控制细菌生物膜感染的可替代策略-噬菌体疗法

在自然界中,细菌常以细菌生物膜的形式存在,其形成给公共卫生、食品安全、环境等诸多领域带来了不利影响。复杂的细菌生物膜结构为生理多样化的细菌细胞提供了保护屏障,细菌生物膜的形成是细菌感染及细菌抗药耐药性问题出现的主要驱动因素。噬菌体是细菌的天敌,细菌与噬菌体之间的共同进化迫使噬菌体开发特定的策略来克服生物膜防御屏障并杀死细菌。本文总结了细菌生物膜的组成、结构、形成过程及噬菌体对细菌生物膜的感染机制;综述了基于噬菌体及其衍生物对抗生物膜和耐药细菌感染的最新研究进展;最后,针对目前噬菌体疗法存在的问题进行了讨论,以期发现和更好地利用噬菌体的天然抗菌潜力,促进新型、高效的细菌生物膜检测及控制技术进一步发展。     

Probiotics interaction with foodborne pathogens: a potential alternative to antibiotics and future challenges

Abstract

Antibiotics are a key tool used nowadays in health care industry to fight against bacterial infections; however, repeated antibiotic use or misuses, have led to bacterial resistance, causing significant threats for many people with common bacterial infections. The use of probiotics to enhance gastrointestinal health has been proposed for many years. In recent years, there has been an increasing interest in the use of probiotic bacteria as alternatives for antibiotics for preventing or treating various intestinal infections. Several important underlying mechanisms responsible for the antagonistic effects of probiotics on different microorganisms include: (1) competitive exclusion for adhesion sites and nutritional sources; (2) secretion of antimicrobial substances; (3) enhancement of intestinal barrier function; and (4) immunomodulation. However, their mode of action is not very well understood and therefore a clearer understanding of these mechanisms is necessitated. This will enable appropriate probiotic strains to be selected for particular applications and may reveal new probiotic functions. The goal of this review was to highlight some studies from literature describing the probiotic interaction with several major foodborne pathogens, as well as explore the mechanisms for such probiotic-pathogen interaction. The review will conclude by presenting future perspective and challenges of probiotic application in food products.     

益生菌与肠道菌群、免疫调节的相互作用与机制研究进展

益生菌在改善宿主肠道微生态平衡、提高宿主健康水平和健康状态等方面发挥有益作用。其主要通过调理肠道微生物群、参与多种疾病的免疫调节,从而改善胃肠道生理机能来影响宿主健康。益生菌在预防和治疗胃肠道疾病等方面具有相当大的潜力,需要对其与肠道菌群、免疫调节的相互作用机制更深入的了解。本文对益生菌在肠道的分布与定植、益生菌对肠道菌群和肠道功能的调控作用以及益生菌与免疫调节的关系做了简单论述,以期为今后益生菌与肠道菌群互作研究以及益生菌的临床应用提供参考。     

Probiotics: An emerging food supplement with health benefits

Probiotics are among the important functional foods. They comprise approximately 65% of the world functional food market. Probiotic products are foods, which improve intestinal microflora and support good health of the consumer. The live bacteria present in the probiotic products are lactic acid bacteria, including Lactobacilli, Bifidobacteria and Enterococci. Apart from health claims and maintenance of intestinal microflora, they protect against infections, alleviate lactose intolerance, reduce blood cholesterol levels and also stimulate the immune system. The interactive research between physiology, microbiology, food technology and molecular biology followed by clinical trials may produce a multi-functional probiotic strain for human consumption.     

Probiotics: An emerging food supplement with health benefits

Probiotics are among the important functional foods. They comprise approximately 65% of the world functional food market. Probiotic products are foods, which improve intestinal microflora and support good health of the consumer. The live bacteria present in the probiotic products are lactic acid bacteria, including Lactobacilli, Bifidobacteria and Enterococci. Apart from health claims and maintenance of intestinal microflora, they protect against infections, alleviate lactose intolerance, reduce blood cholesterol levels and also stimulate the immune system. The interactive research between physiology, microbiology, food technology and molecular biology followed by clinical trials may produce a multi-functional probiotic strain for human consumption.     

