Chlorella, ¿un potencial biofertilizante?

ARTÍCULO DE REVISIÓN/REVIEW ARTICLE Orinoquia, Julio-Diciembre 2019;23(2):71-78 ISSN electrónico 2011-2629. ISSN impreso 0121-3709. http://doi.org/10.22579/20112629.582 Chlorella, ¿un potencial biofertilizante? Chlorella, a potential biofertilizer? Chlorella, um potencial biofertilizante? Martha L Ortiz-Moreno1; Karen X Sandoval-Parra2; Laura V Solarte-Murillo3 1 Biol, MSc, PhD, Departamento de Biología y Química, Facultad de Ciencias Básicas e Ingeniería, Universidad de los Llanos, Villavicencio, Colombia. 2 Biol, Departamento de Biología y Química, Facultad de Ciencias Básicas e Ingeniería, Universidad de los Llanos, Villavicencio, Colombia 3 Biol, Departamento de Biología y Química, Facultad de Ciencias Básicas e Ingeniería, Universidad de los Llanos, Villavicencio, Colombia Email: mlortiz@unillanos.edu.co Recibido: 14 de marzo de 2019 Aceptado: 28 de agosto 2019 Resumen Las microalgas son organismos fotoautótrofos con un rápido crecimiento y la habilidad de adaptarse a diversos ambientes. Convierten el dióxido de carbono en biomasa y debido a esto, se considera que tienen gran potencial biotecnológico. La biomasa algal puede usarse en la industria alimenticia y de compuestos bioactivos, en la producción de biocombustibles, en la bioremediación y biofertilización. Como biofertilizantes, las microalgas clorofitas y cianofitas, producen polisacáridos (mucílago) que pueden evitar la erosión, mejorar la estructura y el contenido de material orgánica de los suelos, y aumentar la concentración de iones en los cultivos. Reduciendo de esta forma la necesidad de fertilizantes químicos convencionales. El uso de estas microalgas como biofertilizantes se denomina algalización. Durante este proceso se usan principalmente clorofitas por su alta tasa de crecimiento, la facilidad de su cultivo a gran escala, y su adaptación a las condiciones del suelo. El género Chlorella es de gran interés porque diversos estudios han mostrado que puede ayudar en la fijación del nitrógeno, mejorar las propiedades físicas y químicas del suelo, y producir sustancias que promueven el desarrollo de la planta y el control de infecciones. Por esta razón, las microalgas del género Chlorella representan una alternativa viable para la biofertilización, generando beneficios no solo para la producción agrícola sino también para el medio ambiente. Palabras clave: algalización; cianofitas; clorofitas; mejoramiento de suelos Abstract Microalgae are photoautotrophic organisms with fast growth and the ability to adapt to different environments. They convert carbon dioxide into biomass and are considered to have great biotechnological potential because of it. Algal biomass can be used in food and bioactive compounds industry, in biofuels production, in bioremediation and biofertilization. As biofertilizers, chlorophytes and cyanophytes microalgae produce polysaccharides (mucilage) that can avoid erosion, improve the Como Citar (Norma Vancouver): Ortiz-Moreno ML, Sandoval-Parra KX, Solarte-Murillo LV. Chlorella, ¿un potencial biofertilizante?. Orinoquia, 2020; 23(2):71-78. http://doi.org/10.22579/20112629.582 Chlorella, ¿un potencial biofertilizante? 71 structure and organic matter content in the soil, and increase the ions concentration for crop plants. Thus, reducing the need for conventional crop chemical fertilizers. The use of this microalgae as biofertilizers is called algalization. Algalization uses mainly chlorophytes due to their high growth rate, their simple large scale cultivation, and their adaptation to soil conditions. Chlorella genus is of special interest because research has shown that it can help with nitrogen fixation, improve physical and chemical properties of the soil, and produce substances that can promote plant development and infections control. Therefore, microalgae from Chlorella genus are a viable alternative for biofertilization, generating benefits for agricultural production and the environment. Keywords: algalization; chlorophytes; cyanophytes; soil improvement Resumo As microalgas são organismos fotoautotróficos com crescimento rápido e capacidade de adaptação a diferentes ambientes. Eles convertem dióxido de carbono em biomassa e, por isso, são considerados com um grande potencial biotecnológico. A biomassa de algas pode ser usada na indústria alimentar e de compostos bioactivos, na produção de biocombustíveis, na biorremediação e biofertilização. Como biofertilizantes, as microalgas clorófitas e cianófitas produzem polissacarídeos (mucilagem) que podem evitar a erosão, melhorar a estrutura e o conteúdo de matéria orgânica do solo, e aumentar a concentração de iões nas culturas, reduzindo assim a necessidade de fertilizantes químicos convencionais. O uso dessas microalgas como biofertilizantes é chamado de algalização. Durante este processo, usam-se eles principalmente clorofíceas por sua alta taxa de crescimento, facilidade de cultura em larga escala, e