Phages and their lysins: Toolkits in the battle against foodborne pathogens in the postantibiotic era

Worldwide, foods waste caused by putrefactive organisms and diseases caused by foodborne pathogens persist as public health problems even with a plethora of modern antimicrobials. Our over reliance on antimicrobials use in agriculture, medicine, and other fields will lead to a postantibiotic era where bacterial genotypic resistance, phenotypic adaptation, and other bacterial evolutionary strategies cause antimicrobial resistance (AMR). This AMR is evidenced by the emergence of multiple drug-resistant (MDR) bacteria and pan-resistant (PDR) bacteria, which produces cross-contamination in multiple fields and poses a more serious threat to food safety. A “red queen premise” surmises that the coevolution of phages and bacteria results in an evolutionary arms race that compels phages to adapt and survive bacterial antiphage strategies. Phages and their lysins are therefore useful toolkits in the design of novel antimicrobials in food protection and foodborne pathogens control, and the modality of using phages as a targeted vector against foodborne pathogens is gaining momentum based on many encouraging research outcomes. In this review, we discuss the rationale of using phages and their lysins as weapons against spoilage organisms and foodborne pathogens, and outline the targeted conquest or dodge mechanism of phages and the development of novel phage prospects. We also highlight the implementation of phages and their lysins to control foodborne pathogens in a farm–table–hospital domain in the postantibiotic era.     

延边地区2011~2015年食品中食源性致病菌的监测

【目的】 了解食品中主要食源性致病菌的污染状况,确定高危食品,为预防和控制食源性疾病提供科学依据。 【方法】 按照《全国食源性致病菌监测工作手册》 的检测技术要求,2011 － 2015 年在延边地区的几个监测点采集食品样品1069份,对沙门氏菌、单核细胞增生李斯特菌（定量）、金黄色葡萄球菌（定量）、铜绿假单胞菌、蜡样芽孢杆菌的污染情况进行监测。 【结果】 1069份样品中,共检出致病菌115株,总检出率为10.76%.熟肉制品、生食动物性水产品、凉拌菜、熟制米面制品、婴幼儿食品、乳及乳制品、速冻米面品、特殊膳食用食品、饮用水、三明治以及流动早餐样品的致病菌检出率分别为17.65%（3/17)、15.79%（3/19)、11.76%(4/34)、34.48%(10/29)、33.80%（24/71）、40.00%(12/30)、6.67%(1/15)、42.86%(6/14)、58.33%（7/12）、10.00%（1/10）和71.43%（10/14）;2011-2015年食源性致病菌检出率分别为0.94% 、1.87% 、6.83% 、0.65%、0.19%。 【结论】 乳及乳制品、特殊膳食用食品、饮用水和流动早餐是延边地区食品的主要污染品种,作为直接入口食品的熟肉制品、凉拌菜、熟制米面制品和婴幼儿食品可能导致较高的食源性疾病风险。     

2013~2014年长春市食品中食源性致病菌检测及分析

目的 了解食源性致病菌在长春市食品中检出情况,为食源性疾病防控工作提供科学的数据。方法 按《2103年国家食品污染和有害因素风险监测工作手册方法》、《 微生物检测方法的标准操作程序 》( 国家食品安全风险评估中心 )和国家标准方法进行食品中的食源性致病菌检测。结果 2013-2014年长春市11类食品433件样本中的食源性致菌的检出率是17.09%,其中蜡样芽胞杆菌、单核细胞增生李斯特氏菌、金黄色葡萄球菌和沙门氏菌的检出率分别是33.87%、12.81%、2.83%和0.58%。2013年和2014年食品中食源性致病菌的检出率无显著性差异(x₂=0.09,P＞0.05)。在乳制品、肉及其制品、婴幼儿食品、水产及其制品、餐饮食品、即食非发酵豆制品和速冻面米制品中食源性致病菌的检出率分别是：73.33%、40%、30.61%、9.52%、7.23%、5%和3.33%。结论 长春市食品存在不同程度上的食源性致病菌污染。乳制品、肉及其制品和婴幼儿食品中的食源性致病菌检出率较高,蜡样芽胞杆菌和单核细胞增生李斯特氏菌对食品污染较严重,需加强对这几类食品的监管。     

2017—2019年辽宁省市售食品中食源性致病菌监测结果分析

目的 了解2017—2019年辽宁省市售食品中食源性致病菌的污染及其分布情况.方法 2017—2019年辽宁省共采集12类4694份样品,按照《国家食品污染物和有害因素风险监测工作手册》对食源性致病菌进行检测分析.结果 4694份样品中各种致病菌的总检出率差异较大,其中蜡样芽胞杆菌的检出率最高为12.78％.不同种类食...     

