Exploring fungal biodiversity for the production of water-soluble pigments as potential natural food colorants

The production of many currently authorized natural food colorants has a number of disadvantages, including a dependence on the supply of raw materials and variations in pigment extraction. Fungi provide a readily available alternative source of naturally derived food colorants that could easily be produced in high yields. The recent authorization of a fungal food colorant has fuelled research to explore the extraordinary chemical diversity and biodiversity of fungi for the biotechnological production of pigments as natural food colorants. These studies require an appropriate use of chemotaxonomic tools and a priori knowledge of fungal metabolites to carry out intelligent screening for known or novel colorants as lead compounds. Such screening would result in the preselection of some potential pigment producers and the deselection of pathogenic strains and toxin producers. With advances in gene technology, in the future it should be possible to employ metabolic engineering to create microbial cell factories for the production of food colorants.     

Impact of genomics on microbial food safety

Genome sequences are now available for many of the microbes that cause food-borne diseases. The information contained in pathogen genome sequences, together with the development of themed and whole-genome DNA microarrays and improved proteomics techniques, might provide tools for the rapid detection and identification of such organisms, for assessing their biological diversity and for understanding their ability to respond to stress. The genomic information also provides insight into the metabolic capacity and versatility of microbes; for example, specific metabolic pathways might contribute to the growth and survival of pathogens in a range of niches, such as food-processing environments and the human host. New concepts are emerging about how pathogens function, both within foods and in interactions with the host. The future should bring the first practical benefits of genome sequencing to the field of microbial food safety, including strategies and tools for the identification and control of emerging pathogens.     

高通量测序技术在食品微生物研究中的应用

高通量测序技术的快速发展对食品微生物发酵过程和机制研究产生了深刻的影响,主要体现在食品微生物生理功能、代谢能力和进化的研究以及食品微生物群落结构、动态变化及其对环境的响应机制等方面。另外,通过对食品微生物基因组和元基因组进行数据分析,也对食品发酵过程优化、微生物功能改造、食源性微生物疾病预防和控制等提供了重要的依据。本文总结了近年来利用高通量测序技术对食品微生物基因组和元基因组进行测序的研究,并探讨了测序技术的发展对食品微生物研究的影响及发展趋势。     

Microbes in food processing technology

Abstract: There is an increasing understanding that the microbial quality of a certain food is the result of a chain of events. It is clear that the microbial safety of food can only be guaranteed when the overall processing, including the production of raw materials, distribution and handling by the consumer are taken into consideration. Therefore, the microbiological quality assurance of foods is not only a matter of control, but also of a careful design of the total process chain. Food industry has now generally adapted quality assurance systems and is implementing the Hazard Analysis Critical Control Point (HACCP) concept. Rapid microbiological monitoring systems should be used in these cases. There is a need for rapid and simple microbiological tests which can be adapted to the technology and logistics of specific production processes. Traditional microbiological methods generally do not meet these high requirements. This paper discusses the tests, based on molecular biological principles, to detect and identify microbes in food-processing chains. Tests based on DNA technology are discussed, including in vitro DNA amplification like the polymerase chain reaction (PCR) method and identifications based on RFLP, RAPD and DNA fingerprinting analysis. PCR-haled methodology can be used for the rapid detection of microbes in food manufacturing environments. In addition, DNA fingerprinting methods are suitable for investigating sources and routes of microbial contamination in the food cycle.     

Methodologies for the characterization of microbes in industrial environments: a review

There is growing interest in research and development to develop novel tools to study, detect, and characterize microbes and their communities in industrial environments. However, knowledge about their validity in practical industrial use is still scarce. This review describes the advantages and limitations of traditional and molecular methods used for biofilm and/or planktonic cell studies, especially those performed with Listeria monocytogenes, Bacillus cereus, and/or Clostridium perfringens. In addition, the review addresses the importance of isolating the microorganisms from the industrial environment and the possibilities and future prospects for exploiting the described methods in the industrial environment.     

