scholarly journals Polyethylene glycol exerted toxicity to growth of Bacillus subtilis NRS-762

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Bacillus Subtilis ◽  
Polyethylene Glycol ◽  
Optical Density ◽  
Culture Broth ◽  
Threshold Concentration ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Ph Variation ◽  
The One ◽  
The Impact

Polyethylene glycol is commonly used in fermentations as an anti-foam for preventing the rise of foam to the top plate of the bioreactor, which increases contamination risk. However, its potential toxicity to growth of various microorganisms is not well understood at the strain and species level. Hence, the objective of this study was to understand the impact of different concentrations of polyethylene glycol (0, 1, 5 and 10 g/L) on the aerobic growth of Bacillus subtilis NRS-762 (ATCC 8473) in LB Lennox medium in shake flasks at 30 oC and 230 rpm rotational shaking. Experiment results indicated that polyethylene glycol (PEG) (molecular weight ~8000 Da), at all concentrations tested, exerted some toxicity towards the growth of B. subtilis NRS-762 in LB Lennox medium. Specifically, maximal optical density obtained declined with greater exposure to PEG in a concentration-dependent manner, up to a threshold concentration of 5 g/L PEG. For example, maximal optical density obtained in B. subtilis NRS-762 without addition of PEG was 4.4, but the value obtained on exposure to 1 g/L of the anti-foam decreased to 4.1 and a further 3.8 on exposure of cells to 5 g/L and 10 g/L PEG. Similarly, growth rates of B. subtilis NRS-762 also decreased in a concentration-dependent manner with PEG concentration up to a threshold concentration of 5 g/L PEG. pH variation in culture broth, however, revealed that the pH profiles for exposure to PEG at all concentrations overlapped each other and was similar to the one of cells without exposure to the anti-foam; thereby, highlighting that metabolic processes in B. subtilis NRS-762 were not significantly affected by exposure to PEG. Collectively, polyethylene glycol anti-foam exerted toxicity effect on B. subtilis NRS-762 biomass formation, and possibly metabolism. The latter may not be sufficiently significant to affect the types of metabolites secreted by the bacterium, and thus, could not be detected by measurement of culture broth pH. Overall, the results should inform the choice and concentration of PEG for culturing B. subtilis in biotechnological applications.

scholarly journals Polyethylene glycol exerted toxicity to growth of Bacillus subtilis NRS-762

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Bacillus Subtilis ◽  
Polyethylene Glycol ◽  
Optical Density ◽  
Culture Broth ◽  
Threshold Concentration ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Ph Variation ◽  
The One ◽  
The Impact

Polyethylene glycol is commonly used in fermentations as an anti-foam for preventing the rise of foam to the top plate of the bioreactor, which increases contamination risk. However, its potential toxicity to growth of various microorganisms is not well understood at the strain and species level. Hence, the objective of this study was to understand the impact of different concentrations of polyethylene glycol (0, 1, 5 and 10 g/L) on the aerobic growth of Bacillus subtilis NRS-762 (ATCC 8473) in LB Lennox medium in shake flasks at 30 oC and 230 rpm rotational shaking. Experiment results indicated that polyethylene glycol (PEG) (molecular weight ~8000 Da), at all concentrations tested, exerted some toxicity towards the growth of B. subtilis NRS-762 in LB Lennox medium. Specifically, maximal optical density obtained declined with greater exposure to PEG in a concentration-dependent manner, up to a threshold concentration of 5 g/L PEG. For example, maximal optical density obtained in B. subtilis NRS-762 without addition of PEG was 4.4, but the value obtained on exposure to 1 g/L of the anti-foam decreased to 4.1 and a further 3.8 on exposure of cells to 5 g/L and 10 g/L PEG. Similarly, growth rates of B. subtilis NRS-762 also decreased in a concentration-dependent manner with PEG concentration up to a threshold concentration of 5 g/L PEG. pH variation in culture broth, however, revealed that the pH profiles for exposure to PEG at all concentrations overlapped each other and was similar to the one of cells without exposure to the anti-foam; thereby, highlighting that metabolic processes in B. subtilis NRS-762 were not significantly affected by exposure to PEG. Collectively, polyethylene glycol anti-foam exerted toxicity effect on B. subtilis NRS-762 biomass formation, and possibly metabolism. The latter may not be sufficiently significant to affect the types of metabolites secreted by the bacterium, and thus, could not be detected by measurement of culture broth pH. Overall, the results should inform the choice and concentration of PEG for culturing B. subtilis in biotechnological applications.

