scholarly journals Effect of Organic Solvents on the Yield of Solvent-Tolerant Pseudomonas putida S12

1999 ◽  
Vol 65 (6) ◽  
pp. 2631-2635 ◽  
Author(s):  
Sonja Isken ◽  
Antoine Derks ◽  
Petra F. G. Wolffs ◽  
Jan A. M. de Bont
Keyword(s):  
Growth Rate ◽  
Pseudomonas Putida ◽  
Organic Solvents ◽  
Critical Concentration ◽  
Bacterial Membrane ◽  
Maximal Growth ◽  
Wild Type ◽  
Active Efflux ◽  
Maximal Growth Rate ◽  
Solvent Tolerant

ABSTRACT Solvent-tolerant microorganisms are useful in biotransformations with whole cells in two-phase solvent-water systems. The results presented here describe the effects that organic solvents have on the growth of these organisms. The maximal growth rate of Pseudomonas putida S12, 0.8 h−1, was not affected by toluene in batch cultures, but in chemostat cultures the solvent decreased the maximal growth rate by nearly 50%. Toluene, ethylbenzene, propylbenzene, xylene, hexane, and cyclohexane reduced the biomass yield, and this effect depended on the concentration of the solvent in the bacterial membrane and not on its chemical structure. The dose response to solvents in terms of yield was linear up to an approximately 200 mM concentration of solvent in the bacterial membrane, both in the wild type and in a mutant lacking an active efflux system for toluene. Above this critical concentration the yield of the wild type remained constant at 0.2 g of protein/g of glucose with increasing concentrations of toluene. The reduction of the yield in the presence of solvents is due to a maintenance higher by a factor of three or four as well as to a decrease of the maximum growth yield by 33%. Therefore, energy-consuming adaptation processes as well as the uncoupling effect of the solvents reduce the yield of the tolerant cells.

1-Aminocyclopropane-1-carboxylate deaminase from Pseudomonas putida UW4 facilitates the growth of canola in the presence of salt

2007 ◽  
Vol 53 (7) ◽  
pp. 912-918 ◽  
Author(s):  
Zhenyu Cheng ◽  
Eunmi Park ◽  
Bernard R. Glick
Keyword(s):  
Growth Rate ◽  
Plant Growth ◽  
Pseudomonas Putida ◽  
Acc Deaminase ◽  
Maximal Growth ◽  
Ethylene Synthesis ◽  
Wild Type ◽  
Bacterial Strains ◽  
Previous Suggestion ◽  
Maximal Growth Rate

The growth of canola plants treated with either wild-type Pseudomonas putida UW4 or a 1-aminocyclopropane-1-carboxylate (ACC) deaminase minus mutant of this strain was monitored in the presence of inhibitory levels of salt, i.e., 1.0 mol/L at 10 °C and 150 mmol/L at 20 °C. This strain is psychrotolerant with a maximal growth rate of approximately 30 °C and the ability to proliferate at 4 °C. Although plant growth was inhibited dramatically by the addition of 1.0 mol/L salt at 10 °C and only slightly by 150 mmol/L salt at 20 °C under both sets of conditions, the addition of the wild type but not the mutant strain of P. putida UW4 significantly improved plant growth. This result confirms the previous suggestion that bacterial strains that contain ACC deaminase confer salt tolerance to plants by lowering salt-induced ethylene synthesis.

Sensitivity of Saccharomyces cerevisiae to tannic acid is due to iron deprivation

2001 ◽  
Vol 47 (4) ◽  
pp. 290-293 ◽  
Author(s):  
T Wauters ◽  
D Iserentant ◽  
H Verachtert
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acids ◽  
Growth Rate ◽  
Tannic Acid ◽  
Unsaturated Fatty Acids ◽  
Acid Resistance ◽  
Maximal Growth ◽  
Wild Type ◽  
Iron Deprivation ◽  
Maximal Growth Rate

