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Implanted medical devices such as central venous catheters are highly susceptible to microbial colonization and biofilm formation, and are a major risk factor for nosocomial infections. The opportunistic pathogen Pseudomonas aeruginosa uses exopolysaccharides, such as Psl, for both initial surface attachment and biofilm formation. We have previously shown that chemically immobilizing the Psl-specific glycoside hydrolase, PslG(h), to a material surface can inhibit P. aeruginosa biofilm formation. Herein we show that PslG(h) can be uniformly immobilized on the lumen surface of medical-grade, commercial polyethylene, polyurethane, and polydimethylsiloxane (silicone) catheter tubing. We confirmed the surface-bound PslG(h) was uniformly distributed along the catheter length and remained active even after storage for 30 days at 4 °C. P. aeruginosa colonization and biofilm formation under dynamic flow culture conditions in vitro showed a 3-log reduction in the number of bacteria during the first 11 days, and a 2-log reduction by day 14 for PslG(h) modified PE-100 catheters, compared to untreated catheter controls. In an in vivo rat infection model, PslG(h)-modified PE-100 catheters showed ~1.5-log reduction in the colonization of the clinical P. aeruginosa ATCC 27853 strain after 24 hours. These results demonstrate the robust ability of surface-bound glycoside hydrolase enzymes to inhibit biofilm formation, and their potential to reduce rates of device-associated infections.

With growing consumer awareness, exploitation of renewable resources is cost-effective and environment friendly. This work examines the potential of citrus peels as natural antioxidants and antimicrobials for food preservation. Extraction yield, total soluble phenols and flavonoids of various citrus peels (sweet orange, lemon, tangerine and grapefruit) were optimized by varying the solvent type. While the highest extract yield (~16 ​g/100g) was obtained from the sweet orange peels in methanol, extraction with ethanol maximized the concentration of total phenols and flavonoids (~80 ​mg catechol equivalents/100 ​g dry weight). In addition, sweet orange peel extract showed the highest DPPH, ABTS and hydroxyl radical scavenging values. UPLC-ESI-MS/MS analysis of aqueous and ethanolic extracts of sweet orange peels revealed more than 40 polyphenolic compounds including phenolic acids and flavonoids, some of which have not been previously reported. The predominant polyphenols were narirutin, naringin, hesperetin-7-O-rutinoside naringenin, quinic acid, hesperetin, datiscetin-3-O-rutinoside and sakuranetin. The incorporation of sweet orange peel extract into two vegetable oils enhanced their oxidative stability. In addition, all citrus peel extracts possessed high antimicrobial activity against several food-borne pathogens, and the activity was highest for the sweet orange peel extract. Overall results suggested the great potential of sweet orange peels as natural antioxidant and antimicrobials, which can be efficiently extracted using a simple and low-cost method, for enhancing the storage stability and safety of vegetable oils., Graphical abstract Image 1, Highlights • Citrus peels extracts exhibited high contents of polyphenols and flavonoids with high antioxidant and antimicrobial capacities. • Sweet orange peel extracts in ethanol and water showed high yield of polyphenols and flavonoids. • The polyphenolic compounds (~40) in sweet orange peel extracts were identified and quantified by UPLC-ESI-MS/MS. • Supplementing orange peel extract into edible oils prevented rancidity.

Fungal growth and mycotoxin production on foods and feeds cause poisoning and serious human diseases that may lead to death. Chemical preservatives and fungicides have negative impacts on both health and environment. In contrast, bio preservatives such as lactic acid bacteria (LAB) are effective, safe, biodegradable and have additional health benefits. Among 23 rod-shaped LAB strains that were isolated from Egyptian traditional fermented milk (Rayeb), strain RM1 showed the highest antifungal potency. Phylogenetic analysis based on complete 16S rRNA gene and unique phenotypic characteristics differentiated strain RM1 from the closely related Lactobacillus species suggesting it represents a novel species, for which the name Lactobacillus sp. RM1 is proposed. The cell-free supernatant (CFS) of Lactobacillus sp. RM1exhibited strong and broad antimicrobial activity against both toxigenic fungi and harmful bacteria. The chemical composition of CFS determined by GC–MS showed a wide variety of antioxidant and antimicrobial compounds. A complete inhibition of both aflatoxins B1 and ochratoxin A production was obtained at a CFS concentration of 15 mg/mL. When the CFS was used to treat wheat grains, the growth mycelia of Aspergillus parasiticus were completely inhibited after 2 weeks of incubation compared with untreated grains, which were covered with a mat of the fungus. The antifungal activity of Lactobacillus sp. RM1 against common toxigenic fungi, and its ability extend the shelf life of wheat grains prove its potential application as a natural preservative for food products. Keywords: Lactic acid bacteria, Lactobacillus sp. RM1, Mycotoxins, Antifungal, Fungal growth, Cell-free supernatant, HPLC, GC–MS

Citrus peels are nonedible by-products that are often discarded. This work explores the bioactive compounds extracted from the peels of 4 local citrus fruits, their antioxidant and antimicrobial activities and applicability as natural antioxidants for vegetable oils. Total soluble phenols and total flavonoids were extracted from orange, lemon, tangerine and grapefruit peels using various solvents. Orange peel methanol extract produced the highest yield (~16 g/100g), however using ethanol maximized the concentration of total phenols (~345 mg Gallic acid equivalents/100g dry weight) as well as total flavonoids (~80 mg catechol equivalents/100g). In general, extracts with high total phenolic contents exhibited high antioxidant capacities. The orange peel ethanol extract showed the highest DPPH and ABTS values while its methanol extract exhibited the highest hydroxyl radical scavenging value. In addition, all citrus peel extracts possessed high antimicrobial activity against several food-borne Gram-negative and Gram-positive pathogenic bacteria and fungi. The composition of polyphenolic compounds in orange peel extracts analyzed by ultra-performance liquid chromatography combined with mass spectrometry (UPLC-ESI-MS/MS) revealed the presence of 22 and 32 compounds in the aqueous and ethanolic extracts, respectively. The predominant compounds were narirutin, naringin, hesperetin-7-O-rutinoside naringenin, quinic acid, hesperetin, datiscetin-3-O-rutinoside and sakuranetin. Importantly, incorporation of orange peel extract into vegetable oils greatly enhanced their oxidative stability compared to a synthetic antioxidant (BHT). Overall results support the potential of citrus peels as natural antioxidants and antimicrobials for enhancing the shelf life, storage stability and safety of food oils.