Plasma modification of textiles: understanding the mechanisms involved

Plasma treatments are acquiring growing commercial recognition as a highly practical means of altering the surface properties of textiles without detriment to their bulk properties. It is clearly desirable that processing conditions are formulated as accurately as possible, so that fewer trials are required to achieve a desired outcome. We discuss how better formulation is achievable from a clearer understanding of the mechanisms comprising the plasma process. This improved understanding comes from not only analysing surface chemical and topographical changes resulting from a plasma treatment, but also monitoring key processes taking place during the treatment. Furthermore, we highlight the application of computational approaches, statistical experimental design and process control as supporting tools and highlight the role that artificial intelligence may play in the future. We also consider three specific plasma treatments of textiles and propose how examples of these approaches extracted from the literature may be combined, to achieve more realistic formulations.     

Dietary fat and gut microbiota: mechanisms involved in obesity control

ABSTRACT

Obesity is a serious global health problem that is directly related to various morbidities manifestation. Intestinal dysbiosis has been implicated on obesity pathogenesis. Diet composition can alter gut microbiota, regardless of energy intake. Dietary fatty acids quality may affect gut microbiota composition, which in turn may affect host metabolic health. The mechanisms by which the different type of FFA modulate gut microbiota is yet poor elucidate and there is a lack of studies regard to this. Fatty acids may act in cell membrane, interfere with energy production, inhibit enzymatic activities, impair nutrient absorption and generate toxic compounds to cells, leading to growth inhibition or even bacterial death. The beneficial effect of the consumption of n-3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acid (CLA) on microbiota, unlike n-6 PUFA and saturated fatty acids has been suggested. n-3 PUFA consumption promotes desirable changes on obese intestinal microbiota making it similar to that of normal weight individuals. More studies are needed to better understand the effect of CLA on microbiota and host health. Long term human controlled clinical trials must be conducted to allow us to understand the complex interaction between dietary fat, intestinal microbiota and obesity.     

Non-dairy Based Probiotics: A Healthy Treat for Intestine

Dairy-based fermented products and yoghurts have been utilized as potential probiotic products since ancient times. However, recent upsurge in interest of consumers towards dairy alternatives has opened up new vistas for non-dairy probiotic research and development. Various matrices and substrates such as cereals, fruit juices, or mixture thereof are being utilized for delivering these beneficial microorganisms. Each matrix offers some advantages over the other. Vast knowledge available on a number of conventional fermented foods can also be utilized for future research in this area. The present review provides an insight on the recent research/developments in the field of non-dairy probiotic foods with particular reference to the foods consumed conventionally, in addition to their commercial availability and a way forward.     

Daphne oleoides: An alternative source of important sesquiterpenes

This study was targeted to characterize the chemical composition and antibacterial properties of Daphne oleoides subsp. oleoides essential oil. The essential oil was analyzed and quantified by gas chromatography and gas chromatography/mass spectrometry. Additionally, the broth dilution method was used to evaluate its antibacterial activity against Bacillus cereus (ATCC 11778), Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 25923), Staphylococcus epidermidis (ATCC 12228), Streptococcus faecalis (ATTC 29212), Escherichia coli (ATCC 25922), Proteus mirabilis (ATCC 25933), Proteus vulgaris (ATCC 13315), Pseudomonas aeruginosa (ATCC 27853), and Salmonella typhi Ty2 (ATCC 19430). Seventy-nine compounds were identified, representing 95.2% of the total oil. Nootkatone (18.5%), nootkatin (12.1%), and daphnauranol C (11.7%) were determined as the main constituents in the oil. Oxygenated sesquiterpenes were dominating in the oil (43.0%), followed by fatty acid derivatives (13.7%) and carbonylic compounds (9.6%). The minimal inhibitory/bactericidal concentrations of essential oils of D. oleoides were in the range from 25–100 μg/mL, which can be considered as high activity in comparison with the reference antibiotic which was active in the rangefrom 3.12–100 μg/mL. The greatest minimal inhibitory concentration value was determined as 25 µg/mL against both two Bacillus strains and S. epidermidis, B. cereus, B. subtilis, and S. aureus were the most sensitive strains against essential oils when compared with the minimal inhibitory concentrations of control antibiotic. Consequently, Daphne oleoides subsp. oleoides can be exploited as a source of natural antibacterial agents and nootkatone for the pharmaceutical, food, and agricultural industries.     

