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Exploration of Bacterial Siderophores for Sustainable Future
Published in Suhaib A. Bandh, Javid A. Parray, Nowsheen Shameem, Climate Change and Microbial Diversity, 2023
Anita V. Handore, S. R. Khandelwal, Rajib Karmakar, D. V. Handore
All the siderophores having binding groups of phenolate or 2, 3-dihydroxy benzoate belong to the catecholate type of siderophores. Each catecholate group supplies two oxygen atoms for chelation with iron in order to form a hexadentate octahedral complex. Certain bacteria like E. coli, S. typhimurium, E. Herbicola, and K. pneumoniae produce enterochelin, also known as enterobactin (Sah and Singh R. 2015). It is reported that Enterobactin with molecular formula C30H27N3O15 is one of the strongest catecholate type of siderophore exhibiting significant potential to chelate iron even from the environment where the concentration of iron is low (Raymond et al., 2003) (Fig. 7.1). It shows ability to bind ferric ion very tightly and this strong binding between enterochelin and iron can be used to determine even very low concentration of iron in the environmental sample. In nature, there are few bacteria exhibiting ability to produce either catecholate siderophore alone or mixed siderophores. It is stated that some bacteria like E. carotovora can produce only catecholate siderophore, whereas some members of Pseudomonas show the ability to produce mixed type of siderophore consisting of both catecholates and hydroxamates (Leong and Neilands, 1982).
Bacterial Polyesters and Their Models Obtained by Ring-Opening Polymerization of β-Lactones
Published in Stanislaw Penczek, H. R. Kricheldorf, A. Le Borgne, N. Spassky, T. Uryu, P. Klosinski, Models of Biopolymers by Ring-Opening Polymerization, 2018
Alain Le Borgne, Nicolas Spassky
and which presents a skeleton derived from a functional β-hydroxyacid, i.e., (S)-serine. The enterobactin is found in several microorganisms25-28 and serves as a strong complexing agent of ferric ions involved in the transport and metabolism of iron.
Metabolic Regulation in Response to Growth Environment
Published in Kazuyuki Shimizu, Metabolic Regulation and Metabolic Engineering for Biofuel and Biochemical Production, 2017
The metal ion levels are often sensed by metal-sensing regulatory RNA, which encodes metal-sensing proteins involved in the transport and storage of intra-cellular metals (Dann et al. 2007, Helmann 2007). In the native environment, the cell continuously faces iron deficiency, where metal ion functions as cofactor in many of the cellular constituents such as flavoproteins, and therefore, the cell furnishes the mechanism for iron uptake and storage system (Zheng et al. 1999, McHugh et al. 2003). However, excess iron causes toxicity by catalyzing the formation of reactive free radicals through Fenton/Haber-Weiss reaction (Storz and Imlay 1999). In combination with inability to convert NADH to NAD+ in the respiration, a decrease in endogeneous O2- causes reductive stress, and in turn activates Fur (ferric uptake regulator) (Jovanovic et al. 2006). Fur generally represses ion transport and ion siderophore biosynthetic genes when complexed with ferrous ion. Under ion limitation, ion dissociates from Fur, where Fur requires binding to Fe2+ to become active. O2- deactivates Fur after its conversion to H2O2 by superoxide dismutase (SOD) through Fenton reaction (H2O2 + Fe2+ HO* + OH- + Fe3+) (Blanchard et al. 2007). Therefore, a decrease in endogeneous O2- increases the availability of Fe2+, through a decrease in H2O2 level, and in effect activates Fur (Brynildsen and Liao 2009). Namely, Fur senses the reductive stress and protects Fe-S clusters to be safe from damage by reactive oxygen species (ROSs). It is essential for the cell to use iron economically, and this is attained by siderophore synthesis and iron transport regulation (Braun et al. 1998). Iron transport and siderophores (e.g., enterobactin) pathway genes such as talB and entF are repressed by Fur (Azpiroz and Lavina 2004, Semsey et al. 2006, Hantash et al. 1997), and enterobactin may be produced in fur mutant E. coli (Kumar and Shimizu 2011). There are functional interactions between carbon and ion utilization via Crp and Fur, where many ion transport genes and several catabolic genes are subject to dual control (Zhang et al. 2005).