Ketocarotenoids are high-value natural pigments. The red diketocarotenoid astaxanthin particularly exhibits an extraordinary antioxidant activity, which raises its market demand for foods and nutraceuticals. We screened for ketocarotenoid-producing bacteria from both marine and freshwater environments. Phylogenetic analysis, based on 16S rRNA gene sequence, revealed 37 potential producers of ketocarotenoids that are related to α-proteobacteria, comprising 32 strains of Brevundimonas and 5 strains of Erythrobacter. Carotenoids analysis by HPLC-DAD and HPLC-MS revealed two groups; astaxanthin-producers (28 Brevundimonas strains) and adonixanthin-producers (Five Brevundimonas and 5 Erythrobacter strains). Strain FrW-Asx16 exhibited the highest carotenoid production (1060 µg g−1 dry cells with 16.6% astaxanthin). Strain FrW-Asx-5 producing 946.1 µg g−1 dry cells carotenoid exhibited the highest astaxanthin content (∼46%). The most intriguing result is the potential of producing natural colorants from freshwater bacterial isolates, and with high productivity and selectivity, suggesting a great promise for their application in food.

Bacterial colonization and biofilm formation on surfaces are typically mediated by the deposition of exopolysaccharides and conditioning protein layers. Pseudomonas aeruginosa is a nosocomial opportunistic pathogen that utilizes strain-specific exopolysaccharides such as Psl, Pel or alginate for both initial surface attachment and biofilm formation. To generate surfaces that resist P. aeruginosa colonization, we covalently bound a Psl-specific glycoside hydrolase (PslGh) to several, chemically-distinct surfaces using amine functionalization (APTMS) and glutaraldehyde (GDA) linking. In situ quartz crystal microbalance (QCM) experiments and fluorescence microscopy demonstrated a complete lack of Psl adsorption on the PslGh-bound surfaces. Covalently-bound PslGh was also found to significantly reduce P. aeruginosa surface attachment and biofilm formation over extended growth periods (8 days). The PslGh surfaces showed a ∼99.9% (∼3-log) reduction in surface associated bacteria compared to control (untreated) surfaces, or those treated with inactive enzyme. This work demonstrates a non-eluting ‘bioactive’ surface that specifically targets a mechanism of cell adhesion, and that surface-bound glycoside hydrolase can significantly reduce surface colonization of bacteria through local, continuous enzymatic degradation of exopolysaccharide (Psl). These results have significant implications for the surface design of medical devices to keep bacteria in a planktonic state, and therefore susceptible to antibiotics and antimicrobials.

Optimizing the macroscopic properties, shelf-life and stability of emulsion products requires a better understanding of the microstructural characteristics such as the type (nano, micro and macro) and the relative distribution of components (i.e., oil and surfactant) within the emulsion droplets. We used Diffusion-Ordered NMR Spectroscopy (DOSY NMR) to evaluate these characteristics in model oil-in-water emulsion containing Tween 80 and medium chain triglycerides (MCT). At low MCT concentrations, the solutions were transparent but from 1 to 5 wt% MCT, they became translucent then opaque. 1 wt% MCT was the upper boundary for the appearance of nanoemulsion phase. From the decays of the chemical shift signals of MCT and Tween 80, the DOSY results clearly demonstrate that the self-diffusion coefficients (D) are dependent on oil concentration. Small microemulsion droplets of almost uniform size (d = 12–22 nm) coexist with two sets of large nanoemulsion (d 200 nm) droplets. The large droplets increase significantly in size with increasing MCT. The most striking result is the clear evidence for the presence of microemulsion droplets of nearly uniform size in the aqueous phase from below to above the nanoemulsion transition concentration at 1 wt% MCT.

Carotenoids are naturally occurring yellow to red pigments with many biological activities including antioxidant, anticancer, anti-inflammatory, membrane stabilizers, and precursors for vitamin A. These biological activities are linked with many health benefits (e.g., anticarcinogenic activity, prevention of chronic diseases, etc.), which grew the interest of several industrial sectors especially in food, feed, nutraceuticals, cosmetics, and pharmaceutical industries. The production of natural carotenoids from microbial sources such as bacteria can help meet the growing global market of carotenoids estimated at $1.5 billion in 2014 and is expected to reach 1.8 billion in 2019. This chapter demonstrates, step-by-step, the development of a rapid and selective screening method for isolation and identification of carotenoid-producing microorganisms and their carotenoid analysis. This method involves three main procedures: UV treatment, sequencing analysis of 16S rRNA genes, and carotenoids analysis using rapid and effective HPLC-diode array-MS methods.

The red diketocarotenoid, astaxanthin, exhibits extraordinary health-promoting activities such as antioxidant, anti-inflammatory, antitumor, and immune booster, which may potentially protect against many degenerative diseases such as cancers, heart diseases, and exercise-induced fatigue. These numerous health benefits and consumer interest in natural products have therefore increased the market demand of astaxanthin as a nutraceutical and medicinal ingredient in food, aquaculture feed, and pharmaceutical industries. Consequently, many research efforts have been made to discover novel microbial sources with effective biotechnological production of astaxanthin. Using a rapid screening method based on 16S rRNA gene, and effective HPLC-Diode array-MS methods for carotenoids analysis, we isolated a novel astaxanthin-producing bacterium (strain TDMA-17

Zeaxanthin is a yellow xanthophyll, dihydroxy-carotenoid, that is naturally found in some of the green, orange, and yellow vegetables and fruits and has a powerful antioxidant activity. Epidemiological evidences suggest that increasing the consumption of zeaxanthin in the diet is associated with a lower risk of age-related macular degeneration (ARMD) and cataracts, two of the leading causes of blindness in the world. Zeaxanthin is a promising nutraceutical/colorant with many applications in feed, food, and pharmaceutical industries. Currently, the commercial production of zeaxanthin is dependent on synthetic routes with limitation in production from biological sources. However, the biotechnological production of natural zeaxanthin is favored due to its safety, potential large-scale production and consumers' preference for natural additives. In this chapter, we describe a rapid screening method based on 16S rRNA gene sequencing and effective HPLC with diode array detector/MS methods for the isolation and identification of zeaxanthin-producing bacteria and their carotenoid analysis.