An alternative heat treatment for milk pasteurization in Cameroon

In order to determine a suitable temperature and time combination for the proper pasteurization of milk under conditions in Cameroon, the destructive effects of heat on the peroxidase and micro-organisms in local milk were studied. In the first step, fresh milk samples were heated at temperatures of 64–100°C for 1 min. Peroxidase was found to be sensitive to heat treatment at temperatures of 74–76°C and completely destroyed above 78°C. In the second step, fresh milk samples were heated to 74°C and held at that temperature for 15 s, 5 min, 10 min, 15 min or 20 min; microbiological analyses revealed that survival rates were 56.7, 1.5, 0.2, 0.06 and 0.05%, respectively. Peroxidase was completely destroyed after 10 min at this temperature. In terms of microbial quality, there were no significant differences ( P  < 0.001) between holding times of 10, 15 and 20 min. A heat treatment of 74°C for 10 min yielded milk free of peroxidase and with < 10 000 cfu/mL. It is recommended that raw milk be given at least this treatment to ensure safe milk supplies in Cameroon.     

Enrichment of mushrooms: An interesting strategy for the acquisition of lithium

The capability of Pleurotus ostreatus mushroom to accumulate lithium (Li) and the accessibility of this Li compared with lithium carbonate (Li₂CO₃), often used as psychiatric medicine, were investigated. Mushrooms were produced on a substrate-based on coffee husk, with different added concentrations of lithium chloride (LiCl). Biological efficiency (BE), the crude protein content, the concentration of Li and other elements present in mushrooms were determined. The sequential extraction and in vitro test were used to verify the accessibility and the degree of solubility of this element. Li concentration in mushrooms was directly influenced by increasing LiCl concentration in the substrate (P < 0.05). The BE was not affected by different concentrations of LiCl. Li present in enriched mushrooms showed greater accessibility than in Li₂CO₃. Therefore, P. ostreatus mushrooms, enriched with lithium can be an alternative source of Li, as well as being a food with high nutritional value.     

Probiotics for cure of Helicobacter pylori infection: A review

Human physiology normally contains pathogenic and non-pathogenic microorganisms in the gastrointestinal flora. Disturbance of these microorganism balance results in the formation of infection. Extensive use of antibiotics for cure of these disturbances like Helicobacter pylori (H. pylori) infection leads to patient discomfort and associated side-effects. There is a need to adopt adjunct or alternative approach in order to minimize such conditions. Probiotics is one of the potential therapies to cure gastrointestinal discomforts especially associated with H. pylori. It competes through non-immune and immune systems. This review article concludes that probiotics are used to eradicate the infection at increased rate, and decreased associated side-effects are caused by triple therapy. A proper evaluation of these probiotics is demanded before their use in future as a commercial product. Furthermore, their effect on immune system requires more research work so that their usage for other chronic disorders can also be considered.     

