User:Shivmirani/Delftia acidovorans/Bibliography

Anissa Powell: Annotated Bibliography
This article seeks to explain the mechanism by which Delftia acidovorans is resistant to the antimicrobial agent Chlorohexidine (CHX). The authors create a mutant strain (MT51) of the wild-type (WT15), and treat both with CHX. They find that upon treatment with CHX, the thickness of the MT51 biofilm decreases significantly. In some cases, the thickness is halved. The WT15 biofilm, however, increases in thickness. Infared spectroscopy, soft X-ray scanning transmission microscopy (STXM), and confocal laser scanning microscopy are all used to measure the biofilm. Consistent results are recorded with each analysis. STXM revealed that the MT51 cells were able to take up five times more CHX than WT15 cells, which could explain the differing thicknesses. The authors suggest that WT15 biofilm consists of two cells, which appear light and dark in the STXM. They believe the light cells are not as responsive to CHX as the dark cells. Furthermore, the light cells are believed to not take up CHX at all. If the light cells can take up CHX, it is very slowly. Therefore, the light cells could be responsible for the antibiotic resistance in Delftia acidovorans.

This study examines patients in a Brazilian ICU. The authors find 24 isolates of Delftia acidovorans in 21 patients via tracheal aspirates. All of the samples were susceptible to treatment with β-lactam, but exhibited resistance to all other antimicrobial agents. Delftia acidovorans appears in high counts when isolated, leading the authors to believe that it is not a simple saprophyte. They argue the bacteria should be considered a pathogen, and carefully removed from clinical settings. The authors believe these results to indicate that careful disinfection of risk items is crucial to protecting the public. Risk factors for Delftia acidovorans include invasive medical devices and intravenous drug paraphernalia.

This article is a case study of a patient with recurrent intravascular-catheter infection. Upon testing with blood cultures, an automated bacterial scanner called the MicroScan WalkAway Panel, and long-chain fatty acid gas chromatography, the bacteria responsible was found to be Delftia acidovorans. The patient was initially treated with cefepime, an antibiotic. After 24 days off cefepime, the patient experienced another infection with D. acidovorans. The second infection was found to be resistant to cefepime. The patient was treated with ceftazidime and vancomycin. The authors explain that there is little research about Delftia acidovorans’ response to antibiotics. The presence of β-lactamase in Delftia acidovorans indicates its resistance to β-lactam antibiotics.

This study examines the similarities and differences between several strains of Delftia acidovorans. C s1-4, SPH1, and ATCC 15668 are among the strains studied. The strains are compared by function prediction, ribosomal genes, and G+C content. Figure 2 is a phylogenetic tree of the Comamonadaceae family and all of the Delftia acidovorans strains. Although strains CCUG 247B and CCUG 15835 belong to Delftia acidovorans, they are more similar to the species Delftia tsuruhatensis, and are therefore grouped with D. tsuruhatensis on the phylogenetic tree.

This study isolates Delftia from the environment to prove its antimicrobial activity. The authors characterize Delftia as, “motile, Gram negative rods, which belong to the Betaproteobacteria lineage.” We know from previous articles that Delftia acidovorans more specifically belongs to the Comamonadaceae family. The authors used mass spectrometers, nuclear magnetic resonance, high-performance liquid chromatography, and minimal inhibitory concentration determination to assess the isolated bacteria. They found that Delftia spp. exhibit antimicrobial activity. Further, they suggest that Delftibactin A can act as an antimicrobial agent towards several drug-resistant pathogens. An integral gene in Delftia acidovorans’ biosynthesis pathway can also be found in Burkholderia pathogens. The authors emphasize the importance of testing antimicrobial activity of other Delftia species as they have here.

Natalie Poirier: Annotated Bibliography
In this article Delftia acidovorans is explored in a patient with an impaired immune system who specifically has leukemia. After being placed in a hospital for three days, this 68-year-old patient developed pneumonia caused by Delftia acidovorans. This bacterium was detected by a reaction test in which the media will turn an orange color if Delftia acidovorans is present. The pneumonia went away and was treated after antibiotics such as piperacillin-tazobactam, ciprofloxacin, vincristine and prednisolone were taken over time. Since Delftia acidovorans is gram negative, this bacterium has to be detected early in order for the antibiotics to work. Besides this pneumonia case, this bacterium has also been reported in patients with lung infections, inflammation of the heart valve, urinary tract infections, eye infections, and peritonitis. Although Delftia acidovorans is not clinically significant, it was important in these cases where the patient is already immuncompromised with a severe illness.