Biofilm formation on stainless steel (SS) surfaces of food-processing plants, leading to food-borne illness outbreaks, is enabled by the attachment and confinement of pathogens within microscale cavities of surface roughness (grooves, scratches). We report foodsafe oil-based slippery coatings (FOSCs) for food-processing surfaces that suppress bacterial adherence and biofilm formation by trapping residual oil lubricant within these surface cavities to block microbial growth. SS surfaces were chemically functionalized with alkylphosphonic acid to preferentially wet a layer of food-grade oil. FOSCs reduced the effective surface roughness, the adhesion of organic food residue, and bacteria. FOSCs significantly reduced Pseudomonas aeruginosa biofilm formation on standard roughness SS-316 by 5 log CFU cm–2, and by 3 log CFU cm–2 for mirror-finished SS. FOSCs also enhanced surface cleanability, which we measured by bacterial counts after conventional detergent cleaning. Importantly, both SS grades maintained the...

A novel highly selective lutein-producing marine microalga was isolated and identified using high throughput screening (HTS). Phylogenetic analysis based on 18S rRNA gene sequence revealed it belongs to a microalgae class (Trebouxiophyceae), and is closely related to Auxenochlorella spp. The novel strain was designated as Auxenochlorella sp. strain LEU27. Based on HPLC-DAD and HPLC-MS analyses, strain LEU27 produced a total of 1203.9 ± 98 μg g−1 dry cells of carotenoids, including a remarkable amount (996.6 ± 98 μg g−1 dry cells) of pure lutein under heterotrophic growth conditions. This is the first report that describes a natural, highly selective lutein-producing marine microalga isolated by HTS approach.

The red diketocarotenoid, astaxanthin, exhibits extraordinary health-promoting activities such as antioxidant, anti-inflammatory, antitumor, and immune booster, which may potentially protect against many degenerative diseases such as cancers, heart diseases, and exercise-induced fatigue. These numerous health benefits and consumer interest in natural products have therefore increased the market demand of astaxanthin as a nutraceutical and medicinal ingredient in food, aquaculture feed, and pharmaceutical industries. Consequently, many research efforts have been made to discover novel microbial sources with effective biotechnological production of astaxanthin. Using a rapid screening method based on 16S rRNA gene, and effective HPLC-Diode array-MS methods for carotenoids analysis, we isolated a novel astaxanthin-producing bacterium (strain TDMA-17T) that belongs to the family Sphingomonadaceae (Asker et al., FEMS Microbiol Lett 273:140-148, 2007).In this chapter, we provide a comprehensive description of the methods used for the analysis and identification of carotenoids produced by strain TDMA-17T. We will also describe the methods of isolation and identification for a novel bacterial carotenoid (an astaxanthin derivative), a major carotenoid that is produced by the novel strain. Finally, the identification methods of the novel strain will be summarized.

Zeaxanthin is a yellow xanthophyll, dihydroxy-carotenoid, that is naturally found in some of the green, orange, and yellow vegetables and fruits and has a powerful antioxidant activity. Epidemiological evidences suggest that increasing the consumption of zeaxanthin in the diet is associated with a lower risk of age-related macular degeneration (ARMD) and cataracts, two of the leading causes of blindness in the world. Zeaxanthin is a promising nutraceutical/colorant with many applications in feed, food, and pharmaceutical industries. Currently, the commercial production of zeaxanthin is dependent on synthetic routes with limitation in production from biological sources. However, the biotechnological production of natural zeaxanthin is favored due to its safety, potential large-scale production and consumers' preference for natural additives. In this chapter, we describe a rapid screening method based on 16S rRNA gene sequencing and effective HPLC with diode array detector/MS methods for the isolation and identification of zeaxanthin-producing bacteria and their carotenoid analysis.

Carotenoids are naturally occurring yellow to red pigments with many biological activities including antioxidant, anticancer, anti-inflammatory, membrane stabilizers, and precursors for vitamin A. These biological activities are linked with many health benefits (e.g., anticarcinogenic activity, prevention of chronic diseases, etc.), which grew the interest of several industrial sectors especially in food, feed, nutraceuticals, cosmetics, and pharmaceutical industries. The production of natural carotenoids from microbial sources such as bacteria can help meet the growing global market of carotenoids estimated at $1.5 billion in 2014 and is expected to reach 1.8 billion in 2019. This chapter demonstrates, step-by-step, the development of a rapid and selective screening method for isolation and identification of carotenoid-producing microorganisms and their carotenoid analysis. This method involves three main procedures: UV treatment, sequencing analysis of 16S rRNA genes, and carotenoids analysis using rapid and effective HPLC-diode array-MS methods.

Optimizing the macroscopic properties, shelf-life and stability of emulsion products requires a better understanding of the microstructural characteristics such as the type (nano, micro and macro) and the relative distribution of components (i.e., oil and surfactant) within the emulsion droplets. We used Diffusion-Ordered NMR Spectroscopy (DOSY NMR) to evaluate these characteristics in model oil-in-water emulsion containing Tween 80 and medium chain triglycerides (MCT). At low MCT concentrations, the solutions were transparent but from 1 to 5 wt% MCT, they became translucent then opaque. 1 wt% MCT was the upper boundary for the appearance of nanoemulsion phase. From the decays of the chemical shift signals of MCT and Tween 80, the DOSY results clearly demonstrate that the self-diffusion coefficients (D) are dependent on oil concentration. Small microemulsion droplets of almost uniform size (d = 12-22 nm) coexist with two sets of large nanoemulsion (d 200 nm) and emulsion (d 200 nm) droplets. The large droplets increase significantly in size with increasing MCT. The most striking result is the clear evidence for the presence of microemulsion droplets of nearly uniform size in the aqueous phase from below to above the nanoemulsion transition concentration at 1 wt% MCT.

Ultrasound is composed of sound waves with frequency beyond the limit of human hearing. By tuning frequency, ultrasound can be utilized in many industrial applications including food. Ultrasound techniques are relatively cheap, simple and energy saving, and thus became an emerging technology for probing and modifying food products. Low power (high frequency) ultrasound is used for monitoring the composition and physicochemical properties of food components and products during processing and storage, which is crucial for controlling the food properties and improving its quality. High power (low frequency) ultrasound, on the other hand, induces mechanical, physical and chemical/biochemical changes through cavitation, which supports many food processing operations such as extraction, freezing, drying, emulsification and inactivation of pathogenic bacteria on food contact surfaces. This review summarizes the major applications of low and high power ultrasound in food science and technology. The basic principles of low and high power ultrasound will be highlighted, and their methods and applications including important research results will be presented. These applications include meat products, vegetables and fruits, cereal products, aerated foods, honey, food gels, food proteins, food enzymes, microbial inactivation, freezing, drying and extraction.