An alternative approach for enumeration of Escherichia coli in foods

A study was carried out in France in collaboration with the meat industry to investigate the occurrence and characteristics of Shiga toxin-producing E. coli (STEC) and O157 E. coli in a population of healthy bovines representative of French livestock. A total of 851 animals belonging to three bovine classes (106 young bulls, 374 dairy cows and 371 meat cows) were included in the study. Samples of feces and of the corresponding carcasses were collected from March 97 to August 97 in seven abattoirs spread throughout the national territory. STEC cultures from the 1702 samples were screened using PCR for the presence of stx genes. Positive samples were further subjected to colony blot hybridization and to O157-specific immunomagnetic separation. Probe-positive colonies and O157 colonies were then analyzed for the presence of virulence genes and phenotypic characters (serotype, Stx production). In 154 (18.1%) feces and 91 (10.7%) carcass samples stx genes were detected. Two hundred and twenty-two STEC colonies were isolated from 67 (7.9%) feces and 16 (1.9%) carcass samples, with 183 STEC isolated from feces and 39 from carcasses. Only eight O157 isolates were collected from feces samples. None of these O157 E. coli isolates presented stx genes and thus could not be considered as pathogenic regarding hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). In 3.2% of STEC isolated from feces and in 10.2% of STEC from carcasses eae genes were detected. In 17% of STEC from feces and in 30.7% from carcasses ehx genes were detected. Using these data, the 222 STEC colonies could be classified in 11 different 'virulence patterns' (presence/absence of stx1, stx2, eae and ehx genes), showing that more than 77% of isolates presented only one virulence factor. Only three STEC on 222 colonies (1.3%) presented the three virulence factors stx, eae and ehx in association, none of them reacting with antisera specific for enterohemorrhagic E. coli. (EHEC). These data, together with the fact that only five isolates on the 222 (2.2%) reacted with such antisera (three O111 and two O26 isolates) demonstrated that the natural bacterial populations isolated during this study were clearly distinct from EHEC.     

An alternative process for the manufacture of whole milk powder

The traditional process of manufacturing whole milk powder has some negative aspects: high heat treatment of the milk and, owing to fouling during evaporation, loss of product. To reduce these negative aspects an alternative way of producing whole milk powder was investigated in pilot-plant experiments. Milk was first separated into skim milk and cream and then treated further. Skim milk was subjected to a low heat treatment and concentrated by evaporation. The cream was subjected to a high heat treatment and mixed with the concentrated skim milk. The standardized whole milk concentrate was then spray dried. This process of manufacturing whole milk powder compared favourably with the traditional process with respect to product losses, the physical properties of the whole milk powder and the flavour of the reconstituted milk.     

An alternative process for cleaning knives used on meat slaughter floors

Traditionally on slaughter floors operator knives are cleaned by rinsing in hand wash water at 20-40 degrees C followed by brief immersion in baths termed "sterilisers" which contain water no cooler than 82 degrees C. Under Australian legislation, both domestic and export, it is possible for a meat processing establishment to apply to the Controlling Authority for permission to implement an alternative procedure providing that it is at least the equivalent of that legislated. No firm evidence appears to exist for the 82 degrees C requirement and the possibility of replacing this element of the knife cleaning procedure with an alternative procedure using 60 degrees C water and a longer immersion time was investigated at an abattoir slaughtering cattle and sheep. Knives were tested at a range of work stations located along beef and mutton slaughter floors for Aerobic Plate Counts (APCs) and E. coli. For knives used on the beef chain the mean log APC/cm(2) was 2.18 by the current knife cleaning process and 1.78 by the alternate procedure (P<0.001). Using the current system E. coli was isolated from cleaned knives on 20/230 (8.7%) occasions compared with 21/230 (9.1%) occasions using the alternative system. The mean log E. coli of positive knives was 0.43/cm(2) and 0.61/cm(2) from the current and alternative systems, respectively. On the mutton chain the mean log APC/cm(2) was 1.95 using the current knife cleaning process and 1.69 by the alternative procedure (P=0.014). Using the current system E. coli was isolated from cleaned knives on 24/130 (18.5%) occasions compared with 29/130 (22.3%) occasions using the alternative system. The mean log E. coli of positive knives was 0.90/cm(2) and 0.76/cm(2) from the current and alternative systems, respectively. It is concluded that using two knives alternatively, rinsing them in hand wash water, then immersing them between uses in 60 degrees C water provides a microbiological outcome equivalent to rinsing them and momentary dipping in 82 degrees C water.     

An alternative strategy for corn drying (Zea mays) resulted in both energy savings and reduction of fumonisins B1 and B2 contamination

The objectives of this study were to investigate the effect of harvest date on fumonisins contamination and to offer an alternative drying procedure with low energy costs. Corn kernel samples above 13% moisture content were dried with hot air (HA), the technique more usually utilised by farmers and compared with infrared and infrared–hot air (IR–HA) combination techniques. The effect of harvest date on fumonisin contamination was found to be significant while drying had no influence. Due to the fact that the corn remains in the field longer than necessary for economic reasons, energy expenses of the drying techniques were calculated in terms of specific energy consumption for unit of evaporated water. It was found that the energy expenses to reduce the moisture level from 15 to 13% with HA drying were higher than the expenses to reduce the moisture level from 29 to 13% with IR–HA drying combination.     

