Department of Food Science and Technology, The University of Georgia, 1109 Experiment St., Griffin, GA 30223-1797, USA.
Appl Environ Microbiol. 2011 Dec;77(24):8532-7. doi: 10.1128/AEM.06450-11. Epub 2011 Oct 14.
Some Shiga toxin-producing Escherichia coli (STEC) strains produce extracellular cellulose, a long polymer of glucose with β-1-4 glycosidic bonds. This study evaluated the efficacies of selected enzymatic and chemical treatments in inactivating STEC and degrading/removing the cellulose on STEC surfaces. Six cellulose-producing STEC strains were treated with cellulase (0.51 to 3.83 U/15 ml), acetic and lactic acids (2 and 4%), as well as an acidic and alkaline sanitizer (manufacturers' recommended concentrations) under appropriate conditions. Following each treatment, residual amounts of cellulose and surviving populations of STEC were determined. Treatments with acetic and lactic acids significantly (P < 0.05) reduced the populations of STEC, and those with lactic acid also significantly decreased the amounts of cellulose on STEC. The residual amounts of cellulose on STEC positively correlated to the surviving populations of STEC after the treatments with the organic acids (r = 0.64 to 0.94), and the significance of the correlations ranged from 83 to 99%. Treatments with cellulase and the sanitizers both degraded cellulose. However, treatments with cellulase had no influence on the fate of STEC, and those with the sanitizers reduced STEC cell populations to undetectable levels. Thus, the correlations between the residual amounts of cellulose and the surviving populations of STEC caused by these two treatments were not observed. The results suggest that the selected enzymatic and chemical agents degraded and removed the cellulose on STEC surfaces, and the treatments with organic acids and sanitizers also inactivated STEC cells. The amounts of cellulose produced by STEC strains appear to affect their susceptibilities to certain sanitizing treatments.
一些产志贺毒素大肠杆菌（STEC）菌株会产生细胞外纤维素，这是一种由β-1-4 糖苷键连接的葡萄糖长聚合物。本研究评估了几种酶和化学处理方法对灭活 STEC 和降解/去除 STEC 表面纤维素的效果。将 6 株产纤维素的 STEC 菌株用纤维素酶（0.51 至 3.83 U/15 ml）、乙酸和乳酸（2%和 4%）以及一种酸性和碱性消毒剂（制造商推荐浓度）在适当的条件下进行处理。在每种处理后，测定纤维素的残留量和 STEC 的存活数量。乙酸和乳酸处理显著（P < 0.05）降低了 STEC 的数量，而乳酸处理也显著降低了 STEC 上纤维素的数量。在处理后，STEC 上纤维素的残留量与存活的 STEC 数量呈正相关（r = 0.64 至 0.94），相关性的显著性范围为 83%至 99%。纤维素酶和消毒剂的处理都能降解纤维素。然而，纤维素酶处理对 STEC 的命运没有影响，消毒剂处理则将 STEC 细胞数量降低到无法检测的水平。因此，这两种处理方法导致的纤维素残留量与 STEC 存活数量之间没有观察到相关性。结果表明，所选的酶和化学试剂降解并去除了 STEC 表面的纤维素，有机酸和消毒剂处理也能使 STEC 细胞失活。STEC 菌株产生的纤维素量似乎影响其对某些消毒处理的敏感性。
