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Background Bacteria have developed different mechanisms for the transformation of metalloid oxyanions to non-toxic chemical forms. A number of bacterial isolates so far obtained in axenic culture has shown the ability to bioreduce selenite and tellurite to the elemental state in different conditions along with the formation of nanoparticles—both inside and outside the cells—characterized by a variety of morphological features. This reductive process can be considered of major importance for two reasons: firstly, toxic and soluble (i.e. bioavailable) compounds such as selenite and tellurite are converted to a less toxic chemical forms (i.e. zero valent state); secondly, chalcogen nanoparticles have attracted great interest due to their photoelectric and semiconducting properties. In addition, their exploitation as antimicrobial agents is currently becoming an area of intensive research in medical sciences. Results In the present study, the bacterial strain Ochrobactrum sp. MPV1, isolated from a dump of roasted arsenopyrites as residues of a formerly sulfuric acid production near Scarlino (Tuscany, Italy) was analyzed for its capability of efficaciously bioreducing the chalcogen oxyanions selenite (SeO 3 2− ) and tellurite (TeO 3 2− ) to their respective elemental forms (Se 0 and Te 0 ) in aerobic conditions, with generation of Se- and Te-nanoparticles (Se- and TeNPs). The isolate could bioconvert 2 mM SeO 3 2− and 0.5 mM TeO 3 2− to the corresponding Se 0 and Te 0 in 48 and 120 h, respectively. The intracellular accumulation of nanomaterials was demonstrated through electron microscopy. Moreover, several analyses were performed to shed light on the mechanisms involved in SeO 3 2− and TeO 3 2− bioreduction to their elemental states. Results obtained suggested that these oxyanions are bioconverted through two different mechanisms in Ochrobactrum sp. MPV1. Glutathione (GSH) seemed to play a key role in SeO 3 2− bioreduction, while TeO 3 2− bioconversion could be ascribed to the catalytic activity of intracellular NADH-dependent oxidoreductases. The organic coating surrounding biogenic Se- and TeNPs was also characterized through Fourier-transform infrared spectroscopy. This analysis revealed interesting differences among the NPs produced by Ochrobactrum sp. MPV1 and suggested a possible different role of phospholipids and proteins in both biosynthesis and stabilization of such chalcogen-NPs. Conclusions In conclusion, Ochrobactrum sp. MPV1 has demonstrated to be an ideal candidate for the bioconversion of toxic oxyanions such as selenite and tellurite to their respective elemental forms, producing intracellular Se- and TeNPs possibly exploitable in biomedical and industrial applications.

Engine oil is a significant environmental contaminant, and its removal is challenging due to its persistent nature in the ecosystem. Engine oil is a significant environmental contaminant, and its removal is challenging due to its persistent nature in the ecosystem. Biodegradation of used engine oil using indigenous bacteria from contaminated soil is a cost-effective approach for environmental cleanup. This study investigated the efficiency of a single bacterial isolate and a formulated bacterial consortium (BC), both sourced from the contaminated soil of a mechanical workshop, in the biodegradation of engine oil. The bacterial strains were identified by 16 S rDNA sequencing as Ochrobactrum intermedium LMG 3301 and Bacillus paramycoides MCCC1A04098/BC. Additionally, the study sought to evaluate the growth and physiological activity of the oil-degrading bacteria in the stirred batch bioreactor (SBR) both individually and in consortia. The biodegradation of 0.675% of used engine oil, bacterial growth, and enzymatic activity was achieved under elevated aerobic conditions and optimal environmental factors for 0–5 days. The BC was more efficient at biodegrading used engine oil with 10% (85%) TPH increased removal compared to O. intermedium (77%) in a stirred batch bioreactor at pH 7.5, temperature 37 °C, and inoculum size 15 ml of OD600nm = 1. The results showed that consortium and single bacteria could both degrade longer-chain alkanes, but their abilities to handle shorter-chain alkanes varied. While a consortium generates more lipase enzymes, a single bacterium produces more dehydrogenase, which is connected to energy generation in the form of NADPH. As a result, O. intermediate bacterium expends a large deal of effort to break down the oil on its own. The single’s faster growth rate and shorter doubling time compared to the consortium indicate the efficacy and growth abilities of O. intermedium when given a UEO substrate. However, the consortium’s slower growth rate and longer doubling time were likely brought on by either the slower-growing partner or the length of time it takes for a syntrophic relationship to develop. The study demonstrated the bioeffectiveness of using a sequencing batch bioreactor for heavy UEO elimination and offered two distinct bacteria formulations for successful bioremediation of hazardous pollutants.

