Effect of Anoxic Conditions and Temperature on Gas Vesicle Formation in Halobacterium salinarum

2011 ◽  
pp. 237-248
Author(s):  
Felicitas Pfeifer ◽  
Regina Frommherz ◽  
Karin Faist ◽  
Torsten Hechler ◽  
Katharina Teufel ◽  
...  
Keyword(s):  
Halobacterium Salinarum ◽  
Vesicle Formation ◽  
Anoxic Conditions

scholarly journals Eight of Fourteen gvp Genes Are Sufficient for Formation of Gas Vesicles in Halophilic Archaea

2000 ◽  
Vol 182 (15) ◽  
pp. 4328-4336 ◽  
Author(s):  
Sonja Offner ◽  
Annette Hofacker ◽  
Gerhard Wanner ◽  
Felicitas Pfeifer
Keyword(s):  
Phase Contrast ◽  
Gene Deletion ◽  
Streptomyces Coelicolor ◽  
Halophilic Archaea ◽  
Halobacterium Salinarum ◽  
Vesicle Formation ◽  
Gas Vesicles ◽  
Minimal Set ◽  
Number Of Genes ◽  
Contrast Microscopy

ABSTRACT The minimal number of genes required for the formation of gas vesicles in halophilic archaea has been determined. Single genes of the 14 gvp genes present in the p-vac region on plasmid pHH1 ofHalobacterium salinarum (p-gvpACNO and p-gvpDEFGHIJKLM) were deleted, and the remaining genes were tested for the formation of gas vesicles in Haloferax volcanii transformants. The deletion of six gvp genes (p-gvpCN, p-gvpDE, and p-gvpHI) still enabled the production of gas vesicles in H. volcanii. The gas vesicles formed in some of thesegvp gene deletion transformants were altered in shape (ΔI, ΔC) or strength (ΔH) but still functioned as flotation devices. A minimal p-vac region (minvac) containing the eight remaining genes (gvpFGJKLM-gvpAO) was constructed and tested for gas vesicle formation in H. volcanii. The minvac transformants did not form gas vesicles; however, minvac/gvpJKLM double transformants contained gas vesicles seen as light refractile bodies by phase-contrast microscopy. Transcript analyses demonstrated that minvac transformants synthesized regular amounts of gvpA mRNA, but the transcripts derived from gvpFGJKLM were mainly short and encompassed onlygvpFG(J), suggesting that thegvpJKLM genes were not sufficiently expressed. SincegvpAO and gvpFGJKLM are the onlygvp genes present in minvac/JKLM transformants containing gas vesicles, these gvp genes represent the minimal set required for gas vesicle formation in halophilic archaea. Homologs of six of these gvp genes are found in Anabaena flos-aquae, and homologs of all eight minimal halobacterialgvp genes are present in Bacillus megateriumand in the genome of Streptomyces coelicolor.

scholarly journals Effect of Mutations in GvpJ and GvpM on Gas Vesicle Formation of Halobacterium salinarum

2021 ◽  
Vol 12 ◽  
Author(s):  
Alisa Jost ◽  
Regine Knitsch ◽  
Kerstin Völkner ◽  
Felicitas Pfeifer
Keyword(s):  
Halobacterium Salinarum ◽  
Haloferax Volcanii ◽  
Vesicle Formation ◽  
Gas Vesicles ◽  
Structural Protein ◽  
Homologous Proteins ◽  
Partner Protein ◽  
Terminal Fragment ◽  
Comparison Of The Results

The two haloarchaeal proteins, GvpM and GvpJ, are homologous to GvpA, the major gas vesicle structural protein. All three are hydrophobic and essential for gas vesicle formation. The effect of mutations in GvpJ and GvpM was studied in Haloferax volcanii transformants by complementing the respective mutated gene with the remaining gvp genes and inspecting the cells for the presence of gas vesicles (Vac+). In case of GvpJ, 56 of 66 substitutions analyzed yielded Vac– ΔJ + Jmut transformants, indicating that GvpJ is very sensitive to alterations, whereas ten of the 38 GvpM variants resulted in Vac– ΔM + Mmut transformants. The variants were also tested by split-GFP for their ability to interact with their partner protein GvpL. Some of the alterations leading to a Vac– phenotype affected the J/L or M/L interaction. Also, the interactions J/A and J/M were studied using fragments to exclude an unspecific aggregation of these hydrophobic proteins. Both fragments of GvpJ interacted with the M1–25 and M60–84 fragments of GvpM, and fragment J1–56 of GvpJ interacted with the N-terminal fragment A1–22 of GvpA. A comparison of the results on the three homologous proteins indicates that despite their relatedness, GvpA, GvpJ, and GvpM have unique features and cannot substitute each other.

