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Arctic Phyto-Technology
Published in Neloy Khare, Climate Change in the Arctic, 2022
Rajesh Kumar Dubey, Priyanka Babel
The discovery of kinetin by Miller et al. (1955) led to the convincing first demonstration by Skoog and Miller (1957), using tobacco callus, or regulation of organ formation, shoots or roots, by changing kinetin-auxin ratio, where more kinetin than auxin favours shoot formation, while the reverse favours root formation, which lays the foundation of study of morphogenesis in vitro. Similarly, the astonishing rate of multiplication of an orchid Cymbidium by meristem culture demonstrated by Morel (1960) forms the basis of micropropagation and precisely clonal multiplication. It cannot be over-emphasised that right from the very beginning PTC has been envisaged to solve applied problems. For example, White (1934) initiated tomato excised root culture actually to study multiplication of viruses in it and their elimination. Similarly, Morel and Martin (1952) undertook shoot meristem culture for virus elimination in Dahlia and later in Cymbidium (Morel 1960). The former investigations by White led to the fundamental discovery that vitamins B1 (thiamine) and B6 (pyridoxine) are the root growth factors (Robbins and Bartley 1937, 1939), while the latter investigations by Morel led to the most applied discovery of mericloning. Along another dimension, i.e. production of useful secondary metabolites by PTC, first significant studies were conducted through large-scale cultivation of cells or mainly tobacco from the late 1950s to the early 1960s at Pfizer, Inc. by Tulecke and Nickell (1959), but it took about 20 years for its industrial utilisation. Now with the technological advancements, increasing interest and being a futuristic technology in the challenging areas like Arctic and Antarctic tissue and cell culture led production of several high-value compounds through cell suspension cultures using fermentation technology is being investigated, while a few have already been produced.
Optimization of biomass and fatty acid productivity of Desmodesmus intermedius as a promising microalga for biodiesel production
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Mostafa M. El-Sheekh, Hamed M. Eladel, Abd El-Fatah Abomohra, Mohamed G. Battah, Soha A. Mohamed
Kinetin is one of the cytokinins, a class of plant hormones that promotes cell division (Tarakhovskaya, Maslov, and Shishova 2007). Kinetin is often used in plant tissue culture for growth induction. In the present study, kinetin led to a slight increase in growth and lipid content of D. intermedius at all tested concentrations. Another study investigated the effects of phytohormones on microalgal growth and lipid accumulation for biodiesel production. For example, phytohormones promoted Chlamydomonas reinhardtii growth which resulted in a reduction of the overall cost of commercial biodiesel production (Park et al. 2013). Other studies confirmed the significant increase of microalgal growth and/or lipid content in the presence of phytohormones (Filomena et al. 2013). In this study, lower concentrations of vitamin B12 recorded a considerable increase in lipid and biomass productivities of D. intermedius. Application of vitamin B12 to the culture of Pleurochrysis carterae resulted in the conversion of vitamin B12 to the coenzyme forms of B12, including methyl malonyl-CoA mutase, which plays a key role in fatty acid metabolism (Palacios, Bashan, and de-Bashan 2014). Chlorella sp. grown in medium supplemented with high ortho-phosphate and vitamins showed an increase in the biomass. In addition, they reported a strong stimulating effect of vitamin addition on lipid production, where the lipid level was 1.7 times higher than that of the control. The increase in lipid content was attributed to vitamin supplementation as the cofactors for enzymes involved in lipid biosynthesis (Danesh et al. 2018). On another hand, vitamin B12 is a very expensive micronutrient and its supply in industrial-scale of microalgae cultivation for biofuel production will face considerable challenges, regarding both technical feasibility, economics and achieving a net positive energy balance. For this reason, the coculture of B12-auxotroph algae and vitamin B12-producing bacteria has been suggested in which the bacteria supply vitamin B12 to the algae in return for fixed carbon (Croft et al. 2005). Light energy is a critical parameter required for algal growth which is converted to chemical energy providing high energetic compounds of NADPH and ATP (Ma et al. 2016). Under high-energy input conditions, non-dividing cells are forced to channel excess light energy and carbon into intracellular high-energy compounds, mainly lipids (Pribyl et al. 2012). These data are consistent with those reported by Breuer et al. (2013) who concluded that the maximum TAG content in Scenedesmus was independent of light intensity.