Detection of a Vibrio sp. by the Bacteriophagous Nematode Pelodera chitwoodi

S ummary . Pelodera chitwoodi was able to distinguish between a Vibrio sp. (food bacterium) and Chromobacterium janthinum (non-food bacterium), and between bacteria and mud. Nematodes migrated preferentially to the Vibrio sp. at various distances, temperatures, and pH values. Migration to food bacteria increased with an increase in bacterial concentration. Resting and dead bacteria failed to attract nematodes. Nematodes were able to detect a vibrio colony separated from them by a plastic barrier, and migrated to areas on agar containing exudate and dialysate from the vibrio. Both exudate and dialyzate contained 4 amino acids and 3 vitamins which attracted nematodes. However, attraction of nematodes to these compounds was not as strong as to metabolizing bacteria, indicating that additional compounds were also involved.     

Antimicrobial properties of phenolic compounds from berries

AIMS: To investigate the antimicrobial properties of phenolic compounds present in Finnish berries against probiotic bacteria and other intestinal bacteria, including pathogenic species. METHODS AND RESULTS: Antimicrobial activity of pure phenolic compounds representing flavonoids and phenolic acids, and eight extracts from common Finnish berries, was measured against selected Gram-positive and Gram-negative bacterial species, including probiotic bacteria and the intestinal pathogen Salmonella. Antimicrobial activity was screened by an agar diffusion method and bacterial growth was measured in liquid culture as a more accurate assay. Myricetin inhibited the growth of all lactic acid bacteria derived from the human gastrointestinal tract flora but it did not affect the Salmonella strain. In general, berry extracts inhibited the growth of Gram-negative but not Gram-positive bacteria. These variations may reflect differences in cell surface structures between Gram-negative and Gram-positive bacteria. Cloudberry, raspberry and strawberry extracts were strong inhibitors of Salmonella. Sea buckthorn berry and blackcurrant showed the least activity against Gram-negative bacteria. CONCLUSION: Different bacterial species exhibit different sensitivities towards phenolics. SIGNIFICANCE AND IMPACT OF THE STUDY: These properties can be utilized in functional food development and in food preservative purposes.     

New insights in agar biorefinery with arylsulphatase activities

Agar is a major gelling agent used both in food and pharmaceutical applications. Traditional purification of agar is generally performed by sequential time consuming chemical and/or physical steps, leading to both poor recovery yields and low productivities. As a consequence, only 30% of the amount of agar produced is actually available under purified form to feed the world market.The current limiting factor for purification is the presence of sulphated compounds such as sulphated-agaropectin, which strongly affect the technological properties of the agar gel such as gel strength, melting and fusion temperatures and electroendosmosis.In this context, this communication aims at discussing about the development of a biorefining agar purification approach which allows overcoming the current limitations associated with traditional purification methods. More specifically, this article focuses on the potential role of arylsulphatases in agar purification processes to reduce the number of purification steps and to improve recovery yields.This review first presents the global gelling agents market before focusing on agar characteristics and production processes. Then, after a brief reminder of the sulphur metabolism, the roles, classes and properties of the different arylsulphatases are described to draw perspectives on their integration in current or new agar production processes.     

Cardoon as a Sustainable Crop for Biomass and Bioactive Compounds Production

Cardoon is a multi‐purpose and versatile Mediterranean crop, adapted to climate change, with a wide spectrum of potential applications due its added value as a rich source of fibers, oils and bioactive compounds. The Cynara species are a component of the Mediterranean diet and have been used as food and medicine since ancient times. The important role of cardoon in human nutrition, as a functional food, is due to its high content of nutraceutical and bioactive compounds such as oligofructose inulin, caffeoylquinic acids, flavonoids, anthocyanins, sesquiterpenes lactones, triterpenes, fatty acids and aspartic proteases. The present review highlights the characteristics and functions of cardoon biomass which permits the development of innovative products in food and nutrition, pharmaceutics and cosmetics, plant protection and biocides, oils and energy, lignocellulose materials, and healthcare industries following the actual trends of a circular economy.     

