User:Shivmirani/Delftia acidovorans

Delftia acidovorans is a Gram-negative, motile, non-sporulating, rod-shaped bacterium known for its ability to biomineralize gold and bioremediation characteristics. It was first isolated from soil in Delft, Netherlands. The bacterium was originally categorized as Psuedamonas acidovorans and Comamonas acidovorans before being reclassified as Delftia acidovorans.

History
Delftia Acidovorans was originally known as Comamonas acidovorans. It was renamed due to rRNA relatedness and differences from other microbes within the Comamonadaceae family. These differences are evidenced by phylogenetic and phenotypic data. The new name, Delftia acidovorans, is a reference to the city of Delft, where it was first discovered and recorded.

Type and morphology
D. acidovorans is a saphrophyte, gram-negative, non-sporulating, non-flourescent, rod shaped bacterium. D. acidovorans exists as a single cell or in pairs that are 0.4-0.8 ųM wide and 2.5-4.1 ųM long. D. acidovorans is motile, with polar or bipolar tufts of flagella. These tufts can have one to five flagella. D. acidovorans is non-denitrify and does not demonstrate autotrophic capabilities.

Strains and phylogeny
Delftia acidovorans exists as part of the Betaproteobacteria lineage. More specifically, D. acidovorans belongs to the Delftia genus of the Comamonadaceae family''. D. acidovorans'' strains SPH1, ATCC 1 15668, and Cs 1-4 are closely related. While strains CCUG 247B and CCUG 15835 belong to Delftia acidovorans, they are more similar to Delftia tsuruhatensis. For this reason, CCUG 247B and CCUG 15835 are often grouped with D. tsuruhatensis rather than D. acidovorans.

Metabolism
Cells grow well on media containing organic acids, amino acids, peptone and carbohydrates (but not glucose).

They are mesophilic and their optimal growing temperature is 30°C. They will not survive in psychrophilic conditions.

D. acidovorans is a non-halophile. It prefers environments with minimal to none salt concentrations for growth.

D. acidovorans strains Cs1-4 and SPH-1 are aerobic bacteria. D. acidovorans strains Cs1-4 and SPH-1 can use Phenathreene, pyruvate, vanillate, succinate, Formic acid, gluconic acid, hydroxybutyric acid, lactic acid and propionic acid as a carbon source. Delftia acidovorans is a nonfermenting bacterium. It utilizes Poly-P-hydroxybutyrate as energy storage for compounds like glucose. D. acidovorans does not produce urease and is catalase and oxidase positive. It oxidizes fructose and mannitol.

Role in disease
Medical case studies identify D. acidovorans as a rare cause of bacterial pneumonia and other lung infections. It is rarely found in immunocompromised patients suffering from underlying conditions. Additionally, it may also be found in immunocompetent patients as well, who do not have underlying conditions. D. acidovorans is known to be resistant to some common antibiotics, further research is required for better understanding of its mechanics.

Another case study finds a male patient with severe knee pain and a lesion on his hand with a high temperature with negative virus and drug screening tests. Cardiothoracic surgery was performed on the patient wherein his aortic valve was replaced. Blood cultures and a tissue culture of the aortic valve identified a gram-negative bacterium, D. acidovorans, being resistant to all aminoglycosides (antibiotics). Since aminoglycoside treatments were unresponsive, the patient was administered ceftriaxone which cleared up the bacteremia after a few days post surgery. The culture tests on D. acidovorans found that it does not oxidize glucose and is resistant to kanamycin, tobramycin, colistin, and penicillin antibiotics. Antimicrobial susceptibility found that the D. acidovorans from the patient is susceptible to ceftazidime, fluroquinolones, carbapenems, tetracycline. The ICEPC study finds that almost 2800 patients from 25 countries diagnosed with definite endocarditis, of which only 6% of pathogens are made up by it. Although D. acidovorans is generally a nonpathogenic environmental organism, it is infrequently encountered in clinical specimens of low virulence. However, it may be an opportunistic pathogen associated with vascular catheters as well. The researchers only found two other cases associated with D. acidovorans in their hospital cases, one of which led to a fatality. D. acidovorans should be considered a causative organism in patients especially when water or soil contamination is suspected. Remarkably, D. acidovorans can survive on the biofilm that forms in plumbing; the patient's use of tap-water to alter his drug test is thought to be the source of D. acidovorans infection. Since D. acidovorans is resistant to aminoglycosides, it is imperative for its quick diagnosis in order to administer the best course of antibiotics. The case study concludes that D. acidovorans is capable of causing acute endocarditis and rapidly destructing the aortic valve that may lead to arterial emboli.

