Marino Marilena, Maifreni Michela, Baggio Anna, Innocente Nadia
Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Università degli Studi di Udine, Udine, Italy.
Front Microbiol. 2018 Aug 28;9:2024. doi: 10.3389/fmicb.2018.02024. eCollection 2018.
In this study, the efficacy of treatments with ozone in water and gaseous ozone against attached cells and microbial biofilms of three foodborne species, , , and , was investigated. Biofilms formed on AISI 304 stainless steel coupons from a mixture of three strains (one reference and two wild strains) of each microbial species were subjected to three types of treatment for increasing times: (i) ozonized water (0.5 ppm) by immersion in static condition, (ii) ozonized water under flow conditions, and (iii) gaseous ozone at different concentrations (0.1-20 ppm). The Excel add-in GinaFit tool allowed to estimate the survival curves of attached cells and microbial biofilms, highlighting that, regardless of the treatment, the antimicrobial effect occurred in the first minutes of treatment, while by increasing contact times probably the residual biofilm population acquired greater resistance to ozonation. Treatment with aqueous ozone under static conditions resulted in an estimated viability reduction of 1.61-2.14 Log CFU/cm after 20 min, while reduction values were higher (3.26-5.23 Log CFU/cm) for biofilms treated in dynamic conditions. was the most sensitive species to aqueous ozone under dynamic conditions. With regard to the use of gaseous ozone, at low concentrations (up to 0.2 ppm), estimated inactivations of 2.01-2.46 Log CFU/cm were obtained after 60 min, while at the highest concentrations a complete inactivation (<10 CFU/cm) of the biofilms of and the reduction of 5.51 and 4.72 Log CFU/cm of and respectively after 60 and 20 min were achieved. Considering the results, ozone in water form might be used in daily sanitation protocols at the end of the day or during process downtime, while gaseous ozone might be used for the treatment of confined spaces for longer times (e.g., overnight) and in the absence of personnel, to allow an eco-friendly control of microbial biofilms and consequently reduce the risk of cross-contamination in the food industry.
在本研究中，考察了水中臭氧和气态臭氧对三种食源性病原体（[具体物种1]、[具体物种2]和[具体物种3]）的附着细胞和微生物生物膜的处理效果。由每种微生物物种的三株菌株（一株参考菌株和两株野生菌株）混合形成的、附着在AISI 304不锈钢试片上的生物膜，接受了三种类型的处理，处理时间逐渐增加：（i）在静态条件下浸泡于臭氧水（0.5 ppm）中，（ii）在流动条件下的臭氧水，以及（iii）不同浓度（0.1 - 20 ppm）的气态臭氧。Excel插件GinaFit工具用于估计附着细胞和微生物生物膜的存活曲线，结果表明，无论采用何种处理方式，抗菌效果均在处理的最初几分钟内出现，而随着接触时间的增加，残留的生物膜群体可能对臭氧处理产生了更大的抗性。在静态条件下用臭氧水处理20分钟后，估计的存活率降低了1.61 - 2.14 Log CFU/cm，而在动态条件下处理的生物膜，存活率降低值更高（3.26 - 5.23 Log CFU/cm）。[具体物种1]是动态条件下对臭氧水最敏感的物种。关于气态臭氧的使用，在低浓度（高达0.2 ppm）下，60分钟后估计的失活率为2.01 - 2.46 Log CFU/cm，而在最高浓度下，[具体物种2]和[具体物种3]的生物膜在60分钟后完全失活（<10 CFU/cm），[具体物种1]和[具体物种2]的生物膜在60分钟和20分钟后分别降低了5.51和4.72 Log CFU/cm。考虑到这些结果，水中的臭氧可在一天结束时或生产过程停机期间用于日常卫生规程，而气态臭氧可用于在较长时间（例如过夜）且无人在场的情况下处理密闭空间，以实现对微生物生物膜的环保控制，从而降低食品工业中的交叉污染风险。
