Search

The research work focuses on the application of Cr(VI)-resistant plant growth–promoting bacteria Pannonibacter phragmetitus for enhancing Cr(VI) uptake by Sorghum bicolor. Significant increase in plant shoot and root characters was found when assisted by P. phragmetitus. The obtained strain showed 700 mg/L of chromium reduction at 24-h incubation. Indole-3 acetic acid (IAA) production by the bacterial strain was found to be 86.45 μg/mL. Pannonibacter phragmetitus solubilized tricalcium phosphate showing maximum solubilizing activity of PSI = 3.31. The qmax of P. phragmetitus was high in the wavelength of 600 nm. Langmuir isotherm best described the Cr(VI) ion uptake by the plant. The RL values reliably reduced with expanding Cr(VI) ion concentration from 25 to 150 mg/L. The outcomes of kinetic studies showed that compared with pseudo first-order, pseudo second-order kinetics better describes the plant Cr(VI) uptake rate. Elovich model describes the increased rates for attaining equilibrium. The equilibrium parameter values for different Cr(VI) ion concentrations range between 0 and 1 which describes the favorable condition for plant metal uptake at different concentrations.

Identification of a heavy metal ion-stimulated nitrilase with broad-spectrum substrate specificity. A novel nitrilase, PaCNit, was identified from Pannonibacter carbonis Q4.6 and its enzymatic properties were investigated. The maximum activity of PaCNit was observed at 65 °C and pH 7.0. PaCNit showed broad substrate specificity towards aliphatic, aromatic, and heterocyclic nitriles, and was tolerant to different organic solvents. Remarkably, PaCNit activity was highly stimulated by metal ions, particularly by Ag+ and Hg2+. PaCNit nitrilase has a broad range of substrate specificity and can be activated by heavy metal ions. This specific characteristic makes it have a great potential for industrial application.

To date, comparatively little research is known about the role of pH conditions in bioremediation of Cr(VI) contaminated aquifers. This study explored microbial Cr(VI) reduction and denitrification under different initial pHs. The underlying mechanism was also investigated. When testing 50 mg/L-N nitrate and 10 mg/L Cr(VI), complete contaminants removal was observed at initial pH 10.0 and 11.0, and only 10 %-30 % of removal achieved under other conditions, which might be ascribe to the significant up-regulation of functional genes narG (8.31 and 10.46 folds) and azoR (24.90 and 15.96 folds) at initial pH 10.0 and 11.0. Metagenomic sequencing showed that alkali tolerant bacteria played major roles in the NO3--Cr(VI) reduction (i.e. Pannonibacter increased by 13.08 % and 25.24 % at initial pH 10.0 and 11.0), and metabolic pathways of Degradation and Energy were found of increased abundant. Furthermore, a significative study suggested that potential interspecies cooperation existed at initial pH 11.0 to facilitating the simultaneous removal of contaminants, and Pannonibacter indicus might be an important participant in the degradation of contaminants. The results of this study will fully understand the metabolic patterns of bacteria under alkaline conditions, expand the range of available functional bacteria, and enhance the practical aspects of co-contaminants remediation.

A pilot-scale photosynthetic bacteria-membrane bioreactor was applied to treat wastewater and culture photosynthetic bacteria (PSB) cells, and microbial communities at different stages were analyzed to reveal the underlying roles of efficient long-time operation of this reactor. After 40 days start-up, the reactor was successfully operated for 180 days. The results showed that the PSB-membrane bioreactor operated stably, with high COD and NH3-N removal efficiency of 95%. The PSB biomass could maintain a high cell concentration with a 10% harvest each day. Analysis of the microbial community showed that bacterial communities changed dramatically at different stages. The dominant bacteria were Ectothiorhodospira in the beginning to Caenispirillum and Pannonibacter during the stable operation. The Shannon index from 1.876 dropped to 1.477 after 6 months. The diversity of PSB community decreased during the process. It revealed that the microbial community on the membrane was more diverse than that inside the bioreactor.

