Competition between Nitrospira spp. and Nitrobacter spp. in nitrite-oxidizing bioreactors

In this work the question was addressed if in nitrite-oxidizing activated sludge systems the environmental competition between Nitrobacterspp. and Nitrospira spp., which only recently has been discovered to play a role in these systems, is affected by the nitrite concentrations. Two parallel chemostats were inoculated with nitrifying-activated sludge containing Nitrospira and operated under identical conditions. After addition of Nitrobacter to both chemostats, the nitrite concentration in the influent of one of the chemostats was increased such that nitrite peaks in the bulk liquid of this reactor were detected. The other chemostat served as control reactor, which always had a constant nitrite influent concentration. The relative cellular area (RCA) of Nitrospira and Nitrobacter was determined by quantitative fluorescence in situ hybridization (FISH). The nitrite perturbation stimulated the growth of Nitrobacter while in the undisturbed control chemostat Nitrospira dominated. Overall, the results of this experimental study support the hypothesis that Nitrobacter is a superior competitor when resources are abundant, while Nitrospira thrive under conditions of resource scarcity. Interestingly, the dominance of Nitrobacter over Nitrospira, caused by the elevated nitrite concentrations, could not be reverted by lowering the available nitrite concentration to the original level. One possible explanation for this result is that when Nitrobacter is present at a certain cell density it is able to inhibit the growth of Nitrospira. An alternative explanation would be that the length of the experimental period was not long enough to observe an increase of the Nitrospira population. (c) 2006 Wiley Periodicals, Inc

Influence of liposome encapsulated essential oils on properties of chitosan films

