Corrigendum: Collective search by ants in microgravity

The problem of collective search is a tradeoff between searching thoroughly and covering as much area as possible. This tradeoff depends on the density of searchers. Solutions to the problem of collective search are currently of much interest in robotics and in the study of distributed algorithms, for example to design ways that without central control robots can use local information to perform search and rescue operations. Ant colonies operate without central control. Because they can perceive only local, mostly chemical and tactile cues, they must search collectively to find resources and to monitor the colony's environment. Examining how ants in diverse environments solve the problem of collective search can elucidate how evolution has led to diverse forms of collective behavior. An experiment on the International Space Station in January 2014 examined how ants (Tetramorium caespitum) perform collective search in microgravity. In the ISS experiment, the ants explored a small arena in which a barrier was lowered to increase the area and thus lower ant density. In microgravity, relative to ground controls, ants explored the area less thoroughly and took more convoluted paths. It appears that the difficulty of holding on to the surface interfered with the ants’ ability to search collectively. Ants frequently lost contact with the surface, but showed a remarkable ability to regain contact with the surface

Wastewater nutrient removal in a mixed microalgae bacteria culture: effect of light and temperature on the microalgae bacteria competition

[EN] The aim of this study was to evaluate the effect of light intensity and temperature on nutrient removal and biomass productivity in a microalgae¿bacteria culture and their effects on the microalgae¿bacteria competition. Three experiments were carried out at constant temperature and various light intensities: 40, 85 and 125¿µE¿m¿2¿s¿1. Other two experiments were carried out at variable temperatures: 23¿±¿2°C and 28¿±¿2°C at light intensity of 85 and 125¿µE¿m¿2¿s¿1, respectively. The photobioreactor was fed by the effluent from an anaerobic membrane bioreactor. High nitrogen and phosphorus removal efficiencies (about 99%) were achieved under the following operating conditions: 85¿125¿µE¿m¿2¿s¿1 and 22¿±¿1°C. In the microalgae¿bacteria culture studied, increasing light intensity favoured microalgae growth and limited the nitrification process. However, a non-graduated temperature increase (up to 32°C) under the light intensities studied caused the proliferation of nitrifying bacteria and the nitrite and nitrate accumulation. Hence, light intensity and temperature are key parameters in the control of the microalgae¿bacteria competition. Biomass productivity significantly increased with light intensity, reaching 50.5¿±¿9.6, 80.3¿±¿6.5 and 94.3¿±¿7.9¿mgVSS¿L¿1¿d¿1 for a light intensity of 40, 85 and 125¿µE¿m¿2¿s¿1, respectivelyThis research work was possible because of Projects CTM2011-28595-C02-01 and CTM2011-28595-C02-02 [funded by the Spanish Ministry of Economy and Competitiveness jointly with the European Regional Development Fund and the Generalitat Valenciana GVA-ACOMP2013/203]. This research was also supported by the Spanish Ministry of Education, Culture and Sport via a pre doctoral FPU fellowship to the first author [FPU14/05082].Gonzalez-Camejo, J.; Barat, R.; Pachés Giner, MAV.; Murgui Mezquita, M.; Seco Torrecillas, A.; Ferrer, J. (2018). Wastewater nutrient removal in a mixed microalgae bacteria culture: effect of light and temperature on the microalgae bacteria competition. Environmental Technology. 