Topic
Citric acid
About: Citric acid is a research topic. Over the lifetime, 17745 publications have been published within this topic receiving 277125 citations. The topic is also known as: citrate & H3cit.
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TL;DR: It is suggested that the E. coli CitT protein is a member of a novel family of eubacterial transporters involved in the transport of di- and tricarboxylic acids.
Abstract: Under anoxic conditions in the presence of an oxidizable cosubstrate such as glucose or glycerol, Escherichia coli converts citrate to acetate and succinate Two enzymes are specifically required for the fermentation of the tricarboxylic acid, ie, a citrate uptake system and citrate lyase Here we report that the open reading frame (designated citT) located at 1390 min on the E coli chromosome between rna and the citrate lyase genes encodes a citrate carrier E coli transformed with a plasmid expressing citT was capable of aerobic growth on citrate, which provides convincing evidence for a function of CitT as a citrate carrier Transport studies with cell suspensions of the transformed strain indicated that CitT catalyzes a homologous exchange of citrate or a heterologous exchange against succinate, fumarate, or tartrate Since succinate is the end product of citrate fermentation in E coli, it is likely that CitT functions in vivo as a citrate/succinate antiporter Analysis of the primary sequence showed that CitT (487 amino acids, 531 kDa) is a highly hydrophobic protein with 12 putative transmembrane helices Sequence comparisons revealed that CitT is related to the 2-oxoglutarate/malate translocator (SODiT1 gene product) from spinach chloroplasts and five bacterial gene products, none of which has yet been functionally characterized It is suggested that the E coli CitT protein is a member of a novel family of eubacterial transporters involved in the transport of di- and tricarboxylic acids
130 citations
TL;DR: It is concluded that the complex formation between Fe(III) and organic acid is a key step for the photocatalytic reduction of Cr(VI) in the presence of Fe( III) andorganic acids with alpha-OH.
130 citations
TL;DR: In this paper, an improved upward-flow anaerobic sludge blanket (UASB) reactor with a working volume 50 m 3 was used for continuous biological hydrogen production using wastewater from citric acid factory as raw materials.
130 citations
TL;DR: Under their optimal conditions, the recovery percentages of Ni, Co, Mn, and Li can reach 98%, 97%, 98%, and 89%, respectively, which is a relatively simple route in which all metal values could be effectively leached and recovered in citric acid media.
130 citations
TL;DR: Experimental results of SR-AOP experimental results indicate that bromine incorporation is distributed among both hydrophobic and hydrophilic NOM fractions, and studies on model precursor reveal that LMW acids are reactive TBM precursors.
Abstract: A sulfate radical-based advanced oxidation process (SR-AOP) has received increasing application interest for the removal of water/wastewater contaminants. However, limited knowledge is available on its side effects. This study investigated the side effects in terms of the production of total organic bromine (TOBr) and brominated disinfection byproducts (Br-DBPs) in the presence of bromide ion and organic matter in water. Sulfate radical was generated by heterogeneous catalytic activation of peroxymonosulfate. Isolated natural organic matter (NOM) fractions as well as low molecular weight (LMW) compounds were used as model organic matter. Considerable amounts of TOBr were produced by SR-AOP, where bromoform (TBM) and dibromoacetic acid (DBAA) were identified as dominant Br-DBPs. In general, SR-AOP favored the formation of DBAA, which is quite distinct from bromination with HOBr/OBr– (more TBM production). SR-AOP experimental results indicate that bromine incorporation is distributed among both hydrophobic and hydrophilic NOM fractions. Studies on model precursors reveal that LMW acids are reactive TBM precursors (citric acid > succinic acid > pyruvic acid > maleic acid). High DBAA formation from citric acid, aspartic acid, and asparagine was observed; meanwhile aspartic acid and asparagine were the major precursors of dibromoacetonitrile and dibromoacetamide, respectively.
130 citations