We examined the effect of lipid phase composition on the crystallization, polymorphic transition and stability of solid lipid nanoparticle (SLN) suspensions. A series of fine-disperse oil-in-water emulsions was prepared at an elevated temperature (75 °C) from a lipid phase containing different amounts of a high melting lipid (tripalmitin) and a low melting lipid (fish oil). These emulsions were cooled to induce crystallization and form SLN suspensions. In the absence of fish oil, the SLN suspensions formed a gel after the emulsified tripalmitin crystallized, which was attributed to particle shape changes leading to aggregation and network formation. Light scattering and rheology measurements indicated that incorporation of fish oil into the lipid phase (≥10 wt %) increased the stability of SLN to aggregation. DSC measurements suggested that crystallization, melting, and polymorphic transitions of SLN were influenced by the amount of fish oil incorporated. The rate of α- to β-polymorphic transitions of tri...

Ultrasound velocity measurements were used to measure accurately the volume fraction of crystallised material in ‘monodispersed’ (120–2440 nm) n-alkane and cocoa butter emulsions during crystallisation. The emulsions were temperature cycled, the ‘quasi’ isothermal nucleation rate determined from ultrasound velocity, and the crystallisation kinetics estimated. Emulsions were prepared using a variety of ‘emulsifiers’ (polyglycerol esters, Tween 20, Caflon phc060 and sodium caseinate). In practice, these emulsifiers behaved as stabilisers, preventing particle coalescence during collisions. The type of surfactant has a relatively small effect on the magnitude of the undercooling, which varied only a little (14.5–16.5 °C) as the emulsifier was changed, at a given particle size. On the other hand, the type of surfactant did make a significant difference to the crystallisation rate, once nucleation had been initiated. The surfactant type also altered the details of the crystallisation process. Reducing the size increased the nucleation rates dramatically in the size range studied in these experiments. It is suggested that dramatically increased droplet diffusion and collision rates are responsible for the observations in the case of droplets in the 100-nm region. In the case of polyglycerol esters, the data suggests that they formed a solution with the n-hexadecane.

A gamma- and UV-radiation-tolerant, pale-pink strain (TDMA-uv53T) was isolated from a freshwater sample collected at Misasa (Tottori, Japan), after exposure of the water sample to UV radiation. The cells stained Gram-positive and were non-motile, rod-shaped and non-spore-forming. The DNA G+C content of the strain was 69.1 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain TDMA-uv53T belongs to the genus Deinococcus, the highest sequence similarities being found with Deinococcus claudionis PO-04-19-125T (96 %), D. altitudinis ME-04-01-32T (96 %), D. radiomollis PO-04-20-132T (95 %), D. deserti VCD115T (91.5 %), D. hopiensis KR-140T (91.0 %) and D. sonorensis KR-87T (91.0 %). Major fatty acids were iso-15 : 0, 15 : 1omega6c, 15 : 0, 16 : 0 and summed feature 3 (iso-15 : 0 2-OH and/or 16 : 1omega7c). MK-8 was the predominant respiratory quinone. Phylogenetic distinctiveness and unique phenotypic characteristics differentiated strain TDMA-uv53T from closely related Deinococcus species. The results of our polyphasic taxonomic analyses suggested that TDMA-uv53T represents a novel Deinococcus species, for which the name Deinococcus aquiradiocola sp. nov. is proposed. The type strain is TDMA-uv53T (=JCM 14371(T) [corrected] =NBRC 102118T =CCUG 53612T).

Solid lipid nanoparticle (SLN) suspensions, which consist of submicron-sized crystalline lipid particles dispersed within an aqueous medium, can be used to encapsulate, protect and deliver lipophilic functional components. Nevertheless, SLN suspensions are susceptible to particle aggregation and gelation during their preparation and storage, which potentially limits their industrial utilization. In this study, we examined the aggregation and gelation behavior of SLN suspensions composed of 10 wt% tripalmitin particles (r < 150 nm) stabilized by 1.5% Tween 20. The tripalmitin and aqueous surfactant solution were homogenized above the lipid melting temperature and cooled under controlled conditions to initiate SLN formation. The aggregation and gelation of SLN suspensions during storage was then examined by shear rheometry, differential scanning calorimetry (DSC), light scattering and microscopy. Rheology measurements indicated that gelation times decreased with increasing storage temperature, e.g., samples formed weak gels after 62, 23, and 10 min at 1, 5, and 10 °C, respectively. DSC revealed increasingly rapid α- to β-polymorphic transformations in SLN dispersions stored at 1, 5, and 10 °C, respectively. We propose that the observed aggregation and gelation of SLN suspensions are associated with a change in the shape of the nanoparticles from spherical (α-form) to non-spherical (β-form) when they undergo the polymorphic transition. When they change shape there is no longer sufficient surfactant present to completely cover the lipid phase, which promotes particle aggregation through hydrophobic attraction. Our results have important implications for the design and fabrication of stable SLN suspensions.

Solid lipid nanoparticle (SLN) suspensions undergo a phase transition from the α- to β-polymorphic forms, which is accompanied by particle aggregation and gel formation. These processes are both time and temperature dependent, and so it is important to study the impact of cooling rates (CRs) and heating rates (HRs) on polymorphic transformations, particle aggregation, and gelation. Rheology measurements indicated that the temperature where gelation was first observed during cooling (T gel) decreased with increasing CRs, with SLN suspensions remaining fluid at HR ≥ 5 °C/min. On the other hand, the temperature where gelation was first observed during heating of stable SLN suspensions increased with increasing HRs: 18, 24, 31, and 45 °C at 2, 5, 10, and 20 °C/min, respectively. When the melted SLN suspensions were cooled again, two exothermic peaks were observed in the differential scanning calorimetry scans at 39 (which was attributed to coalesced oil) and 19 °C (which was attributed to stable SLN). With increasing CR, the enthalpy of the coalescence peak (ΔH CO) decreased, while that of the supercooled SLN (ΔH SLN) increased. With increasing HR, ΔH CO decreased and ΔH SLN increased, with no coalescence being observed at HR ≥ 10 °C/min. These results show that increasing the CRs or HRs retard the α→β polymorphic transformation, which increased the stability of SLN against aggregation and retarded gelation. In addition, this study shows that the careful selection of HRs and CRs is required to examine polymorphic transformations and the stability of SLN suspensions.

