Environmental sustainability is an integral aspect of living a better life, which will continue to be globally highlighted in the future. Sustainable Development Goals (SDGs) are crucial in most research areas to improve natural resources that will ensure the long-term viability of the environment. The rising population may lead to increased pollution due to extensive anthropogenic activities. Natural resources are being increasingly exploited by an ever-increasing human population and rising per capita consumption. A combination of biotechnological approaches to strengthen environmental sustainability in plant fields has often been used. Azolla, an aquatic fern, is a promising candidate for worldwide application and is well established in biotechnology, particularly focusing on environmental sustainability. This review aims to explore the prospective of Azolla using a biotechnology approach. This review highlights current and future research and presents viewpoints on the importance of biotechnology in phytoremediation, genomics, and the animal feed industry.

• Abraham, G., Pandey, N., Mishra, V., Chaudhary, A. A., Ahmad, A., Singh, R., & Singh, P. K. (2013). Development of SCAR based molecular markers for identification of different species of Azolla. Indian Journal of Biotechnology, 12(4), 489–492.

• Adenle, A. A., Sowe, S. K., Parayil, G., & Aginam, O. (2012). Analysis of open-source biotechnology in developing countries: An emerging framework for sustainable agriculture. Technology in Society, 34(3), 256–269. https://doi.org/10.1016/j.techsoc.2012.07.004

• Alemneh, T. (2019). The application of biotechnology on livestock feed improvement. Archives in Biomedical Engineering and Biotechnology, 1(5), 000522. https://doi.org/10.33552/abeb.2019.01.000522

• Azhar, M., Pervez, S., Panda, B. P., & Gupta, S. K. (2018). Cultivation, processing, and analysis of Azolla microphylla and Azolla caroliniana as potential source for nutraceutical ingredients. International Journal of Agriculture and Environmental Science, 5(3), 10–16. https://doi.org/10.14445/23942568/ijaes-v5i3p102

• Behera, S. S., & Ray, R. C. (2021). Bioprospecting of cow dung microflora for sustainable agricultural, biotechnological and environmental applications. Current Research in Microbial Sciences, 2, 100018. https://doi.org/10.1016/j.crmicr.2020.100018

• Bianchi, E., Biancalani, A., Berardi, C., Antal, A., Fibbi, D., Coppi, A., Lastrucci, L., Bussotti, N., Colzi, I., Renai, L., Scordo, C., Del Bubba, M., & Gonnelli, C. (2020). Improving the efficiency of wastewater treatment plants: Bio-removal of heavy metals and pharmaceuticals by Azolla filiculoides and Lemna minuta. Science of the Total Environment, 746, 141219. https://doi.org/10.1016/j.scitotenv.2020.141219

• Brouwer, P., Bräutigam, A., Külahoglu, C., Tazelaar, A. O. E., Kurz, S., Nierop, K. G. J., van der Werf, A., Weber, A. P. M., & Schluepmann, H. (2014). Azolla domestication towards a biobased economy?. New Phytologist, 202(3), 1069–1082. https://doi.org/10.1111/nph.12708

• Brouwer, P., Nierop, K. G. J., Huijgen, W. J. J., & Schluepmann, H. (2019). Aquatic weeds as novel protein sources: Alkaline extraction of tannin-rich Azolla. Biotechnology Reports, 24, e00368. https://doi.org/10.1016/j.btre.2019.e00368

• Brouwer, P., Schluepmann, H., Nierop, K. G. J., Elderson, J., Bijl, P. K., van der Meer, I., de Visser, W., Reichart, G. J., Smeekens, S., & van der Werf, A. (2018). Growing Azolla to produce sustainable protein feed: The effect of differing species and CO2 concentrations on biomass productivity and chemical composition. Journal of the Science of Food and Agriculture, 98(12), 4759–4768. https://doi.org/10.1002/jsfa.9016

• Chang, M. C., Huang, C. T., Tsai, C. C., & Kao, W. Y. (2020). Molecular identification and morphological traits of the native and exotic Azolla species in Taiwan. Taiwania, 65(3), 382–390. https://doi.org/10.6165/tai.2020.65.382

• Chen, J., Huang, M., Cao, F., Pardha-Saradhi, P., & Zou, Y. (2017). Urea application promotes amino acid metabolism and membrane lipid peroxidation in Azolla. PLOS One, 12(9), e0185230. https://doi.org/10.1371/journal.pone.0185230

• Costarelli, A., Cannavò, S., Cerri, M., Pellegrino, R. M., Reale, L., Paolocci, F., & Pasqualini, S. (2021). Light and temperature shape the phenylpropanoid profile of Azolla filiculoides fronds. Frontiers in Plant Science, 12, 727667. https://doi.org/10.3389/fpls.2021.727667