Metal nanoparticle synthesis is an interesting area in nanotechnology due to their remarkable optical, magnetic, electrical, catalytic and biomedical properties, but there needs to develop clean, non-toxic and environmental friendly methods for the synthesis and assembly of nanoparticles. Biological agents in the form of microbes have emerged up as efficient candidates for nanoparticle synthesis due to their extreme versatility to synthesize diverse nanoparticles with varying size and shape. In the present study, an eco favorable method for the biosynthesis of silver nanoparticles using marine bacterial isolate has been attempted. Very interestingly, molecular identification proved it as a strain of Ochrobactrum anhtropi. In addition, the isolate was found to have the potential to form silver nanoparticles intracellularly at room temperature within 24 h. The biosynthesized silver nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). The UV-visible spectrum of the aqueous medium containing silver nanoparticles showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. The SEM and TEM micrographs revealed that the synthesized silver nanoparticles were spherical in shape with a size range from 38 nm - 85 nm. The silver nanoparticles synthesized by the isolate were also used to explore its antibacterial potential against pathogens like Salmonella Typhi, Salmonella Paratyphi, Vibrio cholerae and Staphylococcus aureus.

Abstract Twenty-six lactose non-fermenting, oxidase, urease and citrate-positive Gram-negative rods, isolated from broiler chickens, pigs and cattle at slaughter, were subjected to the matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry and 16S rDNA sequencing for identification. Susceptibility to 14 antimicrobials was determined by the disc diffusion method. Ochrobactrum isolates resistant to third-generation cephalosporins were PCR-screened for the presence of the Ochrobactrum anthropi ampC gene (blaOCH). A 547-bp internal segment of blaOCH in the Ochrobactrum spp isolates was amplified with a newly designed primer set, and a phylogenetic reconstruction based on the complete amino acid sequence of blaOCH obtained from nine Ochrobactrum strains in our collection and 20 O. anthropi available in the GenBank was undertaken. All the Ochrobactrum isolates were resistant to the expanded-spectrum beta-lactams and streptomycin. None of the isolates was resistant to imipenem while 41.7% to 50.0% of them were resistant to fluoroquinolones. The blaOCH gene was detected in 16 (66.7%) and 20 (83.3%) of the 24 Ochrobactrum isolates (O. intermedium/O. tritici species), using primers designed for O. anthropi and the newly designed primer set, respectively. Six blaOCH variants grouped into two divergent clusters were identified. This is the first report of the complete nucleotide sequence of the blaOCH gene in non-antropi Ochrobactrum species. Food animals (broiler chickens, cattle and pigs) act as reservoirs of multi-resistant Ochrobactrum species showing genetic polymorphisms in the class C beta-lactamase codifying blaOCH gene.

Objective Di-2-ethylhexyl phthalate (DEHP) pollution is one of the major environmental concerns all over the world. This research aimed at studying the biodegradation kinetics of DEHP by a newly isolated bacterial strain. Water and sediment samples were collected from Wuhan South Lake and potent bacterial isolates were screened for DEHP degradation, characterized by biochemical, physiological, morphological and 16S rDNA gene sequencing, and optimized under suitable pH, temperature, NaCl and DEHP concentrations. DEHP and its metabolites were quantified by High Performance Liquid Chromatography and their degradation kinetics were studied. Results The newly isolated bacterium was identified as Ochrobactrum anthropi strain L1-W with 99.63% similarity to Ochrobactrum anthropi ATCC 49188. It was capable of utilizing DEHP as the carbon source. The optimum growth temperature, pH, DEHP and NaCl concentration for the strain L1-W were 30 °C, 6, 400 mg/L and 10 g/L respectively. Strain L1-W was capable of degrading almost all (98.7%) of DEHP when the initial concentration was 200 mg/L within a period of 72 h. Besides, it was also found capable of degrading five other phthalates, thus making it a possible candidate for bioremediation of phthalates in the environmental settings.

Background Alkaline thermostable lipase and biosurfactant producing bacteria are very interested at detergent applications, not only because of their eco-friendly characterize, but alsoproduction lipase and biosurfactant by using cheap materials. Ochrobactrum intermedium strain MZV101 was isolated as washing powder resistant, alkaline thermostable lipase and biosurfactant producing bacterium in order to use at detergent applications. Methods O. intermedium strain MZV101 produces was lipase and biosurfactant in the same media with pH 10 and temperature of 60 °C. Washing test and some detergent compatibility character of lipase enzyme and biosurfactant were assayed. The antimicrobial activity evaluated against various bacteria and fungi. Results Lipase and biosurfactant produced by O. intermedium strain MZV101 exhibited high stability at pH 10–13 and temperature of 70–90 °C, biosurfactant exhibits good stability at pH 9–13 and thermostability in all range. Both lipase and biosurfactant were found to be stable in the presence of different metal ions, detergents and organic solvents. The lipase enzyme extracted using isopropanol with yield of 69.2% and biosurfactant with ethanol emulsification index value of 70.99% and yield of 9.32 (g/l). The single band protein after through from G-50 Sephadex column on SDS-PAGE was calculated to be 99.42 kDa. Biosurfactant O. intermedium strain MZV101 exhibited good antimicrobial activity against Gram-negative bacteria and against various bacterial pathogens. Based upon washing test biosurfactant and lipase O. intermedium strain MZV101considered being strong oil removal. Conclusion The results of this study indicate that isolated lipase and biosurfactant with strong oil removal, antimicrobial activity and good stability could be useful for detergent applications. Graphical abstract