To elucidate the stability and phase transition of cubic phases of biomembranes with infinite periodic minimal surface is indispensable from biological and physicochemical aspects. In this report, we investigated the effect of positively charged peptide-3K (LLKKK) and poly(L-lysine) on the phase stability of monoolein (MO) membranes containing negatively charged dioleoylphosphatidic acid (DOPA) (i.e., DOPA/MO membranes) using small-angle X-ray scattering. At first, the effect of peptide-3K on 10% DOPA/90% MO membrane in excess water, which is in the Q229 phase, was investigated. At 3.4 mM peptide-3K, a Q229 to Q230 phase transition occurred, and at >3.4 mM peptide-3K, the membrane was in the Q230 phase. Poly(L-lysine) (M(w) 1K-4K) also induced the Q230 phase, but peptide-2K (LLKK) could not induce it in the same membrane. We also investigated the effect of peptide-3K on the multilamellar vesicle (MLV) of 25% DOPA/75% MO membrane, which is in L(alpha) phase. In the absence of peptide, the spacing of MLV was very large (11.3 nm), but at > or = 8 mM peptide-3K, it greatly decreased to a constant value (5.2 nm), irrespective of the peptide concentration, indicating that peptide-3K and the membranes form an electrostatically stabilized aggregation with low water content. Poly(L-lysine) also decreased greatly the spacing of the 25% DOPA/75% MO MLV, indicating the formation of a similar aggregation. To compare the effects of peptide-3K and poly(L-lysine) with that of osmotic stress on stability of the cubic phase, we investigated the effect of poly(ethylene glycol) with molecular weight 7500 (PEG-6K) on the phase stability of 10% DOPA/90% MO membrane. With an increase in PEG-6K concentration, i.e., with an increase in osmotic stress, the most stable phase changed as follows; Q229 (Schwartz's P surface) --> Q224 (D) --> Q230 (G). On the basis of these results, we discuss the mechanism of the effects of the positively charged short peptides (peptide-3K) and poly(L-lysine) on the structure and phase stability of DOPA/MO membranes.

Based on the difference between the speed of sound in solids and liquids, an ultrasonic velocity technique was employed to monitor the phase transition, nucleation and crystal growth of two palm oils dispersed as oil-in-water (O/W) emulsions. The O/W emulsions of palm mid-fraction (PMF) and palm kernel oil (PKO) crystallized at 12 and 0 °C, respectively. The degree of supercooling of PMF emulsion was 18 °C, while that of PKO emulsion was 28 °C. The effects of different hydrophobic emulsifier additives on the interfacial heterogeneous nucleation, induced at the oil/water interface of emulsion droplets, and crystal growth were studied by monitoring the sound velocity ( V ) during isothermal crystallization. Sucrose oligoesters (SOEs) having stearic (S-170) and palmitic (P-170) fatty acid chains accelerated nucleation, yet SOEs having short chains such as lauric (L-170) showed no effect in the two fats. A polyglycerine ester (DAS-750) had a lesser and different effect on the nucleation of PKO compared to PMF. Moreover, the crystal growth was retarded in the two oils at different degrees by the addition of S-170. Solubility measurements indicated that the solubility degree of DAS-750 was more than that of S-170. In addition, the solubility of DAS-750 was higher in PKO than in PMF. The effects of the additives were thus discussed in terms of their molecular structure in relation to the oil phase composition.

The scaling relationship between the shear elastic modulus and the solid fat content (SFC) was determined for anhydrous milk fat (AMF), palm oil (PO), and cocoa butter (CB). The fats were diluted with canola oil to achieve specific SFCs and crystallized at 5 °C for 24 h. SFC decreased linearly by increasing the canola oil mass fraction as determined by pulsed NMR. Log−log plots of the shear storage modulus (G‘) versus the solids' volume fraction (Φ = SFC/100) of the diluted fats were used to determine the fractal dimension (D) of the networks. Three different linear regions were identified for the range of dilutions studied. The scaling relationship of the stress at the limit of linearity (σo) to Φ indicated that the fats were in the weak-link rheological regime in all three regions. These results suggested that three different types of weak-link rheological regimes could be present in the same material depending on the SFC. Polarized light microscopy showed that varying the solid fat content (SFC) modifi...

Crystallisation and polymorphic behaviour of palm kernel oil (PKO) dispersed in oil-in-water emulsion were observed using the ultrasonic velocity technique, DSC and in situ X-ray diffraction. Three sucrose oligoesters having palmitic acid (P-170), stearic acid (S-170) and lauric acid (L-195) moieties were added to PKO as additives, in an attempt to accelerate the crystallisation of PKO in the O/W emulsions that was suppressed due to dispersion of the oil phase into many droplets. It was found that the S-170 and P-170 additives accelerated the rate and extent of the crystallisation of PKO in the emulsion system. An independent measurement of crystal growth rate showed that the addition of S-170 and P-170 retarded the crystal growth of PKO. In contrast, L-195 did not show any effects of acceleration of crystallisation and retardation of crystal growth of PKO. X-ray diffraction spectra and DSC thermopeaks showed that the emulsion without the additives crystallised in the α polymorph, whereas β′ was crystallised with the addition of S-170. The results are discussed in terms of heterogeneous nucleation occurring at the oil–water interface where the additives may form molecular aggregates that act as a template for nucleation, as previously discussed for n-hexadecane emulsions (Colloids Surf., B 20 (2001) 229).

The core lipids, polar and non polar lipids, of the novel canthaxanthin-producing archaeon, Haloferax alexandrinus strain TM(T), were investigated using thin-layer chromatography (TLC), spectrophotometry, electron ionization-mass spectroscopy (EI-MS), fast atom bombardment mass spectrometry (FAB-MS), nuclear magnetic response spectrometry (13C-NMR) and high performance liquid chromatography (HPLC). This archaeon appeared to contain diphytanyl diether lipids (C20-C20) as core lipids. The major phospholipids were found to be phosphatidylglycero-phosphate-methyl ester (PGP-Me) and phosphatidylglycerol (PG), but no phosphatidylglycero-sulfate was detected. The strain contained two glycolipids, sulfated diglycosyl diether (S-DGD-1) and unsulfated diglycosyl diether (DGD). Analysis of the non polar lipids revealed the presence of beta-carotene, 3-hydroxyechinenone, gamma-carotene, cis-astaxanthin, lycopene, trisanhydro-bacterioruberin,monanhydro-bacterioruberin, bacterioruberin isomer, bacterioruberin and canthaxanthin. Although the polar lipids profile of Hfx. alexandrinus strain TM(T) was similar to those of other species of the genus Haloferax, the non polar lipid (carotenoids) profile was markedly different. Further experiments on the influence of NaCl concentration on the lipids composition of Hfx. alexandrinus strain TM(T) demonstrated the dependence of the proportion of each of bacterioruberin, beta-carotene and canthaxanthin on the NaCl concentration in the growth media.

