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Principles of Biology
Published in Arthur T. Johnson, Biology for Engineers, 2019
There are four general classifications of organisms made by combining energy and car-bon sources (Figure 5.5.5): Photoautotrophs: These use light as the energy source and carbon dioxide as the source of carbon.Photoheterotrophs: Light is the source of energy, and carbon comes from organic compounds such as alcohols, fatty acids, other organic acids, or carbohydrates.Chemoautotrophs: These use electrons from reduced inorganic compounds as their energy source and carbon dioxide as their source of carbon. Inorganic compounds can include hydrogen sulfide (H2S), elemental sulfur (S), ammonia (NH3), nitrite ions (NO2−), hydrogen (H), and ferrous ions (Fe−2).Chemoheterotrophs: Both energy and carbon come from the same organic compound, such as glucose. These organisms are medically important, but some can be beneficial for bioremediation.
Biofuel production from algal biomass
Published in Ozcan Konur, Bioenergy and Biofuels, 2017
Jonah Teo Teck Chye, Lau Yien Jun, Lau Sie Yon, Sharadwata Pan, Michael K. Danquah
In addition to nutrients such as phosphorus, nitrogen, potassium, zinc, and calcium, microalgal cultivation requires water, carbon dioxide, and sunlight to produce biomass through photosynthesis, by transforming solar energy into organic chemical energy stored in the microalgal cells. Three major types of microalgae cultivation techniques have been established based on their growth conditions: photoautotropic, heterotrophic, and mixotrophic cultures. Photoautotrophic cultivation utilizes light as the sole energy source that is converted to chemical energy through photosynthetic reactions. Conversely, heterotrophic production requires organic carbon materials as carbon and energy source to simulate growth. In mixotrophic cultivation, the organisms are able to thrive either autotrophically or heterotrophically, depending on the concentration of organic compounds and available light intensity. Among the aforementioned methods, photoautotrophic production is most widely used because it is economically feasible and suitable for large-scale algal biomass production. The choice of microalgal cultivation system from the most commonly available ones, whether open, closed, or hybrid, is made based on the products and the strains to be cultivated (Gambelli et al., 2017; Narala et al., 2016).
Plants and Biodeterioration
Published in Thomas Dyer, Biodeterioration of Concrete, 2017
Plants and most algae undergo oxygenic photosynthesis—they are photoautotrophs utilising sunlight as a source of energy, carbon dioxide as a source of carbon, and water as the electron donor: photons+2H2O+CO2→[CH2O]+O2+H2O
Exploring the potential of microalgae cell factories for generation of biofuels
Published in Biofuels, 2023
Dixita Chettri, Ashwani Kumar Verma, Anil Kumar Verma
The photoautotrophic nature of algae makes them an excellent feedstock for biofuel production. However, similar to other photosynthetic organisms, only a small fraction of light energy is converted into chemical energy [83]. Energy yield from low-cost biomass is often considered to be a function of three important parameters, namely biomass productivity and energy content, along with biomass harvesting efficiency. Studies have shown that regardless of the algal species, the biomass energy content in different media generally varies between 20 and 24 kJ/g biomass [84]. Biomass energy content is a function of chemical and microbial composition, which is directly influenced by various biological, operational, and environmental parameters. Alterations in microbial composition result in changes in the ratio of lipids, proteins, and carbohydrates within cells, thus affecting biomass energy content [85]. Some principle practical strategies to improve the biomass yield of algae are: (i) addition of CO2 to increase the availability of carbon to algal cells, which can have a positive effect on lipid content and biomass productivity; (ii) recycling of harvested biomass, which allows efficient monitoring of algal dynamics, biomass energy status, and productivity; (iii) operation of culture medium under nutrient limiting conditions under optimized hydraulic retention time (HRT) that enhances biomass lipid content; and (iv) cultivating colonial species to improve biomass harvesting [86].
Influence of potential grazers on picocyanobacterial abundance in Lake Biwa revealed with empirical dynamic modeling
Published in Inland Waters, 2020
Ji Cai, Yoshikuni Hodoki, Masayuki Ushio, Shin-ichi Nakano
Picocyanobacteria, a diverse group of cyanobacteria defined by cell sizes <2 µm, are numerous and ubiquitous in freshwater and marine ecosystems (Stockner and Antia 1986, Stockner 1988). Despite their small size, these photoautotrophic organisms contribute largely to phytoplankton biomass and primary production and play important roles in aquatic ecosystems (Weisse 1993). In freshwaters, single-celled picocyanobacteria (SPcy) dominate in oligotrophic environments and are mainly represented by the genera Synechococcus and Cyanobium (Fogg 1995, Sanchez-Baracaldo et al. 2005). Colonial picocyanobacteria (CPcy) are also common and often abundant in meso-eutrophic environments (Stockner 1991, Stockner et al. 2000). They consist of colonial species (e.g., Aphanothece, Aphanocapsa, Cyanodictyon) and microcolonies formed by SPcy (Passoni and Callieri 2000, Callieri et al. 2012).
Optimizing protocols for microbial induced calcite precipitation (MICP) for soil improvement–a review
Published in European Journal of Environmental and Civil Engineering, 2022
Tong Yu, Hanène Souli, Yoan Péchaud, Jean-Marie Fleureau
MICP is an ubiquitous natural phenomenon (Stocks-Fischer et al., 1999) that occurs with a wide range of microbial species in various environments (soils, oceans, freshwaters, saline lakes, etc.) (Hammes et al., 2003; Wei et al., 2015). There are three groups of microorganisms that can be involved in the precipitation of calcium carbonate. One group is that of photosynthetic microorganisms (such as cyanobacteria and microalgae), which is photoautotrophic. The other two are heterotrophic, and are related to sulphate cycle (sulphate-reducing bacteria) and nitrogen cycle (such as nitrate reducing bacteria and ureolytic bacteria), separately (Al-Salloum et al., 2017; De Muynck et al., 2010).