Two bacterial strains were isolated from coal mine water in China. Isolates were facultatively anaerobic, Gram-stain-negative, rod-shaped, motile by means of a single polar flagellum, and they did not produce bacteriochlorophyll α. Cells grew in tryptic soy broth with 0–5.5 % (w/v) NaCl, at 4–55 °C and pH 3.5–10.5. Isolates were positive for catalase, oxidase, urease, Voges–Proskauer test, gelatin hydrolysis and H2S production. Analysis of 16S rRNA gene sequences indicated that the closest relatives of strains Q4.6T and Q2.11 were the type strains Labrenzia suaedae DSM 22153T (97.4 %), Pannonibacter phragmitetus DSM 14782T (96.9 and 97.0 %) and Pannonibacter indicus DSM 23407T (96.8 %). The genomic average nucleotide identity (ANI) value for Q4.6T and Q2.11 was 100 %; however, this value was less than 77.7 % for the type strains P. phragmitetus and P. indicus , and less than 74.0 % for the type strain L. suaedae . The cellular fatty acid profile of strains Q4.6T and Q2.11 consisted primarily of C18 : 1ω7c. The principal quinone of the isolates was Q-10. The polar lipid profile consisted of diphosphatidyl glycerol, phosphatidyl glycerol, phosphatidyl ethanolamine and phosphatidyl choline. On the basis of phylogenetic analysis, genomic ANI analysis, DNA–DNA hybridization results, as well as phenotypic and chemotaxonomic data, strains Q4.6T and Q2.11 are assigned as a novel species within the genus Pannonibacter . The type strain is Pannonibacter carbonis Q4.6T (=CGMCC 1.15703T=KCTC 52466T).

Culture-independent and -dependent methods were used to evaluate the genetic diversity of hexavalent chromium-resistant bacteria in contaminated soils. Denaturing gradient gel electrophoresis (DGGE) showed that hexavalent chromium-resistant bacteria in contaminated soils had significant structural diversity that was not related to the concentration of hexavalent chromium, while the diversity of soil bacterial communities was correlated with soil pH. Twenty-two chromium-resistant bacterial strains were isolated from contaminated soil, including members of Brevundimonas, Micrococcus, Exiguobacterium, Alcaligenes and Pannonibacter. Repetitive sequence-based polymerase chain reaction showed that the BOX- primer produced the more complex banding patterns than the ERIC- and REP- primers, indicating a high degree of genotypic diversity. These bacterial strains varied in ability to reduce hexavalent chromium. Pannonibacter reduced 300 mg·L−1 of hexavalent chromium in solution within 24 h. X-ray photoelect...

Pannonibacter phragmitetus is a bioremediation reagent for the detoxification of heavy metals and polycyclic aromatic compounds (PAHs) while it rarely infects healthy populations. However, infection by the opportunistic pathogen P. phragmitetus complicates diagnosis and treatments, and poses a serious threat to immunocompromised patients owing to its multidrug resistance. Unfortunately, genome features, antimicrobial resistance, and virulence potentials in P. phragmitetus have not been reported before. A predominant colony (31801) was isolated from a liver abscess patient, indicating that it accounted for the infection. To investigate its infection mechanism(s) in depth, we sequenced this bacterial genome and tested its antimicrobial resistance. Average nucleotide identity (ANI) analysis assigned the bacterium to the species P. phragmitetus (ANI, >95%). Comparative genomics analyses among Pannonibacter spp. representing the different living niches were used to describe the Pannonibacter pan‐genomes and to examine virulence factors, prophages, CRISPR arrays, and genomic islands. Pannonibacter phragmitetus 31801 consisted of one chromosome and one plasmid, while the plasmid was absent in other Pannonibacter isolates. Pannonibacter phragmitetus 31801 may have a great infection potential because a lot of genes encoding toxins, flagellum formation, iron uptake, and virulence factor secretion systems in its genome. Moreover, the genome has 24 genomic islands and 2 prophages. A combination of antimicrobial susceptibility tests and the detailed antibiotic resistance gene analysis provide useful information about the drug resistance mechanisms and therefore can be used to guide the treatment strategy for the bacterial infection.