Modulation of the gut microbiota by nutrients with prebiotic properties: consequences for host health in the context of obesity and metabolic syndrome

The gut microbiota is increasingly considered as a symbiotic partner for the maintenance of health. The homeostasis of the gut microbiota is dependent on host characteristics (age, gender, genetic background...), environmental conditions (stress, drugs, gastrointestinal surgery, infectious and toxic agents...). Moreover, it is dependent on the day-to-day dietary changes. Experimental data in animals, but also observational studies in obese patients, suggest that the composition of the gut microbiota is a factor characterizing obese versus lean individuals, diabetic versus non diabetic patients, or patients presenting hepatic diseases such as non alcoholic steatohepatitis. Interestingly, the changes in the gut microbes can be reversed by dieting and related weight loss. The qualitative and quantitative changes in the intake of specific food components (fatty acids, carbohydrates, micronutrients, prebiotics, probiotics), have not only consequences on the gut microbiota composition, but may modulate the expression of genes in host tissues such as the liver, adipose tissue, intestine, muscle. This in turn may drive or lessen the development of fat mass and metabolic disturbances associated with the gut barrier function and the systemic immunity. The relevance of the prebiotic or probiotic approaches in the management of obesity in humans is supported by few intervention studies in humans up to now, but the experimental data obtained with those compounds help to elucidate novel potential molecular targets relating diet with gut microbes. The metagenomic and integrative metabolomic approaches could help elucidate which bacteria, among the trillions in human gut, or more specifically which activities/genes, could participate to the control of host energy metabolism, and could be relevant for future therapeutic developments.     

Biofilms as a microbial hazard in the food industry: A scoping review

Biofilms pose a serious public health hazard with a significant economic impact on the food industry. The present scoping review is designed to analyse the literature published during 2001–2020 on biofilm formation of microbes, their detection methods, and association with antimicrobial resistance (if any). The peer-reviewed articles retrieved from 04 electronic databases were assessed using PRISMA-ScR guidelines. From the 978 preliminary search results, a total of 88 publications were included in the study. On analysis, the commonly isolated pathogens were Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., Escherichia coli, Bacillus spp., Vibrio spp., Campylobacter jejuni and Clostridium perfringens. The biofilm-forming ability of microbes was found to be influenced by various factors such as attachment surfaces, temperature, presence of other species, nutrient availability etc. A total of 18 studies characterized the biofilm-forming genes, particularly for S. aureus, Salmonella spp., and E. coli. In most studies, polystyrene plate and/or stainless-steel coupons were used for biofilm formation, and the detection was carried out by crystal violet assays and/or by plate counting method. The strain-specific significant differences in biofilm formation were observed in many studies, and few studies carried out analysis of multi-species biofilms. The association between biofilm formation and antimicrobial resistance was not clearly defined. Further, viable but non-culturable form of the foodborne pathogens is posing an unseen (by conventional cultivation techniques) but potent threat to the food safety. The present review recommends the need for carrying out systematic surveys and risk analysis of biofilms in food chain to highlight the evidence-based public health concerns, especially in regions where microbiological food hazards are quite prevalent.     

Challenges in discovering bioactives for the food industry

Nutritional interventions are associated with transient deviations of homeostasis within the human body. The role of a balanced nutrition is, firstly, to ensure an adequate intake of nutrients to efficiently enable all metabolic processes and, secondly, to contribute to sustained human health. This is a new challenge for the food industry because consumers demand taste and convenience in addition to healthy food. The attempts of the food industry to omit health-adverse compounds, and incorporate constituents with identified beneficial health effects has coined the term 'functional food', encompassing fresh or processed food with health-promoting and/or disease-preventing properties. The active ingredients of these products are known as 'nutraceuticals'. This paper outlines scientific concepts applied to the identification of novel bioactive food ingredients.     

Immunoglobulin E mediated food allergy.Modelling and application of diagnostic and predictive tests for existing and novel foods

It is known that some foods cause an allergenic response in certain individuals. Clinical and immunological tests are available for the diagnosis of food allergy and identification of food allergens. However, there are no valid tests for the prediction of the allergenic potential of foods not normally recognized as allergenic. Such foods include: food products developed from foods which may not be recognizable as allergenic in their modified forms; foods produced using novel processes (novel foods), for example genetically modified foods; and foods not normally consumed but that are being used increasingly as alternatives to more traditional foods. Both the risks associated with food allergy and the fact that foods such as the ones described above will become available to the consumer, highlight the need for methods to screen for potential food allergens. This review provides a general overview of food allergy including mechanism, development and prevalence, but focuses on and discusses: 1) the possible risks (with specific reference to food allergy) associated with new and novel foods; and 2) the development/use of food allergy models (in vivo and in vitro) to assess the allergenic potential of new and novel foods.     

