品检验用木糖赖氨酸脱氧胆盐琼脂质量差异分析

Analysis of the Quality Difference of Xylose Lysine Deoxycholate Agar for Food Testing

摘要:

为丰富我国食品微生物检验用培养基验收时的质控菌株，提高商品化培养基质量，该实验采用GB 4789.28-2013中规定的验收方法，以鼠伤寒沙门氏菌ATCC14028、福氏志贺氏菌CMCC 51572、金黄色葡萄球菌ATCC 6538和大肠埃希氏菌ATCC 25922为参照，选取6株鼠伤寒沙门氏菌、1株福氏志贺氏菌、4株金黄色葡萄球菌和5株大肠埃希氏菌对4个品牌的木糖赖氨酸脱氧胆盐培养基（Xylose Lysine Desoxycholate Agar，XLD）的外观、pH值、水分含量等物理指标以及生长率、选择性等微生物指标进行实验评价。结果显示A、B、C、D 4个品牌培养基干粉颜色分别为粉红色，淡粉色、土黄色、粉白色；水分含量分别为5.55%，5.92%、5.46%、5.94%；配置100 mL添加量分别为5.54、5.89、5.69、5.70 g；pH值均符合7.4，6株鼠伤寒沙门氏菌和1株福氏志贺氏菌在4个品牌培养基上生长率均≥0.7，4株金黄色葡萄球菌均不生长，5株大肠埃希氏菌生长指数G均<5。综上，4个品牌的XLD培养基全部符合GB 4789.28-2013，该实验所选菌株可用作验收XLD培养基质控菌株的补充菌株。

Abstract:

In order to enrich the quality control strains during the acceptance of media for food microbiology testing in China and improve the quality of commercial culture media, the medium acceptance method specified in GB 4789.28-2013 was used in this experiment. Salmonella typhimurium ATCC 14028, Shigella fowlerii CMCC 51572, Staphylococcus aureus ATCC6538 and Escherichia coli ATCC 25922 were used as the references. Six strains of Salmonella typhimurium, one strain of Shigella fowleri, four strains of Staphylococcus aureus and five strains of Escherichia coli were selected for evaluating the physical indexes such as appearance, pH value and moisture content, as well as the microbial indicators such as growth rate and selectivity of four brands of XLD. The results showed that the colors of dry powders of four medium brands, A, B, C and D, were pink, light pink, earthy yellow and pinkish white. Their moisture contents were 5.55%, 5.92%, 5.46% and 5.94%, respectively. The dosages were 5.54, 5.89, 5.69, and 5.70 g in 100 mL respectively. All the pH values were 7.4. The growth rates of the six Salmonella typhimurium strains and the Shigella fowleri strain on the four brands of media were not lower than 0.7, whilst none of the four of Staphylococcus aureus strains grew, and all the five Escherichia coli strains had a growth index G lower than 5. In summary, the four brands of XLD all conformed to GB 4789.28-2013, the strain selected for this experiment can be used as a supplementary strain for the acceptance of XLD quality control strains.