A novel bacterium, strain JL1095(T), was isolated from the surface water of the Yangtze Estuary, China (31° N, 122° E). Cells were Gram negative, aerobic, oval-shaped with one peak end and motile by gliding. Cells divided by binary fission. Growth occurred at 15-50 °C (optimum at 35 °C), 2-10 % (w/v) NaCl (optimum at ~3 %) and pH 6.0-9.0 (optimum at pH ~ 7.6). Strain JL1095(T) was able to utilize various sole-carbon-source, such as Tween 40, Tween 80, acetic acid, L-arabinose, D,L-lactic acid, urocanic acid, methyl-pyruvate, α-hydroxy butyric acid, β-hydroxy butyric acid, and γ-hydroxy butyric acid. The major cellular fatty acids were C16:0, C18:0, C19:0 ω8c cyclo, C20:1 ω7c, and Summed Feature 8. The whole respiratory ubiquinone was Q-10. The genomic DNA G+C content of strain JL1095(T) was 51.5 %. According to the phylogenetic analysis, strain JL1095(T) formed a monophyletic branch at the periphery of the evolutionary radiation occupied by the genera Labrenzia, Pannonibacter, Stappia, Wenxnia, and Amaricoccus. The sequence similarity was 92.8 % with the most closely relating strain Stappia indica B106(T), and 92.6 % with the type species Stappia stellulatum IAM 12621(T). Based on the biochemical characteristics, chemotaxonomy and phylogenetic analysis, strain JL1095(T) is considered to be a novel genus which belongs to the family Rhodobacteraceae. The novel strain is named Acuticoccus yangtzensis gen. nov., sp. nov. The type strain of Acuticoccus yangtzensis is JL1095(T) (=CGMCC 1.12795 = DSM 28604).

Microbial diversity and biogeochemical processes of the Gangxi bed with low-mineral water and a temperature gradient from 35 to 54°C were studied. The 16S rRNA gene clone libraries (over 800 clones) were obtained from microbial DNA isolated from formation water and from the primary enrichment cultures for fermenting, sulfate-reducing, methanogenic, and aerobic organotrophic prokaryotes. While both sulfate reduction and methanogenesis were registered in formation water by radioisotope techniques, the genes of sulfate-reducing prokaryotes were not revealed in the 16S rRNA gene clone library from formation water. The 16S rRNA genes of Methanobacterium congolense and Methanococcus vannielii predominated among archaeal sequences retrieved from formation water, while the genes of Methanothermobacter thermoautotrophicus, Methanomethylovorans thermophila, and Methanoculleus sp. predominated in the combined library from enrichment cultures. In the library of Bacteria 16S rRNA genes from formation water, the genes of thermophilic fermentative bacteria of the family Thermoanaerobacteriaceae predominated; the remaining sequences belonged to mesophiles (genera Brevundimonas, Sphingomonas, Oxalicibacterium, and Stenotrophomonas), the phylum Chloroflexi, and unidentified bacteria. The combined library from enrichment cultures, contained, apart from the sequences of the family Thermoanaerobacteriaceae, the genes of fermentative bacteria (genera Anaerobaculum, Coprothermobacter, Thermanaerovibrio, Soehngenia, Bacteroides, and Aminobacterium and the order Thermotogales), of aerobic hydrocarbon-oxidizing bacteria (genera Pannonibacter and Pseudomonas), and of sulfate reducers (genera Desulfomicrobium, Thermodesulfovibrio, and Desulfotomaculum). High coverage was shown for bacterial (97.6%) and archaeal (100%) clone libraries, indicating that a significant portion of the microbial diversity in the studied communities was revealed.

