The use of chemical uncouplers for reducing biomass production during biodegradation

1998 ◽  
Vol 37 (4-5) ◽  
pp. 399-402 ◽  
Author(s):  
Euan W. Low ◽  
Howard A. Chase
Keyword(s):  
Biomass Production ◽  
Cell Mass ◽  
Model System ◽  
Energy Requirements ◽  
Simultaneous Increase ◽  
Maintenance Energy ◽  
Specific Substrate ◽  
Substrate Uptake ◽  
Activated Sludge Process ◽  
Substrate Uptake Rate

Reducing the energy available for anabolism of cell mass was identified as a method to minimise disposal requirements of excess biomass produced in the activated sludge process. A model system consisting of Pseudomonas putida, maintained in a chemostat, was employed to investigate biomass production in the presence of the energy dissipating protonphore, p-nitrophenol (pNP). The efficiency of biomass production was reduced by up to 62% when the feed was supplemented with 100 mg pNP.l−1 with a simultaneous increase in the specific substrate uptake rate. The data obtained have been analysed to reveal maintenance energy requirements and true growth yields. Cells were found to satisfy their maintenance energy requirements prior to utilising energy in anabolism. Decreases in pH alone had no effect on biomass production, but caused additional protonphore induced reduction of biomass production. A pH 6.2 the efficiency of biomass production was reduced by up to 77% when the feed was supplemented with 100 mg pNP.l−1.

Biodegradation of phenolic compounds by an acclimated activated sludge and isolated bacteria

1998 ◽  
Vol 37 (4-5) ◽  
pp. 371-378 ◽  
Author(s):  
Germán Buitrón ◽  
Ariel González ◽  
Luz M. López-Marín
Keyword(s):  
Activated Sludge ◽  
Uptake Rate ◽  
Specific Substrate ◽  
Substrate Uptake ◽  
Pseudomonas Sp ◽  
Uptake Rates ◽  
Viable Biomass ◽  
Substrate Uptake Rate ◽  
Chryseomonas Luteola ◽  
Acclimated Activated Sludge

The degradation of a mixture of phenol, 4-chlorophenol (4CP), 2,4-dichlorophenol (24DCP) and 2,4,6-trichlorophenol (246TCP) by acclimated activated sludge and by isolated bacteria was studied. Activated sludge was acclimated for 70 days to 40 mg phenols/l then the microorganisms responsible for the CP degradation were isolated and identified. Four types of Gram-negative bacteria (Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, and Chryseomonas luteola) were identified. Also, two acid-fast bacilli with distinct glycolipid patterns were isolated. From their chemical composition and their growth characteristics, both isolates appeared to be mycobacteria closely related to Mycobacterium peregrinum. The degradation kinetics of each phenol by Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, Chryseomonas luteola and activated sludge were determined. The acclimated activated sludge degradation rates were from one to two orders of magnitude higher than those of pure strains when uptake rates were calculated in terms of the viable biomass (CFU). The specific substrate uptake rate for acclimated activated sludge varied between 8.2 and 15.8 × 10−7 mg/CFU·d (407-784 mg/gVSS·d). Aeromonas sp. had the highest specific substrate uptake rate of the pure strains, based on a VSS basis (33-57 mg/gVSS·d) but, in terms of viable biomass (5.0-15.6 × 10−8 mg/CFU·d), the Pseudomonas sp. rate was the highest. Specific substrate uptake rates were 1.8 mg chlorinated phenols/g VSS·d for unacclimated activated sludge.

The Roles of Intracellular Organic Storage Materials in the Selection of Microorganisms in Activated Sludge

1991 ◽  
Vol 23 (4-6) ◽  
pp. 889-898 ◽  
Author(s):  
T. Kohno ◽  
K. Yoshina ◽  
S. Satoh
Keyword(s):  
Activated Sludge ◽  
Uptake Rate ◽  
Selective Advantage ◽  
Specific Substrate ◽  
Substrate Uptake ◽  
Storage Materials ◽  
Continuous Feeding ◽  
Selection Of Microorganisms ◽  
Substrate Uptake Rate ◽  
Selection Of