scholarly journals Effect of polyethylene glycol on growth of Escherichia coli DH5α and Bacillus subtilis NRS-762

2020 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Polyethylene Glycol ◽  
Optical Density ◽  
Culture Broth ◽  
Dependent Manner ◽  
Biomass Formation ◽  
E Coli ◽  
Toxicity Effect ◽  
Dose Dependent

AbstractPolyethylene glycol is commonly used in fermentation as an anti-foam for preventing the rise of foam to the top plate of the bioreactor, which increases contamination risk. However, its potential toxicity to growth of various microorganisms is not well understood at the species and strain level. Hence, the objective of this study was to understand the impact of different concentrations of polyethylene glycol at the 1, 5 and 10 g/L level on the aerobic growth of Escherichia coli DH5α and Bacillus subtilis NRS-762 in LB Lennox medium in shake flasks. Experiment results revealed that polyethylene glycol (PEG) (molecular weight ∼8000 Da), at all concentrations tested, did not affect biomass formation and metabolism in E. coli DH5α at 37 °C. This came about through the observation of similar maximal optical density obtained during growth of E. coli DH5α under differing concentrations of PEG. Furthermore, the anti-foam did not affect the pH profile. On the other hand, PEG did exhibit some toxicity towards the growth of B. subtilis NRS-762 in LB Lennox medium. Specifically, maximal optical density obtained decline with higher exposure to PEG in a concentration dependent manner, up to a threshold concentration of 5 g/L. For example, maximal optical density obtained in B. subtilis NRS-762 without addition of PEG was 4.4, but the value obtained with 1 g/L of the anti-foam decreased to 4.1 and a further 3.8 on exposure to 5 g/L and 10 g/L PEG. pH variation in culture broth, however, told a different story, where the profiles for exposure to PEG at all concentrations coincide with each other and was similar to the one without exposure to the anti-foam; thereby, suggesting that metabolic processes in B. subtilis NRS-762 were not significantly affected by exposure to PEG. Collectively, PEG anti-foam exerted species-specific toxicity effect on biomass formation, and possibly metabolism. The latter may not be sufficiently significant to affect the types of metabolites secreted by the bacterium, and thus, be detected by measurement of pH of culture broth. E. coli DH5α was better able to cope with PEG at all concentrations compared to B. subtilis NRS-762, which showed dose-dependent toxicity effect on biomass formation.HighlightsPolyethylene glycol (molecular weight ∼ 8000 Da) did not affect aerobic growth of Escherichia coli DH5α at 37 °C in LB medium at all concentrations tested: 0, 1, 5, 10 g/L.Growth curves of the bacterium at different concentrations of polyethylene glycol (PEG) coincided with each other.Similar pH profiles were also obtained for E. coli DH5α growth in LB medium with different PEG concentrations.However, PEG exerted toxicity effect on Bacillus subtilis NRS-762 during growth in LB medium at 30 °C, with reduction of biomass formation in a dose dependent manner.Similar to the case for E. coli DH5α. pH profiles of B. subtilis NRS-762 coincided with each other irrespective of the concentrations of PEG used.

scholarly journals Ammonium interference reduced copper uptake by formaldehyde-crosslinked Sargassum sp. seaweed

