scholarly journals Multiple exposures to high concentration of selenate significantly improve selenate tolerability, red elemental selenium (Se0) and selenoprotein biosynthesis in Herbaspirillum camelliae WT00C

2021 ◽  
Author(s):  
Xuechen Ni ◽  
Jinbao Tian ◽  
Changmei Chen ◽  
Ling Huang ◽  
Jia Lei ◽  
...  
Keyword(s):  
Conversion Efficiency ◽  
Morphological Changes ◽  
Tea Plant ◽  
Lag Phase ◽  
Elemental Selenium ◽  
Original Strain ◽  
Bacterial Cells ◽  
High Concentration ◽  
Multiple Exposures ◽  
Antioxidative Stress

Abstract Herbaspirillum camelliae WT00C isolated from tea plant has an intact selenate metabolism pathway but its selenate tolerability is poor. In this study, microbiological properties between the strain WT00C and three strains CT00C, NCT00C and NT00C obtained respectively from 4, 6 and 8 rounds of 24-h exposures to 200 mM selenate were studied and compared. The selenate tolerability and the capability of generating red elemental selenium (Se0) and selenoproteins were significantly improved in H. camelliae WT00C via 4–6 rounds of multiple exposures to high concentration of selenate. The original strain WT00C grew in 200 mM selenate with the lag phase of 12 h and 400 mM selenate with the lag phase of 60 h, whereas the strains CT00C and NCT00C grew in 800 mM selenate and showed quite short lag phase when they grew in 50–400 mM selenate. Two stains also significantly improved the biosynthesis of red elemental selenium (Se0) and selenoproteins besides selenate tolerance. The stains CT00C and NCT00C exhibited more than 30% selenium conversion efficiency and 40% selenoprotein biosynthesis as compared to the original strain WT00C. These characteristics of the strains CT00C and NCT00C make them possible to be applied in pharmaceuticals and feed industries. The strain NT00C obtained from 8 rounds of 24-h exposures to 200 mM selenate was unable to grow in ≥ 400 mM selenate, and its selenium conversion efficiency and selenoprotein biosynthesis were similar to the strain WT00C. Too many exposures caused gene inactivation of some key enzymes involving in selenate metabolism and antioxidative stress. In addition, bacterial cells underwent obviously physiological and morphological changes including gene activity, cell enlargement and surface-roughness alterations during the process of multiple exposures to high concentration of selenate.

SELENITE REDUCTION BY SALMONELLA HEIDELBERG

1966 ◽  
Vol 12 (4) ◽  
pp. 703-714 ◽  
Author(s):  
R. G. L. McCready ◽  
J. N. Campbell ◽  
J. I. Payne
Keyword(s):  
Cell Division ◽  
Morphological Changes ◽  
Lag Phase ◽  
Elemental Selenium ◽  
Selenite Reduction ◽  
X Ray ◽  
Growth Studies ◽  
Salmonella Heidelberg ◽  
Selenite Toxicity

When Salmonella Heidelberg is grown in 0.1% w/v Na2SeO3 and examined microscopically during growth, two morphological changes can be seen. Red intracellular granules are seen in most of the population within 10 to 12 hours, and organisms containing granules elongate without cell division. The intracellular granules produced by S. heidelberg in selenite broth have been identified by X-ray analysis as amorphous red selenium. The intermediate in the conversion of selenite to elemental selenium has been trapped and identified as divalent selenium ion. Growth studies have shown that selenite toxicity is primarily associated with the lag phase of growth, and also that the divalent intermediate is more toxic than the tetravalent precursor.

