scholarly journals PAOX1 expression in mixed-substrate continuous cultures of Komagataella phaffii (Pichia pastoris) is completely determined by methanol uptake regardless of the secondary carbon source: a simplifying principle for predicting recombinant protein production.

2021 ◽  
Author(s):  
Anamika Singh ◽  
Atul Narang
Keyword(s):  
Carbon Source ◽  
Oxygen Demand ◽  
Continuous Cultures ◽  
Mixed Substrate ◽  
Komagataella Phaffii ◽  
Uptake Rates ◽  
Wide Range ◽  
Hyperbolic Curve ◽  
Expression Rate ◽  
Secondary Carbon

The expression of recombinant proteins by the AOX1 promoter of Komagataella phaffii is typically induced by adding methanol to the cultivation medium. Since growth on methanol imposes a high oxygen demand, the medium is often supplemented with an additional "secondary" carbon source which serves to reduce the consumption of methanol, and hence, oxygen. Early research recommended the use of glycerol as the secondary carbon source, but more recent studies recommend the use of sorbitol because glycerol represses PAOX1 expression. To assess the validity of this recommendation, we measured the steady state concentrations of biomass, residual methanol, and AOX1 over a wide range of dilution rates (0.02-0.20 h-1) in continuous cultures of the Mut+ strain fed with methanol, methanol + glycerol, and methanol + sorbitol. We find that when the specific AOX1 expression and methanol uptake rates for each of the three feeds are plotted against each other, they collapse into a single hyperbolic curve. The specific AOX1 expression rate is therefore completely determined by the specific methanol uptake rate regardless of the existence (present/absent) and type (repressing/non-repressing) of the secondary carbon source. In particular, cultures fed with methanol + glycerol and methanol + sorbitol that consume methanol at equal rates also express the protein at equal rates and levels. Now, it turns out that the simple unstructured model developed by Egli and co-workers can predict the specific methanol uptake rates of single- and mixed-substrate cultures over a wide range of dilution rates and feed concentrations. By combining this model with our data, we derive simple formulas that predicts the protein expression rates and levels of single- and mixed-substrate cultures over a wide range of conditions.

scholarly journals Assessment of Voltage Influence in Carbon Dioxide Fixation Process by a Photo-Bioelectrochemical System under Photoheterotrophy

2021 ◽  
Vol 9 (3) ◽  
pp. 474
Author(s):  
Sara Díaz-Rullo Edreira ◽  
Silvia Barba ◽  
Ioanna A. Vasiliadou ◽  
Raúl Molina ◽  
Juan Antonio Melero ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Source ◽  
Future Development ◽  
Metabolic Pathways ◽  
Co2 Fixation ◽  
Oxygen Demand ◽  
Carbon Uptake ◽  
Bioelectrochemical System ◽  
Electron Sink ◽  
Soluble Carbon

Bioelectrochemical systems are a promising technology capable of reducing CO2 emissions, a renewable carbon source, using electroactive microorganisms for this purpose. Purple Phototrophic Bacteria (PPB) use their versatile metabolism to uptake external electrons from an electrode to fix CO2. In this work, the effect of the voltage (from −0.2 to −0.8 V vs. Ag/AgCl) on the metabolic CO2 fixation of a mixed culture of PPB under photoheterotrophic conditions during the oxidation of a biodegradable carbon source is demonstrated. The minimum voltage to fix CO2 was between −0.2 and −0.4 V. The Calvin–Benson–Bassham (CBB) cycle is the main electron sink at these voltages. However, lower voltages caused the decrease in the current intensity, reaching a minimum at −0.8 V (−4.75 mA). There was also a significant relationship between the soluble carbon uptake in terms of chemical oxygen demand and the electron consumption for the experiments performed at −0.6 and −0.8 V. These results indicate that the CBB cycle is not the only electron sink and some photoheterotrophic metabolic pathways are also being affected under electrochemical conditions. This behavior has not been tested before in photoheterotrophic conditions and paves the way for the future development of photobioelectrochemical systems under heterotrophic conditions.

Short-term effects of carbon source on the competition of polyphosphate accumulating organisms and glycogen accumulating organisms

2004 ◽  
Vol 50 (10) ◽  
pp. 139-144 ◽  
Author(s):  
A. Oehmen ◽  
Z. Yuan ◽  
L.L. Blackall ◽  
J. Keller
Keyword(s):  
Carbon Source ◽  
In Situ Hybridisation ◽  
Operating Conditions ◽  
Fluorescence In Situ Hybridisation ◽  
Biological Phosphorus Removal ◽  
Short Term ◽  
Uptake Rates ◽  
Polyphosphate Accumulating Organisms ◽  
The Impact ◽  
Short Term Effects

The effectiveness of enhanced biological phosphorus removal (EBPR) systems is directly affected by the competition of polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). This study investigated the short-term effects of carbon source on PAO and GAO performance. The tests were designed to clearly determine the impact of volatile fatty acid (VFA) composition on the performance of two types of biomass, one enriched for PAOs and the other for GAOs. The two populations were enriched in separate reactors using identical operating conditions and very similar influent compositions with acetate as the sole carbon source. The only difference was that a very low level of phosphorus was present in the influent to the GAO reactor. The abundance of PAOs and GAOs was quantified using fluorescence in-situ hybridisation. The results clearly show that there are some very distinctive differences between PAOs and GAOs in their ability to utilise different carbon substrates. While both are able to take up acetate rapidly and completely, the GAOs are far slower at consuming propionate than the PAOs during short-term substrate changes. This provides a potentially highly valuable avenue to influence the competition between PAOs and GAOs. Other VFAs studied seem to be less usable in the short term by both PAOs and GAOs, as indicated by their much lower uptake rates.

Novel biofilm reactor for denitrification of municipal wastewater

2018 ◽  
Vol 78 (7) ◽  
pp. 1566-1575 ◽  
Author(s):  
S. S. Rathnaweera ◽  
B. Rusten ◽  
K. Korczyk ◽  
B. Helland ◽  
E. Rismyhr
Keyword(s):  
Carbon Source ◽  
Municipal Wastewater ◽  
Low Cost ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Biofilm Reactor ◽  
Treated Wastewater ◽  
Removal Rates ◽  
Good Filter ◽  
Solids Removal

Abstract A pilot-scale CFIC® (continuous flow intermittent cleaning) reactor was run in anoxic conditions to study denitrification of wastewater. The CFIC process has already proven its capabilities for biological oxygen demand removal with a small footprint, less energy consumption and low cost. The present study focused on the applicability for denitrification. Both pre-denitrification (pre-DN) and post-denitrification (post-DN) were tested. A mixture of primary treated wastewater and nitrified wastewater was used for pre-DN and nitrified wastewater with ethanol as a carbon source was used for post-DN. The pre-DN process was carbon limited and removal rates of only 0.16 to 0.74 g NOx-N/m²-d were obtained. With post-DN and an external carbon source, 0.68 to 2.2 g NO3-Neq/m²-d removal rates were obtained. The carrier bed functioned as a good filter for both the larger particles coming with influent water and the bio-solids produced in the reactor. Total suspended solids removal in the reactor varied from 20% to 78% (average 45%) during post-DN testing period and 9% to 70% (average 29%) for pre-DN. The results showed that the forward flow washing improves both the DN function and filtration ability of the reactor.

scholarly journals Adaptation limits ecological diversification and promotes ecological tinkering during the competition for substitutable resources

2018 ◽  
Vol 115 (44) ◽  
pp. E10407-E10416 ◽  
Author(s):  
Benjamin H. Good ◽  
Stephen Martis ◽  
Oskar Hallatschek
Keyword(s):  
Evolutionary Dynamics ◽  
Competitive Exclusion ◽  
Directional Selection ◽  
Ecological Niches ◽  
Ecological Diversification ◽  
Effective Competition ◽  
Uptake Rates ◽  
Wide Range ◽  
Dynamical Features ◽  
Adaptation Limits

Microbial communities can evade competitive exclusion by diversifying into distinct ecological niches. This spontaneous diversification often occurs amid a backdrop of directional selection on other microbial traits, where competitive exclusion would normally apply. Yet despite their empirical relevance, little is known about how diversification and directional selection combine to determine the ecological and evolutionary dynamics within a community. To address this gap, we introduce a simple, empirically motivated model of eco-evolutionary feedback based on the competition for substitutable resources. Individuals acquire heritable mutations that alter resource uptake rates, either by shifting metabolic effort between resources or by increasing the overall growth rate. While these constitutively beneficial mutations are trivially favored to invade, we show that the accumulated fitness differences can dramatically influence the ecological structure and evolutionary dynamics that emerge within the community. Competition between ecological diversification and ongoing fitness evolution leads to a state of diversification–selection balance, in which the number of extant ecotypes can be pinned below the maximum capacity of the ecosystem, while the ecotype frequencies and genealogies are constantly in flux. Interestingly, we find that fitness differences generate emergent selection pressures to shift metabolic effort toward resources with lower effective competition, even in saturated ecosystems. We argue that similar dynamical features should emerge in a wide range of models with a mixture of directional and diversifying selection.

scholarly journals Modelization of Nutrient Removal Processes at a Large WWTP Using a Modified ASM2d Model