[EN] The effect of the encapsulation of eugenol and cinnamon leaf essential oil (CLEO) in lecithin liposomes on the losses of these compounds during the chitosan film formation process by casting was evaluated. Film-forming dispersions and films with eugenol or CLEO (either free or encapsulated) were obtained and characterized. The content of eugenol in active films was quantified by means of solvent extraction and gas chromatograph analysis. The encapsulation of eugenol or CLEO in lecithin liposomes led to the films retaining 40% −50% of the incorporated eugenol, whereas only 1%−2% was retained when eugenol was incorporated by direct emulsification. Films with liposomes exhibited a lamellar microstructure which improved film extensibility and increased water vapour barrier capacity with respect to those with free emulsified compounds. Liposomes also modified the optical properties of the films, reducing their gloss, increasing colour saturation and making them redder in colour. The encapsulation of volatile active compounds in liposomes appears to be a good strategy for obtaining antimicrobial films with essential oils.The authors acknowledge the financial support provided by the Ministerio de Economía y Competitividad (Project AGL2013-42989-R). Cristina Valencia Sullca thanks the Programa Nacional de Becas del Perú (Pronabec) for the completion of her doctoral thesis.Valencia-Sullca, CE.; Jiménez Serrallé, M.; Jiménez Marco, A.; Atarés Huerta, LM.; Vargas, M.; Chiralt, A. (2016). Influence of liposome encapsulated essential oils on properties of chitosan films. Polymer International (Online). 65(8):979-987. https://doi.org/10.1002/pi.5143S979987658Jiménez, A., Fabra, M. J., Talens, P., & Chiralt, A. (2013). Physical properties and antioxidant capacity of starch–sodium caseinate films containing lipids. Journal of Food Engineering, 116(3), 695-702. doi:10.1016/j.jfoodeng.2013.01.010Zhai, M., Zhao, L., Yoshii, F., & Kume, T. (2004). Study on antibacterial starch/chitosan blend film formed under the action of irradiation. Carbohydrate Polymers, 57(1), 83-88. doi:10.1016/j.carbpol.2004.04.003Perdones, Á., Vargas, M., Atarés, L., & Chiralt, A. (2014). Physical, antioxidant and antimicrobial properties of chitosan–cinnamon leaf oil films as affected by oleic acid. Food Hydrocolloids, 36, 256-264. doi:10.1016/j.foodhyd.2013.10.003Singh, G., Maurya, S., deLampasona, M. P., & Catalan, C. A. N. (2007). A comparison of chemical, antioxidant and antimicrobial studies of cinnamon leaf and bark volatile oils, oleoresins and their constituents. Food and Chemical Toxicology, 45(9), 1650-1661. doi:10.1016/j.fct.2007.02.031Bajpai, V. K., Baek, K.-H., & Kang, S. C. (2012). Control of Salmonella in foods by using essential oils: A review. Food Research International, 45(2), 722-734. doi:10.1016/j.foodres.2011.04.052Shah, B., Davidson, P. M., & Zhong, Q. (2013). Nanodispersed eugenol has improved antimicrobial activity against Escherichia coli O157:H7 and Listeria monocytogenes in bovine milk. International Journal of Food Microbiology, 161(1), 53-59. doi:10.1016/j.ijfoodmicro.2012.11.020Sebaaly, C., Jraij, A., Fessi, H., Charcosset, C., & Greige-Gerges, H. (2015). Preparation and characterization of clove essential oil-loaded liposomes. Food Chemistry, 178, 52-62. doi:10.1016/j.foodchem.2015.01.067Atarés, L., & Chiralt, A. (2016). Essential oils as additives in biodegradable films and coatings for active food packaging. Trends in Food Science & Technology, 48, 51-62. doi:10.1016/j.tifs.2015.12.001Sánchez-González, L., Chiralt, A., González-Martínez, C., & Cháfer, M. (2011). Effect of essential oils on properties of film forming emulsions and films based on hydroxypropylmethylcellulose and chitosan. Journal of Food Engineering, 105(2), 246-253. doi:10.1016/j.jfoodeng.2011.02.028Bakkali, F., Averbeck, S., Averbeck, D., & Idaomar, M. (2008). Biological effects of essential oils – A review. Food and Chemical Toxicology, 46(2), 446-475. doi:10.1016/j.fct.2007.09.106Wu, J., Liu, H., Ge, S., Wang, S., Qin, Z., Chen, L., … Zhang, Q. (2015). The preparation, characterization, antimicrobial stability and in vitro release evaluation of fish gelatin films incorporated with cinnamon essential oil nanoliposomes. Food Hydrocolloids, 43, 427-435. doi:10.1016/j.foodhyd.2014.06.017Imran, M., Revol-Junelles, A.