A most simple, rapid and sensitive method for the determination of boron compounds using gas chromatograph (model GC-14B) is described. The method is based on the hydride generation technique. A standard sample of boric acid was well dried and mixed with about 50 mg of powdered LiAlH4 and diborane was generated by heating at 160°C. Diborane was trapped at liquid nitrogen temperature (−196°C). Factors effecting the diborane producability such as generation temperature, trapping time, and carrier flow rate have been critically studied and optimized. Boron was determined in the concentration range of 0.01–3 mg; the new system has a detection limit of 10 μg. Natural species that form gaseous hydrides and is expected to interfere with the measured diborane have been studied, It was found that phosphate interfered in this method unless its peak was clearly separated after replacing the GC column with a 1 m column packed with porapack Q. Finally the method was applied to two types of eye treatment solutions and ...

The effects of addition of diacylglycerols (DAGs) on the crystallization behavior of n-hexadecane dispersed in oil-in-water emulsion (oil 20% and water 80%, v/v) were studied by differential scanning calorimetry (DSC) and ultrasonic velocity measurement. In an attempt to modify the crystallization rate of n-hexadecane, five DAGs having the fatty acid moieties of behenic (DAB), stearic (DAS), palmitic (DAP), lauric (DAL) and oleic acid (DAO) were added to n-hexadecane, which was mixed with water and Tween 20 for emulsification. The DSC study showed that the addition of DAB, DAS or DAP (1.0 wt-% with respect to n-hexadecane) increased the crystallization temperature (Tc) of a n-hexadecane/water emulsion from 3 °C (without DAG) to 8 °C, whereas the addition of DAL and DAO showed no effect. The ultrasonic velocity measurement also revealed that the addition of DAGs resulted in increasing the Tc of n-hexadecane in O/W emulsion. These effects were discussed by taking into account the formation of molecular aggregates at the interface due to the addition of DAGs, which act as a template for crystallization of n-hexadecane. The template-assisted crystallization depends on the structure of the fatty acid chains present in the DAG: the longer the fatty acid moiety of DAG, the more is the crystallization of n-hexadecane in O/W emulsion accelerated. La cristallisation de la phase huileuse dans une emulsion huile dans l'eau est une etape importante pour la coagulation de l'emulsion refrigeree, comme par exemple la desemulsification de cremes fouettees ou la congelation de glaces. Les effets de l'addition de diacylglycerols sur la cristallisation de n-hexadecane disperse dans une emulsion huile dans l'eau (20/80% vol.) sont etudies par analyse calorimetrique differentielle et mesure de vitesse de propagation d'ultrasons. On observe que plus la chaine d'acide gras du diacylglycerol est longue, plus la cristallisation du n-hexadecane est rapide.

Ultrasonic velocity measurements and X-ray diffraction were employed to monitor the crystallization behavior of palm mid fraction (PMF) in oil-in-water emulsions (20 vol%). Three hydrophobic emulsifiers—sucrose oligoesters (SOE) containing palmitic acid (P-170) and stearic acid (S-170) moieties and a polyglycerine ester (DAS-750) containing a stearic acid moiety—were added to PMF in an attempt to increase the rate and extent of crystallization of PMF, which are otherwise suppressed owing to emulsification of the oil phase into many droplets. The results revealed that the hydrophobic emulsifiers accelerate the nucleation of PMF in the emulsion system, while retarding the rate of crystal growth. As a results, the crystallization temperature (Tc) of PMF increased with increasing concentrations of the hydrophobic emulsifiers. The effects of the three additives were different; in particular the addition of DAS-750 remarkably enhanced crystallization at low concentrations. By adding the emulsifiers at higher concentrations, the polymorphic behavior of PMF crystallization was also modified to different degrees, depending on the type of emulsifier. With addition of SOE, PMF crystallized predominantly in the β′ form; with addition of DAS-750, the extent of β′ nucleation was reduced by comparison with that observed with SOE. The results were explained in terms of adsorption of the hydrophobic emulsifier additives at the oil-water interface, which provides a template for acceleration of surface heterogeneous nucleation of PMF in the emulsion system.

Astaxanthin is a red ketocarotenoid that exhibits extraordinary health-promoting activities such as antioxidant, anti-inflammatory, antitumor, and immune booster. The recent discovery of the beneficial roles of astaxanthin against many degenerative diseases such as cancers, heart diseases, and exercise-induced fatigue has raised its market demand as a nutraceutical and medicinal ingredient in aquaculture, food, and pharmaceutical industries. To satisfy the growing demand for this high-value nutraceuticals ingredient and consumer interest in natural products, many research efforts are being made to discover novel microbial producers with effective biotechnological production of astaxanthin. Using a rapid screening method based on 16S rRNA gene, and effective HPLC-Diodearray-MS methods for carotenoids analysis, we succeeded to isolate a unique astaxanthin-producing bacterium (strain TDMA-17(T)) that belongs to the family Sphingomonadaceae (Asker et al., Appl Microbiol Biotechnol 77: 383-392, 2007). In this chapter, we provide a detailed description of effective HPLC-Diodearray-MS methods for rapid analysis and identification of the carotenoids produced by strain TDMA-17(T). We also describe the methods of isolation and identification for a novel bacterial carotenoid (astaxanthin derivative), a major carotenoid that is produced by strain TDMA-17(T). Finally, we describe the polyphasic taxonomic analysis of strain TDMA-17(T) and the description of a novel species belonging to genus Sphingomonas.

Carotenoids are natural pigments that exhibit many biological functions, such as antioxidants (i.e., promote oxidative stress resistance), membrane stabilizers, and precursors for vitamin A. The link between these biological activities and many health benefits (e.g., anticarcinogenic activity, prevention of chronic diseases, etc.) has raised the interest of several industrial sectors, especially in the cosmetics and pharmaceutical industries. The use of microorganisms in biotechnology to produce carotenoids is favorable by consumer and can help meet the growing demand for these bioactive compounds in the food, feed, and pharmaceutical industries. This methodological chapter details the development of a rapid and selective screening method for isolation and identification of carotenoid-producing microorganisms based on UV treatment, sequencing analysis of 16S rRNA genes, and carotenoids' analysis using rapid and effective High-Performance Liquid Chromatography-Diodearray-MS methods. The results of a comprehensive 16S rRNA gene-based phylogenetic analysis revealed a diversity of carotenoid-producing microorganisms (104 isolates) that were isolated at a high frequency from water samples collected at Misasa (Tottori, Japan), a region known for its high natural radioactivity content. These carotenoid-producing isolates were classified into 38 different species belonging to 7 bacterial classes (Flavobacteria, Sphingobacteria, α-Proteobacteria, γ-Proteobacteria, Deinococci, Actinobacteria, and Bacilli). The carotenoids produced by the isolates were zeaxanthin (6 strains), dihydroxyastaxanthin (24 strains), astaxanthin (27 strains), canthaxanthin (10 strains), and unidentified molecular species that were produced by the isolates related to Deinococcus, Exiguobacterium, and Flectobacillus. Here, we describe the methods used to isolate and classify these microorganisms.

