The First Bacterial Endocarditis Due to Achromobacter xylosoxidans in a Dog

Infectious endocarditis (IE) in dogs is often associated with a high mortality rate as diagnostic work-up as well as antibiotic treatment might be challenging. The present case describes bacteremia in a dog caused by Achromobacter xylosoxidans, leading to an infectious endocarditis. Achromobacter xylosoxidans (A. xylosoxidans) is an aerobic Gram-negative rod-shaped bacterium, which has been associated with multiple nosocomial opportunistic diseases in human medicine. One such manifestation of A. xylosoxidans infection is endocarditis. A. xylosoxidans infections are challenging to treat due to the reduced effectiveness of a wide range of antimicrobial agents. To date, only a few case reports of infections with A. xylosoxidans in animals have been described. This is the first case report of A. xylosoxidans endocarditis in a dog. Whole-genome sequencing was performed to determine the sequencing type and to gain more information about this bacterium regarding its intrinsic resistance genes. With this case report, we seek to increase awareness of A. xylosoxidans as an opportunistic nosocomial pathogen in dogs and to provide a short summary regarding the current state of general knowledge and known resistance patterns.

Evaluation of Inorganic Phosphate Solubilizing Efficiency and Multiple Plant Growth Promoting Properties of Endophytic Bacteria Isolated From Root Nodules Erythrina Brucei

Background: The majority of phosphorous in the soil is fixed and unavailable to plant nutrition, hence in scarcity. Phosphate solubilizing bacteria, the ecological engineers, are considered as the best, sustainable and eco-friendly options. The objectives of this study were to screen and evaluate inorganic phosphate solubilizing efficiency and assess multiple plant growth promoting traits of E. brucei root nodule bacterial endophytes.Results: A total of 304 nodule bacterial endophytes were screened for phosphate solubilization potential on solid PA medium among which 119 (39%) were potential tricalcium phosphate solubilizers. None of these isolates were able to form clearly visible halos on aluminum phosphate (AlPO4), Al-P or iron phosphate (FePO4), Fe-P supplemented PA medium. Out of 119 inorganic phosphate solubilizing endophytes, 40.3% were IAA producers. Based on phosphate solubilization index, the potential bacterial endophytes were identified to Gluconobacter cerinus, Acinetobacter soli, Achromobacter xylosoxidans and Bacillus thuringiensis using the 16S rRNA gene sequences analysis. All the selected isolates were potential solubilizers of the three inorganic phosphates (Al-P, Fe-P and tricalcium phosphate, TCP) included in liquid NBRIP medium. The highest values of solubilized TCP were recorded by isolates AU4 and RG6 (A. soli), 108.96 mg L-1 and 107.48 mg L-1, respectively at sampling day3 and 120.36 mg L-1 and 112.82 mg L-1, respectively at day 6. The highest values of solubilized Al-P and Fe-P were recorded by isolate RG6, 102.14 mg L-1 and 96.07 mg L-1, respectively at sampling days 3 and 6, respectively. The highest IAA, 313.61µg mL-1 was recorded by isolate DM17 (B. thuringiensis). These selected potential isolates were also HCN, NH3, and hydrolytic enzymes producers. The isolates were also varied in tolerance to eco-physiological stressors and exhibited versatility to carbon and nitrogen substrate utilization. Conclusions: The genera and species Gluconobacter cerinus, Acinetobacter soli, Achromobacter xylosoxidans and Bacillus thuringiensis are the first reports from E .brucei root nodules and Gluconobacter is also the first report to the science as phosphate solubilizer. Isolates AU4 and RG (A. soli) could be potential bio-inoculant candidates for the growth enhancement of the host plant for better agro-forestry practices in acidic and alkaline soils in Ethiopia.

Species and Metabolic Pathways Involved in Bioremediation of Vietnamese Soil From Bien Hoa Airbase Contaminated With Herbicides

Four bacterial strains were isolated from enrichment cultures inoculated with soil from Bien Hoa military base in Vietnam contaminated with the herbicides 2,4-dichlorophenoxyacetate (2,4-D) and 2,4,5-trichlorophenoxyacetate (2,4,5-T). They were classified as Pseudomonas aeruginosa BT1 2.2, Sphingomonas histidinilytica BT1 5.2, Bordetella petrii BT1 9.2, and Achromobacter xylosoxidans BT1 10.2. All four were able to degrade 2,4-D and 2,4,5-T, but only the last three species used them as the sole sources of carbon and energy. Mass balance analyses suggest that between 33 and 46% of the carbon in the herbicides is incorporated into dry weight (DW). We obtained insight into their degradation pathways by the genomic analysis of these strains. A tfdCDEF gene cluster was found in A. xylosoxidans BT1 10.2 with amino acid sequences of their gene products showing high identity to those in B. petrii DSM12804. Bordetella petrii BT1 9.2 has a full complement of the tfdABCDEF genes. Surprisingly, the gene organization along with the amino acid sequences of the gene products are virtually identical to those of Cupriavidus pinatubonensis JMP134, referred to as type I tfd genes, and different from those of A. xylosoxidans BT1 10.2 and B. petrii DSM12804. We hypothesize that some of the genetic potential to degrade the herbicides has been recruited in recent mating events between these species and other members of the proteobacteria. This is the first report showing that B. petrii BT1 9.2 emerges as a key player in the degradation of 2,4-D.