Physiological diversity of bacterial communities from different soil locations on Livingston Island, South Shetland archipelago, Antarctica

Terrestrial food webs of Antarctica are simple and dominated by microorganisms. Soil bacteria play an important role in nutrient cycling, yet little is known about their capacity to utilize different carbon sources and to participate in site nutrient turnover. Biolog EcoPlate? was applied to study the catabolic activity and physiological diversity of bacteria inhabiting the soil of moss, vascular plants, and fell field habitats from Livingston Island, Antarctica. Additionally, the number of oligotrophic and copiotrophic bacteria was counted by the agar plate method. Results indicated a lack of site-specific distribution of bacterial abundance, in contrast to bacterial catabolic activity and community level physiological profiles. Community level physiological profiles revealed a common capacity of soil bacteria to intensively utilize polyols, which are cryoprotectants widely produced by Antarctic organisms, as well as site-specific phenolic compounds (vegetated habitats), amino acids/amines (moss habitats), carbohydrates and carboxylic acids (fell field habitat). It was concluded that the physiology of soil bacteria is habitat specific concerning both the rate of catabolic activity and pattern of carbon source utilization.     

Humus acids as a nutrition source for some white-rot fungi

The rate of growth of 5 species of white-rot fungi on an agar medium with additions of humus acids was used for assessing the ability of these fungi to utilize humus acids as a sole source of nutrition. Differences in the effect of the various fractions of humus acids and their concentrations, as well as in the reaction of the fungi tested were observed. During the growth, loss of colour of agar media with humus acids was observed. Activity of lacease in the discoloured areas was highest.     

Effects of dietary factors on oxidation of low-density lipoprotein particles

Oxidized low-density lipoproteins (ox-LDLs) appear to play a significant role in atherogenesis. In fact, circulating ox-LDL concentrations have been recognized as a risk factor for cardiovascular disease (CVD). A higher intake of some nutrients and specific food compounds such as monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs) and flavonoids have also been associated with a lower risk of CVD. These dietary factors could be associated to a lower risk of CVD through a reduction of the atherogenicity of LDL particles through limited oxidation. Therefore, the purpose of this article is to review human clinical studies that evaluated effects of dietary antioxidant vitamins, fatty acids (MUFA, PUFA) and specific flavonoid-rich foods on LDL particle oxidation and describe potential mechanisms by which dietary factors may prevent oxidation of LDL particles. Antioxidant vitamin supplements such as alpha-tocopherol and ascorbic acid as well as beta-carotene and fish-oil supplements have not been clearly demonstrated to prevent oxidation of LDL particles. Moreover, inconsistent documented effects of flavonoid-rich food such as olive oil, tea, red wine and soy on LDL particle oxidizability may be explained by difference in variety and quantity of flavonoid compounds used among studies. However, a healthy food pattern such as the Mediterranean diet, which includes a combination of antioxidant compounds and flavonoid-rich foods, appears effective to decrease LDL particle oxidizability, which may give some insight of the cardiovascular benefits associated with the Mediterranean diet.     

Lipoxygenases: Potential starting biocatalysts for the synthesis of signaling compounds

Lipoxygenases (LOXs) have attracted a great deal of attention as potential starting biocatalysts for synthesizing signaling compounds. Significant advances during the past decade include the discovery of regiospecific LOXs and structural investigation for their diverse regiospecificity. Eight regiospecific (5-, 8-, 9-, 10-, 11-, 12-, 13-, and 15-) LOXs catalyze positional-specific dioxygenation of polyunsaturated fatty acids, forming positional-specific hydroperoxy fatty acids that are further metabolized into signaling compounds. The LOX-derived signaling compounds can be applied not only for clinical uses but also for industrial uses. For example, animal lipoxin LXA₄, plant jasmonic acids, plant green leaf volatiles, and bacterial lactones have been used as anti-inflammatory agents, anti-pest agents, flavors, and food additives, respectively. Prostaglandins, as controllers of hormone regulation and cell growth, are also suggested as LOX-derived compounds in corals.     