sua adaptação às condições do solo. A Chlorella é de grande interesse porque vários estudos têm mostrado que pode auxiliar na fixação do nitrogênio, melhorar as propriedades físicas e químicas do solo, e produzir substâncias que promovem o crescimento das plantas e o controle de infecções. Por esta razão, as microalgas do gênero Chlorella representam uma alternativa viável para a biofertilização, gerando benefícios não só para a produção agrícola, mas também para o meio ambiente. Palavras chave: algalização; clorofíceas; cianofíceas; melhoramento do solo Introduction Microalgae are a polyphyletic microscopic size photosynthetic group, consisting of eukaryotic organisms and prokaryotic cyanobacteria. Microalgae have unique advantages, including high growth rates, easy cultivation, low growth costs and the ability to adapt to different environments, which allow their cultivation to be established in small areas and in regions normally unsuitable for agricultural crops (Wang et al., 2014; Odjadjare et al., 2017). They obtain nutrients from the soil or aquatic habitats, absorb sunlight, capture CO2 from the air, and produce about 50% of the atmospheric oxygen (Rizwan et al., 2018). Microalgae convert carbon dioxide into biomass, and are, therefore, considered to have great biotechnological potential with several industrial applications, and also, to contribute with greenhouse effect mitigation. From algal biomass a wide variety of practical and potential products can be obtained: food supplements, lipids, enzymes, proteins, starch, phycocolloids, polymers, toxins, pigments, vitamins, antioxidants, stable isotope biochemicals, and green energy products such as biofuels and bio-ethanol (Chen et al., 2014a; Bleakley and Hayes, 2017; Moreno-Garcia et al., 2017; Pemmaraju et al., 2018). Therefore, are commercially used in human food, nutraceuticals, animal and aquatic feed, personal skin and cosmetics products, and in biomedicine and pharmaceutical industries for the synthesis of anti-inflammatory, antithrombogenic, antiatherogenic, 72 anticoagulant, antiviral, antibacterial and anticancer treatments (Suganya et al., 2016; Wells et al., 2017; Sassi et al., 2019). Use of algae has been extended to the treatment of wastewaters (removing heavy metal ions), environmental toxicants monitoring, bioassays, effective bioremediation of organic or recalcitrant pollutants, and even as the photosynthetic gas exchangers for space travel (Iyovo et al., 2010; Subashchandrabose et al., 2011; Rizwan et al., 2018). Additionally, microalgae are thought to have great potential as novel low-cost and environmentally friendly expression systems; for instance, production of PHB bioplastic in diatoms and development of composite materials using Chlorella vulgaris as filler in various polymers (Wijffels, 2013). Some of the major microalgal species used for commercial production include Arthrospira (Spirulina), Chaetoceros, Chlorella, Dunaliella and Isochrysis. Nevertheless, microalgae are versatile, unexplored and diverse microorganisms, and hence, there may be seve-ral features which are yet to be discovered and exploited (Odjadjare et al., 2017; Rizwan et al., 2018). Microalgae can also be employed in agriculture as biofertilizers and soil conditioners. In this role, they have capabilities such as fixing nitrogen, which is used in tropical lowlands, and controlling erosion in temperate climate zones (Iyovo et al., 2010; Odjadjare et al., 2017). Moreover, some allelopathic compounds from microalgae can act as environment-friendly herbicides or biocontrol agents (Liu et al., 2016b). ORINOQUIA - Universidad de los Llanos -Villavicencio, Meta. Colombia. 2019 Julio/Diciembre; 23(2):71-78 Microalgae as biofertilizers The use of chlorophytes and cyanophytes as biofertilizers is called “algalization”, a term developed by G.S Venkataraman in the 1970s. In recent years, more and more attention has been paid worldwide to the use of these microorganisms to intensify organic plant production, particularly in the context of a changing climate (Grzzesik and Romanowska-Duda, 2015). Algalization has a unique potential to enhance productivity in a variety of agricultural and ecological situations and plays an important role in building up soil fertility, consequently increasing the yield. Use of microalgae as a soil additive has been shown to significantly improve germination, nitrate reduction potential, root volumes, chlorophyll formation, carotenoid accumulation, grain yields, shoots dry weight and plant height (Tripathi et al., 2008; Lin et al., 2013; Odjadjare et al., 2017). This alternative has provided better results than traditional chemical fertilizers and uses mainly chlorophytes due to their high growth rate, their simple large-scale cultivation, and their adaptation to soil conditions. Moreover, it has become an essential component of organic farming, maintaining long-term soil fertility and sustainability ensuring economic