39(4):503-515. https://doi.org/10.1080/09593330.2017.1305001S503515394Giménez, J. B., Robles, A., Carretero, L., Durán, F., Ruano, M. V., Gatti, M. N., … Seco, A. (2011). Experimental study of the anaerobic urban wastewater treatment in a submerged hollow-fibre membrane bioreactor at pilot scale. Bioresource Technology, 102(19), 8799-8806. doi:10.1016/j.biortech.2011.07.014Huang, Z., Ong, S. L., & Ng, H. Y. (2011). Submerged anaerobic membrane bioreactor for low-strength wastewater treatment: Effect of HRT and SRT on treatment performance and membrane fouling. Water Research, 45(2), 705-713. doi:10.1016/j.watres.2010.08.035Ruiz-Martinez, A., Martin Garcia, N., Romero, I., Seco, A., & Ferrer, J. (2012). Microalgae cultivation in wastewater: Nutrient removal from anaerobic membrane bioreactor effluent. Bioresource Technology, 126, 247-253. doi:10.1016/j.biortech.2012.09.022Chisti, Y. (2007). Biodiesel from microalgae. Biotechnology Advances, 25(3), 294-306. doi:10.1016/j.biotechadv.2007.02.001Rawat, I., Bhola, V., Kumar, R. R., & Bux, F. (2013). Improving the feasibility of producing biofuels from microalgae using wastewater. Environmental Technology, 34(13-14), 1765-1775. doi:10.1080/09593330.2013.826287Collet, P., Hélias, A., Lardon, L., Ras, M., Goy, R.-A., & Steyer, J.-P. (2011). Life-cycle assessment of microalgae culture coupled to biogas production. Bioresource Technology, 102(1), 207-214. doi:10.1016/j.biortech.2010.06.154Milledge, J. J. (2010). Commercial application of microalgae other than as biofuels: a brief review. Reviews in Environmental Science and Bio/Technology, 10(1), 31-41. doi:10.1007/s11157-010-9214-7Posadas, E., García-Encina, P.-A., Soltau, A., Domínguez, A., Díaz, I., & Muñoz, R. (2013). Carbon and nutrient removal from centrates and domestic wastewater using algal–bacterial biofilm bioreactors. Bioresource Technology, 139, 50-58. doi:10.1016/j.biortech.2013.04.008Podevin, M., De Francisci, D., Holdt, S. L., & Angelidaki, I. (2014). Effect of nitrogen source and acclimatization on specific growth rates of microalgae determined by a high-throughput in vivo microplate autofluorescence method. Journal of Applied Phycology, 27(4), 1415-1423. doi:10.1007/s10811-014-0468-2Meseck, S. L., Smith, B. C., Wikfors, G. H., Alix, J. H., & Kapareiko, D. (2006). Nutrient interactions between phytoplankton and bacterioplankton under different carbon dioxide regimes. Journal of Applied Phycology, 19(3), 229-237. doi:10.1007/s10811-006-9128-5Risgaard-Petersen, N., Nicolaisen, M. H., Revsbech, N. P., & Lomstein, B. A. (2004). Competition between Ammonia-Oxidizing Bacteria and Benthic Microalgae. Applied and Environmental Microbiology, 70(9), 5528-5537. doi:10.1128/aem.70.9.5528-5537.2004Tiquia-Arashiro, S. M., & Mormile, M. (2013). Sustainable technologies: bioenergy and biofuel from biowaste and biomass. Environmental Technology, 34(13-14), 1637-1638. doi:10.1080/09593330.2013.834162Jordan, B. R. (1996). The Effects of Ultraviolet-B Radiation on Plants: A Molecular Perspective. Advances in Botanical Research, 97-162. doi:10.1016/s0065-2296(08)60057-9Znad, H., Naderi, G., Ang, H. M., & Tade, M. O. (2012). CO2 Biomitigation and Biofuel Production Using Microalgae: Photobioreactors Developments and Future Directions. Advances in Chemical Engineering. doi:10.5772/32568Martínez, M. (2000). Nitrogen and phosphorus removal from urban wastewater by the microalga Scenedesmus obliquus. Bioresource Technology, 73(3), 263-272. doi:10.1016/s0960-8524(99)00121-2Xin, L., Hong-ying, H., & Yu-ping, Z. (2011). Growth and lipid accumulation properties of a freshwater microalga Scenedesmus sp. under different cultivation temperature. Bioresource Technology, 102(3), 3098-3102. doi:10.1016/j.biortech.2010.10.055Robles, Á., Durán, F., Ruano, M. V., Ribes, J., Rosado, A., Seco, A., & Ferrer, J. (2015). Instrumentation, control, and automation for submerged anaerobic membrane bioreactors. Environmental Technology, 36(14), 1795-1806. doi:10.1080/09593330.2015.1012180Reynolds, C. S. (2006). The Ecology of Phytoplankton. doi:10.1017/cbo9780511542145Küster, E., Dorusch, F., & Altenburger, R. (2005). EFFECTS OF HYDROGEN SULFIDE TO VIBRIO FISCHERI, SCENEDESMUS VACUOLATUS, AND DAPHNIA MAGNA. Environmental Toxicology and Chemistry, 24(10), 2621. doi:10.1897/04-546r.1Park, J., Jin, H.-F., Lim, B.-R., Park, K.