Pilot studies on scale-up biocatalysis of 7-β-xylosyl-10-deacetyltaxol and its analogues by an engineered yeast

AbstractMetabolic addiction, an organism that is metabolically addicted with a compound to maintain its growth fitness, is an underexplored area in metabolic engineering. Microbes with heavily engineered pathways or genetic circuits tend to experience metabolic burden leading to degenerated or abortive production phenotype during long-term cultivation or scale-up. A promising solution to combat metabolic instability is to tie up the end-product with an intermediary metabolite that is essential to the growth of the producing host. Here we present a simple strategy to improve both metabolic stability and pathway yield by coupling chemical addiction with negative autoregulatory genetic circuits. Naringenin and lipids compete for the same precursor with inversed pathway yield in oleaginous yeast. Negative autoregulation of the lipogenic pathways, enabled by CRISPRi and fatty acid-inducible promoters, repartitioned malonyl-CoA to favor flavonoid synthesis and increased naringenin production by 74.8%. With flavonoid-sensing hybrid promoters to control leucine synthesis, this flavonoid addiction phenotype confers a selective growth advantage to the naringenin-producing cell. The engineered yeast persisted 90.9% of naringenin titer up to 324 generations. Cells without flavonoid addiction regained growth fitness but lost 94.5% of the naringenin titer after cell passage beyond 300 generations. Metabolic addiction and negative autoregulation may be generalized as basic tools to eliminate metabolic heterogeneity, improve strain stability and pathway yield.

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Waste Material Adsorbents for Zinc Removal from Wastewater: A Comprehensive Review

International Journal of Chemical Engineering ◽

10.1155/2014/347912 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13 ◽

Cited By ~ 36

Author(s):

Haider M. Zwain ◽

Mohammadtaghi Vakili ◽

Irvan Dahlan

Keyword(s):

Adsorption Capacity ◽

Rice Husk ◽

Low Cost ◽

Coal Fly Ash ◽

Scale Up ◽

Environmental Benefits ◽

Pilot Studies ◽

Green Macroalgae ◽

Wide Range ◽

Cassava Waste

This review examines a variety of adsorbents and discusses mechanisms, modification methods, recovery and regeneration, and commercial applications. A summary of available researches has been composed by a wide range of potentially low-cost modified adsorbents including activated carbon, natural source adsorbents (clay, bentonite, zeolite, etc.), biosorbents (black gram husk, sugar-beet pectin gels, citrus peels, banana and orange peels, carrot residues, cassava waste, algae, algal, marine green macroalgae, etc.), and byproduct adsorbents (sawdust, lignin, rice husk, rice husk ash, coal fly ash, etc.). From the literature survey, different adsorbents were compared in terms of Zn2+adsorption capacity; also Zn2+adsorption capacity was compared with other metals adsorption. Thus, some of the highest adsorption capacities reported for Zn2+are 168 mg/g powdered waste sludge, 128.8 mg/g dried marine green macroalgae, 73.2 mg/g lignin, 55.82 mg/g cassava waste, and 52.91 mg/g bentonite. Furthermore, modification of adsorbents can improve adsorption capacity. Regeneration cost is important, but if consumption of virgin adsorbent is reduced, then multiple economic, industrial, and environmental benefits can be gained. Finally, the main drawback of the already published Zn2+adsorption researches is that their use is still in the laboratory stage mostly without scale-up, pilot studies, or commercialization.

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Optimization of Unit Operations for Microencapsulating Ferrous Fumarate During Scale-up of Double Fortification of Salt with Iron and Iodine

Food Quality and Safety ◽

10.1093/fqsafe/fyab023 ◽

2021 ◽

Author(s):

Oluwasegun Modupe ◽

Kiruba Krishnaswamy ◽

Yao Olive Li ◽

Levente Diósady

Keyword(s):

Titanium Dioxide ◽

Large Scale ◽

Particle Density ◽

Hydroxypropyl Methylcellulose ◽

Scale Up ◽

Pilot Studies ◽

Unit Operations ◽

Hydrophobic Nature ◽

The Stability ◽

The Impact

Abstract This study evaluates factors responsible for the floating of iron premix in Double Fortified Salt (DFS) and provides solutions to scale-up of the DFS technology. The hydrophobic 10% soy stearin coating that created a barrier between iron and iodine in the Double Fortified Salt caused the iron premix to float in water. This problem initially affected the large-scale implementation of the salt fortification program in India. To mitigate this time-sensitive scale-up challenge: First, the iron premix samples were obtained from the industrial scale-up pilot studies in India, evaluated for the impact of the amount of coating material, type of formulation, amount of titanium dioxide used for color masking. Second, we studied the effect of change in the composition of the coating, from 10% soy stearin to a double coat with 5% hydroxypropyl methylcellulose and 5% soy stearin or 10% soy stearin and 1% lecithin mixture, on particle density, floating or sinking property of the iron premix, and on the stability of iodine in the Double Fortified Salt (DFS). Finally, the extruded iron premix was color masked with 25-35% of titanium dioxide. It was observed that the hydrophobic nature and the amount of soy stearin used for coating caused the floating issue. The double coating with 5% hydroxypropyl methylcellulose and 5% soy stearin was preferred because lecithin in soy stearin enhanced the moisture-aided adverse interaction between iron and iodine. Shelf-life storage studies proved over 80% iodine retention after 1-year of storage in the Double Fortified Salt formulated with iron premix double-coated with hydroxypropyl methylcellulose and soy stearin. This proffered solution enabled the full implementation of the double fortification program in India.