Fermentation of food and feed: A technology for efficient utilization of macro and trace elements in monogastrics

Mineral deficiencies, especially of iron, zinc, and calcium, respectively, negatively affect human health and may lead to conditions such as iron deficiency anemia, rickets, osteoporosis, and diseases of the immune system. Cereal grains and legumes are of global importance in nutrition of monogastrics (humans and the respective domestic animals) and provide high amounts of several minerals, e.g., iron, zinc, and calcium. Nevertheless, their bioavailability is low. Plants contain phytates, the salts of phytic acid, chemically known as inositol-hexakisphosphate, which interact with several minerals and proteins. However, phytate may be hydrolysed by phytase. This enzyme is naturally present in plants and also widely distributed in microorganisms. Several food processing methods have been reported to enhance phytate hydrolysis, due to the activation of endogenous phytase activity or via the enzyme produced by microbes. In recent years, fermentation for food and feed improvement and preservation, respectively, has gained increasing interest as a promising method to degrade phytate and enhance mineral utilization in monogastrics. Indeed, several in vitro as well as in vivo studies confirm a positive effect on the utilization of minerals, such as P, Ca, Fe and Zn, using sourdough fermentation for baking or fermentation of legumes, mainly soybeans. This review summarizes the current knowledge regarding the potential of fermentation to enhance macro and trace element bioavailability in monogastric species.     

Influence of dietary fat on intestinal microbes,inflammation, barrier function and metabolic outcomes

Recent studies using germ-free, gnotobiotic microbial transplantation/conventionalization or antibiotic treatment in rodent models have highlighted the critical role of intestinal microbes on gut health and metabolic functions of the host. Genetic and environmental factors influence the abundance and type of mutualistic vs. pathogenic bacteria, each of which has preferred substrates for growth and unique products of fermentation. Whereas some fermentation products or metabolites promote gut function and health, others impair gut function, leading to compromised nutrient digestion and barrier function that adversely impact the host. Such products may also influence food intake, energy harvest and expenditure, and insulin action, thereby influencing adiposity and related metabolic outcomes. Diet composition influences gut microbiota and subsequent fermentation products that impact the host, as demonstrated by prebiotic studies using oligosaccharides or other types of indigestible fiber. Recent studies also show that dietary lipids affect specific populations of gut microbes and their metabolic end products. This review will focus on studies examining the influence of dietary fat amount and type on the gut microbiome, intestinal health and positive and negative metabolic consequences. The protective role of omega-3-rich fatty acids on intestinal inflammation will also be examined.     

Metabolomics methods for the synthetic biology of secondary metabolism

Many microbial secondary metabolites are of high biotechnological value for medicine, agriculture, and the food industry. Bacterial genome mining has revealed numerous novel secondary metabolite biosynthetic gene clusters, which encode the potential to synthesize a large diversity of compounds that have never been observed before. The stimulation or "awakening" of this cryptic microbial secondary metabolism has naturally attracted the attention of synthetic microbiologists, who exploit recent advances in DNA sequencing and synthesis to achieve unprecedented control over metabolic pathways. One of the indispensable tools in the synthetic biology toolbox is metabolomics, the global quantification of small biomolecules. This review illustrates the pivotal role of metabolomics for the synthetic microbiology of secondary metabolism, including its crucial role in novel compound discovery in microbes, the examination of side products of engineered metabolic pathways, as well as the identification of major bottlenecks for the overproduction of compounds of interest, especially in combination with metabolic modeling. We conclude by highlighting remaining challenges and recent technological advances that will drive metabolomics towards fulfilling its potential as a cornerstone technology of synthetic microbiology.     

Field evidence for a proximate role of food shortage in the regulation of hibernation and daily torpor: a review

Hibernation and daily torpor (heterothermy) have long been assumed to be adaptive responses to seasonal energy shortage. Laboratory studies have demonstrated that food shortage alone can trigger the use of heterothermy. However, their potential to predict heterothermic responses in the wild is limited, and few field studies demonstrate the dependence of heterothermy on food availability under natural conditions. Thus, the view of heterothermy as an energy saving strategy to compensate for food shortage largely remains an untested hypothesis. In this paper, we review published evidence on the proximate role of food availability in heterothermy regulation by endotherms, and emphasize alternative hypotheses that remain to be tested. Most studies have relied on correlative evidence. Manipulations of food availability, that demonstrate the proximate role of food availability, have been conducted in only five free-ranging heterotherms. Several other metabolic constraints covary with food availability and can confound its effect. Shortage in water availability, the nutritional composition of food, or subsequent conversion of food in fat storage all could be actual proximate drivers of heterothermy regulation, rather than food shortage. Social interactions, competition for food and predation also likely modulate the relative strength of food shortage between individuals. The ecological relevance of the dependence of heterothermy on food availability remains to be assessed in field experiments that account for the confounding effects of covarying environmental and internal factors.     