Biofilm induces an electric potential difference on metal pipelines of oil and gas industries which result in accelerated pipeline corrosion. This study evaluated Cymbopogon citratus essential oil nanoparticle performance as an antimicrobial to prevent metal corrosion. This study aims to determine C. citratus essential oil nanoparticle’s minimum inhibitory concentration (MIC), minimum biofilm inhibitory concentration (MBIC), minimum biofilm eradication concentration (MBEC), and its effect on bacterial community dynamics. C. citratus essential oil was encapsulated by ionic gelation. MIC, MBIC, and MBEC were determined by the microdilution method. Bacterial community dynamics were analyzed using Total Plate Count. Biofilm-forming bacteria were isolated from brine water of South Sumatra oil reservoir which identified as Pseudomonas sp. 1, Pseudomonas sp. 2, and Pannonibacter pragmithetus based on 16S rRNA sequence similarity analysis using NCBI-BLAST. C. citratus essential oil nanoparticle was successfully formed which was 174.1 nm in size, having MIC and MBIC value at 0.03%, and MBEC value at 0.06%. Pseudomonas sp. 1 was the most affected by essential oil nanoparticle exposure on planktonic phase while P. pragmithetus was the most affected on sessile phase. Based on this study, C. citratus essential oil nanoparticle has the potential to be an antimicrobial agent to prevent metal corrosion.

The microbial community structure and functionally distinct groups in three kinds of produced water samples from the shallow, mesothermic and low-salinity Daqing oil reservoir were systematically evaluated using both culture-dependent and culture-independent methods. Sequence analysis of the 16S rRNA genes indicated that the bacterial library was dominated by Acinetobacter and Arcobacter and the archaeal community was dominated by Methanosaeta and Methanolinea. Two isolated methanogens were closely related with Methanothermobacter thermautotrophicus and Methanoculleus receptaculi. The fermentative bacteria were identified as Pseudomonas, Haloanaerobium, Alcalibacter, Arcobacter, and Pannonibacter. The predominant nitrate-reducing bacteria fell within the genus Pseudomonas. The dominant members of the cultured hydrocarbon-oxidizing bacteria were phylogenetically associated with Micrococcus, Pseudomonas, and Bacillus. Enrichments of biosurfactants and biopolymer producing groups mainly yielded Pseudomonas, Bacillus, and Acenitobacter-related members. The functional groups related to polymer degradation were also affiliated with Pseudomonas and Bacillus. Results from this study provide the fresh insight into the diversity of microbial communities in Daqing petroleum reservoirs. The vast pool of functional strains retrieved in this study was presumed to include the promising strains that could be applied in microbial-enhanced oil recovery in future.

Pannonibacter phragmitetus CGMCC9175 is a halotolerant polycyclic aromatic hydrocarbon (PAH)-degrading bacterium isolated from PAH-contaminated intertidal zone sediment. Here, we report the 5.7-Mb draft genome sequence of this strain, which will provide insights into the diversity of Pannonibacter and the mechanism of PAH degradation in sediments.

A Gram-negative, beige-pigmented, aerobic, motile, club-shaped bacterium, designated strain CC-SBABM117T, was isolated from the stipe of the edible mushroom Agaricus blazei Murrill. 16S rRNA gene sequence analysis demonstrated that the strain shared Pannonibacter, Methylopila, Nesiotobacter and Stappia. The organism was unable to produce acid from carbohydrates, but utilized a number of organic acids and amino acids. Ubiquinone 10 (Q-10) was the major respiratory quinone and C18 : 1 ω7c, C19 : 0 cyclo ω8c, C16 : 0 and C18 : 0 were the predominant fatty acids. The predominant polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content of strain CC-SBABM117T was 62.7 mol%. On the basis of 16S rRNA gene sequence analysis and chemotaxonomic and physiological data, strain CC-SBABM117T is considered to represent a novel species of a new genus, for which the name Agaricicola taiwanensis gen. nov., sp. nov. is proposed. The type strain of Agaricicola taiwanensis is CC-SBABM117T (=BCRC 17964T =CCM 7684T).