Antibiotics Application Strategies to Control Biofilm Formation in Pathogenic Bacteria

2020 ◽  
Vol 21 (4) ◽  
pp. 270-286 ◽  
Author(s):  
Fazlurrahman Khan ◽  
Dung T.N. Pham ◽  
Sandra F. Oloketuyi ◽  
Young-Mog Kim
Keyword(s):  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Extracellular Polymeric Substances ◽  
Quorum Quenching ◽  
Resistance Mechanisms ◽  
Bacterial Biofilm ◽  
Bacterial Cells ◽  
High Concentration ◽  
Biofilm Inhibition ◽  
Abiotic Surfaces

Background: The establishment of a biofilm by most pathogenic bacteria has been known as one of the resistance mechanisms against antibiotics. A biofilm is a structural component where the bacterial community adheres to the biotic or abiotic surfaces by the help of Extracellular Polymeric Substances (EPS) produced by bacterial cells. The biofilm matrix possesses the ability to resist several adverse environmental factors, including the effect of antibiotics. Therefore, the resistance of bacterial biofilm-forming cells could be increased up to 1000 times than the planktonic cells, hence requiring a significantly high concentration of antibiotics for treatment. Methods: Up to the present, several methodologies employing antibiotics as an anti-biofilm, antivirulence or quorum quenching agent have been developed for biofilm inhibition and eradication of a pre-formed mature biofilm. Results: Among the anti-biofilm strategies being tested, the sub-minimal inhibitory concentration of several antibiotics either alone or in combination has been shown to inhibit biofilm formation and down-regulate the production of virulence factors. The combinatorial strategies include (1) combination of multiple antibiotics, (2) combination of antibiotics with non-antibiotic agents and (3) loading of antibiotics onto a carrier. Conclusion: The present review paper describes the role of several antibiotics as biofilm inhibitors and also the alternative strategies adopted for applications in eradicating and inhibiting the formation of biofilm by pathogenic bacteria.

scholarly journals Zinc Oxide and Silver Nanoparticle Effects on Intestinal Bacteria

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2489
Author(s):  
Ami Yoo ◽  
Mengshi Lin ◽  
Azlin Mustapha
Keyword(s):  
Electron Microscopy ◽  
Zinc Oxide ◽  
Morphological Changes ◽  
Intestinal Bacteria ◽  
Bacterial Cells ◽  
Ag Nps ◽  
Zno Nps ◽  
Bifidobacterium Animalis ◽  
Transmission Electron

The application of nanoparticles (NPs) for food safety is increasingly being explored. Zinc oxide (ZnO) and silver (Ag) NPs are inorganic chemicals with antimicrobial and bioactive characteristics and have been widely used in the food industry. However, not much is known about the behavior of these NPs upon ingestion and whether they inhibit natural gut microflora. The objective of this study was to investigate the effects of ZnO and Ag NPs on the intestinal bacteria, namely Escherichia coli, Lactobacillus acidophilus, and Bifidobacterium animalis. Cells were inoculated into tryptic soy broth or Lactobacilli MRS broth containing 1% of NP-free solution, 0, 12, 16, 20 mM of ZnO NPs or 0, 1.8, 2.7, 4.6 mM Ag NPs, and incubated at 37 °C for 24 h. The presence and characterization of the NPs on bacterial cells were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Membrane leakage and cell viability were assessed using a UV-visible spectrophotometer and confocal electron microscope, respectively. Numbers of treated cells were within 1 log CFU/mL less than those of the controls for up to 12 h of incubation. Cellular morphological changes were observed, but many cells remained in normal shapes. Only a small amount of internal cellular contents was leaked due to the NP treatments, and more live than dead cells were observed after exposure to the NPs. Based on these results, we conclude that ZnO and Ag NPs have mild inhibitory effects on intestinal bacteria.

scholarly journals Association of beta-cytoplasmic actin with high concentrations of acetylcholine receptor (AChR) in normal and anti-AChR-treated primary rat muscle cultures.