Amperometric study of the inhibitory effect of carboxylic acids on tyrosinase

A tyrosinase-modified Pt electrode, based on physical entrapment of the enzyme in agar–agar gel, was constructed and used to investigate the inhibitory effect of six carboxylic acids. At an applied potential of −50 mV versus saturated calomel electrode (SCE), the bioelectrode develops a fast, steady state response, linearly correlated with the phenol concentration up to 10 mg/l, with a sensitivity of 3.7 nA l/mg. A kinetic analysis of the amperometric response to phenol, recorded in the absence and in the presence of carboxylic acids (benzoic, 3-bromobenzoic, 4-ethylbenzoic, acetic, phenylacetic, 2-naphthylacetic acids), revealed that for the first four compounds the inhibition process corresponds to an uncompetitive one. Using the Lineweaver–Burk linearization the inhibition constants as well as the inhibition coefficients were calculated for the strong inhibitors: benzoic, 3-bromobenzoic, 4-ethylbenzoic and acetic acids.     

疏水载体固定化胆碱酯酶的研究

首次摸索了带有疏水基团琼脂珠固定化鸭血清胆碱酯酶的最佳条件,固定化酶活力回收为７０一７６％。探讨了不同疏水基团对固定化酶偶联率、稳定性及对有机磷化合物灵敏度的影响。α－萘氨基、Ｐ－甲苯氨基和苄氨基载体固定化酶连续操作半哀期分别为２２．３ｈ,２１．７ｈ,１２．８ｈ,对有机磷化合物Ｖｘ和ＧＢ的灵敏度分别提高了２．２～１２．６倍和２．３～４．９倍,这对于在环境保护、食品检验、军事侦检等领域检测微量有机磷化合物具有重要意义。     

Dietary fatty acids promote sleep through a taste‐independent mechanism

Consumption of foods that are high in fat contribute to obesity and metabolism‐related disorders. Dietary lipids are comprised of triglycerides and fatty acids, and the highly palatable taste of dietary fatty acids promotes food consumption, activates reward centers in mammals and underlies hedonic feeding. Despite the central role of dietary fats in the regulation of food intake and the etiology of metabolic diseases, little is known about how fat consumption regulates sleep. The fruit fly, Drosophila melanogaster, provides a powerful model system for the study of sleep and metabolic traits, and flies potently regulate sleep in accordance with food availability. To investigate the effects of dietary fats on sleep regulation, we have supplemented fatty acids into the diet of Drosophila and measured their effects on sleep and activity. We found that flies fed a diet of hexanoic acid, a medium‐chain fatty acid that is a by‐product of yeast fermentation, slept more than flies starved on an agar diet. To assess whether dietary fatty acids regulate sleep through the taste system, we assessed sleep in flies with a mutation in the hexanoic acid receptor Ionotropic receptor 56D, which is required for fatty acid taste perception. We found that these flies also sleep more than agar‐fed flies when fed a hexanoic acid diet, suggesting the sleep promoting effect of hexanoic acid is not dependent on sensory perception. Taken together, these findings provide a platform to investigate the molecular and neural basis for fatty acid‐dependent modulation of sleep.     

Mathematical Model of Interaction Between Bacteriocin-Producing Lactic Acid Bacteria and Listeria. Part 2: Bifurcations and Applications

The big challenge for the food industry is the attending to demands for minimally processed foods, avoiding intense heat treatments and reducing the addition of chemical preservatives, but at the same time ensuring microbiological safety of these products. Lactic acid bacteria are traditionally used in the production of fermented foods. They are responsible for the production of antimicrobial compounds, such as organic acids and bacteriocins, which are protein compounds with bactericidal effect against related species and bacteria such as Listeria monocytogenes and Staphylococcus aureus. Aiming to study quantitatively the biological control as a technique of conservation, we developed a mathematical model to describe the interaction between lactic acid bacteria and Listeria in the food. The steady state and dynamical trajectories analyses of the model permit us to study the suitability of including lactic acid bacteria in order to reduce the growth of Listeria in food.     