• Coughlan, N. E., Walsh, É., Bolger, P., Burnell, G., O’Leary, N., O’Mahoney, M., Paolacci, S., Wall, D., & Jansen, M. A. K. (2022). Duckweed bioreactors: Challenges and opportunities for large-scale indoor cultivation of Lemnaceae. Journal of Cleaner Production, 336, 130285. https://doi.org/10.1016/j.jclepro.2021.130285

• Dewi, W. S., Wahyuningsih, G. I., Syamsiyah, J., & Mujiyo. (2018). Dynamics of N-NH4+, N-NO3-, and total soil nitrogen in paddy. In Proceeding of the IOP Conferences Series: Earth and Environmental Science (Vol. 142, p. 012014). IOP Publishing. https://doi.org/10.1088/1755-1315/142/1/012014

• Dohaei, M., Karimi, K., Rahimmalek, M., & Satari, B. (2020). Integrated biorefinery of aquatic fern Azolla filiculoides for enhanced extraction of phenolics, protein, and lipid and methane production from the residues. Journal of Cleaner Production, 276, 123175. https://doi.org/10.1016/j.jclepro.2020.123175

• Dong, Y. H., Chen, J. M., Gituru, R. W., & Wang, Q. F. (2007). Gene flow in populations of the endangered aquatic fern Ceratopteris pteridoides in China as revealed by ISSR markers. Aquatic Botany, 87(1), 69–74. https://doi.org/10.1016/j.aquabot.2007.03.006

• Dong, Y. H., Gituru, R. H., & Wang, Q. F. (2010). Genetic variation and gene flow in the endangered aquatic fern Ceratopteris pteridoides in China, and conservation implications. Annales Botanici Fennici, 47(1), 34-44. https://doi.org/10.5735/085.047.0104

• EuropaBio. (2018). Industrial biotechnology - Contributing towards achieving the UN Global sustainable development goals. Industrial Biotechnology, 14(4), 170–173. https://doi.org/10.1089/ind.2018.29138.ebi

• Ghorbanzadeh Mashkani, S., & Tajer Mohammad Ghazvini, P. (2009). Biotechnological potential of Azolla filiculoides for biosorption of Cs and Sr: Application of micro-PIXE for measurement of biosorption. Bioresource Technology, 100(6), 1915–1921. https://doi.org/10.1016/j.biortech.2008.10.019

• Goala, M., Yadav, K. K., Alam, J., Adelodun, B., Choi, K. S., Cabral-Pinto, M. M. S., Hamid, A. A., Alhoshan, M., Ali, F. A. A., & Shukla, A. K. (2021). Phytoremediation of dairy wastewater using Azolla pinnata: Application of image processing technique for leaflet growth simulation. Journal of Water Process Engineering, 42, 102152. https://doi.org/10.1016/j.jwpe.2021.102152

• Hemalatha, M., Sarkar, O., & Venkata Mohan, S. (2019). Self-sustainable Azolla-biorefinery platform for valorization of biobased products with circular-cascading design. Chemical Engineering Journal, 373, 1042–1053. https://doi.org/10.1016/j.cej.2019.04.013

• Khan, S., Al-Qurainy, F., & Nadeem, M. (2012). Biotechnological approaches for conservation and improvement of rare and endangered plants of Saudi Arabia. Saudi Journal of Biological Sciences, 19(1), 1–11. https://doi.org/10.1016/j.sjbs.2011.11.001

• Khosravi, M. (2005). Toxic effect of Pb, Cd, Ni, and Zn on Azolla filiculoides in the International Anzali Wetland. International Journal of Environment Science and Technology, 2, 35-40.

• Kimani, S. M., Bimantara, P. O., Hattori, S., Tawaraya, K., Sudo, S., Xu, X., & Cheng, W. (2020). Co-application of poultry-litter biochar with Azolla has synergistic effects on CH4 and N2O emissions from rice paddy soils. Heliyon, 6(9), e05042. https://doi.org/10.1016/j.heliyon.2020.e05042

• Kollah, B., Patra, A. K., & Mohanty, S. R. (2016). Aquatic microphylla Azolla: A perspective paradigm for sustainable agriculture, environment, and global climate change. Environmental Science and Pollution Research, 23(5), 4358–4369. https://doi.org/10.1007/s11356-015-5857-9

• Kusmayadi, A., Leong, Y. K., Yen, H. W., Huang, C. Y., & Chang, J. S. (2021). Microalgae as sustainable food and feed sources for animals and humans – Biotechnological and environmental aspects. Chemosphere, 271, 129800. https://doi.org/10.1016/j.chemosphere.2021.129800

• Le, D. T., Chu, H. D., & Le, N. Q. (2016). Improving nutritional quality of plant proteins through genetic engineering. Current Genomics, 17(3), 220–229. https://doi.org/10.2174%2F1389202917666160202215934