-Y., & Lee, K. (2010). Ammonia removal from anaerobic digestion effluent of livestock waste using green alga Scenedesmus sp. Bioresource Technology, 101(22), 8649-8657. doi:10.1016/j.biortech.2010.06.142McGinn, P. J., Dickinson, K. E., Park, K. C., Whitney, C. G., MacQuarrie, S. P., Black, F. J., … O’Leary, S. J. B. (2012). Assessment of the bioenergy and bioremediation potentials of the microalga Scenedesmus sp. AMDD cultivated in municipal wastewater effluent in batch and continuous mode. Algal Research, 1(2), 155-165. doi:10.1016/j.algal.2012.05.001Mara, D. D., & Feachem, R. G. A. (2003). Unitary environmental classification of water- and excreta-related communicable diseases. Handbook of Water and Wastewater Microbiology, 185-192. doi:10.1016/b978-012470100-7/50012-1Jeffrey, S. W., & Humphrey, G. F. (1975). New spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants, algae and natural phytoplankton. Biochemie und Physiologie der Pflanzen, 167(2), 191-194. doi:10.1016/s0015-3796(17)30778-3Laliberté, G., Lessard, P., de la Noüe, J., & Sylvestre, S. (1997). Effect of phosphorus addition on nutrient removal from wastewater with the cyanobacterium Phormidium bohneri. Bioresource Technology, 59(2-3), 227-233. doi:10.1016/s0960-8524(96)00144-7Pachés, M., Romero, I., Hermosilla, Z., & Martinez-Guijarro, R. (2012). PHYMED: An ecological classification system for the Water Framework Directive based on phytoplankton community composition. Ecological Indicators, 19, 15-23. doi:10.1016/j.ecolind.2011.07.003Xin, L., Hong-ying, H., Ke, G., & Jia, Y. (2010). Growth and nutrient removal properties of a freshwater microalga Scenedesmus sp. LX1 under different kinds of nitrogen sources. Ecological Engineering, 36(4), 379-381. doi:10.1016/j.ecoleng.2009.11.003Wang, L., Min, M., Li, Y., Chen, P., Chen, Y., Liu, Y., … Ruan, R. (2009). Cultivation of Green Algae Chlorella sp. in Different Wastewaters from Municipal Wastewater Treatment Plant. Applied Biochemistry and Biotechnology, 162(4), 1174-1186. doi:10.1007/s12010-009-8866-7Pancha, I., Chokshi, K., George, B., Ghosh, T., Paliwal, C., Maurya, R., & Mishra, S. (2014). Nitrogen stress triggered biochemical and morphological changes in the microalgae Scenedesmus sp. CCNM 1077. Bioresource Technology, 156, 146-154. doi:10.1016/j.biortech.2014.01.025Sarat Chandra, T., Deepak, R. S., Maneesh Kumar, M., Mukherji, S., Chauhan, V. S., Sarada, R., & Mudliar, S. N. (2016). Evaluation of indigenous fresh water microalga Scenedesmus obtusus for feed and fuel applications: Effect of carbon dioxide, light and nutrient sources on growth and biochemical characteristics. Bioresource Technology, 207, 430-439. doi:10.1016/j.biortech.2016.01.044Krustok, I., Odlare, M., Truu, J., & Nehrenheim, E. (2016). Inhibition of nitrification in municipal wastewater-treating photobioreactors: Effect on algal growth and nutrient uptake. Bioresource Technology, 202, 238-243. doi:10.1016/j.biortech.2015.12.020Chen, X., Goh, Q. Y., Tan, W., Hossain, I., Chen, W. N., & Lau, R. (2011). Lumostatic strategy for microalgae cultivation utilizing image analysis and chlorophyll a content as design parameters. Bioresource Technology, 102(10), 6005-6012. doi:10.1016/j.biortech.2011.02.061Powell, N., Shilton, A., Chisti, Y., & Pratt, S. (2009). Towards a luxury uptake process via microalgae – Defining the polyphosphate dynamics. Water Research, 43(17), 4207-4213. doi:10.1016/j.watres.2009.06.011Cabello, J., Toledo-Cervantes, A., Sánchez, L., Revah, S., & Morales, M. (2015). Effect of the temperature, pH and irradiance on the photosynthetic activity by Scenedesmus obtusiusculus under nitrogen replete and deplete conditions. Bioresource Technology, 181, 128-135. doi:10.1016/j.biortech.2015.01.034Zhu, W., Wan, L., & Zhao, L. (2010). Effect of nutrient level on phytoplankton community structure in different water bodies. Journal of Environmental Sciences, 22(1), 32-39. doi:10.1016/s1001-0742(09)60071-1Daims, H., Brühl, A., Amann, R., Schleifer, K.-H., & Wagner, M. (1999). The Domain-specific Probe EUB338 is Insufficient for the Detection of all Bacteria: Development and Evaluation of a more Comprehensive Probe Set. Systematic and Applied Microbiology, 22(3), 434-444. doi:10.1016/s0723-2020(99)80053-8Daims, H., Nielsen, J. L., Nielsen, P. H., Schleifer, K.-H., & Wagner, M. (2001). In Situ Characterization of Nitrospira-Like Nitrite-Oxidizing Bacteria Active in Wastewater Treatment Plants. Applied and Environmental Microbiology, 67(11), 5273-5284. doi:10.1128/aem.67.11.5273-5284.2001analysis of nitrifying bacteria in sewage treatment plants. (1996). Water Science and Technology, 34(1-2). doi:10.1016/0273-1223(96)00514-

