Spirulina (Arthrospira) industry in Inner Mongolia of China: current status and prospects

This paper outlines an investigation on current situation of Spirulina (Arthrospira) industry in Inner Mongolia, an internal region of China with temperate continental climate. More than 20 Spirulina plants have been established in Inner Mongolia since 2001, most of which are located at Wulan Town in the Ordos Plateau. By the end of 2009, the total annual production of Spirulina in the Ordos Plateau surpassed 700 t (dw), which account for ca. 80% of the total productivity of Inner Mongolia, and ca. 20% of China. Besides abundant solar radiation and enough freshwater favorable for Spirulina production, the three technical strategies contribute to the prosperity and success of Spirulina industry in the region: (1) reducing the cost or investment by overall advantages of rich local natural resources with low cost for Spirulina production, such as alkaline lakes, coal, electricity, and sandy land; (2) controlling the culture temperature and to avoid contamination by building plastic greenhouses on raceway ponds, (3) reducing investment by simplifying the construction of the ponds and the greenhouses. As the result, the growth period of Spirulina has been prolonged from about 120 to about 165 days, the cost of Spirulina has decreased by 25–30%, and the quality of products has been enhanced substantially. Inner Mongolia is expected to become the largest base for Spirulina production not only in China, but also in the world in the near future

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). 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Behavior of mixed Chlorophyceae cultures under prolonged dark exposure. Respiration rate modeling

[EN] The behavior of three different microalgal cultures, when exposed for a long period (>48 h) to dark conditions, was studied with a methodology based on respirometry. The cultures were transferred to darkness and the oxygen evolution in the reactors was monitored after successive air injections. Several sequential oxygen uptake rates were thus calculated and a respiration constant, assuming a first order decay of a fraction of the biomass, was obtained by calibration. Initial specific oxygen uptake rates were in the range of 0.9 5.1 mg O2 g TSS−1 h−1 and dark respiration constants in the range of 0.005 0.018 h−1.This research work has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO, CTM2011-28595-C02- 01/02) jointly with the European Regional Development Fund (ERDF) which are gratefully acknowledged. This research was also supported by the Spanish Ministry of Science and Innovation via a pre doctoral FPU fellowship to the first author (AP2009-4903). The authors would also like to thank the water management entities of the Generalitat Valenciana (EPSAR).Ruiz Martínez, A.; Serralta Sevilla, J.; Seco Torrecillas, A.; Ferrer, J. (2016). Behavior of mixed Chlorophyceae cultures under prolonged dark exposure. Respiration rate modeling. Ecological Engineering. 91:265-269. https://doi.org/10.1016/j.ecoleng.2016.02.025S2652699

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

Continuous cultivation of photosynthetic microorganisms: approaches, applications and future trends

The possibility of using photosynthetic microorganisms, such as cyanobacteria and microalgae, for converting light and carbon dioxide into valuable biochemical products has raised the need for new cost-efficient processes ensuring a constant product quality. Food, feed, biofuels, cosmetics and pharmaceutics are among the sectors that can profit from the application of photosynthetic microorganisms. Biomass growth in a photobioreactor is a complex process influenced by multiple parameters, such as photosynthetic light capture and attenuation, nutrient uptake, photobioreactor hydrodynamics and gas-liquid mass transfer. In order to optimize productivity while keeping a standard product quality, a permanent control of the main cultivation parameters is necessary, where the continuous cultivation has shown to be the best option. However it is of utmost importance to recognize the singularity of continuous cultivation of cyanobacteria and microalgae due to their dependence on light availability and intensity. In this sense, this review provides comprehensive information on recent breakthroughs and possible future trends regarding technological and process improvements in continuous cultivation systems of microalgae and cyanobacteria, that will directly affect cost-effectiveness and product quality standardization. An overview of the various applications, techniques and equipment (with special emphasis on photobioreactors) in continuous cultivation of microalgae and cyanobacteria are presented. Additionally, mathematical modelling, feasibility, economics as well as the applicability of continuous cultivation into large-scale operation, are discussed.This research work was supported by the grant SFRH/BPD/98694/2013 (Bruno Fernandes) from Fundacao para a Ciencia e a Tecnologia (Portugal). The authors thank the FCT Strategic Project PEst-OE/EQB/LA0023/2013. The authors also thank the Project "BioInd Biotechnology and Bioengineering for improved Industrial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028" Co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDE

Seasonal variation in the nutrient profile of Arthrospira fusiformis biomass harvested from an Ethiopian soda lake, Lake Chitu

The extent of seasonal variation in the nutrient profile of Arthrospira biomass harvested from Lake Chitu was investigated to evaluate the variability of the quality of the product over a period of a year. Protein content varied from 47.9 to 55.7% for wet season biomass samples and from 39.2 to 40.8% for dry season samples. Dry season samples were characterized by relatively higher carbohydrate values (38.0–41.3%). Higher proportion of amino acids and unsaturated fatty acids were recorded for biomass harvested in wet season. Similarly, higher contents of phytonutrients (pigments) were recorded for wet season biomass samples: chlorophyll a (8.2–10.3 mg g−1), phycobiliproteins (104.1–120.7 mg g−1), total carotenoids (3.17–4.31 mg g−1), and β-carotene (1.24–1.61 mg g−1). The contents of Na and K were higher for a dry season biomass whereas other major (Ca, P, Mg) and trace (Mn, Fe, Cu, Zn, Se) minerals were found relatively in higher quantities in a wet season biomass. The nutritional composition of Arthrospira from Lake Chitu was found to be relatively comparable to that found in commercial Arthrospira products in the market. The significance of the findings is discussed in relation to potential sustainable production of Arthrospira biomass from this lake

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