Applications of nonthermal plasma technology on safety and quality of dried food ingredients

Cold plasma technology is an efficient, environmental-friendly, economic and noninvasive technology; and in recent years these advantages placed this novel technology at the centre of diverse studies for food industry applications. Dried food ingredients including spices, herbs, powders and seeds are an important part of the human diet; and the growing demands of consumers for higher quality and safe food products have led to increased research into alternative decontamination methods. Numerous studies have investigated the effect of nonthermal plasma on dried food ingredients for food safety and quality purposes. This review provides critical review on potential of cold plasma for disinfection of dried food surfaces (spices, herbs and seeds), improvement of functional and rheological properties of dried ingredients (powders, proteins and starches). The review further highlights the benefits of plasma treatment for enhancement of seeds performance and germination yield which could be applied in agricultural sector in near future. Different studies applying plasma technology for control of pathogens and spoilage micro-organisms and modification of food quality and germination of dried food products followed by benefits and current challenges are presented. However, more systemic research needs to be addressed for successful adoption of this technology in food industry.     

Planktonic microbes: Tiny cells at the base of the ocean's food webs

Phytoplankton in the size range 5-100 μm was originally thought to be the primary source of food for most life in the sea. However, smaller planktonic microbes, down to 0.2 μm in size, have been the focus of intensive investigation by marine scientists during the past two decades. These microbes attain high abundance and biomass in all parts of the world ocean. They include non-photosynthesizing bacteria, at least two types of photosynthesizing prokaryotes, and eukaryotic phototrophs. The new information has resulted in a greatly revised concept of how pelagic ecosystems in both marine and freshwater environments function. The original idea of a basically linear food chain from diatoms to copepods to fish has given way to an extremely complex model of trophic interactions within a microbial food web, which supports metazoan food webs via biomass production of both heterotrophic and autotrophic cells.     

生物芯片技术在食品检测中的应用

生物芯片检测技术是一种全新的微量分析技术。生物芯片基本技术包括方阵构建、样品制备、化学反应和结果检测 ;生物芯片技术在食品微生物领域、食品毒理学、营养学、转基因产品检测中均有应用     

Pulsed-light system as a novel food decontamination technology: a review

In response to consumer preferences for high quality foods that are as close as possible to fresh products, athermal technologies are being developed to obtain products with high levels of organoleptic and nutritional quality but free of any health risks. Pulsed light is a novel technology that rapidly inactivates pathogenic and food spoilage microorganisms. It appears to constitute a good alternative or a complement to conventional thermal or chemical decontamination processes. This food preservation method involves the use of intense, short-duration pulses of broad-spectrum light. The germicidal effect appears to be due to both photochemical and photothermal effects. Several high intensity flashes of broad spectrum light pulsed per second can inactivate microbes rapidly and effectively. However, the efficacy of pulsed light may be limited by its low degree of penetration, as microorganisms are only inactivated on the surface of foods or in transparent media such as water. Examples of applications to foods are presented, including microbial inactivation and effects on food matrices.     

Review Functional morphology as an aid in determining trophic behaviour: the placement of astigmatic mites in food webs of water-filled tree-hole communities

The arthropod communities of phytotelmata (plant-held waters) are considered excellent subjects for studying and testing community theory. Food webs constructed for phytotelm communities, however, usually exclude mites or determine their placement based on little, if any, actual knowledge of their trophic behaviour. Although individually small, many acarine species attain high population levels and therefore may be important as prey for other inhabitants, as processing chain species in commensal relationships and as competitors of the larger tree-hole inhabitants. An understanding of the trophic relationships of acarine inhabitants is therefore essential to an understanding of the dynamics of phytotelm communities. Studies emphasizing the functional morphology of mouth parts of astigmatic species inhabiting water-filled tree holes in the eastern USA and in Queensland, Australia, reveal a diversity of trophic groups. Among these are 'shredders' who ingest leaf material and associated microbes by biting off chunks of leaves, 'scrapers' (= grazers) who crop fungal hyphae and/or other microbes and detritus from the substrate surface and 'collectors' who filter microbes and fine particulate matter from the water. This information allows for the more exact placement of acarine inhabitants in food webs of water-filled tree holes.