Best practices in heterotrophic high-cell-density microalgal processes: achievements, potential and possible limitations

Microalgae of numerous heterotrophic genera (obligate or facultative) exhibit considerable metabolic versatility and flexibility but are currently underexploited in the biotechnological manufacturing of known plant-derived compounds, novel high-value biomolecules or enriched biomass. Highly efficient production of microalgal biomass without the need for light is now feasible in inexpensive, well-defined mineral medium, typically supplemented with glucose. Cell densities of more than 100 g l−1 cell dry weight have been achieved with Chlorella, Crypthecodinium and Galdieria species while controlling the addition of organic sources of carbon and energy in fedbatch mode. The ability of microalgae to adapt their metabolism to varying culture conditions provides opportunities to modify, control and thereby maximise the formation of targeted compounds with non-recombinant microalgae. This review outlines the critical aspects of cultivation technology and current best practices in the heterotrophic high-cell-density cultivation of microalgae. The primary topics include (1) the characteristics of microalgae that make them suitable for heterotrophic cultivation, (2) the appropriate chemical composition of mineral growth media, (3) the different strategies for fedbatch cultivations and (4) the principles behind the customisation of biomass composition. The review confirms that, although fundamental knowledge is now available, the development of efficient, economically feasible large-scale bioprocesses remains an obstacle to the commercialisation of this promising technology

Climate mediates the effects of disturbance on ant assemblage structure

Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about howclimate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effectwas manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 98C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk. © 2015 The Author(s) Published by the Royal Society. All rights reserved

Perennials but not slope aspect affect the diversity of soil bacterial communities in the northern Negev Desert, Israel

Underneath the canopy of perennials in arid regions, moderate soil temperature and evaporation, as well as plant litter create islands of higher fertility in the low-productivity landscape, known as ‘resource islands’. The sparse distribution of these resource islands is mirrored by soil microbial communities, which mediate a large number of biogeochemical transformations underneath the plants. We explored the link between the bacterial community composition and two prevalent desert shrubs, Zygophyllum dumosum and Artemisia herba-alba, on northern- and southern-facing slopes in the northern highlands of the Negev Desert (Israel), at the end of a drought winter mild rainy season. We sequenced the bacterial community and analysed the physicochemical properties of the soil under the shrub canopies and from barren soil in replicate slopes. The soil bacterial diversity was independent of slope aspect, but differed according to shrub presence or type. Links between soil bacterial community composition and their associated desert shrubs were found, enabling us to link bacterial diversity with shrub type or barren soils. Our results suggest that plants and their associated bacterial communities are connected to survival and persistence under the harsh desert conditions