viability (Kumar et al., 2015; Grzzesik and Romanowska-Duda, 2015). Soil-forming characteristics Chlorophytes and cyanophytes are soil-forming agents because they secrete polysaccharides and mucilaginous substances with high aggregating capacity, which provide the cohesiveness for binding soil mineral particles and thereby help in soil structure formation (Ghosh, 2018). These polysaccharides are the first biological cementing agents providing an initial stabilization of the soil surface, are the first source of organic carbon during soil development, and are also able to decrease rivers bed load (Mager 2010; Arce et al., 2019). This mechanism is more potent in microalgae than in other types of organic matter such as compost; since it is capable of avoiding water and wind erosion in the soil, even in desert zones, because the substances exuded contribute significantly to the immobilization of unstable sandy soils and consequently, sand dunes are formed, increasing soil strength, resistance, and fertility (Cólica et al., 2014; Felde et al., 2018; Lan et al., 2014). Overall, the contribution of these microorganism to soil stabilisation make them essential components of precarious environments such as arid, semi-arid, polar and alpine areas (Chamizo et al., 2016; Williams et al., 2016) and suitable elements for restoring degraded dryland ecosystems, trigger soil rehabilitation and counteract desertification (Antoninka et al., 2016; Adessia et al., 2018). Chlorella, ¿un potencial biofertilizante? Some of those adhesives polysaccharides exhibit strong intrinsic mechanical properties, and in addition to avoiding erosion, they are able to improve soil structure by inducing microaggregates formation, which can entangle clay particles and form clusters. These clusters or microaggregates, in turn, grow and take the shape of macroaggregates and subsequently of larger soil aggregates. These macroaggregates allow gas exchange and water percolation, and therefore, can release nutrients from mineral particles (Mager and Thomas, 2011). Generally, high soil aggregate stability and greater amounts of stable aggregates are desirable for sustaining agricultural productivity and protection of environmental quality, because they favor high water infiltration rates, provide adequate aeration and enhance root growth (Awale et al., 2017; Baumann et al., 2017). Simultaneously, microalgae were reported to reduce the water penetration into the soil by inducing surface sealing and pore clogging, thus impinging on its hydraulic conductivity, allowing the creation of moistened microenvironments that retain water for longer periods than the surroundings and form dew (Fischer et al., 2012). Therefore, they can affect water retaining properties of soil, mainly due to their hygroscopicity, becoming a key factor for reducing evapotranspiration, increasing water availability, slowing down water loss and possibly contributing to expedite the recovery of microbial activities after dry periods (Maqubela et al., 2009; Lan et al., 2010). Mineral and nutrients source Besides improving soil properties, polysaccharides and mucilage from microalgae represent a huge source of utilizable carbon for the heterotrophic microbial soil community and adjacent plants, being also involved in physically and chemically trapping nutrients, and so, the level of soil microbial activity is increased (Mager and Thomas, 2011; Chen et al., 2014b). These organic matter accumulation leads to rising soil buffer capacity, enhance thermal conductivity and buffer temperature oscillations (Nain et al., 2010). In general, soil fertility is improved by the organic matter produced by microalgae (Lin et al., 2013). Furthermore, microalgae play an important role as one of the major sources of nitrogen atmospheric fixation, converting it into bioavailable forms like ammonium, which is required for plant growth. Moreover, mucilage from chlorophytes and cyanophytes, present in the cell wall, allows the concentration and mobilization of macro and micronutrients and ions, which can then be made available to plants and soil by exudation, 73 autolysis and microbial decomposition (Zhuang et al., 2014). This permits to reduce the needed amount of crop chemical fertilizers, increase the soil cation exchange capacity (CTC), and improve pH and electrical conductivity of the soil (Osman et al., 2010; Rizwan et al., 2018). Likewise, microalgae cause a higher phosphorus content due to their ability to produce excretions of enzymes or acidic metabolites that make this element available to plants, thereby increasing their efficiency and availability (Sahu et al., 2012; Liu et al., 2016a). Additionally, soil microalgae are ameliorators in the reclamation of saline and metals, thereby improving soil quality as well (Lin et al., 2013). in plants favoring their response against pathogenic microorganisms (Beltrame and Pascholati, 2011). It has also been reported microalgae elicitors