4-Aminobenzenesulfonate (4-ABS) is a representative intermediate of some sulfonated azo dyes. A novel Pannonibacter sp. strain W1 capable of degrading 4-ABS as sole carbon as well as energy, nitrogen and sulfur source was isolated and identified from the activated sludge of a municipal wastewater treatment plant. Strain W1 was able to completely degrade 4-ABS with initial concentrations of 200-2500 mg L(-1) within 40 h. Haldane inhibition model was used to fit the special degradation rate at different initial concentrations, and the parameters micro(max), K(s) and K(i) were determined to be 227.977 mg (gh)(-1), 84.306 mg L(-1) and 1270.675 mg L(-1), respectively. Elements N and S of 4-ABS were released in respective forms of ammonia and sulfate while degrading 4-ABS by strain W1, accounting for 77.6% and 92.2% of theoretical values, respectively. Relatively low recoveries of dissolved N and S were probably owing to the fact that part of the released ammonia and sulfate were utilized by strain W1 for cell growth. It was found that the reduction of total organic carbon (TOC) was proportional to the degradation of 4-ABS and 84.4% TOC removal rate, corresponding to a 4-ABS degradation rate of 94.7%, was achieved at the end of the test. Additionally, HPLC and UV analyses indicated that there were no other aromatic intermediates detectable, suggesting the achievement of a complete mineralization of 4-ABS with strain W1.

Three bacterial strains isolated from oysters recovered at the Spanish Mediterranean coast have been phenotypically and genetically characterized. The results of the phylogenetic analysis based on almost complete 16S rDNA sequences clustered all three strains together with 99.9% average sequence similarity and situated them in the neighbourhood of the genera Stappia , Roseibium and Pannonibacter , Stappia aggregata being their closest neighbour with sequence similarities between 98.8% and 98.9%. DNA–DNA hybridization experiments using DNA of strains 5OM6 T and S. aggregata CECT 4269 T as reference DNAs confirmed the independent status at species level of the oyster isolates. Phenotypically, they can be distinguished from the closest relatives by the ionic requirements, growth temperatures and use of carbon compounds. We propose these oyster strains constitute a new species of Stappia , for which the name Stappia alba sp. nov. has been chosen, and strain 5OM6 T (=CECT 5095 T =CIP 108402 T ) as its type strain.

The bacterial community and genes involved in geobiocycling of arsenic (As) from sediment impacted by long-term gold mining were characterized through culture-based analysis of As-transforming bacteria and metagenomic studies of the arsC, arrA, and aioA genes. Sediment was collected from the historically gold mining impacted Mina stream, located in one of the world's largest mining regions known as the "Iron Quadrangle". A total of 123 As-resistant bacteria were recovered from the enrichment cultures, which were phenotypically and genotypically characterized for As-transformation. A diverse As-resistant bacteria community was found through phylogenetic analyses of the 16S rRNA gene. Bacterial isolates were affiliated with Proteobacteria, Firmicutes, and Actinobacteria and were represented by 20 genera. Most were AsV-reducing (72%), whereas AsIII-oxidizing accounted for 20%. Bacteria harboring the arsC gene predominated (85%), followed by aioA (20%) and arrA (7%). Additionally, we identified two novel As-transforming genera, Thermomonas and Pannonibacter. Metagenomic analysis of arsC, aioA, and arrA sequences confirmed the presence of these genes, with arrA sequences being more closely related to uncultured organisms. Evolutionary analyses revealed high genetic similarity between some arsC and aioA sequences obtained from isolates and clone libraries, suggesting that those isolates may represent environmentally important bacteria acting in As speciation. In addition, our findings show that the diversity of arrA genes is wider than earlier described, once none arrA-OTUs were affiliated with known reference strains. Therefore, the molecular diversity of arrA genes is far from being fully explored deserving further attention.

