Department of Nutrition and Food Science, University of Maryland, College Park, Maryland, USA.
Appl Environ Microbiol. 2012 Oct;78(19):6789-98. doi: 10.1128/AEM.01094-12. Epub 2012 Jun 29.
The effect of the washing aid T-128 (generally recognized as safe [GRAS] formulation, composed mainly of phosphoric acid and propylene glycol) on inactivation of Salmonella and Pseudomonas populations in biofilms on stainless steel was evaluated under conditions of increasing organic matter loads in chlorinated wash solutions dominated by hypochlorous acid. Biofilms were formed statically on stainless steel coupons suspended in 2% lettuce extract after inoculation with Salmonella enterica serovar Thompson or Newport or with Pseudomonas fluorescens. Coupons with biofilms were washed in chlorine solutions (0, 0.5, 1, 2, 5, 10, or 20 mg/liter at pH 6.5, 5.0 and 2.9), with or without T-128, and with increasing loads of organic matter (0, 0.25, 0.5, 0.75, or 1.0% lettuce extract). Cell populations on coupons were dispersed using intermittent, pulsed ultrasonication and vortexing and enumerated by colony counts on XLT-4 or Pseudomonas agars. Cell responses to fluorescent viability staining of biofilm treatment washing solutions were examined using confocal laser scanning microscopy. Results showed that 0.1% T-128 (without chlorine) reduced P. fluorescens biofilm populations by 2.5 log(10) units but did not reduce Salmonella populations. For both Salmonella and Pseudomonas, the sanitizing effect of free chlorine (1.0 to 5.0 mg/liter) was enhanced (P < 0.05) when it was combined with T-128. Application of T-128 decreased the free chlorine depletion rate caused by increasing organic matter in wash waters and significantly (P < 0.05) augmented inactivation of bacteria in biofilms compared to treatments without T-128. Image analysis of surfaces stained with SYTO and propidium iodide corroborate the cultural assay results showing that T-128 can aid in reducing pathogen viability in biofilms and thus can aid in sanitizing stainless steel contact surfaces during processing of fresh-cut produce.
在以次氯酸为主的含氯洗涤液中有机物负荷不断增加的条件下，评估了洗涤助剂 T-128（通常被认为是安全的[GRAS]制剂，主要由磷酸和丙二醇组成）对不锈钢生物膜中沙门氏菌和假单胞菌群体失活的影响。将生物膜静态形成于经接种了肠炎沙门氏菌血清型汤普森或纽波特或荧光假单胞菌的不锈钢试片上的生菜提取物（2%）中。将附有生物膜的试片在含氯溶液（0、0.5、1、2、5、10 或 20 mg/L，pH 值为 6.5、5.0 和 2.9）中进行洗涤，含有或不含有 T-128，并随着有机物负荷（0、0.25、0.5、0.75 或 1.0%生菜提取物）的增加进行洗涤。使用间歇脉冲超声和涡旋将试片上的细胞群分散，并通过 XLT-4 或假单胞菌琼脂上的菌落计数对其进行计数。使用共聚焦激光扫描显微镜检查生物膜处理洗涤液中荧光活细胞染色的细胞反应。结果表明，0.1%的 T-128（无氯）使荧光假单胞菌生物膜群体减少了 2.5 个对数（10）单位，但并未减少沙门氏菌群体。对于沙门氏菌和假单胞菌，当自由氯（1.0 至 5.0 mg/L）与 T-128 结合时，其杀菌效果得到增强（P<0.05）。在含有不断增加的有机物的洗涤水中应用 T-128 可降低自由氯的消耗率，并与不含 T-128 的处理相比，显著（P<0.05）增强了生物膜中细菌的失活。用 SYTO 和碘化丙啶染色的表面图像分析证实了文化分析结果，表明 T-128 可以帮助减少生物膜中的病原体活力，并有助于在处理鲜切农产品期间对不锈钢接触表面进行消毒。