-M., René, N., Jamshidian, M., Akhtar, M. J., Arab-Tehrany, E., … Desobry, S. (2012). Microstructure and physico-chemical evaluation of nano-emulsion-based antimicrobial peptides embedded in bioactive packaging films. Food Hydrocolloids, 29(2), 407-419. doi:10.1016/j.foodhyd.2012.04.010Zhang, H. Y., Arab Tehrany, E., Kahn, C. J. F., Ponçot, M., Linder, M., & Cleymand, F. (2012). Effects of nanoliposomes based on soya, rapeseed and fish lecithins on chitosan thin films designed for tissue engineering. Carbohydrate Polymers, 88(2), 618-627. doi:10.1016/j.carbpol.2012.01.007Jiménez, A., Sánchez-González, L., Desobry, S., Chiralt, A., & Tehrany, E. A. (2014). Influence of nanoliposomes incorporation on properties of film forming dispersions and films based on corn starch and sodium caseinate. Food Hydrocolloids, 35, 159-169. doi:10.1016/j.foodhyd.2013.05.006Olasupo, N. A., Fitzgerald, D. J., Gasson, M. J., & Narbad, A. (2003). Activity of natural antimicrobial compounds against Escherichia coli and Salmonella enterica serovar Typhimurium. Letters in Applied Microbiology, 37(6), 448-451. doi:10.1046/j.1472-765x.2003.01427.xMcHUGH, T. H., AVENA-BUSTILLOS, R., & KROCHTA, J. M. (1993). Hydrophilic Edible Films: Modified Procedure for Water Vapor Permeability and Explanation of Thickness Effects. Journal of Food Science, 58(4), 899-903. doi:10.1111/j.1365-2621.1993.tb09387.xHutchings, J. B. (1999). Food Colour and Appearance. doi:10.1007/978-1-4615-2373-4Falguera, V., Quintero, J. P., Jiménez, A., Muñoz, J. A., & Ibarz, A. (2011). Edible films and coatings: Structures, active functions and trends in their use. Trends in Food Science & Technology, 22(6), 292-303. doi:10.1016/j.tifs.2011.02.004Leceta, I., Guerrero, P., & de la Caba, K. (2013). Functional properties of chitosan-based films. Carbohydrate Polymers, 93(1), 339-346. doi:10.1016/j.carbpol.2012.04.031Pérez-Gago, M. B., & Krochta, J. M. (2001). Lipid Particle Size Effect on Water Vapor Permeability and Mechanical Properties of Whey Protein/Beeswax Emulsion Films. Journal of Agricultural and Food Chemistry, 49(2), 996-1002. doi:10.1021/jf000615fFabra, M. J., Talens, P., & Chiralt, A. (2008). Tensile properties and water vapor permeability of sodium caseinate films containing oleic acid–beeswax mixtures. Journal of Food Engineering, 85(3), 393-400. doi:10.1016/j.jfoodeng.2007.07.022Sánchez-González, L., Vargas, M., González-Martínez, C., Chiralt, A., & Cháfer, M. (2009). Characterization of edible films based on hydroxypropylmethylcellulose and tea tree essential oil. Food Hydrocolloids, 23(8), 2102-2109. doi:10.1016/j.foodhyd.2009.05.006McHugh, T. H., & Krochta, J. M. (1994). Water vapor permeability properties of edible whey protein-lipid emulsion films. Journal of the American Oil Chemists’ Society, 71(3), 307-312. doi:10.1007/bf02638058Ma, X., Chang, P. R., & Yu, J. (2008). Properties of biodegradable thermoplastic pea starch/carboxymethyl cellulose and pea starch/microcrystalline cellulose composites. Carbohydrate Polymers, 72(3), 369-375. doi:10.1016/j.carbpol.2007.09.002Fabra, M. J., Talens, P., & Chiralt, A. (2010). Water sorption isotherms and phase transitions of sodium caseinate–lipid films as affected by lipid interactions. Food Hydrocolloids, 24(4), 384-391. doi:10.1016/j.foodhyd.2009.11.004Shen, Z., & Kamdem, D. P. (2015). Development and characterization of biodegradable chitosan films containing two essential oils. International Journal of Biological Macromolecules, 74, 289-296. doi:10.1016/j.ijbiomac.2014.11.046Ojagh, S. M., Rezaei, M., Razavi, S. H., & Hosseini, S. M. H. (2010). Development and evaluation of a novel biodegradable film made from chitosan and cinnamon essential oil with low affinity toward water. Food Chemistry, 122(1), 161-166. doi:10.1016/j.foodchem.2010.02.033Fabra, M. J., Talens, P., & Chiralt, A. (2009). Microstructure and optical properties of sodium caseinate films containing oleic acid–beeswax mixtures. Food Hydrocolloids, 23(3), 676-683. doi:10.1016/j.foodhyd.2008.04.015Cano, A., Jiménez, A., Cháfer, M., Gónzalez, C., & Chiralt, A. (2014). Effect of amylose:amylopectin ratio and rice bran addition on starch films properties. Carbohydrate Polymers, 111, 543-555. doi:10.1016/j.carbpol.2014.04.075Van Roon, A., Parsons, J. R., & Govers, H. A. . (2002). Gas chromatographic determination of vapour pressure and related thermodynamic properties of monoterpenes and biogenically related compounds. Journal of Chromatography A, 955(1), 105-115. doi:10.1016/s0021-9673(02)00200-5Devlieghere, F., Vermeulen, A., & Debevere, J. (2004). Chitosan: antimicrobial activity, interactions with food components and applicability as a coating on fruit and vegetables. Food Microbiology, 21(6), 703-714. doi:10.1016/j.fm.2004.02.00