Bacterial strains capable of utilizing methylphosphonic acid (MP) or glyphosate (GP) as the sole sources of phosphorus were isolated from soils contaminated with these organophosphonates. The strains isolated from MP-contaminated soils grew on MP and failed to grow on GP. One group of the isolates from GP-contaminated soils grew only on MP, while the other one grew on MP and GP. Strains Achromobacter sp. MPS 12 (VKM B-2694), MP degraders group, and Ochrobactrum anthropi GPK 3 (VKM B-2554D), GP degraders group, demonstrated the best degradative capabilities towards MP and GP, respectively, and were studied for the distribution of their organophosphonate catabolism systems. In Achromobacter sp. MPS 12, degradation of MP was catalyzed by C-P lyase incapable of degrading GP (C-P lyase I). Adaptation to growth on GP yielded the strain Achromobacter sp. MPS 12A, which retained its ability to degrade MP via C-P lyase I and was capable of degrading GP with formation of sarcosine, thus suggesting the involvement of a GP-specific C-P lyase II. O. anthropi GPK 3 also degraded MP via C-P lyase I, but degradation of GP in it was initiated by glyphosate oxidoreductase, which was followed by product transformation via the phosphonatase pathway. [PUBLICATION ABSTRACT]

Soil bacteria may have properties of plant growth promotion but not be sufficiently beneficial for plants under stress conditions. This challenge has led researchers to extend their searches into extreme environments for potential soil bacteria with multiple plant beneficial traits as well as abiotic stress tolerance abilities. In the current study, an attempt was made to evaluate soil bacteria from an extreme environment, volcano soils, based on plant growth promoting and abiotic stress mitigating characteristics. The screening led to the isolation of eight (NBRISH4, NBRISH6, NBRISH10, NBRISH11, NBRISH13, NBRISH14, NBRISH16 and NBRISH26) bacterial isolates capable of withstanding stresses, namely temperature (up to 45 °C), salt (up to 2 M NaCl) and drought (up to 60% Poly Ethylene Glycol 6000) in vitro. Further, the selected isolates were notable for their in vitro temporal performance with regards to survival (in terms of colony count), phosphate solubilisation, biofilm formation, auxin, alginate and exo-polysaccharide production abilities under abiotic stresses i.e. 40 °C temperature; 500 mM NaCl salt and drought (PEG) conditions. In vivo seed treatments of individual selected bacteria to maize plants resulted into significant enhancement in root and shoot length, root and shoot fresh and dry weight and number of leaves per plant. Overall, the plant growth promoting and abiotic stress tolerance ability was most evident for bacterial isolate NBRISH6 which was identified as an Ochrobactrum sp. using 16S rRNA based phylogenetic analysis.

The petroleum hydrocarbons in seawater have been worldwide concern contaminants. Biological method, with the advantages of low cost, minimal environmental impact, and no secondary pollution, is a promising method for petroleum hydrocarbon treatment. In this study, two strains, identified as Stenotrophomonas acidaminiphila and Ochrobactrum , were demonstrated to possess the ability to degrade petroleum hydrocarbons. The mixed culture composed of Stenotrophomonas acidaminiphila and Ochrobactrum at a 2:1 ratio was able to achieve 79.41% degradation of the total petroleum hydrocarbons after 5 days. Besides, the average removal efficiencies of C10-C30 components in petroleum hydrocarbons by Stenotrophomonas acidaminiphila , Ochrobactrum , and mixed culture were 62.98%, 59.14% and 73.30%, respectively. The possible degradation pathways of petroleum hydrocarbons had been speculated through gas chromatography-mass spectrometry (GC-MS) and differential gene expression metabolomics analyses. The toxicity of products from the biodegradation of petroleum hydrocarbons was greatly reduced.

A Gram stain negative, motile, non-spore-forming, rod-shaped, strictly aerobic, beige-pigmented bacterium, designated strain BO-7T, was isolated from soil of cattle farm, in Seosan, Republic of Korea. On the basis of 16S rRNA gene sequencing, strain BO-7T clustered with species of the genus Ochrobactrum and appeared closely related to O. haematophilum CCUG 38531T (98.9%), O. daejeonense KCTC 22458T (98.1%), O. rhizosphaerae DSM 19824T (98.1%), O. pituitosum DSM 22207T (98.0%), and O. pecoris DSM 23868T (98.0%). The digital DNA-DNA hybridization and average nucleotide identity between strain BO-7T and the closely related strains were 21.9–39.1%, 78.5–89.5%, respectively, indicating that BO-7T is a novel species of the genus Ochrobactrum. The DNA G + C content of the genomic DNA was 57.1 mol%, and ubiquinone Q-10 was the predominant respiratory quinone. The polar lipids consisted of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylmonomethyl-ethanolamine, di-phosphatidylglycerol, the major polyamines were spermidine, putrescine, and sym-homospermidine. The major cellular fatty acids (> 5%) were C16:0, C19:0 cycle ω7c, and C18:1ω7c and/or C18:1ω6c (summed feature 8). ANI calculation, digital DNA-DNA hybridization, physiological and biochemical characteristics indicated that strain BO-7T represents a novel species of the genus Ochrobactrum, for which the name Ochrobactrum soli sp. nov. is proposed. The type strain is BO-7T (= KACC 19676T = LMG 30809T).