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Microalgae Based Biofertilizers And Biostimulants For Agricultural Crops
Published in Gustavo Molina, Zeba Usmani, Minaxi Sharma, Abdelaziz Yasri, Vijai Kumar Gupta, Microbes in Agri-Forestry Biotechnology, 2023
Alex Consani Cham Junior, Ana Claudia Zanata, Sofia de Souza Oliveira, Eduardo Bittencourt Sydney, Andréia Anschau
During photosynthesis, an enzyme called RuBisCO is responsible for the conversion of CO2 into organic compounds. However, the CO2-catalytic center of this enzyme suffers competition with oxygen, which is way more abundant in the air than CO2. Increasing the content of CO2 in the cultivation medium would, thus, favor its absorption and the production of organic matter (biomass and bioproducts) (Bhola et al., 2014).
Cyanobacteria: A Biocatalyst in Microbial Fuel Cell for Sustainable Electricity Generation
Published in Lakhveer Singh, Durga Madhab Mahapatra, Waste to Sustainable Energy, 2019
Thingujam Indrama, O.N. Tiwari, Tarun Kanti Bandyopadhyay, Abhijit Mondal, Biswanath Bhunia
Chlorophyll-b shows the absorption maximum at 680 nm. It is already established that both centers are boosted to higher energy levels during adsorption of light energy. However, it is further emitted and passed to electron carriers. It is obviously true that passed energy is reduced due to splitting of water, and electron is passed towards potential gradient through redox active species (Kruse et al. 2005). Therefore, the energy is released in the form of ATP, and release of protons takes place from the stroma into the thylakoid lumen due to pH gradient (Kruse et al. 2005). As the protons are diffused against the concentration gradient, they flow with ATP synthetase (Kruse et al. 2005). Cyclic phosphorylation can take place if large amounts of NADPH exist and subsequently, electrons drive from the electron transport chain to PSI. The above electron from PSI is further passed to PSII. However, during formation of ATP, the electrons return to PSI and make PSII redundant. Depending on conditions, electrons can reduce protons to molecular hydrogen or reduce oxygen to water (Maly et al. 2005). The stroma of chloroplasts is the place where light independent reactions occur; however, previously generated ATP for energy is required. In the Calvin cycle, rubisco catalysed the combination process between carbon dioxide and sugar ribulose-1,5-bisphosphate RuBP (Kruse et al. 2005).
Biofuel and Biochemical Production by Photosynthetic Organisms
Published in Kazuyuki Shimizu, Metabolic Regulation and Metabolic Engineering for Biofuel and Biochemical Production, 2017
RubisCO is subject to low carboxylation efficiency and competitive inhibition of oxygen. The carboxylation reaction of RubisCO is confined in the carboxysome of cyanobacteria to avoid the competing oxygenase reaction (Zarzycki et al. 2013, Burnap et al. 2015). As for carboxylation, CO2 is first transported to plasma membrane in the form of bicarbonate by bicarbonate transporter, and then converted to CO2 by carboxylic anhydrase (CA), where CO2 is finally carboxylated by RubisCO in the carboxysome (Zarzycki et al., 2013). This indicates that overexpression or enhancement of both RubisCO and CA in carboxysome may contribute to the increase in CO2 fixation in cyanobacteria (Zhou et al., 2016). In fact, introduction of an extra bicarbonate transporter resulted in the increased cell growth (Kamennaya et al. 2015), and also the overexpression of CA resulted in the increase in the heterotrophic CO2 fixation in E. coli (Gong et al. 2015).
Exploration of green integrated approach for effluent treatment through mass culture and biofuel production from unicellular alga, Acutodesmus obliquus RDS01
Published in International Journal of Phytoremediation, 2019
Silambarasan Tamil Selvan, Balasubramani Govindasamy, Sanjivkumar Muthusamy, Dhandapani Ramamurthy
The photosynthetic organisms produce the ribulose 1,5-bisphosphate carboxylase (RuBisCO) enzyme intracellularly, however, the RuBisCO enzyme activated in the process of Calvin Benson Bassham pathway enriched the fixation of carbon dioxide into biomass (Loganathan et al.2016). RuBisCO enzymes has involved in the first major step of CO2 fixation. The energy conversion of atmospheric CO2 by photosynthetic organisms, would improve the bio-sequestration of CO2 and occur as important climate change strategy (Parry et al.2003). The main-purpose of microalgal biomass is for the biofuel, which completely relies on cultivation and harvesting at cheaper value (Pouliot et al.1989; Roeges 1994; Chisti 2007; Shen et al.2008).
Production of biodiesel by autotrophic Chlorella pyrenoidosa in a sintered disc lab scale bubble column photobioreactor under natural sunlight
Published in Preparative Biochemistry and Biotechnology, 2019
Navodit K. Singh, Venkateswara R. Naira, Soumen K. Maiti
From the previous experiment, the inhibitory effect of higher CO2 concentration on growth of Chlorella sp has already been seen. Two experiments are performed to test the reversibility of this inhibition effect in bubble column reactor under sunlight. Both the experiments were done in two phases. In the first experiment, initially, a higher concentration of CO2 (33%) was supplied followed by air supply. At the initial phase of growth with 33% CO2, algae was not growing well due to inhibition (Fig. 6). The growth is hampered probably due to the decrease of intracellular pH by endogenous carbonic anhydrase (CA). This acidification of stroma is known to inhibit the Calvin–Benson cycle.[45] But when this 33% grown culture was grown under air again from 144 hr, cells started to grow with very high growth rate after one-day lag period (Fig. 6). It indicates the inhibition of high concentration CO2 on Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo) enzyme involved in the Calvin–Benson cycle in C. pyrenoidosa is reversible. In another experiment air grown algae transfer to 33% CO2 condition at 141 hr. Initially, C. pyrenoidosa was growing slowly due to less CO2, but when 33% CO2 started to sparge at 141 hr it started to grow well immediately (Fig. 6). Here the inhibition of photosynthetic carbon fixation is not shown when the air grown cells were exposed to high concentration of CO2 (at 33%). This result is consistent to Chlorella sp. UK001.[45] Therefore, a stepwise increment of CO2 (low to high CO2) can be a possible option to grow at high concentrations of CO2 as the real flue gas contains 2% to 33% CO2 released from various industry. The information of reversibility of CO2 inhibition can be used in a real situation where flow sensor fault can happen.
Development of a carbon accumulation model for estimating the concentration of 14C in Japanese radish
Published in Journal of Nuclear Science and Technology, 2023
where Pc(t) and Pj(t) are the rates of carboxylation limited by Rubisco activity and ribulose-1,5-bisphosphate (RuBP) regeneration (µmol C m−2 s−1), respectively. Pc(t) is expressed as: