scholarly journals Effects of the Photosystem II Inhibitors CCCP and DCMU on Hydrogen Production by the Unicellular Halotolerant CyanobacteriumAphanothece halophytica

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Sunisa Pansook ◽  
Aran Incharoensakdi ◽  
Saranya Phunpruch
Keyword(s):  
Photosystem Ii ◽  
Respiration Rate ◽  
Dry Weight ◽  
Hydrogenase Activity ◽  
Dark Incubation ◽  
Carbonyl Cyanide ◽  
Bidirectional Hydrogenase ◽  
Splitting Water ◽  
Inhibitor Treatment ◽  
In Cells

The unicellular halotolerant cyanobacteriumAphanothece halophyticais a potential dark fermentative producer of molecular hydrogen (H2) that produces very little H2under illumination. One factor limiting the H2photoproduction of this cyanobacterium is an inhibition of bidirectional hydrogenase activity by oxygen (O2) obtained from splitting water molecules via photosystem II activity. The present study aimed to investigate the effects of the photosystem II inhibitors carbonyl cyanide m-chlorophenyl hydrazone (CCCP) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on H2production ofA.halophyticaunder light and dark conditions and on photosynthetic and respiratory activities. The results showed thatA.halophyticatreated with CCCP and DCMU produced H2at three to five times the rate of untreated cells, when exposed to light. The highest H2photoproduction rates,2.26 ± 0.24and3.63 ± 0.26  μmol H2 g−1dry weight h−1, were found in cells treated with 0.5μM CCCP and 50μM DCMU, respectively. Without inhibitor treatment,A.halophyticaincubated in the dark showed a significant increase in H2production compared with cells that were incubated in the light. Only CCCP treatment increased H2production ofA.halophyticaduring dark incubation, because CCCP functions as an uncoupling agent of oxidative phosphorylation. The highest dark fermentative H2production rate of39.50 ± 2.13  μmol H2 g−1dry weight h−1was found in cells treated with 0.5μM CCCP after 2 h of dark incubation. Under illumination, CCCP and DCMU inhibited chlorophyll fluorescence, resulting in a low level of O2, which promoted bidirectional hydrogenase activity inA.halophyticacells. In addition, only CCCP enhanced the respiration rate, further reducing the O2level. In contrast, DCMU reduced the respiration rate inA.halophytica.

scholarly journals Accumulation of Norfloxacin byBacteroides fragilis

2000 ◽  
Vol 44 (9) ◽  
pp. 2361-2366 ◽  
Author(s):  
Vito Ricci ◽  
Laura J. V. Piddock
Keyword(s):  
Dry Weight ◽  
Aerobic Bacteria ◽  
External Concentration ◽  
Low Concentrations ◽  
Carbonyl Cyanide ◽  
The Mean ◽  
Time Required ◽  
State Concentration ◽  
Anaerobic Environment ◽  
Burk Plot

ABSTRACT The accumulation of norfloxacin by Bacteroides fragilisNCTC 9343 was determined by the modified fluorescence method. The time required to achieve a steady-state concentration (SSC) after allowingB. fragilis to accumulate norfloxacin in an aerobic or an anaerobic environment was ∼2 min; the SSC achieved in air was 90.28 ± 9.32 ng of norfloxacin/mg (dry weight) of cells, and that achieved anaerobically was 98.45 ± 3.7 ng of norfloxacin/mg (dry weight) of cells. Initial rates of accumulation were determined with a range of external concentrations, as up to 8 μg/ml the concentration of norfloxacin accumulated increased proportionally to the external concentration, 12.13 ng/mg (dry weight) of cells per μg of exogenous norfloxacin per ml. At concentrations above 10 μg/ml no increase in the rate of norfloxacin accumulation was observed. From the kinetic data, a Lineweaver-Burk plot calculated a Km of 5.03 μg/ml and a V max of 25.1 ng of norfloxacin/s. With an increase in temperature of between 0 and 30°C, the concentration of norfloxacin accumulated also increased proportionally at 4.722 ng of norfloxacin/mg (dry weight) of cells/°C. At low concentrations of glucose (<0.2%; 11 mM), the concentration of norfloxacin accumulated was decreased. With the addition of 100 μM carbonyl cyanidem-chlorophenylhydrazone (CCCP) the mean SSC of norfloxacin was increased to 116 ± 7.01 ng of norfloxacin/mg (dry weight) of cells; glucose had no significant effect in the presence of CCCP. Magnesium chloride (20 mM) decreased the SSC of norfloxacin to 40.5 ± 3.76 ng of norfloxacin per mg (dry weight) of cells. These data suggest that the mechanism of accumulation of norfloxacin byB. fragilis is similar to that of aerobic bacteria and that the fluoresence procedure is suitable for use with an anaerobic bacterium.