Determination of amino acids in diverse polymeric matrices using HPLC, with emphasis on agars and agaroses

Determination of amino acids in polymers with varying structure and charge was performed using vapor phase acid hydrolysis and subsequent precolumn derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). Percent load of neutral, cationic and anionic peptide-modified synthetic polymers was accurately determined using this technique. Assay utility was shown for glycosaminoglycans and other sulfated polymers, neutral carbohydrate polymers such as agar, agarose, and cellulose, and polymers such as lipopolysaccharide and deoxyribonucleic acid. The carboxylated and sulfated molecules included chondroitin sulfate, hyaluronic acid, dermatan sulfate, and heparin, and the sulfated polymers included fucoidan, carrageenan, and dextran sulfate, as examples. Assayed cumulative amino acid concentrations (i.e. protein levels) are reported, although amino acid distribution data was also available from the analysis. Recovery was acceptable for the various compounds tested and did not correlate with structure. However, different sample sizes were necessary to achieve acceptable recovery, depending on the level of protein present in the matrix. While some matrices contained peaks in addition to the amino acids and amino sugars, they were not found to interfere using the standard gradient separation. Assayed amino acid profiles were compared for agaroses with differing electroendosmosis values and for agar samples from different parts of the globe. While the amounts of protein varied depending on source, the relative distribution of amino acids was very similar across the agar samples surveyed.     

Efficient use of shrimp waste: present and future trends

The production of shrimp waste from shrimp processing industries has undergone a dramatic increase in recent years. Continued production of this biomaterial without corresponding development of utilizing technology has resulted in waste collection, disposal, and pollution problems. Currently used chemical process releases toxic chemicals such as HCl, acetic acid, and NaOH into aquatic ecosystem as byproducts which will spoil the aquatic flora and fauna. Environmental protection regulations have become stricter. Now, there is a need to treat and utilize the waste in most efficient manner. The shrimp waste contains several bioactive compounds such as chitin, pigments, amino acids, and fatty acids. These bioactive compounds have a wide range of applications including medical, therapies, cosmetics, paper, pulp and textile industries, biotechnology, and food applications. This current review article present the utilization of shrimp waste as well as an alternative technology to replace hazardous chemical method that address the future trends in total utilization of shrimp waste for recovery of bioactive compounds.     

不同酶对草鱼蛋白功能特性及风味成分的影响

通过蛋白酶对草鱼进行酶解,对其酶解产物的功能特性和酶解液的风味成分进行研究。结果显示,风味蛋白酶、胰蛋白酶酶解产物的溶解性、热稳定性均优于胃蛋白酶酶解产物(P0.05)。经酶处理后鱼肉酶解液鲜甜味氨基酸占比增加,苦味氨基酸占比减少;利用SPME-GC-MS共检测出83种挥发性成分,以醛酮类和醇类为主,酶解处理后醇类的相对含量显著减少,醛酮类的相对含量则显著增加,酶解液具有独特风味。经胰蛋白酶、风味蛋白酶酶解后的草鱼肉酶解产物及酶解液均可作为食品基料应用于加工中。     

The synergism of natural compounds in the pursuit of safe and healthier food

Food producers apply modern processing techniques and use a variety of preservative additives to guarantee safe food and a longer shelflife. Regrettably many of these impact the sensory characteristics of the foodstuffs, such as colour, texture, and flavour, which can result in low consumer acceptance. Additionally, strategies used to reduce growth of spoilage and pathogenic bacteria are not selective enough and may inactivate also desired microbiota. Food is usually overdosed with antimicrobials that are supplemented ‘just in case.’ Consequently, food producers are searching for natural preservation methods that are not harmful to humans. Nature offers a wide spectrum of biologically active (phyto) chemicals that can be used as potential natural preservatives. Compounds with bacterial growth-limiting properties are detected in all parts of plants, including their leaves, flowers, fruits, roots, etc. These are mostly acids, alcohols, medium and long-chain organic acids, terpenic compounds, and their derivatives. This study focused on the effectiveness of plant extracts, i.e., synergism between terpenoids and medium chain fatty acids in cured cooked meat. Bacterial strains that were tested include typical members of the spoilage microflora in vacuum (Lactobacillus curvatus) and MA-packed meats (Brochothrix thermosphacta). These were isolated and identified in a separate study. L. curvatus was observed to be very resistant against either terpenoids or fatty acids when used separately, whereas its growth was strongly inhibited when both chemicals were combined. Growth of B. thermosphacta was significantly inhibited when antimicrobial compounds were solely applied, whereas a blend of terpenoids and fatty acids showed an almost bactericidal effect.     

