At 22°C a flagellin mutant of Listeria monocytogenes was found to attach to stainless steel at levels 10-fold lower than wild-type cells, even under conditions preventing active motility. At 37°C, when flagella are not produced, attachment of both strains was identical. Therefore, flagella per se facilitate the early stage of attachment.Communities of microorganisms which adhere to various surfaces form biofilms (3, 5); these sessile microorganisms have advantages in both growth and survival compared with their planktonic forms (6,8,25). Several factors are thought to affect surface attachment, including extracellular material, nutrients, and temperature (7,11,20). It has been suggested that flagellation and motility play a role at the cell level in several stages of biofilm formation (13, 16), and motility has been shown to facilitate attachment to both biotic (2, 14, 18) and abiotic (12,13,17,23) surfaces. Flagella, in addition to being the locomotive organelles of bacteria, have also been reported to serve as an adhesive structure (16); however, no evidence has demonstrated that flagella alone are involved in attachment.To investigate the importance of flagella, in the absence of motility, for initial attachment to stainless steel surfaces, we have used the food-borne pathogen Listeria monocytogenes, wild-type strain NCTC 7973 (serotype 1/2a), and a nonflagellated (fla2) mutant. The wild-type bacterium is peritrichous in a temperature-dependent manner, being flagellated and motile at 20 to 25°C but nonmotile and with very few flagella above 35°C (21,22). The nonflagellated (fla2) mutant was constructed by insertion of the luxAB genes (10) into the flaA gene by double homologous recombination using the temperaturesensitive shuttle vector pAUL-A (4). The mutant produces a 7-kDa truncate representing the N-terminal end of the flagellin protein. The use of a mutant which lacks the ability to produce flagella allowed us both to investigate the role of the flagellum in attachment and to separate this from the effect of temperature on the ability of Listeria to attach to a surface.To confirm that the conditions to be used in attachment studies did not allow the cells to be motile, cell motility was first examined. Cultures were grown in brain heart infusion broth (Oxoid, Ltd., Hampshire, United Kingdom), incubated statically overnight at either 22 or 37°C, and then centrifuged at 2,000 ϫ g (Centaur 2; Fisons, Leicester, United Kingdom) for 20 min at room temperature. Cells were washed twice with phosphate-buffered saline (PBS) (pH 7.2; Oxoid), centrifuged at 2,000 ϫ g for 15 min, and resuspended in PBS to ϳ8 ϫ 10 8 CFU ml Ϫ1 (A 600 ϭ 0.5). Motility was observed by dark-field microscopy at a ϫ400 magnification. When suspended in PBS to provide nutrient-limiting conditions, both the wild-type and mutant strains of L. monocytogenes grown at 22°C were not motile, although the wild type was flagellated. As expected, neither strain was motile at 37°C because of the temperaturedependent flagellum production in Listeria spp...

Marine gelatin is one of the food proteins used in food and non-food products, offering desirable functionalities such as gelling, thickening, and binding. Jellyfish has been chosen for this gelatin research, in view of the benefits of its main collagen protein and lower fat content, which may reduce the amounts of chemicals used in the preparative steps of gelatin production. To date, the lack of identified proteins in gelatin has limited the understanding of differentiating intrinsic factors quantitatively and qualitatively affecting gel properties. No comparison has been made between marine gelatin of fish and that of jellyfish, regarding protein type and distribution differences. Therefore, the study aimed at characterizing jellyfish gelatin extracted from by-products, that are i.e., pieces that have broken off during the grading and cleaning step of salted jellyfish processing. Different pretreatment by hydrochloric acid (HCl) concentrations (0.1 and 0.2 M) and hot water extraction time (12 and 24 h) were studied as factors in jellyfish gelatin extraction. The resultant jellyfish gelatin with the highest gel strength (JFG1), as well as two commercial gelatins of fish gelatin (FG) and bovine gelatin (BG), were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results show that the jellyfish gelatin (JFG1) extracted with 0.1 M HCl at 60°C for 12 h delivered a maximum gel strength of 323.74 g, which is lower than for FG and BG, exhibiting 640.65 and 540.06 g, respectively. The gelling and melting temperatures of JFG1 were 7.1°C and 20.5°C, displaying a cold set gel and unstable gel at room temperature, whereas the gelling and melting temperatures of FG and BG were 17.4°C, 21.3°C, and 27.5°C, 32.7°C, respectively. Proteomic analysis shows that 29 proteins, of which 10 are types of collagen proteins and 19 are non-collagen proteins, are common to all BG, FG, and JFG1, and that JFG1 is missing 3 other collagen proteins (collagen alpha-2 (XI chain), collagen alpha-2 (I chain), and collagen alpha-2 (IV chain), that are important to gel networks. Thus, the lack of these 3 collagen types influences the inferior gel properties of jellyfish gelatin.

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Gamma oryzanol (GO), a bioactive ingredient found in rice bran oil, performs a variety of biological effects such as antioxidant activity, reduction of total cholesterol, anti‐inflammation, and antidiabetes. However, GO is water‐insoluble and normally degrades through oxidation. Thus a nano‐encapsulation technique was investigated to improve its stability and quality. In this research, gamma oryzanol was successfully encapsulated into zein nanoparticles. The fabrication parameters including pH, zein concentration (0.3, 0.4, and 0.5% w/v), and % GO loading (30, 40, and 50% by weight) were investigated. Particle size, zeta potential, yield, encapsulation efficiency and the stability or GO retention during the storage were determined. The morphology of gamma oryzanol loaded zein nanoparticles (GOZNs) was observed by scanning electron micrographs and transmission electron microscope. The increase of zein concentration and % GO loading resulted to an increase of yield, encapsulation efficiency, and particle size. The particle size of the GOZNs ranged from 93.24–350.93, and 144.13–833.27, and 145.27–993.13 nm for each zein concentration with 3 loading levels, respectively. Nano‐encapsulation exhibited higher % GO retention compared with nonencapsulated GO during 60 days storage both at 4°C and −18°C. In vitro study indicated the sustained release of GO in the simulated gastric fluid followed by simulated intestinal fluid. This finding indicated a high potential for the application of insoluble GO with improved stability by encapsulation with the hydrophobic zein protein.