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Heavy Metals ◽  
Metal Removal ◽  
Sorption Kinetics ◽  
Threshold Concentration ◽  
Dependent Manner ◽  
Dilute Solutions ◽  
Brown Macroalgae ◽  
Concentration Dependent Manner ◽  
Nitrogenous Compounds ◽  
Copper Sorption

Sargassum sp., a marine brown macroalgae, is an efficient sorbent for various heavy metals at high concentrations. However, the efficiency at which seaweed removes heavy metals from dilute solutions and the effect of ammonium on metal removal is not well understood; an issue of importance given the ubiquity of nitrogenous compounds in the environment arising from various surface runoffs. Herein, the effect of ammonium on copper removal (at trace to low concentration) by formaldehyde crosslinked Sargassum sp. (treated SW) was studied. Due to high copper background, equilibrium sorption experiments was inconclusive concerning treated SW’s ability in removing copper (<1000 ppb), but rapid copper sorption observed in kinetic experiments suggested potential feasibility of the process. Within initial copper concentration of 4 to 20 ppm and pH 2 to 5, experiments revealed that, above a threshold concentration of [NH4+-N] of 50 ppm, ammonium impede copper update on treated SW in a concentration dependent manner. Specifically, sorption kinetics slowed, and uptake capacity decreased with increase in [NH4+-N] from 0 to 2500 ppm. Collectively, beyond demonstrating that treated SW could remove copper from dilute solutions, revelations that ammonium reduced copper sorption highlighted the importance of accounting for the effect in data interpretation and modelling.

Regulation of KCa-channel activity by cyclic ADP-ribose and ADP-ribose in coronary arterial smooth muscle

1998 ◽  
Vol 275 (3) ◽  
pp. H1002-H1010 ◽  
Author(s):  
Pin-Lan Li ◽  
Ai-Ping Zou ◽  
William B. Campbell
Keyword(s):  
Smooth Muscle ◽  
Time Course ◽  
Control Level ◽  
Internal Surface ◽  
Threshold Concentration ◽  
Dependent Manner ◽  
Channel Activity ◽  
Arterial Smooth Muscle ◽  
Concentration Dependent Manner ◽  
Cyclic Adp Ribose

The enzymatic pathway responsible for the production and metabolism of cyclic ADP-ribose (cADP-R) in small bovine coronary arteries was characterized, and the role of cADP-R and ADP-ribose (ADP-R) in the regulation of the activity of large-conductance Ca2+-activated K+(KCa) channels was determined in vascular smooth muscle cells (SMC) prepared from these vessels. We found that cADP-R and ADP-R were produced when the coronary arterial homogenates were incubated with 1 mM β-NAD. The time course of the enzyme reactions showed that the maximal conversion rate (1.37 ± 0.03 nmol ⋅ min−1 ⋅ mg protein−1) of β-NAD to cADP-R was reached after 3 min of incubation. As incubation time was prolonged, the production of ADP-R was increased to a maximal rate of 3.66 ± 0.03 nmol ⋅ min−1 ⋅ mg protein−1, whereas cADP-R production decreased. Incubation of the homogenate with cADP-R produced a time-dependent increase in the synthesis of ADP-R. Comparison of coronary arterial microsomes with cytosols shows that the production of both cADP-R and ADP-R in microsomes was significantly greater. In excised inside-out membrane patches of single coronary SMC, the KCa channels were activated when β-NAD, the precursor for both cADP-R and ADP-R, was applied to the internal surface. This effect of β-NAD may be associated with the production of ADP-R, because the KCa-channel activity was increased by ADP-R in a concentration-dependent manner. The open-state probability of the KCa channels increased from a control level of 0.08 ± 0.03 to 0.17 ± 0.05 even at the lowest ADP-R concentration (0.1 μM) studied. However, cADP-R reduced the KCa-channel activity, and the threshold concentration of cADP-R that decreased the average channel activity of the KCa channels was 1 μM. These results provide evidence that cADP-R is produced and metabolized in the coronary arterial smooth muscle and that a cADP-R/ADP-R pathway participates in the control of the KCa-channel activity in vascular SMC.