Due to gold being found in numerous products, such as in electronics, this has been proven to be a concern for the environment since gold and other elements are not biodegradable. More harmful, the ions in gold have been shown to have negative health effects on humans. This article talks about a solution that would stop these gold ions from being harmful to humans and the environment when products they are in are thrown away. Their solution included using the bacteria Delftia acidovorans. When this bacterium is in the presence of gold ions, it neutralizes the toxicity of the gold by releasing a peptide that has no ribosomes. These are called nonribosomal peptides and most bacteria and fungi produce them. In turn, this nonribosomal peptide makes extremely small gold nuggets outside of Delftia acidovorans.

This article talks about a patient who had a condition in which blood cannot normally clot and form platelets. Specifically, this patient had cavitary and interstitial pneumonia. The patient then developed severe pneumonia, specifically cavitary and interstitial pneumonia, and Delftia acidovorans was detected in her lungs. According to the article, this was the first known case they were aware of where this bacteria strain was found in a patient with this type of pneumonia. Since it was the first, this discovery was claimed to be clinically significant. The patient recovered fully from this pneumonia type and responded well to the treatment administered which was piperacillin-tazobactam and clarithromycin, both which are antibiotics.

A man was hospitalized after coming down with a UTI, which is a urinary tract infection. In this article, they highlight that this 93-year-old patient had traces of Delftia acidovorans bacteria in his system after urine and blood tests were taken. The bacteria strain was specifically identified using a technique called pulse field gel electrophoresis. The main was successfully cured of his UTI after a certain antibiotic therapy was administered. This included 500 mg of imipenem that was given to him through an IV every 6 hours. Since this case occurred in Taiwan, and was the first case ever reported of Delftia acidovorans causing a urinary tract infection in this region of the globe, this instance was seen as clinically significant.

This article highlights the case of a male patient, 30 years old, who was a drug user, had contracted hepatitis C and PTSD. The patient was admitted into a hospital after complaints of progressive knee pain, fever, and a lesion on one of his fingers. After receiving a arteriogram, he was seen by a cardiothoracic surgeon, and eventually received heart surgery where he got an aortic valve replacement. The aortic valve that was removed was tested and Delftia acidovorans was detected in the culture. The previous antibiotics administered to him, vancomycin and piperacillin-tazobactam, had no effect on his condition. Once the patient was given the antiobiotic ceftriaxone, the bacterium cleared up in a matter of days. The changes in antibiotics made doctors and researchers realize that Delftia acidovorans was resistant to aminoglycosides. Aminoglycosides are antibiotics used to treat aerobic, gram-negative bacteria strains. They also learned that Delftia acidovorans had a drastic health effect on heart valves and large arteries.

Kristina Stayer: Annotated Bibliography
This article discusses the ability of different kinds of Delftia acidovorans to create secondary gold biominerals. Gold is a toxic substance Delftia acidovorans is able to deal with this toxicity outside the cell by excreting a metabolite known as delftibactin. This metabolite can create small gold particles through reduction. This bacteria can exist alone in its own biofilm but it can also exist in a biofilm composed of many other bacteria that have a role in gold detoxification and precipitation. Living in a biofilm allows the bacteria to have higher survival when compared to singular bacteria cells.

This article discusses the ability of Delftia acidovorans to extract gold from sludges containing seawater and calcium carbonate. seawater is known to contain gold in the form of AuCl3 like the other article the solid gold is created by reduction in this case of the Au3+ cation by delftibactin. The article did not mention where the seawater was obtained from. Though Delftia acidovorans was able to extract gold from the seawater the amount extracted was not enough to make this a practical way to obtain gold.

This article was about utilizing Delftia acidovorans to extract gold from electronic waste. Though there are already existing ways to extract metals from this kind of waste it is costly and not environmentally friendly utilizing the natural ability of Delftia acidovorans or other bacteria. It was found that Delftia acidovorans had the ability to extract gold from electronics treated with nitric acid to remove the copper that interferes with the ability of cyanide to dissolve gold so that the delftibactin produced by Delftia acidovorans can reduce the resulting ions.