Using lytic bacteriophages to eliminate or significantly reduce contamination of food by foodborne bacterial pathogens

Bacteriophages (also called ‘phages’) are viruses that kill bacteria. They are arguably the oldest (3 billion years old, by some estimates) and most ubiquitous (total number estimated to be 10³⁰–10³²) known organisms on Earth. Phages play a key role in maintaining microbial balance in every ecosystem where bacteria exist, and they are part of the normal microflora of all fresh, unprocessed foods. Interest in various practical applications of bacteriophages has been gaining momentum recently, with perhaps the most attention focused on using them to improve food safety. That approach, called ‘phage biocontrol’, typically includes three main types of applications: (i) using phages to treat domesticated livestock in order to reduce their intestinal colonization with, and shedding of, specific bacterial pathogens; (ii) treatments for decontaminating inanimate surfaces in food‐processing facilities and other food establishments, so that foods processed on those surfaces are not cross‐contaminated with the targeted pathogens; and (iii) post‐harvest treatments involving direct applications of phages onto the harvested foods. This mini‐review primarily focuses on the last type of intervention, which has been gaining the most momentum recently. Indeed, the results of recent studies dealing with improving food safety, and several recent regulatory approvals of various commercial phage preparations developed for post‐harvest food safety applications, strongly support the idea that lytic phages may provide a safe, environmentally‐friendly, and effective approach for significantly reducing contamination of various foods with foodborne bacterial pathogens. However, some important technical and nontechnical problems may need to be addressed before phage biocontrol protocols can become an integral part of routine food safety intervention strategies implemented by food industries in the USA. © 2013 Society of Chemical Industry     

2015年江苏省网店自制食品中食源性致病菌的 监测分析

目的 监测江苏省网店自制食品食源性致病菌的污染状况。了解金黄色葡萄球菌产毒及耐药特点。方法 GB4789《食品安全国家标准 食品微生物学检验》方法,选取无锡、常州、盐城等3个监测点,采集我省范围内的网店自制食品共214份,进行沙门氏菌、金黄色葡萄球菌、单增李斯特菌的检验。对分离得到的金黄色葡萄球菌进行葡萄球菌肠毒素检验和药物敏感性试验。结果 共检出食源性致病菌13株,总检出率为6.1%。其中金黄色葡萄球菌9株单增李斯特菌4株,未检出沙门菌。3份样品金黄色葡萄球菌污染超出国家食品限量值。9株金黄色葡萄球菌中6株产生葡萄球菌肠毒素。结论 江苏地区网店自制食品存在食源性致病菌污染状况。其中金黄色葡萄球菌污染比较严重,产肠毒素比例高,且对多种抗生素耐药,对青霉素产生普遍耐药, 对四环素、万古霉素和利福平耐药率较高, 对苯唑西林、环丙沙星、奎奴普丁/达福普汀和呋喃妥英等耐药率相对较低;对耐莫西沙星、利奈唑胺、替加环素和甲氧苄氨嘧啶/磺胺甲恶唑有较好的敏感性。     

2010~2015年吉林市食品食源性致病菌的风险监测结果分析

目的 分析吉林市市售食品中食源性致病菌的污染情况,确定高危食品的种类和分布,预防和控制食源性疾病的发生。方法 2010～2015年采集吉林市市售样品21类1212份,按照《全国食源性致病菌监测工作手册》的要求分离和鉴定10种食源性致病菌。结果 检出致病菌株121株,总检出率为9.98%。致病菌检出率前3位食品类别分别是速冻米面制品(26/96,27.08%);乳与乳制品、婴幼儿配斱食品(23/101,22.77%);肉及肉制品(40/178, 22.47%)。检出致病菌前3位是蜡样芽胞杆菌(43/206, 20.87%)、副溶血性弧菌(6/77, 7.79%)、单核细胞增生李斯特菌(42/643, 6.53%)。2010～2015年每年食源性致病菌检出率分别为8.56%、2.99%、6.55%、2.86%、1.83%、3.49%。结论 吉林市市售食品的现状不容乐观,食源性致病菌污染严重,致病菌检出率进高于同期本省及国内其他省市。建议长期注意其引起的食源性疾病风险,加强市售食品的监测和食品经营部门的管理,防止食源性疾病的发生。     

Short chain and polyunsaturated fatty acids in host gut health and foodborne bacterial pathogen inhibition

As a major source of microbes and their numerous beneficial effects, the gut microflora/microbiome is intimately linked to human health and disease. The exclusion of enteric pathogens by these commensal microbes partially depends upon the production of bioactive compounds such as short-chain fatty acids (SCFAs) and polyunsaturated fatty acids (PUFAs). These key intestinal microbial byproducts are crucial to the maintenance of a healthy gut microbial community. Moreover, SCFAs and PUFAs play multiple critical roles in host defense and immunity, including anti-cancer, anti-inflammation, and anti-oxidant activities, as well as out-competition of enteric bacterial pathogens. In this review article, we hereby aim to highlight the importance of SCFAs and PUFAs and the microbes involved in production of these beneficial intestinal components, and their biological functions, specifically as to their immunomodulation and interactions with enteric bacterial pathogens. Finally, we also advance potential applications of these fatty acids with regards to food safety and human gut health.     