scholarly journals Forced Expression of Keratin 16 Alters the Adhesion, Differentiation, and Migration of Mouse Skin Keratinocytes

2000 ◽  
Vol 11 (10) ◽  
pp. 3315-3327 ◽  
Author(s):  
Matthew Wawersik ◽  
Pierre A. Coulombe
Keyword(s):  
Mouse Skin ◽  
Cellular Level ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Keratin 16 ◽  
Skin Keratinocytes ◽  
Steady State Levels ◽  
And Migration ◽  
Mouse Skin Keratinocytes ◽  
The Impact

Injury to the skin results in an induction of keratins K6, K16, and K17 concomitant with activation of keratinocytes for reepithelialization. Forced expression of human K16 in skin epithelia of transgenic mice causes a phenotype that mimics several aspects of keratinocyte activation. Two types of transgenic keratinocytes, with forced expression of either human K16 or a K16-C14 chimeric cDNA, were analyzed in primary culture to assess the impact of K16 expression at a cellular level. High K16-C14-expressing and low K16-expressing transgenic keratinocytes behave similar to wild type in all aspects tested. In contrast, high K16-expressing transgenic keratinocytes show alterations in plating efficiency and calcium-induced differentiation, but proliferate normally. Migration of keratinocytes is reduced in K16 transgenic skin explants compared with controls. Finally, a subset of high K16-expressing transgenic keratinocytes develops major changes in the organization of keratin filaments in a time- and calcium concentration-dependent manner. These changes coincide with alterations in keratin content while the steady-state levels of K16 protein remain stable. We conclude that forced expression of K16 in progenitor skin keratinocytes directly impacts properties such as adhesion, differentiation, and migration, and that these effects depend upon determinants contained within its carboxy terminus.

The cytoprotective effects of bilirubin and biliverdin on rat hepatocytes and human erythrocytes and the impact of albumin

1991 ◽  
Vol 69 (12) ◽  
pp. 828-834 ◽  
Author(s):  
Tai-Wing Wu ◽  
Doug Carey ◽  
Jun Wu ◽  
Hiroshi Sugiyama
Keyword(s):  
Rat Hepatocytes ◽  
Human Erythrocytes ◽  
Red Cells ◽  
Peroxyl Radicals ◽  
Blood Levels ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Hepatocyte Necrosis ◽  
The Impact ◽  
First Time

The hypothesis that unconjugated bilirubin and biliverdin are cytoprotective antioxidants has been examined for the first time in systems containing cells. In primary rat hepatocytes exposed to xanthine oxidase and hypoxanthine, bilirubin (0–60 μM) failed to prolong cell survival. In contrast, biliverdin (20–100 μM) markedly delayed hepatocyte necrosis in a concentration-dependent manner. When 0.3 mM of albumin was present, bilirubin (0–50 μM) became protective of hepatocytes, while biliverdin was less dramatically enhanced in its cytoprotective effect. In human erythrocytes exposed to peroxyl radicals, bilirubin and biliverdin inhibited 50% cell lysis at lower concentrations than Trolox and ascorbate, respectively. Albumin alone appeared less cytoprotective in red cells than in hepatocytes, but its presence enhanced the effects of both pigments on erythrocytes. Of probable physiologic relevance, bilirubin with albumin present or biliverdin alone protected hepatocytes substantially (and to a lesser extent red cells) at the normal blood levels of bilirubin (3.4–26 μM). Moreover, the fact that the pigments are cytoprotective at higher bilirubin levels (e.g., 50–100 μM) tempts the speculation that they may be circulating cytoprotectors of overlooked importance in jaundice.Key words: cytoprotection, biliverdin, bilirubin, albumin.

scholarly journals Cell-free Expression of Proton-Coupled Folate Transporter in the Presence of Nanodiscs

