Comparison of denitrification at low temperature using encapsulated Paracoccus denitrificans, Pseudomonas fluorescens and mixed culture

A special cuvette was designed to measure optical changes of MHQ (microsecond freeze–hyperquench) powder samples [Wiertz, Richter, Cherepanov, MacMillan, Ludwig and de Vries (2004) FEBS Lett. 575, 127–130] at temperatures below approx. 250 K. Reduced cytochrome c oxidase from Paracoccus denitrificans was reacted with O2 for 100 μs, frozen as a powder and transferred to the cuvette. Subsequently, cytochrome oxidase was allowed to react further following stepwise increments of the temperature from 100 K up to 250 K while recording spectra between 300 and 700 nm. The temperature was raised only when no further changes in the spectra could be detected. The experiment yielded spectra of the A, PM, F and O intermediate states. This demonstrated that the catalytic cycle of cytochrome oxidase at low temperature is similar to that at room temperature and so verifies the suitability of this method for the study of enzymes with high catalytic-centre activity.

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Biodegradation of Crude Oil Under Low Temperature by Mixed Culture Isolated from Alpine Meadow Soil

Water Air & Soil Pollution ◽

10.1007/s11270-021-05060-z ◽

2021 ◽

Vol 232 (3) ◽

Author(s):

Tingting Teng ◽

Jidong Liang ◽

Man Zhang ◽

Zijun Wu ◽

Xin Huo

Keyword(s):

Low Temperature ◽

Crude Oil ◽

Mixed Culture ◽

Alpine Meadow ◽

Meadow Soil

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Bioleaching and Electrochemical Behavior of Chalcopyrite by a Mixed Culture at Low Temperature

Frontiers in Microbiology ◽

10.3389/fmicb.2021.663757 ◽

2021 ◽

Vol 12 ◽

Author(s):

Tangjian Peng ◽

Wanqing Liao ◽

Jingshu Wang ◽

Jie Miao ◽

Yuping Peng ◽

...

Keyword(s):

Low Temperature ◽

Mixed Culture ◽

Pure Culture ◽

High Throughput Sequencing ◽

Electrochemical Impedance ◽

Corrosion Current ◽

Charge Transfer Resistance ◽

Microbial Consortia ◽

Cyclic Voltammograms ◽

Transfer Resistance

Low-temperature biohydrometallurgy is implicated in metal recovery in alpine mining areas, but bioleaching using microbial consortia at temperatures <10°C was scarcely discussed. To this end, a mixed culture was used for chalcopyrite bioleaching at 6°C. The mixed culture resulted in a higher copper leaching rate than the pure culture of Acidithiobacillus ferrivorans strain YL15. High-throughput sequencing technology showed that Acidithiobacillus spp. and Sulfobacillus spp. were the mixed culture’s major lineages. Cyclic voltammograms, potentiodynamic polarization and electrochemical impedance spectroscopy unveiled that the mixed culture enhanced the dissolution reactions, decreased the corrosion potential and increased the corrosion current, and lowered the charge transfer resistance and passivation layer impedance of the chalcopyrite electrode compared with the pure culture. This study revealed the mechanisms via which the mixed culture promoted the chalcopyrite bioleaching.

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Spatial distributions of Pseudomonas fluorescens colony variants in mixed-culture biofilms

BMC Microbiology ◽

10.1186/1471-2180-13-175 ◽

2013 ◽

Vol 13 (1) ◽

pp. 175 ◽

Cited By ~ 8

Author(s):

Matthew L Workentine ◽

Siyuan Wang ◽

Howard Ceri ◽

Raymond J Turner

Keyword(s):

Pseudomonas Fluorescens ◽

Mixed Culture ◽

Spatial Distributions

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Denitrification performance of Pseudomonas fluorescens Z03 immobilized by graphene oxide-modified polyvinyl-alcohol and sodium alginate gel beads at low temperature

Royal Society Open Science ◽

10.1098/rsos.191542 ◽

2020 ◽

Vol 7 (3) ◽

pp. 191542 ◽

Cited By ~ 1

Author(s):

Meizhen Tang ◽

Jie Jiang ◽

Qilin Lv ◽

Bin Yang ◽

Mingna Zheng ◽

...