A case study reports that a female child with metastatic neuroblastoma developed recurrent bacteremia caused by D. acidovorans. D. acidovorans was found to be resistant against penicillin and cephalosporins. Similar to the case study above, the removal of this patient's vascular catheter resulted in the infection subsiding. The patient suffered recurrent central venous catheter bacteremia caused by D. acidovorans. The patient had surgery but still sustained neutropenia and high fever so blood samples were drawn for culturing, which found D. acidovorans and Alcaligenes xylosoxidans. D. acidovorans' antibiotic profile is similar to the case study reported above. Although the patient received betamipron and her condition improved, fever recurred and blood cultures still detected the presence of D. acidovorans. The patient was then administered ceftazidime, after which her condition improved and D. acidovorans was no longer present. This case was the first known D. acidovorans bacteremia in Japan. Whilst the patient's treatment, D. acidovorans developed resistance against piperacillin and cephalosprorins like cefeozopran and cefepime. Removal of the infected catheter and immediate antibiotic therapy successfully eradicated D. acidovorans from the patient.

D. acidovorans is largely nonpathogenic, but some case studies do report it to be the cause behind endocarditis, nosocomial bacteremia, and ocular infections.

Biomineralization
D. acidovorans is one of the few bacteria along with Cupriavidus metallidurans and a few others that can metabolize gold. In Australia D. acidovorans has been found working in a biofilm with C. metallidurans.

It was discovered that D. acidovorans is able to reduce Au3+ extracellularly using a metabolite called delftibactin. Delfibactin is a non-ribosomal metabolite .Johnston also described two variants of delftibactin referred to as delftibactin A and delftibactin B. It was found that the delftibactin B variant was less efficient in gold reduction and not as protective against gold toxicity when compared to delftibactin A. Delftibactin is unique among secondary metabolites as it can protect the bacteria from gold toxicity as well as reduce gold ions to solid form. D. acidovorans has also been shown to remove gold from sludges containing seawater and calcium carbonate. Gold is found in AuCl3 form in seawater. It exist at a constant level however, no amount of gold is guaranteed in any seawater sample collected making this an impractical way to make solid gold.

Delfibactin is critical in retrieving gold from electronic waste. It is used to precipitate gold, when placed in solutions composed of metallic gold ions. Delftibactin is aimed to be used in large scale recycling projects to recycle gold and reduce electronic pollution. Gold recycled from electronic waste is reused in advanced technology. Delftibactin is an affordable, efficient, and environmentally-friendly alternative of recycling gold.

Delftibactin is encoded by the Del cluster of genes which contains 21 genes. 4 of the proteins created by the gene cluster are responsible for the creation of delftibactin in D. acidovorans while the other 6 proteins created by the gene cluster are responsible for the maturation and post translational modification of delftibactin. Since delftibactin has been shown to parcipitate gold researchers wanted to clone the gene cluster in to E. coli. This is because E. coli grows faster than D. acidovorans and is able to be grown efficiently on a cheaper medium than D. acidovorans . The introduction of delftibactin genes in E. coli was achieved using Gibson Assembly. The one of the proteins encoded by the delftibactin genes cloned into E. coli known as DelH is slightly different from the orignal DelH protein in D. acidovorans because the DelH protein, which is important in for the creation of delftibactin, is changed by one amino acid. It is unknown how well the recombinant E. coli will be able to produce delftibactin .

Bioremediation
Delftia is capable of converting toxic metals like selenium and chromium ions into useful elements. Although non-denitrifying, Delftia promotes plant growth through nitrogen fixation of nutrients and by providing resistance against pathogens. Delftia can absorb lead which proves useful in medical cases related to poisoning and in reduction of e-waste. It can recycle lead from discarded electronics. Delftia's antibiotic resistance is linked to the spread of microbes due to metals contaminating natural environments. Delftia is a viable model organism for progressing biotechnology and reducing electronics pollution through recycling and reusing metal components.

Delftia is able to contribute to microbial degradation by playing a crucial role in phenanthrene degradation, a carbon source from polycylic aromatic hydrocarbons (PAH), which are known to be chemicals capable of polluting the environment. The genome sequence of Delftia provides insight on the effects and mechanics of PAH degradation, in efforts to contribute as a ways of remediation.

Other applications
D. acidovorans also produces polyhydroxyalkanoate, otherwise known as PHAs. However, these do not work on wastes comprised of fatty acids. A DNA recombinant strain of D. acidovorans to convert fatty acids into PHAs. PHAs are a favorable alternative towards traditional plastic equipment used in medical settings. Plastic manufacturing uses natural resources and pollutes the environment, so using D. acidovorans to produce PHAs is an environmentally friendly substitute that is proposed to be used on a large-scale. To power this process, animal-derived fatty acids like lard and butter are used as carbon sources.

Taxonomy
Under the Delftia genus, there are four different species: tsuhatensis, litopenaei, acidovorans, and lacustris.