中国造纸装备制造业创新战略研究导论

“中国造纸装备制造业创新战略研究导论”（以下简称“导论”）一文,是由胡楠先生为《轻工专用设备制造业研究报告》写的“前言”简化而成。该“前言”着眼于轻工各行业进行综合分析,篇幅较长,限于本刊专业范畴,只好忍痛割爱,有所删简。《轻工专用设备制造业研究报告》是中国工程院《装备制造业自主创新战略研究》的一部分,旱在2006年6月就已经发布。本刊之所以当前重新发表“导论”一文,缘于三大因素。其一,不久前,即20（17年10月底,国家发改委在北京召开宣贯会,我国首部《造纸产业发展政策》颁布实施,其中第四章“技术与装备”着重论述了装备制造自主创新问题,这应当被视为中国造纸装备制造业自主创新战略研究进入新阶段的一个标志。其二,近年来,由于产学研多方面成功合作,尤其是一些先行企业的勇敢探索,中国造纸装备制造自主创新在实践上有了重大突破,取得了新的成果。其三,以上两方面,从理论和实践上恰恰印证了胡楠先生文章观点的正确性和前瞻性,彰显了胡楠先生缜密思考的睿智。胡楠先生早年毕业于清华大学机械制造专业,先后在我国大型知名企业和轻工机械行业高管层任职多年,有扎实的专业功底和丰富的实践经验。加之多年来,他读书不倦、笔耕不断、学识渊博、著作颇丰,是一位勇于探索、敢于直言、知行一致的实战型专家学者。“导论”以轻工装备制造业自主创新问题为核心,从宏观层面到具体案例,加以综合分析。高屋建瓴,有的放矢,给人以深刻启迪,值得认真阅读。从本期开始,本刊将分三部分,连续刊登“导论”一丈,敬请关注。     

中国造纸装备制造业创新战略研究导论（续二）

5 提高我国装备制造业自主创新能力的经济环境建设及政策措施 5．1从认识装备制造业的主要特征和发展趋势中。不断清除观念上的障碍 5．1．1对比较优势的认识（略）5．1．2对世界产业分工的认识（略）5．1．3对科技全球化的认识     

中国造纸装备制造业创新战略研究导论（续一）

3．1自主创新案例 多数分行业报告提供的自主创新案例较多,主要是在引进技术、消化吸收再创新（即模仿、学习再创新）的基础上,在21世纪以来通过集成创新（适应市场需求,将现有世界上众多的成熟技术进行综合、集成,其成果从市场得到回报）产生的企业自主创新成功的案例。     

Epigenetic modulation of mechanisms involved in inflammation: Influence of selected polyphenolic substances on histone acetylation state

In the present study, we have investigated the influence of low concentrations of polyphenols (5 μM) on histone acetyltransferase (HAT) and histone deacetylase (HDAC) activity, a monocyte cell system related to the inflammatory process. We selected gallic acid, ellagic acid, oenothein B, valoneic acid dilactone and penta-O-galloyl-β-d-glucose, which are known to affect inflammatory responses, such as IL-6 secretion and/or NF-κB down-regulation and polyphenol metabolites (urolithins A, B and C). TNF-α stimulation resulted in a reduction of THP-1 cell viability by 28.9%, reduced HDAC activity from 25.2 to 13.5 pmol/μg protein and increased HAT activity from 24.0 to 45.5 pmol/μg protein. The coincubation with ellagic acid and oenothein B restored the viability and reversed the effect of TNF-α on HAT and HDAC activities. Urolithins B and C, gallic acid and penta-O-galloyl-β-d-glucose only showed significant reductions of HAT activity, by 40-50%. Our results prove that polyphenols act as epigenetic modulators.