Tannic acid inhibited the growth of the yeast Saccharomyces cerevisiae. Growth medium supplementation with more nitrogen or metal ions showed that only iron ions could restore the maximal growth rate of S. cerevisiae. Tannic acid resistant mutants were previously isolated by screening for tannic acid resistance and were all cytoplasmic petite mutants. While the wild type was very sensitive to iron deprivation conditions when grown in aerobic conditions, the mutants, whether grown aerobically or anaerobically, showed the same growth rate under iron-limited conditions as under iron-repleted conditions. Also, the wild type grown anaerobically was not affected by iron-limited conditions. Cytoplasmic petite mutants obtained by ethidium bromide mutagenesis behaved like the other mutants. During iron limitation, the wild type showed a reduced oxygen uptake rate. Maximal growth rate of the wild type in iron-limited conditions could be restored by the addition to the media of unsaturated fatty acids and sterol. Iron deprivation caused by tannic acid may thus affect the synthesis of a functional respiratory chain as well as the synthesis of unsaturated fatty acids and (or) sterol.Key words: Saccharomyces cerevisiae, tannic acid resistance, iron deprivation, cytoplasmic petite mutant.

Osteosarcoma Developed in the Period of Maximal Growth Rate Have Inferior Prognosis

2008 ◽  
Vol 30 (6) ◽  
pp. 419-424 ◽  
Author(s):  
Jun Ah Lee ◽  
Min Suk Kim ◽  
Dong Ho Kim ◽  
Jung Sub Lim ◽  
Kyung Duk Park ◽  
...  
Keyword(s):  
Growth Rate ◽  
Maximal Growth ◽  
Maximal Growth Rate

scholarly journals Effect of Salt Stress on Mutation and Genetic Architecture for Fitness Components in Saccharomyces cerevisiae

2020 ◽  
Vol 10 (10) ◽  
pp. 3831-3842
Author(s):  
Christopher Kozela ◽  
Mark O. Johnston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rate ◽  
Salt Stress ◽  
Mutation Rate ◽  
Genetic Architecture ◽  
Maximal Growth ◽  
Fitness Components ◽  
Environmental Variance ◽  
Maximal Growth Rate ◽  
Mutational Variance

Mutations shape genetic architecture and thus influence the evolvability, adaptation and diversification of populations. Mutations may have different and even opposite effects on separate fitness components, and their rate of origin, distribution of effects and variance-covariance structure may depend on environmental quality. We performed an approximately 1,500-generation mutation-accumulation (MA) study in diploids of the yeast Saccharomyces cerevisiae in stressful (high-salt) and normal environments (50 lines each) to investigate the rate of input of mutational variation (Vm) as well as the mutation rate and distribution of effects on diploid and haploid fitness components, assayed in the normal environment. All four fitness components in both MA treatments exhibited statistically significant mutational variance and mutational heritability. Compared to normal-MA, salt stress increased the mutational variance in growth rate by more than sevenfold in haploids derived from the MA lines. This increase was not detected in diploid growth rate, suggesting masking of mutations in the heterozygous state. The genetic architecture arising from mutation (M-matrix) differed between normal and salt conditions. Salt stress also increased environmental variance in three fitness components, consistent with a reduction in canalization. Maximum-likelihood analysis indicated that stress increased the genomic mutation rate by approximately twofold for maximal growth rate and sporulation rate in diploids and for viability in haploids, and by tenfold for maximal growth rate in haploids, but large confidence intervals precluded distinguishing these values between MA environments. We discuss correlations between fitness components in diploids and haploids and compare the correlations between the two MA environmental treatments.

Extracytoplasmic storage as the nickel resistance mechanism in a natural isolate ofPseudomonas putidaS4

2006 ◽  
Vol 52 (4) ◽  
pp. 287-292 ◽  
Author(s):  
V N Tripathi ◽  
S Srivastava
Keyword(s):  
Pseudomonas Putida ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Resistance Mechanism ◽  
Metal Resistance ◽  
Periplasmic Space ◽  
Natural Isolate ◽  
Wild Type ◽  
Nickel Resistance ◽  
Active Efflux

Metal resistances in microbes are important to study not only to understand metal homeostasis but also to use such organisms further in environmental bioremediation. Nickel (Ni2+) is an important micronutrient, which at higher concentration becomes toxic. Many Ni2+-resistant organisms are known, which resist metal by active efflux. Pseudomonas putida S4, a natural isolate from India, is reported to show a multi-metal resistance profile. In the present study, the Ni2+-resistance mechanism in strain S4 was examined. Wild-type cells gradually accumulated Ni2+but kept it preferentially in the periplasmic space in a bound form. In Ni2+-sensitive mutants, periplasmic storage was disturbed and more metal accumulated cytoplasmically, producing toxicity. Sodium dodecyl sulphate – polyacrylamide gel electrophoresis analysis of periplasmic proteins revealed a band of approximately 18 kDa, which appeared only in Ni2+-exposed wild-type cells, and which was absent from cells not exposed to Ni2+as well as from Ni2+-sensitive mutants. On the basis of these observations, we propose a Ni2+-resistance mechanism in P. putida S4 based on sequestration of metal in the periplasmic space. This is the first study of sequestration-based Ni2+resistance.Key words: nickel, resistance, periplasmic storage, Pseudomonas putida.