that inhibit growth and adhesion of pathogenic bacteria and fungi and triggered systemic acquired resistance in crop plants such as wheat (Rana et al., 2012; Raposo et al., 2013), and tomato (El Modafar et al., 2012). Further, they may support the development of beneficial microorganisms in the rhizosphere of plants and thus avoid colonization by pathogens. For instance, extracts of C. pyrenoidosa had shown to stimulate the colonization and development of arbuscular mycorrhizae in papaya and passion fruit (Grzzesik and Romanowska-Duda, 2015). Growth-promoting agents Soil microalgae excrete growth-promoting bioregulators such as hormones, vitamins, sugars, amino acids, and organic acids that benefit plants and may be responsible for their high productivity (Osman et al., 2010; Maqubela et al., 2012; Awale et al., 2017). Specifically, microalgae from Chlorella genus produce phytohormones similar to cytokinins identified as iso-pentenyladenine, zeatin, and its conjugated ribosides, which influence cell division and differentiation, and are also important in chloroplast development, apical dominance and delay of senescence. These molecules were identified in tests with hypocotyls from cucumber and bean, showed to increase growth and development of gillyflower and grapevine, and has also exhibited effectiveness in controlling cell division in plants by in vitro tests with lilies and rice (Shanan and Higazy 2009; Tarkowsky et al., 2009; Hussain et al., 2010; Romanowska-Duda et al., 2010). In this order of ideas, Hussain and Hasnain (2012), observed that phytohormones of microalgal origin proved to be better at inducing adventitious roots and shoots on internodal and petiolar segments of cabbage than regular plant-derived phytohormones. Antipathogen activities In addition to promoting plant growth, chlorophytes and cyanophytes can also help control infections in plants and animals. For example, Chlorella and Nostoc genus have compounds with antimicrobial and anti-herbivorous activity, such as C. vulgaris clorelin, that control the development of bacteria such as Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa; and phycocyanins that inhibit pathogenic growth of bacteria and fungi (Grzzesik and Romanowska-Duda, 2015; Liu et al., 2016b). Besides this direct mechanism, extracts of chlorophytes and cyanophytes can induce phytoalexins production 74 Antioxidant activity Microalgae can develop a defense system by producing polysaccharides to cope with oxidative stress. Cyanophytes that develop naturally in the soil have a high tolerance to oxidative stress because their biomass contains different antioxidant molecules (Mohamed 2008). Aqueous extracts of C. vulgaris, N. ellipsosporum, and N. muscorum have also reported antioxidant activity (Hajimahmoodi et al., 2010). To explain this tolerance to oxidative stress, a variety of mechanisms such as extra-cellular detoxification, reduced uptake, efflux and sequestration by polysaccharides have been proposed (El-Sheekh et al., 2012). This characteristic makes application of chlorophytes and cyanophytes in seeds good for germination, since in the process of lysing the endosperm and in infections by pathogenic fungi, where high amounts of free radicals are produced, and they can ultimately be neutralized with the algae extracts (Osman et al., 2010). Use of Chlorella as biofertilizer Out of all microalgae, Chlorella genus has been most used for biofertilization so far and was the first microalga to be cultivated (Wijffels, 2013). Mainly because Chlorella provides with high amounts of macro and micronutrients, constituents or metabolites, such as carbohydrates and proteins (Elarroussia et al., 2016), and growth promoting factors, like cytokinins (Kholssi et al., 2018). Due to these multiple benefits, several research has been done. Faheed and Fattah (2008), evaluated its effect on lettuce and found an increase of up to 186% in several characteristics like growth, and biomass and pigment content in seedlings that were fertilized with Chlorella vulgaris. Chacón (2010), tested suspensions of C. vulgaris lyophilized cells and their effect on functional phytochemical compounds content in broccoli, finding increases of up to 100% in ascor- ORINOQUIA - Universidad de los Llanos -Villavicencio, Meta. Colombia. 