Antimicrobial activity of whey protein isolate edible films with essential oils against food spoilers and foodborne pathogens

The use of antimicrobial edible film is proposed as a means of improving food safety and extending the shelf-life of food systems by controlling the release of antimicrobials on food surfaces. In this work we first selected and studied 8 different essential oils (EOs) from plants, namely, oregano, clove, tea tree, coriander, mastic thyme, laurel, rosemary, and sage as natural antimicrobials against 2 gram-positive bacteria (Listeria innocua and Staphylococcus aureus) and 2 gram-negative bacteria (Salmonella enteritidis and Pseudomona fragi) by using the agar disk diffusion method. EOs from oregano, clove, and tea tree produced the largest surfaces of inhibition against the growth of the 4 bacterial strains tested. Second and following the assessment of compatibility, stable antimicrobial edible films based on whey protein isolate (WPI) with increasing concentrations (0.5% to 9%) of the 8 EOs were developed and tested for antimicrobial activity against the same gram-positive and gram-negative bacteria. WPI-edible films incorporating oregano or clove EO were found to have the most intense inhibitory effect of microbial growth. The bacterial strain gram-negative P. fragi presented the less susceptibility to the effect of those films. Moreover, only the edible films based on these 2 EOs were active against all 4 studied microorganisms. On the other hand, the edible films incorporating tea tree, coriander, mastic thyme, laurel, rosemary, or sage EOs even at high concentrations (7% to 9%) did not cause any antimicrobial effect against the pathogens S. aureus or S. enteritidis. PRACTICAL APPLICATION: Potential applications of this technology can introduce direct benefits to the food industry by improving safety and microbial product quality. The results of this research have direct application in the food industry with potential applications in various foodstuffs, including meat and poultry products where the control of spoilage bacteria such as P. fragi throughout their chilled storage or the improvement of food safety by controlling pathogens such as S. enteritidis are topics of particular interest for the industry.     

Using Photocatalyst Metal Oxides as Antimicrobial Surface Coatings to Ensure Food Safety—Opportunities and Challenges

Cross‐contamination of foods with pathogenic microorganisms such as bacteria, viruses, and parasites may occur at any point in the farm to fork continuum. Food contact and nonfood contact surfaces are the most frequent source of microbial cross‐contamination. In the wake of new and emerging food safety challenges, including antibiotic‐resistant human pathogens, conventional sanitation and disinfection practices may not be sufficient to ensure safe food processing, proper preparation, and also not be environmentally friendly. Nanotechnology‐enabled novel food safety interventions have a great potential to mitigate the risk of microbial cross‐contamination in the food chain. Especially engineered nanoparticles (ENPs) are increasingly finding novel applications as antimicrobial agents. Among various ENPs, photocatalyst metal oxides have shown great promise as effective nontargeted disinfectants over a wide range of microorganisms. The present review provides an overview of antimicrobial properties of various photocatalyst metal oxides and their potential applications as surface coatings. Further, this review discusses the most common approaches to developing antimicrobial coatings, methods to characterize, test, and evaluate antimicrobial efficacy as well as the physical stability of the coatings. Finally, regulations and challenges concerning the use of these novel photocatalytic antimicrobial coatings are also discussed.     

pH treatment as an effective tool to select the functional and structural properties of yak milk caseins

Qula is made from yak milk after defatting, acidifying, and drying. Yak milk caseins are purified from Qula by dissolving in alkali solution. The effects of different pH treatments on the functional and structural properties of yak milk caseins were investigated. Over a broad range of pH (from 6.0 to 12.0), functional properties of yak milk caseins, including solubility, emulsifying activities, and thermal characteristics, and the structural properties, including 1-anilino-8-naphthalene-sulfonate fluorescence, turbidity and particle diameter, were evaluated. The results showed that the yak milk casein yield increased as the pH increased from 6.0 to 12.0. The solubility dramatically increased as the pH increased from 6.0 to 8.0, and decreased as the pH increased from 9.0 to 12.0. The changes in emulsifying activity were not significant. Caseins were remarkably heat stable at pH 9.0. The turbidity of the casein solution decreased rapidly as the pH increased from 6.0 to 12.0, and the results suggested that reassembled casein micelles were more compact at low pH than high pH. At pH values higher than 8.0, the yield of yak milk caseins reached more than 80%. The highest solubility was at pH 8.0, the best emulsification was at pH 10.0 and the greatest thermal stability was at pH 9.0. According to the functional characteristics of yak milk caseins, alkali conditions (pH 8.0–10.0) should be selected for optimum production. These results suggested that pH-dependent treatment could be used to modify the properties of yak milk caseins by appropriate selection of the pH level.