Genomic-wide analysis approach revealed genomic similarity for environmental Mexican S. Oranienburg genomes
Published in International Journal of Environmental Health Research, 2023
J. R. Aguirre-Sanchez, I. F. Vega-Lopez, N. Castro Del Campo, J. A. medrano-Felix, J. Martínez-Urtaza, C. Chaidez-Quiroz
Regarding the virulence profile, an average of 146 virulence genes were found as a conservative collection for all strains (Supplementary Figure 1). Major regulator genes fur and rpoS for ferric uptake and the production of fimbriae were found. The fim cluster fimA, I, C, D, H, F, Z, Y, and W, and the single operon were found for all isolates. The curli fimbriae operon csgBAC and the master regulatory gene for adhesive curli fimbriae expression csgD were consistent for all strains. Virulence cassette ssaA belonging to Salmonella pathogenicity island (SPI-2) was found. Its main role is the secretion of effector proteins to facilitate the replication of intracellular bacteria. The genes sopAD, avrA, sipABC related to the TTSS-1 secreted effectors were constant for the genome collection. The magnesium uptake genes mgtBC necessary for intracellular survival and virulence were also found. The gene duo entAB associated with iron acquisition was found. Interestingly, in the sporadic episodes of diarrhea in humans and animals the EAST1 toxin was found for only a strain that was isolated from serrano pepper (SORA2008JA02). In addition to this, the precursor of an enterobactin pathway 2,3-dihydrobenzoic acid was found for a single strain isolated from river water (C-ORA09001). The only not consistent gene among all isolates was ratB which has an intestinal persistence role.
Theoretical insight and experimental elucidation of desferrioxamine B from Bacillus sp. AS7 as a green corrosion inhibitor
Published in Corrosion Engineering, Science and Technology, 2021
S. Pérez-Miranda, L.S. Zamudio-Rivera, R. Cisneros-Dévora, R. George-Téllez, F.J. Fernández
Molecular identification of the microorganism was achieved after comparison with deposited bacterial sequences through a standard nucleotide BLAST homology search [52]. Results showed a 100% identity with sequences belonging to three species of the genus Bacillus: Bacillus atrophaeus, Bacillus vallismortis, Bacillus amyloliquefaciens and several entries deposited only as Bacillus sp. Some biosynthetic clusters of siderophores (petrobactin, bacillibactin, 3,4-DHB) in Bacillus sp. have been reported [53,54]. Bacillus sp. has multiple iron acquisition systems that are used to uptake the produced siderophores, as well as to exogenous pirate siderophores such as enterobactin or ferrioxamine B [55,56]. To date, there is still no evidence that Bacillus sp. can produce hydroxamate-type siderophores.
Experimental and theoretical studies on structure, bonding and luminescence properties of Eu(III) and Tb(III) complexes of a new macrocyclic based 8HQ ligand
Published in Journal of Coordination Chemistry, 2019
Enterobactin, a natural occurring siderophore (Figure 1), is probably the most prominent example of ligand which has high thermodynamic stability [logK = 49 for Fe(III)] that met the above criteria, that has encouraged the synthesis of a wide range of nonnatural compounds used for the binding of metal ions. This incorporates a highly symmetric (C3) serine unit linked to three catechol units through amide spacers. Many biomimetic siderophores have served as excellent chelators for lanthanide luminescence and coordination [13]. Polyaza-macrocycles have a framework similar to L-serine. Incorporation of 8HQ units to the flexible puckered ring of the macrocyclic 9N3 results in the existence of several rotamers/conformers [14]: this has an additional advantage that can adjust its geometry to minimum energy on coordination with metal ions giving extra stability. The macrocycle offers the ability to fine-tune the properties of metal chelation by varying the cycle’s size and flexibility. Very few macrocycles have been described with 8HQ coordinating groups as shown in Figure 2(a–c) [15, 16]. It may be emphasized here that the position of attachment of 8HQ unit plays a significant role in properties and coordination of metal complexes. There are many examples of poly-8HQ chelates in which the 8HQ ring is attached at positions 2, 3, or 7. Tripods incorporating 8HQ substituted at position 5 are scarce. The coordinating property of –N pyridyl group mainly depends upon substitution position at the C-2, C-3, C-5 and/or C-7 in the 8HQ. In the case, where 8HQ is substituted at the position C-2 or C-7, a photoinduced electron transfer (PET) process leads to fluorescence quenching [17].