2019 Julio/Diciembre; 23(2):71-78 bic acid, sulforaphane, and β-carotene in seedlings. C. vulgaris was also found to improve germination and growth of rice plants (Zayadan et al., 2014; Rajasekaran et al., 2015). In 2016, Özdemir et al., used this same species as biofertilizer in organically grown tomato production in greenhouses obtaining an increase in plant growth, yield and some fruit qualities like dry weight, total soluble solids, titratable acidity, and vitamin C. Agwa et al., (2017) showed that C. vulgaris application is efficient and economical in improving soil nutrients for greater productivity of okra. Okra seeds had higher moisture, organic matter and phosphorus when compared to control, and exhibited lower germination time. Moreover, okra plants displayed higher protein, lipid and chlorophyll content, also a higher plant height and fruit number. Furthermore, Schreiber et al., (2018) described too, the potential of C. vulgaris to accumulate phosphorus and fertilize nutrient-poor soil substrates. Lastly, leaf application of C. vulgaris has shown suppression of diseases in strawberry (Kim et al., 2014), cucumber seedlings (Abd Elhafiz et al., 2015), and grapevine (Bileva 2013). Other species such as Chlorella sorokiniana, produced a higher percentage of germination, root and stem weight, length and total plant biomass when applied in wheat. A greater number of leaves with the bigger surface area were observed in soybean seedlings irrigated with Chlorella pyrenoidosa (Dubey and Dubey, 2010). Organic Chinese chives and spinach treated with Chlorella fusca showed an increased number and thickness in leaves, better mineral content, and improvement of commercialization yield because of higher fresh weight. Besides, gray mold disease severity was reduced by treatment with C. fusca (Kim et al., 2018). Positive effects had also been seen in willow plants when biofertilized with Chlorella, rooting of cuttings, number and length of formed roots or shoots, plant growth, physiological activity, and fresh and dry weight were found to be significantly increased. Indeed, plants developed faster and showed a higher health status, indicating that Chlorella contains a potential source of bioactive compounds that activate several metabolic processes, regulating the growth and development of plants (Grzzesik and Romanowska-Duda, 2015). Similar results were obtained by Grzzesik et al., (2017) in this same plant with foliar application of Chlorella sp. Two strains of Chlorella (C. oocystoides and C. minutissima), were recommended as biostimulator and liquid biofertilizer for maize crops as well (Al-Shakankery et al., 2014; Taher and Mohammed, 2015). Parallel effects were seen in grapes, sunflower, and corn (Grzzesik and Romanowska-Duda, 2015). This overall positive influence on the seed germination and plant growth Chlorella, ¿un potencial biofertilizante? in different species is possible because of Chlorella positive effect on the nutrient uptake which enhances all physiological reactions (Grzzesik and Romanowska-Duda, 2014; Ghiloufi et al., 2016; Borchhardt et al., 2017). Finally, C. vulgaris has too been tested mixed with other microalgae such as Spirulina platensis, both playing a key role in improvement of rice plants, in terms of plant height, number of leaves, leaf area, fresh and dry weight, availability of nitrogen, phosphorus and potassium in plant soil, performance during germination and yield characters (Dineshkumar et al., 2018). C. vulgaris has also been tried in consortium with plant growth-promoting bacteria such as Pseudomonas putida, Serratia proteomaculans, and Stenotrophomonas maltophilia, in clove pelleted seeds, finding a better development and increased root biomass when comparing to the control (Raposo and De Morais, 2011). Further, this microalga along with cow dung manure has shown effects on growth performance, soil characteristics, macro and micronutrients, and the microbial population at the flowering stage of maize (Dineshkumar et al., 2017). Conclusion Although application and quantities of algal inoculum, in addition to the experimental conditions, are dissimilar, an overall positive effect of Chlorella on plant growth is established in all of the experiments mentioned above. In this context, biofertilizers from these microalgae can provide a suitable supplement to the chemical fertilizers, and organic farming can become a reality in the future with cleaner and healthy harvests, securing food production and human health, as well as protecting the environment and the natural resources. References Abd Elhafz A, Abd Elhafz A, Gaur SS, Hamdany N, Osman M, Lakshmi TVR. Recent Res Sci Technol. 2015;7:14-21. Adessia A, De Carvalhoc RC, De Philippisa R, Branquinhoc C, Da Silva JM. Microbial extracellular polymeric substances improve water retention indryland biological soil crusts. Soil Biol Biochem. 2018;116:67-69. Agwa OK, Ogugbue CJ, Williams EE. Field Evidence of Chlorella vulgaris potentials as a biofertilizer for Hibiscus esculentus. Int J Agric Res. 2017;12(4):181-189. Al-Shakankery FM, Hamouda RA, Ammar MM. The promotive effect of different concentrations of marine algae as biofertilizers on growth and yield of maize (Zea mays L.) plants. J chem Biol Phys Sci. 2014; 4:43201-43211. 75 Antoninka A, Bowker MA, Reed SC, Doherty K. Production of greenhouse-grown biocrust mosses and associated cyanobacteria to rehabilitate dryland soil function: cultivating biocrust mosses. Restor Ecol. 2016;24:324-335. DOI: 10.1111/rec.12311 Dineshkumar R, Subramanian J, Gopalsamy J, Jayasingam P, Arumugam A, Kannadasan S, Sampathkumar P. The impact of using microalgae as biofertilizer in maize (Zea mays L.). Waste Biomass Valor. 