This article is similar to the second article in this bibliography as it considers the action of biofilms containing Delftia acidovorans on Au3+ cations the purpose of this paper was to compare how Delftia acidovorans deals with the toxic soluble gold in comparison to another bacteria that deals with it intracellularly. The researchers found that Delftia acidovorans deals with the toxic gold by using the metabolite delftibactin as mentioned in other sources. This source did genetic analysis on Delftia acidovorans to try and find which genes may be responsible for the precipitation of gold. The Daci_4754 gene referred to as delG by researchers was found to be responsible for the creation of the metabolite. Delftibactin is unique among secondary metabolites as one that can protect the bacteria from toxic gold and reduce that gold to solid form.

This article discusses a protocol to recycle gold from electronic waste using Delftia acidovorans this protocol was found to be efficient on a small scale but the growth time needed for Delftia acidovorans was considered to long to be practical and the ideal growth plates that efficiently produce delftibactin are more expensive than plates used for E .coli. This lead researchers to try and produce strains of E.coli that produced delftibactin. While there attempts were successful how well the recombinant E. coli are able to precipitate gold is unknown.

Daiza Norman: Annotated Bibliography
Delftia acidovorans is an aerobic, Gram negative, rod shaped bacterium. It was originally categorized as Psuedamonas acidovorans and Comamonas acidovorans before being reclassified as Delftia acidovorans. Some Strains of Delftia acidovorans can form biofilms such as the WT15 Strain Delftia acidovorans also has the ability to biomineralize gold from gold solutions using a protein called delftibactin.

Zainab Zubair: Annotated Bibliography
The research article titled "Phylogenetic relationships among members of the Comamonadaceae, and description of Delftia acidovorans" discusses Delftia and its similarities and characteristics in relation to other genus and species within the family Comamonadaceae. An important decision made by the researchers was to rename Comamonas acidovorans as Delftia acidovorans .The name change occurred due to sufficient differences against the family, supported by phylogenetic and phenotypic evidence. The word Delftia refers to the city of Delft, and it is categorized as straight or moderately curved rods. The Delftia bacteria are gram-negative, occurring singularly or in pairs. Delftia is capably of motility due to flagella around the cell surface. Catalase and oxidase enzymes are present in Delftia, and it is aerobic and Poly-P-hydroxybutyrate is used as energy storage (glucose). Delftia produces neither endospores nor fluorescent pigmentation; it does not denitrify and it is not autotrophic. Delftia grows well on nutrient agar plates that do not consist of glucose. Delftia is mesophilic, with the optimum growth temperature of 30 degrees celsius; it does not survive in psychrophilic conditions. Delftia is a non-halophile, meaning that it prefers environments with minimal to no salt concentrations (NaCl). Delftia can be found in the soil, freshwater, sludge, oxidase, and samples taken for clinical use. This research article paved the way for future Delftiaresearch by creating a separate niche for it.

The research study "Delftia acidovorans: A rare pathogen in immunocompetent and immunocompromised patients" looks at the case of a patient with D. acidovorans pneumonia who as successfully cured using antibiotic therapy. A leukemia cancer patient was admitted to the hospital due to developing cough, fever, and other pneumonia-like symptoms. Her conditions worsened in the following days due to the unknown cause of pneumonia, but direct examination of sputum identified the bacteria as gram-negative; it was plated on MacConkey Agar and the cells were recognized as Delftia acidovorans. MacConkey Agar allows the growth of gram-negative bacteria that can ferment lactose. Apart from this case study, numerous but infrequent cases have also identified D. acidovorans as the cause/source behind bacterial pneumonia and other lung infections. Delftia is rarely found in immunocompromised patients with underlying conditions, but it is clinically important whenever it arises. However, it may also (rarely) be found in immunocompetent patients who do not suffer from conditions like HIV and AIDS or chronic kidney diseases. The rareness of Delftia as a disease causing agent is guilty for the difficulty in recording its pathogenicity. It is known that Delftia is resistant to some antibiotic treatments, but the researchers state that more research is needed to fully understand Delftia and its characteristics.