Commercial steel wool used for Zero Valent Iron and as a source of disolved iron in a combined red-ox processfor pentachlorophenol degradationm in tap water

[EN] Pentachlorophenol solutions in tap water were treated with a combined process of zero valent iron (ZVI) reduction followed by a photo-Fenton oxidation. Commercial steel wool was used as ZVI source, demonstrating its effectivity for pentachlorophenol de-chlorination at acidic pH values. The reductive pathway was monitored by the use of excitation emission matrices, showing the transformation of the initial compound into the fluorescent species 4-chlorophenol and phenol. While the use of tap water represented a drawback in photo-Fenton oxidative reactions (at least half kinetic constants values) an improvement was achieved when the reductive stage was applied in the studied pH range. The transformation of pentachlorophenol into phenol produced an increase in oxidative stage rate of about 8 times. This fact could be related to the treatment time and hydrogen peroxide consumption of the photo-Fenton process, enhancing the economic viability. Furthermore, the de-chlorination of the pentachlorophenol minimized the possibility of releasing toxic by-products in the photo-Fenton process.Authors want to acknowledge the financial support of Spanish Ministerio de Economia y Competitividad (CTQ2015-69832-C4-4-R), European Union (645551-RISE-2014, MAT4TREAT).Santos-Juanes Jordá, L.; García-Ballesteros, S.; Vercher Pérez, RF.; Amat Payá, AM.; Arqués Sanz, A. (2019). Commercial steel wool used for Zero Valent Iron and as a source of disolved iron in a combined red-ox processfor pentachlorophenol degradationm in tap water. Catalysis Today. 328:252-258. https://doi.org/10.1016/j.cattod.2019.01.007S25225832

Use optimization of natural antioxidants in refined, bleached, and deodorized palm olein during repeated deep-fat frying using response surface methodology

An optimization study on the use of oleoresin rosemary extract, sage extract, and citric acid added into refined, bleached, and deodorized (RBD) palm olein in deep-fat frying of potato chips was carried out using response surface methodology (RSM). Results showed that oleoresin rosemary extract was the most important factor affecting the sensory acceptability of potato chips. For taste and odor, its effects were highly significant (P<0.01), while for crispiness and overall acceptability, the effects were significant (P<0.05). As for sage extract, the level of this antioxidant had a highly significant (P<0.01) effect on appearance and taste and a significant effect (P<0.05) on odor and overall acceptability, but had no effect on crispiness. Although there was no significant synergistic correlation between citric acid and oleoresin rosemary extract or sage extract at the first order, its second order was significantly (P<0.05) related to taste, crispiness, and overall acceptability. An interaction between oleoresin rosemary and sage extracts also significantly (P<0.05) improved the score of overall acceptability of the potato chips. Contour maps of the sensory scores of potato chips indicated that the optimal points for appearance were achieved using 0.062% oleoresin rosemary extract, 0.066% sage extract, and 0.023% citric acid, while optimal task was achieved with 0.063% oleoresin rosemary extract, 0.075% sage extract, and 0.025% citric acid. With the same sequence of ingredients added into oil, the combinations required to achieve the optimal odor, crispiness, and overall acceptability scores were 0.058-0.046-0.026, 0.060-0.071-0.022, and 0.060-0.064-0.026%, respectively

Supplemental Information 4: Raw data.

This study evaluated pollution levels in water and sediments of Península de Paraguaná and related these levels with benthic macrofauna along a coastal area where the largest Venezuelan oil refineries have operated over the past 60 years. For this, the concentration of heavy metals, of hydrocarbon compounds and the community structure of the macrobenthos were examined at 20 sites distributed along 40 km of coastline for six consecutive years, which included windy and calm seasons. The spatial variability of organic and inorganic compounds showed considerably high coastal pollution along the study area, across both years and seasons. The southern sites, closest to the refineries, had consistently higher concentrations of heavy metals and organic compounds in water and sediments when compared to those in the north. The benthic community was dominated by polychaetes at all sites, seasons and years, and their abundance and distribution were significantly correlated with physical and chemical characteristics of the sediments. Sites close to the oil refineries were consistently dominated by families known to tolerate xenobiotics, such as Capitellidae and Spionidae. The results from this study highlight the importance of continuing long-term environmental monitoring programs to assess the impact of effluent discharge and spill events from the oil refineries that operate in the western coast of Paraguaná, Venezuela