2021 ◽  
Author(s):  
Hoa Quynh Do ◽  
Carla M Bassil ◽  
Elizabeth I Andersen ◽  
Michaela Jansen
Keyword(s):  
Tumor Cells ◽  
Plasma Membranes ◽  
In Vitro Translation ◽  
Translation System ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
E Coli ◽  
Membrane Scaffold ◽  
The Impact

The Proton-Coupled Folate Transporter (PCFT) is a transmembrane transport protein that controls the absorption of dietary folates in the small intestine. PCFT also mediates uptake of chemotherapeutically used antifolates into tumor cells. PCFT has been identified within lipid rafts observed in phospholipid bilayers of plasma membranes, a micro environment that is altered in tumor cells. The present study aimed at investigating the impact of different lipids within Lipid-protein nanodiscs (LPNs), discoidal lipid structures stabilized by membrane scaffold proteins, to yield soluble PCFT expression in an E. coli lysate-based cell-free transcription/translation system. In the absence of detergents or lipids, we observed PCFT quantitatively as precipitate in this system. We then explored the ability of LPNs to support solubilized PCFT expression when present during in-vitro translation. LPNs consisted of either dimyristoyl phosphatidylcholine (DMPC), palmitoyl-oleoyl phosphatidylcholine (POPC), or dimyristoyl phosphatidylglycerol (DMPG). While POPC did not lead to soluble PCFT expression, both DMPG and DMPC supported PCFT translation directly into LPNs, the latter in a concentration dependent manner. The results obtained through this study provide insights into the lipid preferences of PCFT. Membrane-embedded or solubilized PCFT will enable further studies with diverse biophysical approaches to enhance the understanding of the structure and molecular mechanism of folate transport through PCFT.

scholarly journals (R,S)-Ketamine Metabolites (R,S)-norketamine and (2S,6S)-hydroxynorketamine Increase the Mammalian Target of Rapamycin Function

2014 ◽  
Vol 121 (1) ◽  
pp. 149-159 ◽  
Author(s):  
Rajib K. Paul ◽  
Nagendra S. Singh ◽  
Mohammed Khadeer ◽  
Ruin Moaddel ◽  
Mitesh Sanghvi ◽  
...  
Keyword(s):  
Parent Compound ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Pathway ◽  
Target Of Rapamycin ◽  
Dependent Manner ◽  
Α7 Nicotinic Acetylcholine Receptor ◽  
Concentration Dependent Manner ◽  
Pheochromocytoma Cells ◽  
The Impact

Abstract Background: Subanesthetic doses of (R,S)-ketamine are used in the treatment of neuropathic pain and depression. In the rat, the antidepressant effects of (R,S)-ketamine are associated with increased activity and function of mammalian target of rapamycin (mTOR); however, (R,S)-ketamine is extensively metabolized and the contribution of its metabolites to increased mTOR signaling is unknown. Methods: Rats (n = 3 per time point) were given (R,S)-ketamine, (R,S)-norketamine, and (2S,6S)-hydroxynorketamine and their effect on the mTOR pathway determined after 20, 30, and 60 min. PC-12 pheochromocytoma cells (n = 3 per experiment) were treated with escalating concentrations of each compound and the impact on the mTOR pathway was determined. Results: The phosphorylation of mTOR and its downstream targets was significantly increased in rat prefrontal cortex tissue by more than ~2.5-, ~25-, and ~2-fold, respectively, in response to a 60-min postadministration of (R,S)-ketamine, (R,S)-norketamine, and (2S,6S)-hydroxynorketamine (P &lt; 0.05, ANOVA analysis). In PC-12 pheochromocytoma cells, the test compounds activated the mTOR pathway in a concentration-dependent manner, which resulted in a significantly higher expression of serine racemase with ~2-fold increases at 0.05 nM (2S,6S)-hydroxynorketamine, 10 nM (R,S)-norketamine, and 1,000 nM (R,S)-ketamine. The potency of the effect reflected antagonistic activity of the test compounds at the α7-nicotinic acetylcholine receptor. Conclusions: The data demonstrate that (R,S)-norketamine and (2S,6S)-hydroxynorketamine have potent pharmacological activity both in vitro and in vivo and contribute to the molecular effects produced by subanesthetic doses of (R,S)-ketamine. The results suggest that the determination of the mechanisms underlying the antidepressant and analgesic effects of (R,S)-ketamine requires a full study of the parent compound and its metabolites.