Bioaccumulation and detoxification of trivalent arsenic by Achromobacter xylosoxidans BHW-15 and electrochemical detection of its transformation efficiency

Arsenotrophic bacteria play an essential role in lowering arsenic contamination by converting toxic arsenite [As (III)] to less toxic and less bio-accumulative arsenate [As (V)]. The current study focused on the qualitative and electrocatalytic detection of the arsenite oxidation potential of an arsenite-oxidizing bacteria A. xylosoxidans BHW-15 (retrieved from As-contaminated tube well water), which could significantly contribute to arsenic detoxification, accumulation, and immobilization while also providing a scientific foundation for future electrochemical sensor development. The minimum inhibitory concentration (MIC) value for the bacteria was 15 mM As (III). Scanning Electron Microscopy (SEM) investigation validated its intracellular As uptake capacity and demonstrated a substantial association with the MIC value. During the stationary phase, the strain’s As (III) transformation efficiency was 0.0224 mM/h. Molecular analysis by real-time qPCR showed arsenite oxidase (aioA) gene expression increased 1.6-fold in the presence of As (III) compared to the untreated cells. The immobilized whole-cell also showed As (III) conversion up to 18 days. To analyze the electrochemical oxidation in water, we developed a modified GCE/P-Arg/ErGO-AuNPs electrode, which successfully sensed and quantified conversion of As (III) into As (V) by accepting electrons; implying a functional As oxidase enzyme activity in the cells. To the best of our knowledge, this is the first report on the electrochemical observation of the As-transformation mechanism with Achromobactersp. Furthermore, the current work highlighted that our isolate might be employed as a promising candidate for arsenic bioremediation, and information acquired from this study may be helpful to open a new window for the development of a cost-effective, eco-friendly biosensor for arsenic species detection in the future.

Characterization of a New L-Glutaminase Produced by Achromobacter xylosoxidans RSHG1, Isolated from an Expired Hydrolyzed L-Glutamine Sample

As significant biocatalyst, L-glutaminases find potential applications in various fields, from nourishment to the pharmaceutical industry. Anticancer activity and flavor enhancement are the most promising applications of L-glutaminases. In this study, L-glutaminase was isolated and purified from an old glutamine sample. A selected bacterial isolate was characterized taxonomically by morphological characters, biochemical testing and 16S rDNA sequence homology testing. The taxonomical characterization of the isolate identified it as Achromobacter xylosoxidans strain RSHG1. The isolate showed maximum enzyme production at 30 °C, pH 9, with Sorbitol as a carbon source and L-Glutamine as a nitrogen and inducer source. L-Glutaminsae was purified by using column chromatography on a Sephadex G-75. The enzyme has a molecular weight of 40 KDa, pH optimal 7 and is stable in the pH range of 6–8. The optimum temperature for the catalyst was 40 °C and stable at 35–50 °C. The kinetic studies of the purified L-glutaminase exhibited Km and Vmax of 0.236 mM and 443.8 U/mg, respectively. L-Glutaminase activity was increased when incubated with 20 mM CaCl2, BaCl2, ZnSO4, KCl, MgSO4 and NaCl, whereas EDTA, CoCl2, HgCl, ZnSO4 and FeSO4 decreased the activity of the enzyme. The addition of 8% NaCl enhanced the glutaminase activity. L-Glutaminase immobilized on 3.6% agar was stable for up to 3 weeks.

Potential Use of Papaya Waste as a Fuel for Bioelectricity Generation

Papaya (Carica papaya) waste cause significant commercial and environmental damage, mainly due to the economic losses and foul odours they emit when decomposing. Therefore, this work provides an innovative way to generate electricity for the benefit of society and companies dedicated to the import and export of this fruit. Microbial fuel cells are a technology that allows electricity generation. These cells were produced with low-cost materials using zinc and copper electrodes; while a 150 mL polymethylmethacrylate tube was used as a substrate collection chamber (papaya waste). Maximum values of 0.736 ± 0.204 V and 5.57 ± 0.45 mA were generated, while pH values increased from 3.848 to 8.227 ± 0.35 and Brix decreased slowly from the first day. The maximum power density value was 878.38 mW/cm2 at a current density of 7.245 A/cm2 at a maximum voltage of 1072.77 mV. The bacteria were identified with an identity percentage of 99.32% for Achromobacter xylosoxidans species, 99.93% for Acinetobacter bereziniae, and 100.00% for Stenotrophomonas maltophilia. This research gives a new way for the use of papaya waste for bioelectricity generation.

Effect of N-Acetylcysteine in Combination with Antibiotics on the Biofilms of Three Cystic Fibrosis Pathogens of Emerging Importance

Cystic fibrosis (CF) is a genetic disorder causing dysfunctional ion transport resulting in accumulation of viscous mucus that fosters chronic bacterial biofilm-associated infection in the airways. Achromobacter xylosoxidans and Stenotrophomonas maltophilia are increasingly prevalent CF pathogens and while Burkholderia cencocepacia is slowly decreasing; all are complicated by multidrug resistance that is enhanced by biofilm formation. This study investigates potential synergy between the antibiotics ciprofloxacin (0.5–128 µg/mL), colistin (0.5–128 µg/mL) and tobramycin (0.5–128 µg/mL) when combined with the neutral pH form of N-Acetylcysteine (NACneutral) (0.5–16.3 mg/mL) against 11 cystic fibrosis strains of Burkholderia, Stenotrophomonas and Achromobacter sp. in planktonic and biofilm cultures. We screened for potential synergism using checkerboard assays from which fraction inhibitory concentration indices (FICI) were calculated. Synergistic (FICI ≤ 0.5) and additive (0.5 > FICI ≥ 1) combinations were tested on irreversibly attached bacteria and 48 h mature biofilms via time-course and colony forming units (CFU/mL) assays. This study suggests that planktonic FICI analysis does not necessarily translate to reduction in bacterial loads in a biofilm model. Future directions include refining synergy testing and determining further mechanisms of action of NAC to understand how it may interact with antibiotics to better predict synergy.