Abiotic reduction of 2,4-dinitrotoluene in the presence of sulfide minerals under anoxic conditions

1996 ◽  
Vol 34 (10) ◽  
pp. 25-33 ◽  
Author(s):  
Cheng Jiayang ◽  
Makram T. Suidan ◽  
Albert D. Venosa
Keyword(s):  
Electron Donor ◽  
Chemical Reduction ◽  
Sulfide Minerals ◽  
Sulfide Concentration ◽  
Magnesium Ions ◽  
High Concentration ◽  
Anoxic Conditions ◽  
High Affinity ◽  
Iron Nickel ◽  
Abiotic Reduction

Abiotic reduction of 2,4-dinitrotoluene (DNT) in the presence of sulfide minerals has been investigated under anoxic conditions at 35°C. 2,4-DNT was abiotically reduced to 4-amino-2-nitrotoluene (4-A-2-NT) and 2-amino-4-nitrotoluene (2-A-4-NT) in the presence of high concentration of sulfide (0.84 mM). No abiotic reduction of 2,4-DNT was observed in the presence of low sulfide concentration (0.42 mM). The rate and the extent of the abiotic reduction of 2,4-DNT were increased with an increase in sulfide concentration. Sulfide served as an electron donor for the reduction of 2,4-DNT. The 2-nitro group was preferentially reduced, making the 2-A-4-NT:4-A-2-NT ratio in the final products 2:1. The addition of iron, nickel, and cobalt minerals significantly enhanced the abiotic reduction. The FeS, NiS, and CoS solids formed in the serum bottles catalyzed the reduction of 2,4-DNT preferentially to 4-A-2-NT. MnS and CuS solids also catalyzed the reduction of 2,4-DNT to 4-A-2-NT, but did not change the overall reduction of 2,4-DNT. However, the presence of calcium, zinc, and magnesium minerals impeded 2,4-DNT reduction. The calcium, zinc, and magnesium ions have a high affinity to sulfide, inactivating sulfide as an electron donor for the chemical reduction of 2,4-DNT.

The effect of heterotrophic yield on the assessment of the correction factor for anoxic growth

1996 ◽  
Vol 34 (5-6) ◽  
pp. 67-74 ◽  
Author(s):  
D. Orhon ◽  
S. Sözen ◽  
N. Artan
Keyword(s):  
Correction Factor ◽  
Domestic Sewage ◽  
Yield Coefficient ◽  
Heterotrophic Growth ◽  
Metabolic Processes ◽  
Anoxic Conditions ◽  
Industrial Wastewaters ◽  
Systems Modelling ◽  
Kinetics Of ◽  
Very High

For single-sludge denitrification systems, modelling of anoxic reactors currently uses the kinetics of aerobic heterotrophic growth together with a correction factor for anoxic conditions. This coefficient is computed on the basis of respirometric measurements with the assumption that the heterotrophic yield remains the same under aerobic and anoxic coditions. The paper provides the conceptual proof that the yield coefficient is significantly lower for the anoxic growth on the basis of the energetics of the related metabolic processes. This is used for the interpretation of the very high values for the correction factor experimentally determined for a number of industrial wastewaters. A default value for the anoxic heterotrophic yield coefficient is calculated for domestic sewage and compatible wastewaters and proposed for similar evaluations.

Intracellular trafficking and cytoplasmic streaming under abiotic stress conditions

2019 ◽  
Vol 6 (04) ◽  
Author(s):  
JESHIMA KHAN YASIN ◽  
ANIL KUMAR SINGH
Keyword(s):  
Plasma Membrane ◽  
Abiotic Stress ◽  
Confocal Microscopy ◽  
Fusion Protein ◽  
Intracellular Trafficking ◽  
Cytoplasmic Streaming ◽  
Living Cells ◽  
Stress Conditions ◽  
Vesicle Formation ◽  
External Stimuli

Cytoplasmic streaming is one among the vital activities of the living cells. In plants cytolplasmic streaming could clearly be seen in hypocotyls of growing seedlings. To observe cytoplsmic streaming and its correlated intracellular trafficking an investigation was conducted in legumes in comparison with GFP-AtRab75 and 35S::GFP:δTIP tonoplast fusion protein expressing arabidopsis lines. These seedlings were observed under confocal microscopy with different buffer incubation treatments and under different stress conditions. GFP expressing 35S::GFP:δTIP tonoplast lines were looking similar to the control lines and differ under stress conditions. Movement of cytoplasmic invaginations within the tonoplast and cytoplasmic sub vesicle or bulb budding during cytoplasmic streaming was observed in hypocotyls of At-GFP tonoplast plants. We found the cytoplasmic bulbs/ vesicles or sub vesicle formation from the plasma membrane. The streaming speed also depends on the incubation medium in which the specimen was incubated, indicating that the external stimuli as well as internal stimuli can alter the speed of streaming

Microbial population selection in integrated fixed-film sequencing batch reactors operated with different lengths of oxic and anoxic conditions

2021 ◽  
Author(s):  
Hussain Aqeel ◽  
Mahendran Basuvaraj ◽  
Steven N. Liss
Keyword(s):  
Microbial Population ◽  
Denitrifying Bacteria ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Anoxic Conditions ◽  
Population Selection ◽  
Fixed Film

BNR granules rich in amyloid adhesins and denitrifying bacteria were formed in the SBRs that were operated with extended anoxic conditions.

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