The nature of organic energy reserves, and their relation to the microbial selection in activated sludge were of interest. The cellular carbohydrate and PHB were first examined in relation to their accumulation and degradation with activated sludge cultivated on glucose under batch and continuous feeding conditions. Then, CH accumulation was related with substrate uptake rate using activated sludge bearing different amounts of storage materials for both sludge. The cellular carbohydrate and PHB were of prime importance with both activated sludge. However, cellular carbohydrate was accumulated and decomposed more readily compared with PHB. The accumulation of cellular carbohydrate retarded its synthesis as well as glucose uptake. While no such relation was observed with PHB. The cellular carbohydrate accumulation capacity and attainable maximum specific substrate uptake rate were far greater for the batch-wise-fed activated sludge. Thus, the ability to accumulate cellular carbohydrate was found to be a prime selective advantage for floc formers in batch-wise-fed activated sludge. On the other hand, a sudden drastic stimulation of Sphaerotilusnatans in the continuously-fed activated sludge could not be well explained even though aided with Chudoba's kinetic selection theory.

Modeling of mass transfer in biofilms in oscillatory flow conditions using k-ɛ turbulence model

2003 ◽  
Vol 3 (1-2) ◽  
pp. 201-207
Author(s):  
H. Nagaoka ◽  
T. Nakano ◽  
D. Akimoto
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Turbulence Model ◽  
Uptake Rate ◽  
Oscillatory Flow ◽  
Substrate Uptake ◽  
Flow Conditions ◽  
Mass Transfer Mechanism ◽  
Substrate Uptake Rate ◽  
Good Agreement

The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions. Numerical simulation of turbulence near a biofilm was conducted using the low Reynold’s number k-ɛ turbulence model. Substrate transfer in biofilms under oscillatory flow conditions was assumed to be carried out by turbulent diffusion caused by fluid movement and substrate concentration profile in biofilm was calculated. An experiment was carried out to measure velocity profile near a biofilm under oscillatory flow conditions and the influence of the turbulence on substrate uptake rate by the biofilm was also measured. Measured turbulence was in good agreement with the calculated one and the influence of the turbulence on the substrate uptake rate was well explained by the simulation.

scholarly journals Gene Expression Space Shapes the Bioprocess Trade-Offs among Titer, Yield and Productivity

2021 ◽  
Vol 11 (13) ◽  
pp. 5859
Author(s):  
Fernando N. Santos-Navarro ◽  
Yadira Boada ◽  
Alejandro Vignoni ◽  
Jesús Picó
Keyword(s):  
Gene Expression ◽  
Gene Transcription ◽  
Performance Metrics ◽  
Cell Mass ◽  
Gene Copy ◽  
Substrate Uptake ◽  
Promoter Strength ◽  
Expression Levels ◽  
Trade Offs ◽  
Wide Range

Optimal gene expression is central for the development of both bacterial expression systems for heterologous protein production, and microbial cell factories for industrial metabolite production. Our goal is to fulfill industry-level overproduction demands optimally, as measured by the following key performance metrics: titer, productivity rate, and yield (TRY). Here we use a multiscale model incorporating the dynamics of (i) the cell population in the bioreactor, (ii) the substrate uptake and (iii) the interaction between the cell host and expression of the protein of interest. Our model predicts cell growth rate and cell mass distribution between enzymes of interest and host enzymes as a function of substrate uptake and the following main lab-accessible gene expression-related characteristics: promoter strength, gene copy number and ribosome binding site strength. We evaluated the differential roles of gene transcription and translation in shaping TRY trade-offs for a wide range of expression levels and the sensitivity of the TRY space to variations in substrate availability. Our results show that, at low expression levels, gene transcription mainly defined TRY, and gene translation had a limited effect; whereas, at high expression levels, TRY depended on the product of both, in agreement with experiments in the literature.

scholarly journals Determination of Maintenance Energy Requirements for Fattening Castrated Korean Black Goats (Capra hircus coreanae)