利用酵母菌生产有机酸的研究进展

有机酸是含有一种或多种低分子量酸性基团(如羧基、磺酸基)的可生物合成的有机化合物,广泛应用于食品、农业、医药、生物基材料工业等领域。酵母菌具有生物安全、抗逆性强、底物谱广泛、方便遗传改造,以及大规模培养技术成熟等独特优点,因此利用酵母菌生产有机酸的研究日益受到国内外学者的关注。目前利用酵母生产有机酸还存在浓度低、副产物多,以及发酵效率低等缺陷。随着酵母菌代谢工程和合成生物学技术的发展,利用酵母菌生产有机酸取得了快速进展。本文总结了利用酵母合成11种有机酸的研究,包括内源和异源合成的大宗羧酸和高价值有机酸,并对该领域的未来研究方向进行了展望。     

In vitro genotoxicity assessment of caffeic, cinnamic and ferulic acids

Phenols are a large and diverse class of compounds, many of which occur naturally in a variety of food plants; they exhibit a wide range of biological effects, including antibacterial, anti-inflammatory, antiallergic, hepatoprotective, antithrombotic, antiviral, anticarcinogenic, and vasodilatory actions. We examined the genotoxic and clastogenic potential of three phenolic compounds: caffeic, cinnamic and ferulic acids, using the comet and micronucleus assays in vitro. Drug-metabolizing rat hepatoma tissue cells (HTCs) were used. Three different concentrations (50, 500 and 1500 μM) of these phenolic acids were tested on the HTCs for 24 h. The caffeic, cinnamic and ferulic acids were not genotoxic by the comet assay (P > 0.05). However, the micronucleus test showed an increase in the frequency of micronucleated cells for the three compounds, indicating that these substances have clastogenic effects in HTC.     

Hydrocarbons,free fatty acids,and amino acids of sclerotia of Sclerotinia sclerotiorum

Summary Sclerotia of Sclerotinia sclerotiorum (Lib.) D By. were obtained from commercial pea-and bean-cleaning operations or grown on potato-dextrose agar and synthetic glucose-and sucrose-salts agar media. The crude fat (ether extract) content of sclerotia varied from 0.8 to 1.5%. Extraction and fractionation of the lipids followed by gas chromatographic analysis showed that sclerotia from pea cleanings contained one predominant hydrocarbon which was absent from sclerotia produced in the laboratory. Sclerotia from natural sources and grown in the laboratory contained a similar distribution of C₁₈ unsaturated free fatty acids, however, quantitative differences were noted. Palmitic, oleic and linoleic were the major free fatty acids of the laboratory-grown sclerotia while a high proportion of linoleic acid was also found in sclerotia from natural sources. Sclerotia were fractionated into water-soluble and water-insoluble fractions. After acid hydrolysis of the waterinsoluble fraction, both fractions were analyzed for amino acids. Twenty-one compounds, including 2 unknowns, were detected in the soluble fraction. The hydrolyzates contained 19 amino acids, including the same 2 unknowns. Two compounds tentatively identified as ornithine and -aminobutyric acid were found only in the water-soluble fraction. The relative amino acid composition of the water-insoluble fraction of sclerotia from various sources was fairly constant but the arginine content decreased on the synthetic media.     

Nutrient medium for the isolation of hemocultures from brucellosis patients]

To isolate brucellosis causative agent from the blood of patients against the background of antibiotic therapy the authors used for the first time the medium consisting of aminopeptide, beta-globulin agar with glucose, glycerine, and twin-60. No valuable food products--meat, liver--were required to prepare the medium; by-product of gamma-globulin production being used. With the aid of the suggested medium there was isolated 2.4 times more hemocultures than on the widely used meat-peptone medium. This is attributed to the presence in the medium of human protein, essential amino acids, and blood mineral substances, which, in combination, facilitated adaptation of brucellosis causative agent to the nutrient medium similar to human blood by composition. Economical effect in using the mentioned medium constituted 53.8% annually.