Keyword(s):

Graphene Oxide ◽

Low Temperature ◽

Polyvinyl Alcohol ◽

Pseudomonas Fluorescens ◽

Sodium Alginate ◽

Removal Efficiency ◽

Nitrogen Removal ◽

Extracellular Polymeric Substances ◽

Aerobic Denitrification ◽

Gel Beads

Improving the effect of microbial denitrification under low-temperature conditions has been a popular focus of research in recent years. In this study, graphene oxide (GO)-modified polyvinyl-alcohol (PVA) and sodium alginate (SA) (GO/PVA–SA) gel beads were used as a heterotrophic nitrification–aerobic denitrification (HN–AD) bacteria ( Pseudomonas fluorescens Z03) carrier to enhance nitrogen removal efficiency levels at low temperatures (6–8°C). The removal efficiency of N H 4 + -N and N O 3 − -N and the variations in concentrations of extracellular polymeric substances (EPS) under different GO doses (0.03–0.15 g l −1 ) were studied. The results indicated that the addition of GO can improve the efficiency of nitrogen removal, and the highest removal efficiency level and highest carbohydrate, protein, and total EPS content levels (50.28 mg, 132.78 mg and 183.06 mg (g GO/PVA–SA gel) −1 , respectively) were obtained with 0.15 g l −1 GO. The simplified Monod model accurately predicted the nitrogen removal efficiency level. These findings suggested that the application of GO serves as an effective means to enhance nitrogen removal by stimulating the activity of HN–AD bacteria.

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Use of Microwave Ovens to Pasteurize Milk

Journal of Food Protection ◽

10.4315/0362-028x-51.9.715 ◽

1988 ◽

Vol 51 (9) ◽

pp. 715-719 ◽

Cited By ~ 26

Author(s):

KATHLEEN M. KNUTSON ◽

ELMER H. MARTH ◽

MARY K. WAGNER

Keyword(s):

Escherichia Coli ◽

High Temperature ◽

Low Temperature ◽

Salmonella Typhimurium ◽

Pseudomonas Fluorescens ◽

Water Bath ◽

Streptococcus Faecalis ◽

High Temperature Short Time ◽

Long Time ◽

Short Time

High-temperature short-time (HTST) and low-temperature long-time (LTLT) pasteurization were simulated using uninoculated and inoculated milks that were heated in microwave ovens. Heating milk (76 ml) for 59 s at 700 W achieved a temperature of 71.7°C, but heating for 60–65 s and holding for 15 s failed to inactivate all added cells of Salmonella typhimurium, Escherichia coli or Pseudomonas fluorescens. Milk, 453.6 g (ca. one-half quart) or 604.8 g (ca. two-thirds quart), was heated to >62.8°C, but <71.7°C, in 4.5 to 5 min, depending on power (550 or 700 W) that was used, and refrigerated overnight. Such treatments failed to reduce the population of Streptococcus faecalis in the milks by the degree that occurred when inoculated milk was heated in a water bath at 62.8°C for 30 min.

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Influence of incubation conditions on biofilm formation by Pseudomonas fluorescens isolated from dairy products and dairy manufacturing plants

Italian Journal of Food Safety ◽

10.4081/ijfs.2016.5793 ◽

2016 ◽

Vol 5 (3) ◽

Cited By ~ 14

Author(s):

Chiara Rossi ◽

Clemencia Chaves-López ◽

Annalisa Serio ◽

Elisa Goffredo ◽

Beniamino Terzo Cenci Goga ◽

...

Keyword(s):

Low Temperature ◽

Pseudomonas Fluorescens ◽

Incubation Time ◽

Food Processing ◽

Biofilm Formation ◽

Dairy Products ◽

Great Variability ◽

Manufacturing Plants ◽

Cleaning And Disinfection ◽

Strain Dependent

In this study, biofilm formation of 64 <em>Pseudomonas fluorescens</em> strains isolated from milk, dairy products and dairy plants was compared. The strains were grown on Tryptic Soy Broth supplemented with 0.2% of glucose, on polystyrene microplates at 10 and 30°C for 48 h. In general, 57/64 <em>P. fluorescens</em> strains formed biofilm, although with great variability at both tested temperatures. Moreover, our results evidenced that the biofilm-forming ability of the strains was temperature- and strain-dependent. Interestingly, the ability of several isolates to form biofilms was associated with the low temperature after 48 h. Our findings evidenced that temperature was more important than incubation time for biofilm formation. Considering the origin of the strains, it is relevant to underline the importance of performing accurate cleaning and disinfection procedures on food processing surfaces.

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