Influence of fertilizer treatment on apple fruit composition and physiology. II. Influence on respiration rate and contents of nitrogen, phosphorus, and titratable acidity

1969 ◽  
Vol 20 (6) ◽  
pp. 1073 ◽  
Author(s):  
DS Letham
Keyword(s):  
Nitrogen Content ◽  
Respiration Rate ◽  
Phosphorus Content ◽  
Titratable Acidity ◽  
Dry Weight ◽  
Apple Fruit ◽  
Fertilizer Treatment ◽  
Soluble Nitrogen ◽  
Tissue Contents ◽  
Nitrogen Phosphorus

The respiration rates and tissue contents of nitrogen, phosphorus, and titratable acidity were determined for apple fruit from trees receiving differential fertilizer treatments U, N, P, NP, and NPK (U, no fertilizer; N, 2 lb ammonium sulphate; P, 4 1b superphosphate; and K, 1 Ib potassium sulphate, per tree per year). The results obtained (expressed on a dry weight basis) are summarized as follows: Respiration rate: N > NP = NPK = U > P. Total nitrogen content: NPK > NP = N > U = P. Ethanol-insoluble nitrogen content: NPK = NP = N > U = P. Ethanol-soluble nitrogen content: NPK > NP = N > U = P. Phosphorus content : P > NP = NPK > U > N. Titratable acidity content: NPK > N > NP = U > P. The incidence of internal breakdown in stored fruit from these treatments has positively correlated with respiration rate per cell and negatively correlated with phosphorus content. Phosphorus content was negatively correlated with cell volume and respiration rate. Mechanisms by which phosphorus content might regulate the incidence of internal breakdown are discussed.

scholarly journals Growth of the facultative chemolithoautotroph Ralstonia eutropha on organic waste materials: growth characteristics, redox regulation and hydrogenase activity

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Anna Poladyan ◽  
Syuzanna Blbulyan ◽  
Mayramik Sahakyan ◽  
Oliver Lenz ◽  
Armen Trchounian
Keyword(s):  
Fuel Cells ◽  
Redox Regulation ◽  
Ralstonia Eutropha ◽  
Membrane Vesicles ◽  
Dry Weight ◽  
Negative Influence ◽  
Model Organisms ◽  
Hydrogenase Activity ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential

Abstract Background The chemolithoautotrophic β-proteobacterium Ralstonia eutropha H16 (Cupriavidus necator) is one of the most studied model organisms for growth on H2 and CO2. R. eutropha H16 is also a biologically significant bacterium capable of synthesizing O2-tolerant [NiFe]-hydrogenases (Hyds), which can be used as anode biocatalysts in enzyme fuel cells. For heterotrophic growth of R. eutropha, various sources of organic carbon and energy can be used. Results Growth, bioenergetic properties, and oxidation–reduction potential (ORP) kinetics were investigated during cultivation of R. eutropha H16 on fructose and glycerol or lignocellulose-containing brewery spent grain hydrolysate (BSGH). BSGH was used as carbon and energy source by R. eutropha H16, and the activities of the membrane-bound hydrogenase (MBH) and cytoplasmic, soluble hydrogenase (SH) were measured in different growth phases. Growth of R. eutropha H16 on optimized BSGH medium yielded ~ 0.7 g cell dry weight L−1 with 3.50 ± 0.02 (SH) and 2.3 ± 0.03 (MBH) U (mg protein)−1 activities. Upon growth on fructose and glycerol, a pH drop from 7.0 to 6.7 and a concomitant decrease of ORP was observed. During growth on BSGH, in contrast, the pH and ORP stayed constant. The growth rate was slightly stimulated through addition of 1 mM K3[Fe(CN)6], whereas temporarily reduced growth was observed upon addition of 3 mM dithiothreitol. The overall and N,N′-dicyclohexylcarbodiimide-sensitive ATPase activities of membrane vesicles were ~ 4- and ~ 2.5-fold lower, respectively, upon growth on fructose and glycerol (FGN) compared with only fructose utilization (FN). Compared to FN, ORP was lower upon bacterial growth on FGN, GFN, and BSGH. Conclusions Our results suggest that reductive conditions and low ATPase activity might be signals for energy depletion, which, in turn, leads to increased hydrogenase biosynthesis to overcome this unfavorable situation. Addition of fructose or microelements have no, or a negative, influence on hydrogenase activity. Organic wastes (glycerol, BSGH) are promising carbon and energy sources for the formation of biomass harboring significant amounts of the biotechnologically relevant hydrogenases MBH and SH. The results are valuable for using microbial cells as producers of hydrogenase enzymes as catalysts in enzymatic fuel cells.