• Lencucha, R., Pal, N. E., Appau, A., Thow, A. M., & Drope, J. (2020). Government policy and agricultural production: A scoping review to inform research and policy on healthy agricultural commodities. Global Health, 16, 11. https://doi.org/10.1186/s12992-020-0542-2

• Li, F. W., & Pryer, K. M. (2014). Crowdfunding the Azolla fern genome project: A grassroots approach. GigaScience, 3(1), 2047-217X-3-16. https://doi.org/10.1186/2047-217X-3-16

• Li, F. W., Brouwer, P., Carretero-Paulet, L., Cheng, S., De Vries, J., Delaux, P. M., Eily, A., Koppers, N., Kuo, L. Y., Li, Z., Simenc, M., Small, I., Wafula, E., Angarita, S., Barker, M. S., Bräutigam, A., Depamphilis, C., Gould, S., Hosmani, P. S., & Pryer, K. M. (2018). Fern genomes elucidate land plant evolution and cyanobacterial symbioses. Nature Plants, 4(7), 460–472. https://doi.org/10.1038/s41477-018-0188-8

• Lumpkin, T. A., & Plucknett, D. L. (1980). Azolla: Botany, physiology, and use as green manure. Economic Botany, 34, 111–153. https://doi.org/10.1007/BF02858627

• Madeira, P. T., Hill, M. P., Dray, F. A., Coetzee, J. A., Paterson, I. D., & Tipping, P. W. (2016). Molecular identification of Azolla invasions in Africa: The Azolla specialist, Stenopelmus rufinasus proves to be an excellent taxonomist. South African Journal of Botany, 105, 299–305. https://doi.org/10.1016/j.sajb.2016.03.007

• Matthews, N. E., Cizauskas, C. A., Layton, D. S., Stamford, L., & Shapira, P. (2019). Collaborating constructively for sustainable biotechnology. Scientific Reports, 9, 19033. https://doi.org/10.1038/s41598-019-54331-7

• Metzgar, J. S., Schneider, H., & Pryer, K. M. (2007). Phylogeny and divergence time estimates for the fern genus Azolla (Salviniaceae). International Journal of Plant Sciences, 168(7), 1045–1053. https://doi.org/10.1086/519007

• Miranda, A. F., Liu, Z., Rochfort, S., & Mouradov, A. (2018). Lipid production in aquatic plant Azolla at vegetative and reproductive stages and in response to abiotic stress. Plant Physiology and Biochemistry, 124, 117–125. https://doi.org/10.1016/j.plaphy.2018.01.012

• Naghipour, D., Ashrafi, S. D., Gholamzadeh, M., Taghavi, K., & Naimi-Joubani, M. (2018). Phytoremediation of heavy metals (Ni, Cd, Pb) by Azolla filiculoides from aqueous solution: A dataset. Data in Brief, 21, 1409–1414. https://doi.org/10.1016/j.dib.2018.10.111

• Nasir, N.A.N. M, Islam, A. K. M. A., Anuar, N., & Yaakob, Z. (2018). Genetic improvement and challenges for cultivation of microalgae for biodiesel: A review. Mini-Reviews in Organic Chemistry, 16(3), 277–289. https://doi.org/10.2174/1570193x15666180627115502

• Nedjimi, B. (2021). Phytoremediation: A sustainable environmental technology for heavy metals decontamination. SN Applied Sciences, 3, 286. https://doi.org/10.1007/s42452-021-04301-4

• Oyange, W. A., Kanya, J. I., Chemining’Wa, G. N., & Njiruh, P. N. (2020). Morphological and molecular characterization of Azolla accessions in Kenya. Tropical and Subtropical Agroecosystems, 23(2), 1-12.

• Pereira, A. L., Martins, M., Oliveira, M. M., & Carrapiço, F. (2011). Morphological and genetic diversity of the family Azollaceae inferred from vegetative characters and RAPD markers. Plant Systematics and Evolution, 297(3–4), 213–226. https://doi.org/10.1007/s00606-011-0509-0

• Rahman, M., Billah, M. M., Hack-Polay, D., & Alam, A. (2020). The use of biotechnologies in textile processing and environmental sustainability: An emerging market context. Technological Forecasting and Social Change, 159, 120204. https://doi.org/10.1016/j.techfore.2020.120204

• Rawat, J., Saxena, J., & Sanwal, P. (2019). Biochar: A sustainable approach for improving plant growth and soil properties. In V. Abrol & P. Sharma (Eds.), Biochar - An imperative amendment for soil and the environment (pp. 1-17). IntechOpen. https://doi.org/10.5772/intechopen.82151