1984 ◽  
Vol 32 (9) ◽  
pp. 973-981 ◽  
Author(s):  
B W Lubit
Keyword(s):  
Acetylcholine Receptor ◽  
Acetylcholine Receptors ◽  
Neuromuscular Junctions ◽  
Morphological Changes ◽  
Muscle Cells ◽  
High Concentration ◽  
Rat Muscle ◽  
Cytoplasmic Actin ◽  
High Concentrations

Previous immunocytochemical studies in which an antibody specific for mammalian cytoplasmic actin was used showed that a high concentration of cytoplasmic actin exists at neuromuscular junctions of rat muscle fibers such that the distribution of actin corresponded exactly to that of the acetylcholine receptors. Although clusters of acetylcholine receptors also are present in noninnervated rat and chick muscle cells grown in vitro, neither the mechanism for the formation and maintenance of these clusters nor the relationship of these clusters to the high density of acetylcholine receptors at the neuromuscular junction in vivo are known. In the present study, a relationship between beta-cytoplasmic actin and acetylcholine receptors in vitro has been demonstrated immunocytochemically using an antibody specific for the beta-form of cytoplasmic actin. Networks of cytoplasmic actin-containing filaments were found in discrete regions of the myotube membrane that also contained high concentrations of acetylcholine receptors; such high concentrations of acetylcholine receptors have been described in regions of membrane-substrate contact. Moreover, when primary rat myotubes were exposed to human myasthenic serum, gross morphological changes, accompanied by an apparent rearrangement of the cytoplasmic actin-containing cytoskeleton, were produced. Although whether the distribution of cytoplasmic actin-containing structures was influenced by the organization of acetylcholine receptor or vice versa cannot be determined from these studies, these findings suggest that in primary rat muscle cells grown in vitro, acetylcholine receptors and beta-cytoplasmic actin-containing structures may be somehow connected.

Kinetics of growth and multi substrate degradation by an indigenous mixed microbial culture isolated from a wastewater treatment plant in Guwahati, India

2008 ◽  
Vol 58 (5) ◽  
pp. 1101-1106
Author(s):  
Pichiah Saravanan ◽  
K. Pakshirajan ◽  
P. K. Saha
Keyword(s):  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Lag Phase ◽  
Microbial Culture ◽  
High Concentration ◽  
Mixed Microbial Culture ◽  
Phenol Biodegradation ◽  
Low Concentration ◽  
Culture Growth

An indigenous mixed culture of microorganisms, isolated from a sewage treatment plant, was investigated for its potential to simultaneously degrade phenol and m-cresol during its growth in batch shake flasks. 22 full factorial designs with the two substrates as the factors, at two different levels and two different initial concentration ranges, were employed to carry out the biodegradation experiments. For complete utilisation of phenol and m-cresol, the culture took a minimum duration of 21 hrs at their low concentration of 100 mg/L each, and a maximum duration of 187 hrs at high concentration of 600 mg/L each in the multisubstrate system. The biodegradation results also showed that the presence of phenol in low concentration range (100–300 mg/L did not inhibit m-cresol biodegradation; on the other hand, presence of m-cresol inhibited phenol biodegradation by the culture. Moreover, irrespective of the concentrations used, phenol was degraded preferentially and earlier than m-cresol. During the culture growth, a lag phase was observed above a combined concentration of 500 mg/L i.e., 200 mg/L m-cresol and 300 mg/L of phenol and above). Statistical analysis of the specific growth rate of the culture in the multisubstrate system was also performed in the form of ANOVA and Student ‘t’ test, which gave good interpretation in terms of main and interaction effects of the substrates.

Significance of External Carbon Sources on Simultaneous Removal of Nutrients from Wastewater

1992 ◽  
Vol 26 (5-6) ◽  
pp. 1047-1055 ◽  
Author(s):  
N. F. Y. Tam ◽  
Y. S. Wong ◽  
G. Leung
Keyword(s):  
Sodium Acetate ◽  
Batch Reactor ◽  
Inorganic Nitrogen ◽  
Carbon Sources ◽  
Simultaneous Removal ◽  
Bacterial Cells ◽  
High Concentration ◽  
P Content ◽  
Carbon Substrates ◽  
Effective Source