This research article titled "Gold Recycling. Using Delftibactin to Recycle Gold from Electronic Waste." examines how gold can be recycled using Delftia avidovorans by sequencing and analyzing mechanisms. The important discovery represented by this article is the gold precipitating nature of delfibactin. Delfibactin is a metabolite that is non-ribosomal, and it is a peptide produced by Delftia acidovorans. Specifically, delfibactin is what can be used to recycle gold from electronics. Being able to use delfibactin on a large scale for recycling gold and reducing electronic waste would be a great step towards reducing pollution and it is environmentally friendly too. The researchers utilized delfibactin to precipitate gold from solutions that contain gold metal ions. The researchers developed clones of the genes that encode the delfibactin peptide in D. acidovorans in order to express them in the gram-negative, universally known, E. coli bacteria. They first attempted to insert the genes into the "methylmalonyl-CoA" pathway, but they were unsuccessful in getting viable results. So, they developed a new strategy. They amplified two plasmids from the mm-CoA pathway and "PPTase sfp" from Bacillus subtillis. Their experiments and analyses find that delfibactin can be used as an efficient compound for recycling gold to combat the immense electronic pollution problem that is steadily increasing. Recycling gold from electronic waste can be reused in modern technology especially since there is a high demand and expanding market of technology. Using delfibactin to recycle gold will be an efficient, quicker, cost-effective, cleaner, and less energy consuming method as compared to current slow and high-energy consuming methods. By inputting the delfibactin genes of D. acidovorans into E. coli, delfibactin can be mass produced due to the commonality of E. coli. Thus gold recycling can be conducted on a large scale as well.

The research article "Engineering Delftia acidovorans DSM39 to produce polyhydroxyalkanoates from slaughterhouse waste" develops a way to use D. acidovorans to produce PHAs for slaughterhouse waste. D. acidovorans is a well-known PHA producer, but it does not work on waste material consisting of fatty acids. Their research was aimed at developing a DNA recombinant strain of D. acidovorans that is able to produces PHAs on fatty acids as the only carbon source. The aim of their research is to use D. acidovorans as an efficient way of converting fatty acids into PHAs that have multiple uses in the medical industry. PHAs are becoming an increasingly important and viable alternative to plastic equpiment made from depleting natural resources and through the burning of fossil fuels. By using D. acidovorans as a PHA producer on a large scale, environmentally-friendly alternatives can be developed that will still be as useful and strong as regular plastic. Through their experiments and results, the researchers were able to fatty-acid related bacteria were successfully isolated from the slaughterhouse waste. The success in experiments led to the animal fats like lard and butter being used as the sole carbon source in powering the pathways. Their research and results are significant because it creates a whole field of utilizing D. acidovorans for this purpose; since there is no real shortage of animal fat, they can be recycled as non-petroleum based products. The nature of the fatty acids, meaning its chemical structure, should be accounted for individually, but there are a plethora of uses that stem from using D. acidovorans to produce PHAs using fatty acids.

The research study titled "The Versatility of Delftia sp. Isolates as Tools for Bioremediation and Biofertilization Technologies" examine how Delftia can be beneficial in cleaning up the environment and reducing electronic pollution. Under the Delftia genus, there are four species: acidovorans, tsuruhatensis, lacustris, and litopenaei. Delftia can transform toxic metal elements like selenium and chromium ions. Delftia also promotes plant growth by providing nutrients to the plant through nitrogen fixation, or by helping the plants in resistance against pathogens. The aim of the research is to isolate microbes that are capable of absorbing lead while being resistant to it as well in order to develop therapies for lead-associated medical cases. Their results show that the Delftia bacterium is a valid candidate for absorbing lead that can be helpful in medical situations as well as in reducing electronic waste. Delftia can be used to recycle and/or reuse the lead found in electronics that have been discarded. Delftia is also resistant to many antibiotics, which may be due to metal components polluting natural environments and thereby spreading microbial resistance. Their resistance abilities may be significant when evolving isolates in polluted locations. The researchers conclude that the varying characteristics of Delftia make it a practical option for progressing biotechnology and reducing electronic pollution while recycling metals on a large scale.