• Reid, J. D., Plunkett, G. M., & Peters, G. A. (2006). Phylogenetic relationships in the heterosporous fern genus Azolla (Azollaceae) based on DNA sequence data from three noncoding regions. International Journal of Plant Sciences, 167(3), 529-538. https://doi.org/10.1086/501071

• Sadegh Kasmaei, L., Yasrebi, J., Zarei, M., Ronaghi, A., Ghasemi, R., Saharkhiz, M. J., Ahmadabadi, Z., & Schnug, E. (2019). Influence of plant growth promoting Rhizobacteria, compost, and biochar of Azolla on rosemary (Rosmarinus Officinalis L.) growth and some soil quality indicators in a calcareous soil. Communications in Soil Science and Plant Analysis, 50(2), 119–131. https://doi.org/10.1080/00103624.2018.1554669

• Schor-Fumbarov, T., Goldsbrough, P. B., Adam, Z., & Tel-Or., E. (2005). Characterization and expression of a metallothionein gene in the aquatic fern Azolla filiculoides under heavy metal stress. Planta, 223(1), 69–76. https://doi.org/10.1007/s00425-005-0070-6

• Sessa, E. B., Banks, J. A., Barker, M. S., Der, J. P., Duffy, A. M., Graham, S. W., Hasebe, M., Langdale, J., Li, F. W., Marchant, D. B., Pryer, K. M., Rothfels, C. J., Roux, S. J., Salmi, M. L., Sigel, E. M., Soltis, D. E., Soltis, P. S., Stevenson, D. W., & Wolf, P. G. (2014). Between two fern genomes. GigaScience, 3(1), 2047-217X-3-15. https://doi.org/10.1186/2047-217X-3-15

• Sobhani, A., Khanahmadi, M., Jalali, A., Moradi, K., & Noormohammadi, N. (2020). Development of a low-cost disposable bioreactor for pilot scale production of Hypericum perforatum L. adventitious roots. Industrial Crops and Products, 160, 113096. https://doi.org/10.1016/j.indcrop.2020.113096

• Sood, A., Prasanna, R., & Singh, P. K. (2008). Fingerprinting of freshly separated and cultured cyanobionts from different Azolla species using morphological and molecular markers. Aquatic Botany, 88(2), 142–147. https://doi.org/10.1016/j.aquabot.2007.09.004

• Talebi, M., Tabatabaei, B. E. S., & Akbarzadeh, H. (2019). Hyperaccumulation of Cu, Zn, Ni, and Cd in Azolla species inducing expression of methallothionein and phytochelatin synthase genes. Chemosphere, 230, 488–497. https://doi.org/10.1016/j.chemosphere.2019.05.098

• Tona, G. O. (2018). Current and future improvements in livestock nutrition and feed resources. In B. Yucel & T. Taskin (Eds.), Animal husbandry and nutrition (pp. 147-169). IntechOpen. https://doi.org/10.5772/intechopen.73088

• Tran, T. L. N., Miranda, A. F., Abeynayake, S. W., & Mouradov, A. (2020). Differential production of phenolics, lipids, carbohydrates and proteins in stressed and unstressed aquatic plants, Azolla filiculoides and Azolla pinnata. Biology, 9(10), 342. https://doi.org/10.3390/biology9100342

• Van Coppenolle, B., Watanabe, I., Van Hove, C., Second, G., Huang, N., & McCouch, S. R. (1993). Genetic diversity and phylogeny analysis of Azolla based on DNA amplification by arbitrary primers. Genome, 36(4), 686–693. https://doi.org/10.1139/g93-092

• Verma, A. S., Agrahari, S., Rastogi, S., & Singh, A. (2011). Biotechnology in the realm of history. Journal of Pharmacy and Bioallied Sciences, 3(3), 321–323. https://doi.org/10.4103/0975-7406.84430

• Wang, F. H., Lu, J. M., Wen, J., Ebihara, A., & Li, D. Z. (2016). Applying DNA barcodes to identify closely related species of ferns: A case study of the Chinese Adiantum (Pteridaceae). PLOS One, 11(9), e0160611. https://doi.org/10.1371/journal.pone.0160611

• Yang, G. L., Feng, D., Liu, Y. T., Lv, S. M., Zheng, M. M., & Tan, A. J. (2021). Research progress of a potential bioreactor: Duckweed. Biomolecules, 11(1), 93. https://doi.org/10.3390/biom11010093

• Zhang, X., Lin, A. J., Zhao, F. J., Xu, G. Z., Duan, G. L., & Zhu, Y. G. (2008). Arsenic accumulation by the aquatic fern Azolla: Comparison of arsenate uptake, speciation, and efflux by A. caroliniana and A. filiculoides. Environmental Pollution, 156(3), 1149–1155. https://doi.org/10.1016/j.envpol.2008.04.002