2017;8:1-10. DOI: 10.1007/s12649-017-0123-7 Arce MI, Méndoza-Lera C, Almagro M, Catalán N, Romaní A, Martí E, Gómez R, et al. A conceptual framework for understanding the biogeochemistry of dry riverbeds through the lens of soil science. Earth-Sci Rev. 2019;188:441-453. Dubey A, Dubey DK. 2010. Evaluation of cost effective organic fertilizer. Organic eprints. http://orgprints.org/17043/1/17043.pdf (5 March, 2019). Awale R, Machado S, Ghimire R, Bista P. 2017. Soil Health. In: Yorgey G, Kruger C, (Editors). Advances in dryland farming in the Inland Pacifc Northwest. Washington State University. p. 47-98. Baumann K, Glaser K, Mutz JE, Karsten U, Maclennan A, Hu Y, Michalikd D, et al. Biological soil crusts of temperate forests: Their role in P cycling. Soil Biol Biochem. 2017;109:156-166. DOI: 10.1016/j.soilbio.2017.02.011 Beltrame A, Pascholati SF. Cianobactérias e algas reduzem os sintomas causados por Tobacco mosaic virus (TMV) em plantas de fumo. Summa Phytopathol. 2011;37(2):140-145. Bileva T. Influence of green algae Chlorella vulgaris on infested Xiphinema index grape seedlings. J Earth Sci Clim Change. 2013;4:136-138. Elarroussia H, Elmernissia N, Benhimaa R, Isam MEK, Najib B, Abedelaziz S, Imane W. Microalgae polysaccharides a promising plant growth biostimulant. J Algal Biomass Util. 2016;7:55-63. El Modafar C, Elgadda M, El Boutachfaitib R, Abouraicha E, Zehhara N, Petit E, et al. Induction of natural defence accompanied by salicylic aciddependant systemic acquired resistance in tomato seedlings in response to bioelicitors isolated from green algae. Sci Hort. 2012;138:55-63. doi.org/10.1016/j.scienta.2012.02.011 El-Sheekh MM, Khairy HM, El-Shenody R. Algal production of extra and intra-cellular polysaccharides as an adaptive response to the toxin crude extract of Microcystis aeruginosa. Iranian J Environ Health Sci Eng. 2012;9(1):10. DOI: 10.1186/1735-27469-10 Bleakley S, Hayes M. Algal proteins: extraction, application, and challenges concerning production. Foods. 2017;6:33. Faheed FA, Fattah ZA. Effect of Chlorella vulgaris as bio-fertilizer on growth parameters and metabolic aspects of lettuce plant. J Agric Soc Sci. 2008;4:165-169. Borchhardt N, Baum C, Mikhailyuk T, Karsten U. Biological soil crusts of Arctic Svalbard - Water availability as potential controlling factor for microalgal biodiversity. Front Microbiol. 2017;8:1485. DOI: 1485. DOI: 10.3389/fmicb.2017.01485 Felde VJMNL, Chamizo S, Felix-Henningsen P, Drahorad SL. What stabilizes biological soil crusts in the Negev Desert?. Plant soil. 2018;429(1-2):9-18. DOI: 10.1007/s11104-017-3459-7 Chacón TL. 2010. Efecto de la aplicación de soluciones de Chlorella vulgaris y Scenedesmus obliquus sobre el contenido de compuestos funcionales en germinados de brócoli (Brassica oleracea var itálica). Magister en diseño y gestión de procesos, Facultad de Ingeniería, Universidad de la Sabana, Bogotá DC, Colombia. 106 p. Chamizo S, Rodríguez-Caballero E, Román JR, Cantón Y. Effects of biocrust on soil erosion and organic carbon losses under natural rainfall. Catena. 2016;148(2): 117-125. DOI: 10.1016/j. catena.2016.06.017 Chen X, He G, Deng Z, Wang N, Jiang W, Chen S. Screening of microalgae for biodiesel feedstock. Adv Microbiol. 2014a;4:365376. Chen L, Rossi F, Deng S, Liu Y, Wang G, Adessi A, De Philippis R. Macromolecular and chemical features of the excreted extracellular polysaccharides in induced biological soil crusts of different ages. J Arid Environ. 2014b;67:521-527. Fischer T, Veste M, Bens O, Hüttl RF. Dew formation on the surface of biological soil crusts in central european sand ecosystems. Biogeosciences Discussions. 2012;9:8075-8092. Ghiloufi W, Büdel B, Chaieb M. Effects of biological soil crusts on a mediterranean perennial grass (Stipatanacissima, L.). Plant Biosyst. 2016;151:158-167. DOI: 10.1080/11263504.2015.1118165 Ghosh AK. Functions and bio-functions of soil and its restoration. IJRAR - Int J Res Anal Rev. 2018;5(3):672-677. Grzzesik M, Romanowska-Duda Z. Improvements germination, growth, and metabolic activity of corn seedlings by grain conditioning and root application with cyanobacteria and microalgae. Pol J Environ Stud. 2014;23:1147-1153. Grzzesik M, Romanowska-Duda Z. Ability of Cyanobacteria and green algae to improve metabolic activity and development of willow plants. Pol J Environ Stud. 2015;24(3): 1003-1012. DOI: 10.15244/pjoes/34667 Cólica G, Li H, Rossi F, Li D, Liu Y, De Philippis R. Microbial secreted exopolysaccharides affect the hydrological behavior of induced biological soil crusts in desert sandy soils. Soil Biol Biochem. 2014;68:62-70. DOI: 10.1016/j.soilbio.2013.09.017 Grzzesik M, Romanowska-Duda Z, Kalaji HM. Effectiveness of cyanobacteria and green algae in enhancing the photosynthetic performance and growth of willow (Salix viminalis L.) plants under limited synthetic fertilizers application. Photosynthetica. 