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Reaction Kinetics in Food Systems
Published in Dennis R. Heldman, Daryl B. Lund, Cristina M. Sabliov, Handbook of Food Engineering, 2018
Ricardo Villota, James G. Hawkes
Vitamin B12 is chemically the largest and most complex of all the vitamins, composed of a central cobalt atom planarly coordinated via nitrogen atoms to a porphyrin-like group referred to as corrin with axial coordination sites occupied by a 5,6-dimethylbenzimidazole base and a cyano group. Vitamin B12 is also referred to as cyanocobalamin and part of a larger group collectively known as cobalamins and plays a critical role in the methylation process as well as in lipid and carbohydrate metabolism. It is synthesized by a select group of microorganisms, and its main source in foods is of animal origin (e.g., meats [beef liver], fish, eggs, milk); consequently, deficiency risks commonly exist among groups with low intake of animal products (Gille and Schmid, 2015). Deficiency is particularly critical during pregnancy and lactation with potential risks of megaloblastic anemia (Pawlak et al., 2013; Griebe, 2017). One of the predominant forms of this vitamin is referred to as coenzyme B12, where the cyano group at the sixth coordination position is substituted by 5-deoxyadenosine, attached to the cobalt atom via a methylene group. Another common form found in foods is the hydroxocobalamin (also called vitamin B12a or hydroxo-B12), where the cyano group is replaced with a hydroxy group (Farquharson and Adams, 1976; Schneider, 1987). Other cobalamins include methyl- (CH3), nitrito- (NO2), and sufito- (HSO3) groups substituting for the cyano group. Vitamin B12 analogues refer to a group where the 5,6-dimethylbenzimidazole base is replaced with other substituent groups (Figure 3.16).
Enzyme Catalysis
Published in Harvey W. Blanch, Douglas S. Clark, Biochemical Engineering, 1997
Harvey W. Blanch, Douglas S. Clark
Vitamin B12 (cyanocobalamin) is a hematopoietic factor in mammals. It is synthesized by many microbes and is required by all animals. It is supplied by meat in the animal diet or is synthesized by the intestinal flora of the animal. It was originally supplied from beef liver, but is currently obtained from Propionibacteria. Various other species produce B12, including Pseudomonas. The complexity of the B12 molecule means that its chemical synthesis is not an economically viable alternative to fermentation. Fermentation with Propionibacteria employs carbohydrates such as glucose or molasses at ∼100gm/l, and salts, including cobalt salts. Nitrogen is supplied as either yeast extracts, casein hydrolysates or corn steep liquor. Growth of the bacteria on the carbohydrate occurs first, with little production of the B12 precursor, 5,6-dimethylbenzimidazole, as the culture is conducted under nearly anaerobic conditions. In the second stage of the fermentation, aeration induces precursor formation and the synthesis of 5 '-deoxyadenosylcobalamin (coenzyme B12 ) from etiocobalamin. Concentrations range from 50 to hundreds of mg/literB12. The product is isolated by adsorption onto supports such as amberlite or alumina, or by extraction of the aqueous solutions by phenol or cresol. B12 is then purified by chromatography and is precipitated from aqueous alcohol solution with ether. The world market is not large, about 10,000kg/yr.
Cultivation of Nannochloropsis algae for simultaneous biomass applications and carbon dioxide capture
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Abdul Hai Alami, Muhammad Tawalbeh, Shamma Alasad, Mennatalah Ali, Maitha Alshamsi, Haya Aljaghoub
The used growth medium is F/2 nutrient solution: NaNO3, 75 g/L; NaH2PO4•H2O, 5 g/L; Na2CO3, 30 g/L; FeCl3•6(H2O), 3.15 g; Na2(EDTA)2•(H2O), 4.36 g; CuSO4•5(H2O), 9.8 g/L; Na2MoO4•2(H2O), 6.3 g/L; ZnSO4•7(H2O), 22 g/L; CoCl2•6(H2O), 10 g/L; MnCl2•4(H2O), 180 g/L; thiamine HCl, 200 mg; Biotin, 0.1 g/L; Cyanocobalamin, 1 g/L (all purchased from www.algaeresearchsupply.com, Carlsbad, CA USA) with saltwater used to grow marine microalgae. 2 mL of growth medium is used per liter of saltwater each day. The culture salts are consisting of NaNO3 and NaPO4 as the nitrogen and phosphorus sources which are suitable for marine algae growth.
Improvement of ethanol production using green alga Chlorococcum minutum
Published in Environmental Technology, 2021
Duddela Varaprasad, Dokka Narasimham, Kurva Paramesh, Narravula Raga Sudha, Yeduguri Himabindu, Meruva Keerthi Kumari, Shaik Nazaneen Parveen, Thummala Chandrasekhar
The microalgae, Chlamydomonas reinhardtii (C. reinhardtii or Cr) and Chlorococcum minutum (C. minutum or Cm), belongs to class Chlorophyaceae of green algae that lives in freshwater conditions and both are unicellular in nature [12]. Most of the basic works related to ethanol production have been conducted using feedstock of model C. reinhardtii through the fermentation process in the presence of yeast as accompanier [13–16]. Various forms of carbohydrates such as starch, cellulose and other sugars are synthesized in algae, but these profiles are not same as in the case of land plants [17,18]. In fact, the composition of various carbohydrates differs significantly between different algae [19]. Specifically, Prochazkova et al. [20] reported the importance of nutrients on biomass composition in microalgae. Hence, improvement of biomass in algae is one of the solutions to enhance the ethanol production. It is a well-known fact that the addition of growth factors and hormones improves the biomass, but most of the algal species are auxotroph for one or more vitamins [21]. Vitamin B1 or thiamin was the first vitamin found to be an algal growth factor and found in bulk amounts. Thiamin is involved in biosynthesis of certain amino acids and is an essential co-factor in carbohydrate metabolism. It also exhibits synergistic interaction with cytokinins, an important growth hormone [22]. Similarly, vitamin B7 or biotin found in all living organisms as prototroph or auxotroph, but certain plants including primitive groups also synthesize biotin. It also acts as a cofactor for several essential carboxylase enzymes including acetyl Co-A carboxylase [23]. In contrast, vitamin B12 or cyanocobalamin is structurally complex of all the vitamins and cannot be made by plants and animals except bacteria and archaea. Vitamin B12 also acts as a coenzyme and is involved in nitrogen metabolism [24]. Moreover, number of reports proved that all these vitamins improved the biomass in algae as well as in advanced plants [17,21]. In our previous study, the enhancement of biohydrogen production in C. minutum was observed under ambient and different environmental conditions when compared with model alga C. reinhardtii [12]. So, the present investigation aims to check the ethanol production levels from feedstock of C. minutum keeping C. reinhardtii as control. As mentioned above, C. reinhardtii is a model alga because most of the research specifically related to ethanol production was carried out with this species. Further, the present study also aims to standardize the media to augment the biomass in turn reducing sugars through vitamin assistance in both the species for the enhancement of ethanol production.