scholarly journals Ferredoxin-NADP+ Reductase from Pseudomonas putida Functions as a Ferric Reductase

2008 ◽  
Vol 191 (5) ◽  
pp. 1472-1479 ◽  
Author(s):  
Jinki Yeom ◽  
Che Ok Jeon ◽  
Eugene L. Madsen ◽  
Woojun Park
Keyword(s):  
Growth Rate ◽  
Pseudomonas Putida ◽  
Reductase Activity ◽  
Flavin Mononucleotide ◽  
Flavin Reductase ◽  
Ferric Reductase ◽  
Wild Type ◽  
Cell Extracts ◽  
Mutant Strains ◽  
First Time

ABSTRACT Pseudomonas putida harbors two ferredoxin-NADP+ reductases (Fprs) on its chromosome, and their functions remain largely unknown. Ferric reductase is structurally contained within the Fpr superfamily. Interestingly, ferric reductase is not annotated on the chromosome of P. putida. In an effort to elucidate the function of the Fpr as a ferric reductase, we used a variety of biochemical and physiological methods using the wild-type and mutant strains. In both the ferric reductase and flavin reductase assays, FprA and FprB preferentially used NADPH and NADH as electron donors, respectively. Two Fprs prefer a native ferric chelator to a synthetic ferric chelator and utilize free flavin mononucleotide (FMN) as an electron carrier. FprB has a higher k cat/Km value for reducing the ferric complex with free FMN. The growth rate of the fprB mutant was reduced more profoundly than that of the fprA mutant, the growth rate of which is also lower than the wild type in ferric iron-containing minimal media. Flavin reductase activity was diminished completely when the cell extracts of the fprB mutant plus NADH were utilized, but not the fprA mutant with NADPH. This indicates that other NADPH-dependent flavin reductases may exist. Interestingly, the structure of the NAD(P) region of FprB, but not of FprA, resembled the ferric reductase (Fre) of Escherichia coli in the homology modeling. This study demonstrates, for the first time, the functions of Fprs in P. putida as flavin and ferric reductases. Furthermore, our results indicated that FprB may perform a crucial role as a NADH-dependent ferric/flavin reductase under iron stress conditions.

scholarly journals New Types of Dissipative Streaming Instabilities

2021 ◽  
Author(s):  
Eduard V. Rostomyan
Keyword(s):  
Growth Rate ◽  
Initial Perturbation ◽  
Classical Problem ◽  
Negative Energy ◽  
Plasma Waveguide ◽  
Limiting Current ◽  
Maximal Growth ◽  
Weak Beam ◽  
Beam Plasma ◽  
Maximal Growth Rate

Two new, previously unknown types of dissipative streaming instabilities (DSI) are substantiated. They follow from new approach, which allows solving in general form the classical problem of an initial perturbation development for streaming instabilities (SI). SI is caused by relative motion of the streams of plasma components. With an increase in level of dissipation SI transforms into a DSI. The transformation occurs because dissipation serves as a channel for energy removal for the growth of the negative energy wave of the stream. Until recently, only one type of DSI was known. Its maximal growth rate depends on the beam density nb and the collision frequency ν in the plasma as ∼nb/ν. All types of conventional beam-plasma instabilities (Cherenkov, cyclotron, etc.) transform into it. The solution of the problem of the initial perturbation development in systems with weak beam-plasma coupling leads to a new type of DSI. With an increase in the level of dissipation, the instability in these systems transforms to the new DSI. Its maximal growth rate is ∼nb/ν. The second new DSI develops in beam-plasma waveguide with over-limiting current of e-beam. Its growth rate ∼nb/ν. In addition, the solutions of abovementioned problem provide much information about SI and DSI, significant part of which is unavailable by other methods.

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