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Early-stage Studies to Larger-scale Trials: Investigators’ Perspectives on Scaling-Up Childhood Obesity Interventions

10.21203/rs.3.rs-514474/v1 ◽

2021 ◽

Author(s):

Lauren von Klinggraeff ◽

Roddrick Dugger ◽

Anthony Okely ◽

David Lubans ◽

Russ Jago ◽

...

Keyword(s):

Childhood Obesity ◽

Pilot Study ◽

Behavioral Interventions ◽

Voltage Drop ◽

Early Stage ◽

Scale Up ◽

Scaling Up ◽

Lead Author ◽

Pilot Studies ◽

Potential Efficacy

Abstract Background: Pilot/feasibility studies play an important role in the development and refinement of behavioral interventions by providing information about feasibility, acceptability, and potential efficacy. Despite their importance and wide-spread use, the approaches taken by behavioral scientists to scale-up early-stage studies to larger-scale trials has received little attention. The aim of our study was to understand the role that pilot studies play in the development and execution of larger-scale trials.Methods: We conducted interviews with behavioral interventionists identified in a systematic review as the lead author of a published pilot study that had also published larger-scale trial on a topic related to childhood obesity. Questions were asked about the role of pilot studies in developing larger-scale trials and the challenges encountered when scaling-up an intervention based upon pilot findings. Data were coded and analyzed using an inductive analytic approach to identify themes.Results: 24 Interventionists (54% women, 37-70 yrs old, mean 20 years since terminal degree) completed a total of 148 pilot studies across their careers (mean 6.4, range 1-20), of which 59% were scaled-up. Scaling was described as resource intensive and pilot work was considered essential to successfully competing for funding by 63% of the sample (n=15). When asked to define a high-quality pilot study, interventionists described studies that allowed them to evaluate components of their intervention (e.g., acceptability, feasibility) and study parameters (e.g., sample size, measures). Interventionists expressed that more process implementation measures, different study designs, and additional iterations could improve decisions to scale-up. Most agreed that pilot studies were likely to produce inflated estimates of potential efficacy though only nine interventionists provided potential solutions for decreasing inflated measures of efficacy. Suggested major causes of inflated effects included high levels of oversight in pilot studies (e.g., researcher support), reliance on subjective measures, and utilizing convenience or highly motivated samples. Potential solutions included designing pilots for real-world implementation, only conducting randomized controlled pilot studies, and pre-registering pilot studies. Conclusions: Pilot studies purposes are multifaceted and deemed essential to obtaining funding for larger-scale trials. Clarifying the form and function of preliminary, early-stage research may enhance the productive utilization of early-stage studies and reduced “voltage drop”.

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NiAl precipitation in Fe-12w/o Cr-5w/o Ni-4w/o Al

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007480x ◽

1983 ◽

Vol 41 ◽

pp. 202-203

Author(s):

L.E. Murr ◽

J.S. Dunning ◽

S. Shankar

Keyword(s):

Solid Solution ◽

Stainless Steel ◽

Stainless Steels ◽

Alloy Composition ◽

Chromium Content ◽

Scale Up ◽

Optical Metallography ◽

Property Evaluation ◽

310 Stainless Steel ◽

Microstructural Studies

Aluminum additions to conventional 18Cr-8Ni austenitic stainless steel compositions impart excellent resistance to high sulfur environments. However, problems are typically encountered with aluminum additions above about 1% due to embrittlement caused by aluminum in solid solution and the precipitation of NiAl. Consequently, little use has been made of aluminum alloy additions to stainless steels for use in sulfur or H2S environments in the chemical industry, energy conversion or generation, and mineral processing, for example.A research program at the Albany Research Center has concentrated on the development of a wrought alloy composition with as low a chromium content as possible, with the idea of developing a low-chromium substitute for 310 stainless steel (25Cr-20Ni) which is often used in high-sulfur environments. On the basis of workability and microstructural studies involving optical metallography on 100g button ingots soaked at 700°C and air-cooled, a low-alloy composition Fe-12Cr-5Ni-4Al (in wt %) was selected for scale up and property evaluation.

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