2018 ◽  
Vol 15 (12) ◽  
pp. 2817 ◽  
Author(s):  
Jakub Drewnowski ◽  
Jacek Makinia ◽  
Lukasz Kopec ◽  
Francisco-Jesus Fernandez-Morales
Keyword(s):  
Nutrient Removal ◽  
Carbon Sources ◽  
Oxygen Demand ◽  
Full Scale ◽  
Biological Nutrient Removal ◽  
Organic Substrates ◽  
Modified Model ◽  
Rate Limiting Step ◽  
Uptake Rates ◽  
Rate Limiting

The biodegradation of particulate substrates starts by a hydrolytic stage. Hydrolysis is a slow reaction and usually becomes the rate limiting step of the organic substrates biodegradation. The objective of this work was to evaluate a novel hydrolysis concept based on a modification of the activated sludge model (ASM2d) and to compare it with the original ASM2d model. The hydrolysis concept was developed in order to accurately predict the use of internal carbon sources in enhanced biological nutrient removal (BNR) processes at a full scale facility located in northern Poland. Both hydrolysis concepts were compared based on the accuracy of their predictions for the main processes taking place at a full-scale facility. From the comparison, it was observed that the modified ASM2d model presented similar predictions to those of the original ASM2d model on the behavior of chemical oxygen demand (COD), NH4-N, NO3-N, and PO4-P. However, the modified model proposed in this work yield better predictions of the oxygen uptake rate (OUR) (up to 5.6 and 5.7%) as well as in the phosphate release and uptake rates.

scholarly journals Cost Effective Method for Toxicity Screening of Pharmaceutical Wastewater Containing Inorganic Salts and Harmful Organic Compounds

2019 ◽  
Vol 23 (1) ◽  
pp. 52-63 ◽  
Author(s):  
Elina Strade ◽  
Daina Kalnina
Keyword(s):  
Activated Sludge ◽  
Biological Treatment ◽  
Oxygen Demand ◽  
Cost Effective ◽  
Practical Implementation ◽  
Toxicity Screening ◽  
Pharmaceutical Wastewater ◽  
Cost Effective Method ◽  
Wide Range ◽  
Wastewater Biological Treatment

Abstract Pharmaceutical wastewater biological treatment plants are stressed with multi-component wastewater and unexpected variations in wastewater flow, composition and toxicity. To avoid operational problems and reduced wastewater treatment efficiency, accurate monitoring of influent toxicity on activated sludge microorganisms is essential. This paper outlines how to predict highly toxic streams, which should be avoided, using measurements of biochemical oxygen demand (BOD), if they are made in a wide range of initial concentration. The results indicated that wastewater containing multivalent Al3+ cations showed a strong toxic effect on activated sludge biocenosis irrespectively of dilutions, while toxicity of phenol and formaldehyde containing wastewater decreased considerably with increasing dilution. Activated sludge microorganisms were not sensitive to wastewater containing halogenated sodium salts (NaCl, NaF) and showed high treatment capacity of saline wastewater. Our findings confirm that combined indicators of contamination, such as chemical oxygen demand (COD), alone do not allow evaluating potential toxic influence of wastewater. Obtained results allow identifying key inhibitory substances in pharmaceutical wastewater and evaluating potential impact of new wastewater streams or increased loading on biological treatment system. Proposed method is sensitive and cost effective and has potential for practical implementation in multiproduct pharmaceutical wastewater biological treatment plants.

scholarly journals First in situ estimations of small phytoplankton carbon and nitrogen uptake rates in the Kara, Laptev, and East Siberian seas

2018 ◽  
Author(s):  
Bhavya P. Sadanandan ◽  
Jang Han Lee ◽  
Ho Won Lee ◽  
Jae Joong Kaang ◽  
Jae Hyung Lee ◽  
...  
Keyword(s):  
Sea Ice ◽  
Nitrogen Uptake ◽  
N Uptake ◽  
Total Carbon ◽  
The Arctic ◽  
Carbon And Nitrogen ◽  
Uptake Rates ◽  
Wide Range ◽  
Small Phytoplankton

Abstract. Carbon and nitrogen uptake rates by small phytoplankton (0.7–5 μm) in the Kara, Laptev, and East Siberian seas in the Arctic Ocean were quantified using in situ isotope labelling experiments for the first time as part of the NABOS (Nansen and Amundsen Basins Observational System) program during August 21 to September 22, 2013. The depth integrated C, NO3−, and NH4+ uptake rates by small phytoplankton showed a wide range from 0.54 to 15.96 mg C m−2 h−1, 0.05 to 1.02 and 0.11 to 3.73 mg N m−2 h−1, respectively. The contributions of small phytoplankton towards the total C, NO3−, and NH4+ was varied from 24 to 89 %, 32 to 89 %, and 28 to 89 %, respectively. The turnover times for NO3− and NH4+ by small phytoplankton during the present study point towards the longer residence times (years) of the nutrients in the deeper waters, particularly for NO3−. Relatively, higher C and N uptake rates by small phytoplankton obtained during the present study at locations with less sea ice concentrations points towards the possibility of small phytoplankton thrive under sea ice retreat under warming conditions. The high contributions of small phytoplankton towards the total carbon and nitrogen uptake rates suggest capability of small size autotrophs to withstand in the adverse hydrographic conditions introduced by climate change.