Laboratory-scale studies were undertaken to examine the effects of easily-biodegradable organic substances upon the nutrient removal by a simulated sequencing batch reactor (SBR). The fill and react period of the SBR was 14 hours, including an instant fill, 7 hours aeration, 4 hours anoxic and 3 hours aeration period. Three kinds of commonly used carbon sources, namely methanol, glucose and sodium acetate, at the concentrations equivalent to theoretical COD values of 50, 100 and 150 mg O2 l-1 were added to each reactor prior to the anoxic stage. The results showed that the concentration of NH4+-N dropped from its initial 50 to 18 mg l-1 (64 % removal) during the first aeration period, with the NO3−-N content increased from 2 to 33 mg l−1. A 60% depletion of COD was also recorded in this period. Denitrification occurred during the anoxic period, higher amount of NO3−1-N was removed in the reactors supplemented with carbon substrates at the concentrations of 100 and 150 mg l-1. The final inorganic nitrogen content was less than 5 mg l-1 in the reactor supplemented with 150 mg l-1 sodium acetate. Simultaneous removal of phosphorus was reported in reactors supplied with high concentration of sodium acetate. In these reactors, large amount of P was released during the anoxic/anaerobic period but the released P was taken up by bacterial cells in the subsequent aeration stage, and the final P content was less than 1.5 mg l-1 (84 % removal was achieved). Among the three carbon sources used, sodium acetate was the most efficient and effective source in removing wastewater nutrients, followed by methanol, and glucose was the least reliable substrate.

Species Composition of the Lichen Biota in Industrially Polluted Territories of Leninsky District of Irkutsk

2021 ◽  
Vol 31 (4) ◽  
pp. 541-545
Author(s):  
Evgeny Kharin ◽  
Olga Belykh
Keyword(s):  
Species Composition ◽  
Morphological Changes ◽  
Environmental Damage ◽  
High Concentration ◽  
Passive Monitoring ◽  
Industrial Pollutants ◽  
Lichen Biota ◽  
Complex Influence ◽  
Lichen Indication

In the context of the development of infrastructure in Siberian cities, the issues of the state of the areas with accumulated environmental damage is especially relevant. It is mentioned in the article that lichen indication is an efficient method of passive monitoring of environment for industrial pollutants caused by morphological changes occurring in sensitive objects. The results of the lichen floristic research of Leninsky district of Irkutsk are presented, a list of revealed lichens including 9 genera and 12 species is given, a taxonomic list of this area is discussed. Lichenological objects were mapped. Distribution of lichens in the area of research is investigated with regard to the presence of recreational and residential zones. The authors draw a conclusion about the presence of «lichens deserts» which are caused both by the absence of the respective substratum and high concentration of pollutants. High concentration of pollutants is caused by complex influence of different enterprises on the quality of air.

scholarly journals Mobilization of Selenite by Ralstonia metallidurans CH34

2001 ◽  
Vol 67 (2) ◽  
pp. 769-773 ◽  
Author(s):  
Murielle Roux ◽  
Géraldine Sarret ◽  
Isabelle Pignot-Paintrand ◽  
Marc Fontecave ◽  
Jacques Coves
Keyword(s):  
Alcaligenes Eutrophus ◽  
Culture Conditions ◽  
Lag Phase ◽  
Elemental Selenium ◽  
Kinetics Analysis ◽  
X Ray ◽  
Polluted Sites ◽  
Ralstonia Metallidurans ◽  
X Ray Absorption ◽  
Bioremediation Processes

ABSTRACT Ralstonia metallidurans CH34 (formerlyAlcaligenes eutrophus CH34) is a soil bacterium characteristic of metal-contaminated biotopes, as it is able to grow in the presence of a variety of heavy metals. R. metalliduransCH34 is reported now to resist up to 6 mM selenite and to reduce selenite to elemental red selenium as shown by extended X-ray absorption fine-structure analysis. Growth kinetics analysis suggests an adaptation of the cells to the selenite stress during the lag-phase period. Depending on the culture conditions, the medium can be completely depleted of selenite. Selenium accumulates essentially in the cytoplasm as judged from electron microscopy and energy-dispersive X-ray analysis. Elemental selenium, highly insoluble, represents a nontoxic storage form for the bacterium. The ability of R. metallidurans CH34 to reduce large amounts of selenite may be of interest for bioremediation processes targeting selenite-polluted sites.