scholarly journals Interaction of Graphene Oxide Modified with Linear and Branched PEG with Monocytes Isolated from Human Blood

Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 126
Author(s):  
Pavel Khramtsov ◽  
Maria Bochkova ◽  
Valeria Timganova ◽  
Anton Nechaev ◽  
Sofya Uzhviyuk ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Immune Cells ◽  
Human Peripheral Blood ◽  
Oxide Surface ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Composition And Structure ◽  
Luminescent Signal ◽  
Ros Formation ◽  
The Impact

Multiple graphene-based therapeutics have recently been developed, however potential risks related to the interaction between nanomaterials and immune cells are still poorly understood. Therefore, studying the impact of graphene oxide on various populations of immune cells is of importance. In this work, we aimed to investigate the effects of PEGylated graphene oxide on monocytes isolated from human peripheral blood. Graphene oxide nanoparticles with lateral sizes of 100–200 nm and 1–5 μm were modified with linear and branched PEG (GO-PEG). Size, elemental composition, and structure of the resulting nanoparticles were characterized. We confirmed that PEG was successfully attached to the graphene oxide surface. The influence of GO-PEG on the production of reactive oxygen species (ROS), cytokines, phagocytosis, and viability of monocytes was studied. Uptake of GO-PEG by monocytes depends on PEG structure (linear or branched). Branched PEG decreased the number of GO-PEG nanoparticles per monocyte. The viability of monocytes was not altered by co-cultivation with GO-PEG. GO-PEG decreased the phagocytosis of Escherichia coli in a concentration-dependent manner. ROS formation by monocytes was determined by measuring luminol-, lucigenin-, and dichlorodihydrofluorescein-dependent luminescence. GO-PEG decreased luminescent signal probably due to inactivation of ROS, such as hydroxyl and superoxide radicals. Some types of GO-PEG stimulated secretion of IL-10 by monocytes, but this effect did not correlate with their size or PEG structure.

scholarly journals Size of Cells and Physicochemical Properties of Membranes are Related to Flavor Production during Sake Brewing in the Yeast Saccharomyces cerevisiae

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 440
Author(s):  
Tsuyoshi Yoda ◽  
Tomoaki Saito
Keyword(s):  
Isoamyl Alcohol ◽  
Lipid Vesicles ◽  
Caproic Acid ◽  
Yeast Cells ◽  
Dependent Manner ◽  
Yeast Saccharomyces Cerevisiae ◽  
Concentration Dependent Manner ◽  
Generalized Polarization ◽  
Flavor Components ◽  
The Impact

Ethyl caproate (EC) and isoamyl acetate (IA) are key flavor components of sake. Recently, attempts have been made to increase the content of good flavor components, such as EC and IA, in sake brewing. However, the functions of EC and IA in yeast cells remain poorly understood. Therefore, we investigated the effects of EC and IA using cell-sized lipid vesicles. We also investigated lipid vesicles containing EC and/or caproic acid (CA) as well as IA and/or isoamyl alcohol (IAA). CA and IAA are precursors of EC and IA, respectively, and are important flavors in sake brewing. The size of a vesicle is influenced by flavor compounds and their precursors in a concentration-dependent manner. We aimed to establish the conditions in which the vesicles contained more flavors simultaneously and with different ratios. Interestingly, vesicles were largest in a mixture of 50% of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) with 25% EC and 25% CA or a mixture of 50% DOPC with 25% IA and 25% IAA. The impact of flavor additives on membrane fluidity was also studied using Laurdan generalized polarization. During the production process, flavors may regulate the fluidity of lipid membranes.

Sign in / Sign up

Export Citation Format

Share Document