scholarly journals Sucking or lapping: facultative feeding mechanisms in honeybees ( Apis mellifera )

2020 ◽  
Vol 16 (8) ◽  
pp. 20200449
Author(s):  
Jiangkun Wei ◽  
Zixin Huo ◽  
Stanislav N. Gorb ◽  
Alejandro Rico-Guevara ◽  
Zhigang Wu ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Recent Literature ◽  
Sugar Content ◽  
Behavioural Flexibility ◽  
Low Viscosity ◽  
Uptake Rates ◽  
Wide Range ◽  
The One ◽  
Large Groups ◽  
Mode A

Nectarivorous insects generally adopt suction or lapping to extract nectar from flowers and it is believed that each species exhibits one specific feeding pattern. In recent literature, large groups of nectarivores are classified as either ‘suction feeders', imbibing nectar through their proboscis, or ‘lappers', using viscous dipping. Honeybees ( Apis mellifera ) are the well-known lappers by virtue of their hairy tongues. Surprisingly, we found that honeybees also employ active suction when feeding on nectar with low viscosity, defying their classification as lappers. Further experiments showed that suction yielded higher uptake rates when ingesting low-concentration nectar, while lapping resulted in faster uptake when ingesting nectar with higher sugar content. We found that the optimal concentration of suction mode in honeybees coincided with the one calculated for other typical suction feeders. Moreover, we found behavioural flexibility in the drinking mode: a bee is able to switch between lapping and suction when offered different nectar concentrations. Such volitional switching in bees can enhance their feeding capabilities, allowing them to efficiently exploit the variety of concentrations presented in floral nectars, enhancing their adaptability to a wide range of energy sources.

scholarly journals Lipid accumulation capability of typical non‐acclimated activated sludge microbial consortia using methane gas as secondary carbon source

2020 ◽  
Vol 2 (4) ◽  
Author(s):  
Dhan Lord B. Fortela ◽  
Wayne Sharp ◽  
Emmanuel Revellame ◽  
Andrei Chistoserdov ◽  
William Holmes ◽  
...  
Keyword(s):  
Carbon Source ◽  
Activated Sludge ◽  
Lipid Accumulation ◽  
Microbial Consortia ◽  
Methane Gas ◽  
Acclimated Activated Sludge ◽  
Secondary Carbon

Bioremediation of synthetic fatliquors under microaerobic condition

2016 ◽  
Vol 75 (5) ◽  
pp. 1118-1127 ◽  
Author(s):  
B. Umamaheswari ◽  
K. Priya ◽  
Rama Rajaram
Keyword(s):  
Oxygen Demand ◽  
Polar Compounds ◽  
Industrial Applications ◽  
Gas Chromatography Mass Spectrometry ◽  
Microaerobic Condition ◽  
Wide Range ◽  
End Products ◽  
Emulsifying Agent ◽  
Microaerobic Conditions ◽  
Layer Chromatography

Synthetic fatliquors are useful as a fatliquoring agent, flotation agent and emulsifying agent in a wide range of industrial applications such as leather, pharmacy and farm chemicals. These fatliquors remain recalcitrant to natural biota in existing treatment plants. In the present study, the isolated microaerophilic Serratia sp. HA1 strain CSMB3 is capable of utilizing structurally different fatliquors as the sole substrate for their growth under microaerobic conditions. Degradation of vegetable fatliquors was observed from 95 to 97% in terms of lipids, with the production of lipase at 72 h. Degradation of synthetic fatliquors was observed in terms of chemical oxygen demand from 85% to a minimum of 25%. It is in the order of sulfited/sulfated fatliquors > sulfochlorinated fatliquors > chlorinated fatliquors. A thin layer chromatography chromatogram confirmed the degradation of non polar fatliquor to polar compounds. Production of the red pigment prodigiosin in synthetic fatliquors enhanced the growth of the isolate. Fourier transform infrared spectroscopy (FTIR) confirmed the bioremediation of sulfochlorinated fatliquor into lipids and fatty acids and gas chromatography–mass spectrometry (GC-MS) results confirmed that alcohols and esters are the final end products. Thus the isolated strain CSMB3 may be used in the treatment of wastewaters containing vegetable and synthetic fatliquors.

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