scholarly journals Influence of Fluoride Concentration and pH Value of 35% Hydrogen Peroxide on the Hardness, Roughness and Morphology of Bovine Enamel

2014 ◽  
Vol 15 (4) ◽  
pp. 392-398 ◽  
Author(s):  
Wilcilene Costa Nascimento ◽  
Yasmin do Socorro Batista de Lima Gomes ◽  
Larissa Dias Alexandrino ◽  
Hilton Tulio Costi ◽  
José Otávio Carrera Silva ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Ph Value ◽  
Morphological Changes ◽  
Fluoride Concentration ◽  
Knoop Hardness ◽  
Scanning Electron Micrographs ◽  
High Concentration ◽  
Acidic Group ◽  
Bovine Enamel

ABSTRACT Aim The aim of this in vitro study was to evaluate the effects of different sodium fluoride (NaF) concentrations and pH values on the Knoop hardness (KHN), surface roughness (SR), and morphology of bovine incisors bleached with 35% hydrogen peroxide (HP). Materials and methods Sixty-five bovine incisors were fragmented (5 mm2 × 2 mm) and distributed in 5 groups: Control (unbleached), Low NaF/Acidic (35% HP + 1.3% NaF, pH 5.5), Low NaF/Neutral (35% HP + 1.3% NaF, pH 7.0), High NaF/ Acidic (35% HP + 2% NaF, pH 5.5), and High NaF/Neutral (35% HP + 2% NaF, pH 7.0). KHN analysis was performed with a microhardness tester under a load of 25 gf for 5 seconds. The average SR was obtained with a rugosimeter. KHN and SR were analyzed before and after treatments. For morphological analysis, specimens were dehydrated and gold-sputtered, and scanning electron micrographs were obtained and analyzed by 3 examiners with a double-blinded technique. KHN and SR results were analyzed by one-way ANOVA and Tukey's test (p < 0.05). Results Only the Low NaF/Acidic and Low NaF/Neutral groups showed significant differences between the initial and final KHN values. All bleached groups presented significant differences between the initial and final SR values. Among the bleached groups, the least and most morphological changes were shown by the High NaF/Neutral and the Low NaF/Acidic group, respectively. Conclusion Treatment with 35% HP and 2% NaF at pH 7.0 promoted the least changes in morphology, hardness and roughness among the bleached groups. Clinical significance In-office bleaching with high-concentration HP and 2% NaF at neutral pH promoted the least changes in enamel hardness, SR, and morphology compared to other treatments. How to cite this article Nascimento WC, Gomes YSBL, Alexandrino LD, Costi HT, Silva JOC Jr, Silva CM. Influence of Fluoride Concentration and pH Value of 35% Hydrogen Peroxide on the Hardness, Roughness and Morphology of Bovine Enamel. J Contemp Dent Pract 2014;15(4):392-398.

Reduction of selenate and selenite to elemental selenium by Wolinella succinogenes

1992 ◽  
Vol 38 (12) ◽  
pp. 1328-1333 ◽  
Author(s):  
Francisco A. Tomei ◽  
Larry L. Barton ◽  
Cheryl L. Lemanski ◽  
Thomas G. Zocco
Keyword(s):  
Stationary Growth Phase ◽  
Elemental Selenium ◽  
Bacterial Cells ◽  
Wolinella Succinogenes ◽  
Stationary Growth ◽  
X Ray ◽  
Dense Granules ◽  
Transmission Electron ◽  
Final Electron ◽  
Final Electron Acceptor

Cultures of Wolinella succinogenes were adapted to grow in the presence of 1 mM [Formula: see text] or 10 mM [Formula: see text]. Both selenium salts were reduced to red, amorphous, elemental selenium but only after the culture reached the stationary growth phase. Bacterial cells taken from a culture actively reducing selenium were examined by transmission electron microscopy and were found to have large, electron-dense granules in the cytoplasm. These granules were verified by energy-dispersive X-ray spectroscopy to consist of selenium. Wolinella succinogenes was unable to grow with [Formula: see text] or [Formula: see text] as the final electron acceptor. Key words: Wolinella, selenium, cytology, selenate.

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