Bacteria were isolated from roots of sugarcane varieties grown in the fields of Punjab. They were identified by using API20E/NE bacterial identification kits and from sequences of 16S rRNA and amplicons of the cpn60 gene. The majority of bacteria were found to belong to the genera of Enterobacter, Pseudomonas, and Klebsiella, but members of genera Azospirillum, Rhizobium, Rahnella, Delftia, Caulobacter, Pannonibacter, Xanthomonas, and Stenotrophomonas were also found. The community, however, was dominated by members of the Pseudomonadaceae and Enterobacteriaceae, as representatives of these genera were found in samples from every variety and location examined. All isolates were tested for the presence of five enzymes and seven factors known to be associated with plant growth promotion. Ten isolates showed lipase activity and eight were positive for protease activity. Cellulase, chitinase, and pectinase were not detected in any strain. Nine strains showed nitrogen fixing ability (acetylene reduction assay) and 26 were capable of solubilizing phosphate. In the presence of 100 mg/l tryptophan, all strains except one produced indole acetic acid in the growth medium. All isolates were positive for ACC deaminase activity. Six strains produced homoserine lactones and three produced HCN and hexamate type siderophores. One isolate was capable of inhibiting the growth of 24 pathogenic fungal strains of Colletotrichum, Fusarium, Pythium, and Rhizoctonia spp. In tests of their abilities to grow under a range of temperature, pH, and NaCl concentrations, all isolates grew well on plates with 3% NaCl and most of them grew well at 4 to 41degrees C and at pH 11.

Tert-butyl alcohol (TBA) is a metabolite of methyl tert-butyl ether and is itself possibly a fuel oxygenate. The goals of this study were to enrich and characterize TBA-degrading micro-organism(s) from a granular activated carbon (GAC) unit currently treating TBA. The results reported herein describe the first aerobic, TBA-degrading cultures derived from GAC. Strains KR1 and YZ1 were enriched from a GAC sample in a bicarbonate-buffered freshwater medium. TBA was degraded to 10% of the initial concentration (2-5 mM) within 5 days after initial inoculation and was continuously degraded within 1 day of each re-amendment. Resting cell suspensions mineralized 70 and 60% of the TBA within 24 h for KR1 and YZ1, respectively. Performance optimization with resting cells was conducted to investigate kinetics and the extent of TBA degradation as influenced by oxygen, pH and temperature. The most favorable temperature was 37 degrees C; however, TBA was degraded from 4 to 60 degrees C, indicating that the culture will sufficiently treat groundwater without heating. This is also the first report of psychrotolerant or thermotolerant TBA biodegradation. The pH range for TBA degradation ran from 5.0 to 9.0. Phylogenetic data using a partial 16S rRNA gene sequence (570 bases) suggest that the primary members of KR1 and YZ1 include uncharacterized organisms within the genera Hydrogenophaga, Caulobacter, and Pannonibacter.

Bacteria play a major role in marine CO cycling, yet very little is known about the microbes involved. Thirteen CO-oxidizing Stappia isolates obtained from existing cultures, macroalgae, or surf samples representing geographically and ecologically diverse habitats were characterized using biochemical, physiological, and phylogenetic approaches. All isolates were aerobic chemoorganotrophs that oxidized CO at elevated (1,000 ppm) and ambient-to-subambient concentrations (coxL gene for aerobic CO dehydrogenase and also the form II (BMS) putative coxL gene. In addition, some strains possessed cbbL , the large subunit gene for ribulose-1,5-bisphosphate carboxylase/oxygenase, suggesting the possibility of lithotrophic or mixotrophic metabolism. All isolates used a wide range of sugars, organic acids, amino acids, and aromatics for growth and grew at salinities from 5 to 45 ppt. All but one isolate denitrified or respired nitrate. Phylogenetic analyses based on 16S rRNA gene sequences indicated that several isolates could not be distinguished from Stappia aggregata and contributed to a widely distributed species complex. Four isolates (of strains GA15, HI, MIO, and M4) were phylogenetically distinct from validly described Stappia species and closely related genera (e.g., Ahrensia , Pannonibacter , Pseudovibrio , and Roseibium ). Substrate utilization profiles, enzymatic activity, and membrane lipid composition further distinguished these isolates and supported their designations as new Stappia species. The observed metabolic versatility of Stappia likely accounts for its cosmopolitan distribution and its ability to contribute to CO cycling as well as other important biogeochemical cycles.