Zeaxanthin is a powerful antioxidant that is widely found in vegetables and fruits. Epidemiological evidences suggest that increasing the consumption of zeaxanthin in the diet is associated with a lower risk of age-related macular degeneration, helps prevent glaucoma and cataracts, and supports normal eye health. Zeaxanthin is a promising nutraceutical with many applications in the feed, food, and pharmaceutical industries. Currently, the commercial production of zeaxanthin is still dependant on synthetic routes with limitation for the biological one. Nevertheless, the biotechnological production of zeaxanthin is emerging due to its safety, potential large-scale production, and consumers' demand and preference for natural additives. Using a rapid screening method based on 16S rRNA gene and effective high-performance liquid chromatography (HPLC)-Diodearray-MS methods for carotenoids' analysis, we isolated effective zeaxanthin-producing bacteria (strain TDMA-5(T) and -16(T)) that belong to the family Sphingobacteriaceae and Sphingomonadaceae, respectively. In this chapter, we provide a detailed description of the HPLC-Diodearray-MS methods used for rapid analysis and identification of the carotenoids produced by both strains. In addition, the polyphasic taxonomic analysis of both novel strains and the description of a novel species and genus are described.

Zeaxanthin is a powerful antioxidant that is widely found in vegetables and fruits. Epidemiological evidences suggest that increasing the consumption of zeaxanthin in the diet is associated with a lower risk of age-related macular degeneration, helps prevent glaucoma and cataracts, and supports normal eye health. Zeaxanthin is a promising nutraceutical with many applications in the feed, food, and pharmaceutical industries. Currently, the commercial production of zeaxanthin is still dependant on synthetic routes with limitation for the biological one. Nevertheless, the biotechnological production of zeaxanthin is emerging due to its safety, potential large-scale production, and consumers' demand and preference for natural additives. Using a rapid screening method based on 16S rRNA gene and effective high-performance liquid chromatography (HPLC)-Diodearray-MS methods for carotenoids' analysis, we isolated effective zeaxanthin-producing bacteria (strain TDMA-5(T) and -16(T)) that belong to the family Sphingobacteriaceae and Sphingomonadaceae, respectively. In this chapter, we provide a detailed description of the HPLC-Diodearray-MS methods used for rapid analysis and identification of the carotenoids produced by both strains. In addition, the polyphasic taxonomic analysis of both novel strains and the description of a novel species and genus are described.

Astaxanthin is a red ketocarotenoid that exhibits extraordinary health-promoting activities such as antioxidant, anti-inflammatory, antitumor, and immune booster. The recent discovery of the beneficial roles of astaxanthin against many degenerative diseases such as cancers, heart diseases, and exercise-induced fatigue has raised its market demand as a nutraceutical and medicinal ingredient in aquaculture, food, and pharmaceutical industries. To satisfy the growing demand for this high-value nutraceuticals ingredient and consumer interest in natural products, many research efforts are being made to discover novel microbial producers with effective biotechnological production of astaxanthin. Using a rapid screening method based on 16S rRNA gene, and effective HPLC-Diodearray-MS methods for carotenoids analysis, we succeeded to isolate a unique astaxanthin-producing bacterium (strain TDMA-17(T)) that belongs to the family Sphingomonadaceae (Asker et al., Appl Microbiol Biotechnol 77: 383-392, 2007). In this chapter, we provide a detailed description of effective HPLC-Diodearray-MS methods for rapid analysis and identification of the carotenoids produced by strain TDMA-17(T). We also describe the methods of isolation and identification for a novel bacterial carotenoid (astaxanthin derivative), a major carotenoid that is produced by strain TDMA-17(T). Finally, we describe the polyphasic taxonomic analysis of strain TDMA-17(T) and the description of a novel species belonging to genus Sphingomonas.

Carotenoids are natural pigments that exhibit many biological functions, such as antioxidants (i.e., promote oxidative stress resistance), membrane stabilizers, and precursors for vitamin A. The link between these biological activities and many health benefits (e.g., anticarcinogenic activity, prevention of chronic diseases, etc.) has raised the interest of several industrial sectors, especially in the cosmetics and pharmaceutical industries. The use of microorganisms in biotechnology to produce carotenoids is favorable by consumer and can help meet the growing demand for these bioactive compounds in the food, feed, and pharmaceutical industries. This methodological chapter details the development of a rapid and selective screening method for isolation and identification of carotenoid-producing microorganisms based on UV treatment, sequencing analysis of 16S rRNA genes, and carotenoids' analysis using rapid and effective High-Performance Liquid Chromatography-Diodearray-MS methods. The results of a comprehensive 16S rRNA gene-based phylogenetic analysis revealed a diversity of carotenoid-producing microorganisms (104 isolates) that were isolated at a high frequency from water samples collected at Misasa (Tottori, Japan), a region known for its high natural radioactivity content. These carotenoid-producing isolates were classified into 38 different species belonging to 7 bacterial classes (Flavobacteria, Sphingobacteria, α-Proteobacteria, γ-Proteobacteria, Deinococci, Actinobacteria, and Bacilli). The carotenoids produced by the isolates were zeaxanthin (6 strains), dihydroxyastaxanthin (24 strains), astaxanthin (27 strains), canthaxanthin (10 strains), and unidentified molecular species that were produced by the isolates related to Deinococcus, Exiguobacterium, and Flectobacillus. Here, we describe the methods used to isolate and classify these microorganisms.

Four gamma- and UV-radiation-resistant bacterial strains, designated TDMA-24T, TDMA-24-2, TDMA-24-3 and TDMA-24-4, were isolated from a fresh-water sample collected at Misasa, Tottori, Japan. Cells of these strains were Gram-reaction-positive, non-motile, non-spore-forming, rod-shaped and formed red colonies. The genomic DNA G+C contents ranged from 70.5 to 70.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel isolates belong to the genus Deinococcus, the highest sequence similarities being with Deinococcus aquaticus PB314T (98 %) and Deinococcus caeni Ho-08T (97 %). The polar lipid profile of strain TDMA-24T comprised three unidentified phosphoglycolipids, five unidentified glycolipids and seven unidentified polar lipids. MK-8 was the predominant respiratory quinone. Major fatty acids were iso-C15 : 0, C15 : 1ω6c, C15 : 0, C16 : 0 and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c). On the basis of their phylogenetic positions and chemotaxonomic and phenotypic characteristics, the novel isolates represent a novel species of the genus Deinococcus, for which the name Deinococcus depolymerans sp. nov. is proposed. The type strain is TDMA-24T ( = JCM 14369T = NBRC 102115T = CCUG 53609T).