Patterns of Variation in The Prosome Length of Overwintering Stage V Copepodites of Calanus Finmarchicus in The Firth of Clyde

1981 ◽  
Vol 61 (4) ◽  
pp. 885-899 ◽  
Author(s):  
H. Grigg ◽  
S. J. Bardwell ◽  
S. Tyzack
Keyword(s):  
Respiration Rate ◽  
Biochemical Composition ◽  
Biological Response ◽  
Dry Weight ◽  
Sexual Differences ◽  
Calanus Finmarchicus ◽  
Calanoid Copepods ◽  
Prosome Length ◽  
Environmental Fluctuations ◽  
Males And Females

In attributing variations in growth and metabolism within a population to environmental fluctuations, and in interpreting the biological response to environmental fluctuations, it is important to recognize the variations that are intrinsic to the population or species. Consequently, it is common practice in studies on the growth and metabolism of calanoid copepods to separate instars and, in the case of adults, males and females when analysing measurements. Although studies on calanoids, in particular species of Calanus and Euchaeta, have demonstrated the existence of pronounced sexual differences in parameters such as dry weight, biochemical composition and respiration rate (e.g. Comita, Marshall & Orr, 1966; Marshall, 1973; Bamstedt, 1975, 1979; Gatten et al. 1979, 1980), the possibility that similar differences might occur in pre-adult instars has not been examined, this despite the fact that in many species in this group it is possible to distinguish the sex of copepodites IV and V, the two instars preceding the adult.

The respiration rate and loss of dry matter from stored bran

1945 ◽  
Vol 35 (3) ◽  
pp. 126-132 ◽  
Author(s):  
Douglas Snow ◽  
Norman C. Wright
Keyword(s):  
Moisture Content ◽  
Respiration Rate ◽  
Total Nitrogen ◽  
Dry Matter ◽  
Dry Weight ◽  
Air Stream ◽  
Continuous Absorption ◽  
High Respiration Rate ◽  
Micro Organisms ◽  
Absorption Apparatus

1. Experiments were made on the respiration of bran at different moisture levels using a continuous absorption apparatus in which the humidity of the air-stream was adjusted to be at equilibrium with the respiring bran. The rate of respiration was accelerated with increasing moisture content and was very rapid deterioration due to the high respiration rate and microbiological damage.2. Experiments were made on the storage of bran at known moisture contents in closed tins in the laboratory and also in sacks kept under farm conditions. The total nitrogen content of the bran stored in the tins appeared to increase during storage. From similar increases in total phosphorus, it is clear that the increase in total nitrogen was caused by a loss of dry matter from the stored feeding stuff, a fact which was further demonstrated by the loss in dry weight of the sacks of bran with attributed to two causes: (1) the respiration of the plant cells still active in the bran itself, and (2) the respiration of developing micro-organisms. It is evident from these experiments that fresh bran, free from insect infestation and stored at a moisture content of less than 13%, will have a very low respiration rate and will, therefore, not be liable to heating. Bran of 15–19% moisture content respires at a much faster rate and the time for which such material can be stored with freedom from heating or other types of deterioration will be limited.

scholarly journals Changes in Dry Weight and Respiration Rate in Konjak Seed Corms during Storage.

1999 ◽  
Vol 68 (3) ◽  
pp. 419-423
Author(s):  
Kunio MIURA ◽  
Yoshiharu WADA ◽  
Kazuyuki WATANABE
Keyword(s):  
Respiration Rate ◽  
Dry Weight

Rational Utilization of Photoelectrochemistry of Photosystem II for Self-Powered Photocathodic Detection of MicroRNA in Cells

2021 ◽  
Author(s):  
Li-Bang Zhu ◽  
Hai-Yan Wang ◽  
Tian-Yang Zhang ◽  
Feng-Zao Chen ◽  
De-Man Han ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Rational Utilization ◽  
Self Powered ◽  
In Cells

scholarly journals Analytic studies in plant respiration VII—Aerobic respiration in barley seedlings and its relation to growth and carbohydrate supply

1937 ◽  
Vol 123 (832) ◽  
pp. 321-342 ◽  
Keyword(s):  
Respiration Rate ◽  
Carbon Metabolism ◽  
Dry Matter ◽  
Dry Weight ◽  
Numerical Comparison ◽  
Carbohydrate Reserves ◽  
Common Basis ◽  
Oxygen Medium ◽  
Plant Respiration ◽  
Hydrolysis Of

Preliminary to a study of seedling respiration as affected by varying concentrations of oxygen, some sets of experiments were carried out in air as a standard oxygen medium. In these experiments growth was also measured and the relation between the rates of these two processes was determined. The major features of the carbon metabolism in the young seedling are, (1) hydrolysis of starch in the endosperm, (2) formation of new dry matter in the embryo by growth, (3) respiration of carbohydrates to carbon dioxide and water in both endosperm and embryo. By relating (1) with (2) and (3) we arrive at (4) the rate of translocation of carbohydrates from endosperm to embryo. All these activities may be expressed, for numerical comparison, in terms of hexose units per unit of time, so that it is possible to survey, on this common basis, the balance and relative rates of these processes. The rates of the component parts of the system are to be labelled as follows: H , production rate of liexoses by hydrolysis of carbohydrate reserves in the endosperm; R 1 ,respiration rate of hexoses in the endosperm; T , translocation rate of hexoses from the endosperm to the embryo; R 2 , the respiration rate of the embryo; G , the rate of growth of dry weight of the embryo material. We may add to this series P (as a subsection of G ) the rate of transitory deposition in the embryo of mobile reversible carbohydrate reserves such as starch, which are later available for respiration. G less P would stand for the irreversible growth of new tissue substance, in a restrictive sense, while G stands for the whole dry-weight increase.

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