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 ''Pseudomonas 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.

Biology and biochemistry

Type and morphology

''Delftia acidovorans'' is a saphrophyte, Gram-negative, non-sporulating, non-denitrifying, non-fermentative 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 through polar or bipolar tufts of flagella. Tufts can have one to five flagella.

Strains and phylogeny

''Delftia acidovorans'' exists as part of the Betaproteobacteria lineage within 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''. CCUG 247B and CCUG 15835 are often grouped with '' D. tsuruhatensis'' rather than ''D. acidovorans.''

Metabolism

''Delftia acidovorans'' is mesophilic and the optimal growing temperature is 30 °C. It will not survive in psychrophilic conditions. ''D. acidovorans'' is a non-halophile that prefers environments with minimal to none salt concentrations for growth. ''D. acidovorans'' strains Cs1-4 and SPH-1 are aerobic bacteria.

''Delftia acidovorans strains'' Cs1-4 and SPH-1 can use phenanthrene, pyruvate, vanillate, succinate, Formic acid, gluconic acid, hydroxybutyric acid, lactic acid and propionic acid as a carbon source. ''D. acidovorans'' does not produce urease, is catalase and oxidase positive, and oxidizes fructose and mannitol

Biomineralization

''Delftia acidovorans'' is one of the few bacteria, along with ''Cupriavidus metallidurans'', that can metabolize gold. Au³⁺ is reduced extracellularly by the non-ribosomal secondary metabolite delftibactin. Delftibactin is a unique metabolite, as it can protect the bacteria from gold toxicity as well as reduce gold ions to solid form. Delftibactin can remove gold from sludges containing seawater and calcium carbonate, and is also capable of retrieving gold from electronic waste. Biohydrometallurgy techniques using ''D. acidovorans'' improve recycling profitability and are sustainable alternatives to cyanide leaching. Lead can also be recovered from discarded electronics with ''D. acidovorans''. Attempts to induce delftibactin expression in ''Escherichia coli'' were unsuccessful due to the toxicity of the DelH protein.

Bioremediation and biomanufacturing

''Delftia acidovorans'' is capable of converting toxic metals like selenium and chromium ions into harmless products. It can also degrade phenanthrene, which is a carbon source from polycylic aromatic hydrocarbons (PAHs). Phenanthrene is a common environmental pollutant.

''Delftia acidovorans'' can be used to manufacture polyhydroxyalkanoates (PHAs). PHAs are a favorable alternative towards traditional plastic equipment used in medical settings. Traditional plastic manufacturing is resource-consuming and polluting, while PHA production through ''D. acidovorans'' is a more sustainable solution.

Role in disease

''Delftia acidovorans'' is an emergent opportunistic pathogen that demonstrates antibiotic resistance. The infection can cause bacteremia, keratitis, pneumonia, empyema, otitis, and peritonitis. Known sources of infection include contaminated water and catheters. ''D. acidovorans'' should be considered a causative organism in patients when water or soil contamination is suspected. ''D. acidovorans'' has been isolated from clinical settings as well, such as RO systems, surgical vacuums, and operating bay sinks. Some strains can tolerate chlorhexidine, a common surgical disinfectant.

Infections of ''D. acidovorans'' can be confirmed through an orange indole test. Antibiotic resistance to aminoglycosides is common.

References

External links

Type strain of ''Delftia acidovorans'' at Bac''Dive'' - the Bacterial Diversity Metadatabase

{{Taxonbar, from=Q4167431

Comamonadaceae
Bacteria described in 1999