The impact of surfactant type on the physical and chemical stability of solid lipid nanoparticle (SLN) suspensions containing encapsulated beta-carotene was investigated. Oil-in-water emulsions were formed by homogenizing 10% w/w lipid phase (1 mg/g beta-carotene in carrier lipid) and 90% w/w aqueous phase (surfactant + cosurfactant) at pH 7 and 75 degrees C and then cooling to 20 degrees C. The impact of surfactant type was investigated using aqueous phases containing different water-soluble surfactants [2.4% w/w high-melting (HM) lecithin, 2.4% w/w low-melting (LM) lecithin, and 1.4% w/w Tween 60 or 1.4% w/w Tween 80] and a cosurfactant (0.6% taurodeoxycholate). The impact of the physical state of the carrier lipid was investigated by using either a high melting point lipid (tripalmitin) to form solid particles or a low melting point lipid (medium chain triglycerides, MCT) to form liquid droplets. A higher fraction of alpha-crystals was detected in solid particles prepared with high-melting surfactants (HM-lecithin and Tween 60) than with low-melting surfactants (LM-lecithin and Tween 80). With the exception of the HM-lecithin-coated solid particles, the suspensions were stable to particle aggregation during 21 days of storage. beta-Carotene degradation after 21 days of storage was 11, 97, 100, and 91% in the solid particles (tripalmitin) and 16, 21, 95, and 90% in the liquid droplets (MCT) for HM-lecithin, LM-lecithin, Tween 80, and Tween 60, respectively. These results suggest that beta-carotene may be stabilized by (1) LM- or HM-lecithin when liquid carrier lipids are used and (2) HM-lecithin when solid carrier lipids are used. The origin of this latter effect is attributed to the impact of the surfactant tails on the generation of a crystal structure better suited to maintain the chemical stability of the encapsulated bioactive.

The effect of surfactant surface coverage on formation and stability of Tween 20 stabilized tripalmitin solid lipid nanoparticles (SLN) was investigated. A lipid phase (10% w/w tripalmitin) and an aqueous phase (2% w/w Tween 20, 10 mM phosphate buffer, pH 7) were heated to 75 degrees C and then homogenized using a microfluidizer. The resulting oil-in-water emulsion was kept at a temperature (37 degrees C) above the crystallization temperature of the tripalmitin to prevent solidification of emulsion droplets, and additional surfactant at various concentrations (0-5% w/w Tween 20) was added. Droplets were then cooled to 5 degrees C to initiate crystallization and stored at 20 degrees C for 24 h. Particle size and/or aggregation were examined visually and by light scattering, and crystallization behavior was examined by differential scanning calorimetry (DSC). Excess Tween 20 concentration remaining in the aqueous phase was measured by surface tensiometry. Emulsion droplets after homogenization had a mean particle diameter of 134.1+/-2.0 nm and a polydispersity index of 0.08+/-0.01. After cooling to 5 degrees C at low Tween 20 concentrations, SLN dispersions rapidly gelled due to aggregation of particles driven by hydrophobic attraction between insufficiently covered lipid crystal surfaces. Upon addition of 1-5% w/w Tween 20, SLN dispersions became increasingly stable. At low added Tween 20 concentration (1% w/w) the SLN formed gels but only increased slightly at higher surfactant concentrations (1% w/w). The Tween 20 concentration in the aqueous phase decreased after tripalmitin crystallization suggesting additional surfactant adsorption onto solid surfaces. At higher Tween 20 concentrations, SLN had increasingly complex crystal structures as evidenced by the appearance of additional thermal transition peaks in the DSC. The results suggest that surfactant coverage at the interface may influence crystal structure and stability of solid lipid nanoparticles via surface-mediated crystal growth.

The purpose of this study was to determine whether temperature scanning ultrasonic velocity measurements could be used to monitor the complex thermal transitions that occur during the crystallization and melting of triglyceride solid lipid nanoparticles (SLNs). Ultrasonic velocity ( u) measurements were compared with differential scanning calorimetry (DSC) measurements on tripalmitin emulsions that were cooled (from 75 to 5 degrees C) and then heated (from 5 to 75 degrees C) at 0.3 degrees C min (-1). There was an excellent correspondence between the thermal transitions observed in deltaDelta u/delta T versus temperature curves determined by ultrasound and heat flow versus temperature curves determined by DSC. In particular, both techniques were sensitive to the complex melting behavior of the solidified tripalmitin, which was attributed to the dependence of the melting point of the SLNs on particle size. These studies suggest that temperature scanning ultrasonic velocity measurements may prove to be a useful alternative to conventional DSC techniques for monitoring phase transitions in colloidal systems.

Two gamma- and UV-radiation resistant, Gram-positive, red- or pink-pigmented, rod-shaped, strictly aerobic, oxidase- and catalase-positive bacterial strains, TDMA-25T and TDMA-uv51T, were isolated from fresh water collected at Misasa, a radioactive site in Japan. Phylogenetic analysis based on 16S rRNA gene sequences placed both in a distinct lineage in the family Deinococcaceae, and the highest degrees of sequence similarity determined belonged to Deinococcus maricopensis LB-34T (88.8-89.3%), Deinococcus pimensis KR-235T (86.4-86.7%) and Deinococcus yavapaiensis KR-236T (86.1%). The DNA G+C content of the strains was 53-58 mol%. The major respiratory quinone was MK-8. The predominant fatty acids were C15:0 iso, C16:0 iso, C13:0 iso, C17:0 iso, C16:0, C13:0 anteiso, C15:0 and C12:0 iso. The strains degraded gelatin, casein, starch and Tween 80. Unique physiological characteristics, differences in their fatty acid profiles, and genotypic and phylogenetic features, differentiated strains TDMA-25T and TDMA-uv51T from closely related Deinococcus species. Hence, the two strains are described as novel species of the genus Deinococcus. The names Deinococcus misasensis sp. nov. (type strain TDMA-25T=JCM 14369=NBRC 102116=CCUG 53610) and Deinococcus roseus sp. nov. (type strain TDMA-uv51T=JCM 14370=NBRC 102117=CCUG 53611) are proposed.