2017;55:510-521. Dineshkumar R, Kumaravel R, Gopalsamy J, Sikder MNA, Sampathkumar P. Microalgae as bio-fertilizers for rice growth and seed yield productivity. Waste Biomass Valor. 2018;9(5):793800. DOI: 10.1007/s12649-017-9873-5 Hajimahmoodi M, Faramarzi MA, Mohammadi N, Soltani N, Oveisi MR, Nafissi-Varcheh N. Evaluation of antioxidant properties and total phenolic contents of some strains of microalgae. J Appl Phycol. 2010;22:43-50. 76 ORINOQUIA - Universidad de los Llanos -Villavicencio, Meta. Colombia. 2019 Julio/Diciembre; 23(2):71-78 Hussain A, Hasnain S. Comparative assessment of the efficacy of bacterial and cyanobacterial phytohormones in plant tissue culture. World J Microbiol Biotechnol. 2012;28(4):1459-1466. Hussain A, Krischke M, Roitsch T, Hasnain S. Rapid determination of cytokinins and auxins in cyanobacteria. Curr Microbiol. 2010;6(5)1:361-369. Iyovo GD, Du G, Chen J. Sustainable biomethane, biofertilizer and biodiesel system from poultry waste. Indian J Sci Technol. 2010;3(10):1062-1069. Kholssi R, Marks EAN, Miñón J, Montero O, Debdoubi A, Rad C. Biofertilizing efect of Chlorella sorokiniana suspensions on wheat growth. J Plant Growth Regul. 2018; 1-6. DOI: 10.1007/ s00344-018-9879-7 Kim MJ, Shim CK, Kim YK, Ko BG, Park JH, Hwang SG, Kim BH. Effect of biostimulator, Chlorella fusca on improving growth and qualities of chinese chives and spinach in organic farm. Plant Pathol J. 2018;34(6):567-574. DOI: 10.5423/PPJ.FT.11.2018.0254 Kim MJ, Shim CK, Kim YK, Park JH, Hong SJ, Ji HJ, Han EJ, Yoon JC. Effect of Chlorella vulgaris CHK0008 fertilization on enhancement of storage and freshness in organic strawberry and leaf vegetables. Korean J Hortic Sci Technol. 2014;32:872-878. Kumar D, Purakayastha TJ, Shivay YS. Long-term effect of organic manures and biofertilizers on physical and chemical properties of soil and productivity of rice-wheat system. International Journal of Bio-resource and Stress Management (IJBSM). 2015; 6(2):176-181. DOI: 10.5958/0976-4038.2015.00030.5 Lan SB, Hu CX, Rao BQ, Wu L, Zhang DL, Liu YD. Non-rainfall water sources in the topsoil and their changes during formation of man-made algal crusts at the eastern edge of Qubqi Desert, Inner Mongolia. Sci China Life Sci. 2010;53:1135-1141. Lan S, Zhang Q, Wu L, Liu Y, Zhang D, Hu C. Artificially accelerating the reversal of desertification: cyanobacterial inoculation facilitates the succession of vegetation communities. Environ Sci Technol. 2014;48:307-315. DOI: 10.1021/es403785j Lin CS, Chou TL, Wu JT. Biodiversity of soil algae in the farmlands of mid-taiwan. Bot Stud. 2013;54:41. DOI: 10.1186/1999-311054-41 Liu J, Chen F. Biology and industrial applications of Chlorella: Advances and prospects. Adv Biochem Eng Biotechnol. 2016a;153:135. Liu L, Pohnert G, Wei D. Extracellular metabolites from industrial microalgae and their biotechnological potential. Mar Drugs. 2016b;14(10):191. DOI: 10.3390/md14100191 Mager DM. Carbohydrates in cyanobacterial soil crusts as a source of carbon in the Southwest Kalahari, Botswana. Soil Biol Biochem. 2010;42:313-318. DOI: 10.1016/j.soilbio.2009.11.009 enhances soil structure, fertility, and maize growth. Plant Soil. 2009;315:79-92. Maqubela MP, Muchaonyerwa P, Mnkeni NS. Inoculation effects of two south african cyanobacteria strains on aggregate stability of a silt loam soil. Afr J Biotechnol. 2012;11:10726-10735. Mohamed ZA. Polysaccharides as a protective response against microcystin-induced oxidative stress in Chlorella vulgaris and scenedesmus quadricauda and their possible significance in the aquatic ecosystem. Ecotoxicology. 2008;17(6): 504-516. DOI: 10.1007/s10646-008-0204-2 Moreno-García L, Adjallé K, Barnabé S, Raghavan G. Microalgae biomass production for a biorefinery system: recent advances and the way towards sustainability. Renew Sust Energ Rev. 2017;76:493-506. Nain L, Rana A, Joshi M, Jadhav SD, Kumar D, Shivay YS, Paul S, Prasanna R. Evaluation of synergistic effects of bacterial and cyanobacterial strains as biofertilizers for wheat. Plant soil. 2010;331:217. Odjadjare EC, Mutanda T, Olaniran AO. Potential biotechnological application of microalgae: a critical review. Crit Rev Biotechnol. 2017;37(1):37-52. DOI: 10.3109/07388551.2015.1108956 Osman M, El-Sheekh M, El-Naggar A, Gheda S. Effect of two species of cyanobacteria as biofertilizers on some metabolic activities, growth, and yield of pea plant. Biol Fertil Soils. 2010;46:861875. Özdemir S, Sukatar A, Öztekin GB. Production of Chlorella vulgaris and its effects on plant growth, yield and fruit quality of organic tomato grown in greenhouse as biofertilizer. J Agric Sci. 2016;22:596-605. Pemmaraju D, Appidi T, Minhas G, Singh SP, Khan N, Pal M, Srivastava R, Rengan AK. Chlorophyll rich biomolecular fraction of a cadamba loaded into polymeric nanosystem coupled with photothermal therapy: a synergistic approach for cancer theranostics. Int J Biol Macromol. 