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1543
Author(s):  
Sang-Ho Moon ◽  
Yeong Sik Yun ◽  
Na Yeon Kim ◽  
Sanguk Chung ◽  
Qi Man Zhang ◽  
...  
Keyword(s):  
Body Weight ◽  
Energy Intake ◽  
Energy Levels ◽  
Average Daily Gain ◽  
Nutrient Digestibility ◽  
Metabolic Energy ◽  
Energy Requirements ◽  
Capra Hircus ◽  
Maintenance Energy ◽  
Daily Gain

Twelve adult (10 months old) castrated Korean black goats, with an average initial body weight of 24.98 ± 3.7 kg, were used in this experiment to determine their maintenance energy requirements. Dry matter intakes (g/d, p = 0.945) were not affected by energy levels, but metabolic energy intake (kcal/d, p < 0.002) and average daily gain (g/d, p < 0.001) were significantly increased at higher energy levels. Nutrient digestibility was similar in the treatments, but crude fat digestibility increased with the addition of protective fat powder (p = 0.001). The energy required for fattening the castrated Korean black goats was estimated using the correlation between metabolic energy intake per dietary body weight and average daily gain per dietary body weight. The Y-axis intercept value was calculated to be 108.76 kcal/kg BW0.75 (p < 0.05, r2 = 0.6036), which was the metabolic energy requirement for maintaining the lives of the fattening Korean black goats. The estimated energy requirements of the black goat can improve specification techniques, such as the energy level and the amount of feed supply required for domestic black goats.

Maintenance energy requirements of grazing sheep: A detailed comparison between models

1984 ◽  
Vol 15 (1) ◽  
pp. 1-22 ◽  
Author(s):  
Daniel Wallach ◽  
Jean Michel Elsen ◽  
Jean Louis Charpenteau
Keyword(s):  
Detailed Comparison ◽  
Energy Requirements ◽  
Maintenance Energy ◽  
Grazing Sheep

scholarly journals Toward a systems approach to cytochrome P450 ensemble: interactions of CYP2E1 with other P450 species and their impact on CYP1A2

2019 ◽  
Vol 476 (23) ◽  
pp. 3661-3685 ◽  
Author(s):  
Nadezhda Y. Davydova ◽  
Bikash Dangi ◽  
Marc A. Maldonado ◽  
Nikita E. Vavilov ◽  
Victor G. Zgoda ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Human Liver ◽  
Systems Approach ◽  
Liver Microsomes ◽  
Model System ◽  
Human Liver Microsomes ◽  
Microsomal Membrane ◽  
Specific Substrate ◽  
Main Route ◽  
Functional Differences

In this study, we investigate the ability of ethanol-inducible CYP2E1 to interact with other cytochrome P450 species and affect the metabolism of their substrates. As a model system, we used CYP2E1-enriched human liver microsomes (HLM) obtained by the incorporation of purified CYP2E1. Using a technique based on homo-FRET in oligomers of CYP2E1 labeled with BODIPY 577/618 maleimide we demonstrated that the interactions of CYP2E1 with HLM result in the formation of its mixed oligomers with other P450 species present in the microsomal membrane. Incorporation of CYP2E1 results in a multifold increase in the rate of metabolism of CYP2E1-specific substrates p-Nitrophenol and Chlorzaxozone. The rate of their oxidation remains proportional to the amount of incorporated CYP2E1 up to the content of 0.3–0.4 nmol/mg protein (or ∼50% CYP2E1 in the P450 pool). The incorporated CYP2E1 becomes a fully functional member of the P450 ensemble and do not exhibit any detectable functional differences with the endogenous CYP2E1. Enrichment of HLM with CYP2E1 results in pronounced changes in the metabolism of 7-ethoxy-4-cyanocoumarin (CEC), the substrate of CYP2C19 and CYP1A2 suggesting an increase in the involvement of the latter in its metabolism. This effect goes together with an augmentation of the rate of dealkylation of CYP1A2-specific substrate 7-ethoxyresorufin. Furthermore, probing the interactions of CYP2E1 with model microsomes containing individual P450 enzymes we found that CYP2E1 efficiently interacts with CYP1A2, but lacks any ability to form complexes with CYP2C19. This finding goes inline with CYP2E1-induced redirection of the main route of CEC metabolism from CYP2C19 to CYP1A2.

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