2018;110:383-391. Rana A, Joshi M, Prasanna R, Shivay RS, Nain L. Biofortification of wheat through inoculation of plant growth promoting rhizobacteria and cyanobacteria. Eur J Soil Biol. 2012;50:118. Rajasekaran S, Sundaramoorthy P, Sankar GK. Effect of FYM, N, P fertilizers and biofertilizers on germination and growth of paddy (Oryza sativa L.). Int Lett Nat Sci. 2015;35:59-65. Raposo MFDJ, De Morais RMSC. Chlorella vulgaris as soil amendment: influence of encapsulation and enrichment with rhizobacteria. Int J Agric Biol. 2011;13:719-724. Raposo MF, De Morais RM, Bernardo de Morais AM. Bioactivity and applications of sulphated polysaccharides from marine microalgae. Mar Drugs. 2013;11(1): 233-252. DOI:10.3390/ md11010233 Mager DM, Thomas AD. Extracellular polysaccharides from cyanobacterial soil crusts: a review of their role in dryland soil processes. J Arid Environ. 2011;75:91-97. Rizwan M, Mujtaba G, Memon SA, Lee K, Rashid N. Exploring the potential of microalgae for new biotechnology applications and beyond: a review. Renew Sust Energ Rev. 2018;92:394-404. DOI: 10.1016/j.rser.2018.04.034 Maqubela M, Mnkeni P, Malam Issa O, Pardo M, D’Acqui L. Nostoc cyanobacterial inoculation in South African agricultural soils Romanowska-Duda ZB, Grzesik M, Owczarczyk A, Mazur-Marzec H. 2010. Impact of intra and extracellular substances from Chlorella, ¿un potencial biofertilizante? 77 cyanobacteria on the growth and physiological parameters of grapevine (Vitis vinifera). In: 20th International Conference on Plant Growth Substance (IPGSA), book of abstracts 28.0702.08.2010. Universitat Rovira I Virgili, Tarragona, Spain, 118. Sahu D, Priyadarshani L, Rath B. Cyanobacteria as potential biofertilizer. CIBTech Journal of Microbiology. 2012;1(2-3):20-26. Sassi KKB, Silva JA, Calixto CD, Sassi R, Sassi CFC. Metabolites of interest for food technology produced by microalgae from the Northeast Brazil. Rev Ciênc Agron. 2019;50(1):54-65. DOI: 10.5935/1806-6690.20190007 Schreiber C, Henning S, Lucy H, Christoph B, Bärbel A, Josefne K, Silvia DS, et al. Evaluating potential of green alga Chlorella vulgaris to accumulate phosphorus and to fertilize nutrientpoor soil substrates for crop plants. J Appl Psychol. 2018; 30(5):2827-2836 Shanan NT, Higazy AM. Integrated biofertilization management and cyanobacteria application to improven growth and flower quality of Matthiola incana. Res J Agric Biol Sci. 2009;5(6):11621168. Subashchandrabose SR, Ramakrishnan B, Megharaj M, Venkateswarlu K, Naidu R. Consortia of cyanobacteria/microalgae and bacteria: biotechnological potential. Biotechnol Adv. 2011;29(6):896-907. DOI: 10.1016/j.biotechadv.2011.07.009 Suganya T, Varman M, Masjuki HH, Renganathan S. Macroalgae and microalgae as a potential source for commercial applications along with biofuels production: a biorefinery approach. Renew Sust Energ Rev. 2016;55:909-941. DOI: 10.1016/j. rser.2015.11.026 Taher MT, Mohamed AY. Improvement of growth parameters of Zea mays and properties of soil inoculated with two Chlorella species. Rep Opinion. 2015;7: 22-27. Tarkowski P, Ge LY, Yong JWH, Tan SN. Analytical methods for cytokinins. Trends Anal Chem. 2009;28:323-335. Tripathi RD, Dwivedi S, Shukla MK, Mishra S, Srivastava S, Singh R. Role of blue green algae biofertilizer in ameliorating the nitrogen demand and fly-ash stress to the growth and yield of rice (Oryza sativa L.) plants. Chemosphere. 2008;70: 1919-1928. DOI: 10.1016/j.chemosphere.2007.07.038 Venkataraman, GS. 1972. Algal biofertilizers and rice cultivation, Today and Tommorrow’s. New Delhi. Pp 71. Wang SK, Hu YR, Wang F, Stiles AR, Liu CZ. Scale-up cultivation of Chlorella ellipsoidea from indoor to outdoor in bubble column bioreactors. Bioresource Technology. 2014;156:117-122. Wells ML, Potin P, Craigie JS, Raven JA, Merchant SS, Helliwell KE, et al. Algae as nutritional and functional food sources: revisiting our understanding. J Appl Phycol. 2017;29:949-982. Wijffels RH, Kruse O, Hellingwerf KJ. Potential of industrial biotechnology with cyanobacteria and eukaryotic microalgae. Curr Opin Biotech. 2013;4(3):405-413. DOI:10.1016/j.copbio.2013.04.004 Williams L, Loewen-Schneider K, Maier S, Büdel B. Cyanobacterial diversity of western european biological soil crusts along a latitudinal gradient. FEMS Microbiol Ecol. 2016;92(10): fiw157. DOI: 10.1093/femsec/fiw157 Zayadan BK, Matorin DN, Baimakhanova GB, Bolathan K, Oraz GD, Sadanov AK. Promising microbial consortia for producing biofertilizers for rice fields. Microbiology. 2014;83:391-397. Zhuang WW, Downing A, Zhang YM. The influence of biological soil crust on 15 N traslocation in soil and vascular plant in a temperate desert of Nortwest China. J Plant Ecol. 2014;8:1-9. Martha Ortiz:https://orcid.org/0000-0003-0172-9111 Karen Sandoval:https://orcid.org/0000-0002-3431-8549 Laura Solarte:https://orcid.org/0000-0002-9097-0734 78 ORINOQUIA - Universidad de los Llanos -Villavicencio, Meta. Colombia. 2019 Julio/Diciembre; 23(2):71-78