Abstract:This research was performed based on a comparative study on fungal lipid production by a locally isolated strain Cunninghamella bainieri 2A1 in batch culture and repeated-batch culture using a nitrogen-limited medium. Lipid production in the batch culture was conducted to study the effect of different agitation rates on the simultaneous consumption of ammonium tartrate and glucose sources. Lipid production in the repeated-batch culture was studied by considering the effect of harvesting time and harvesting vol… Show more
“…Results in this study exhibited that increasing the time of drain and fill from 12 h to 48 h led to enhance butanol production, productivity and yield. This is in agreement with a study reported by Dashti and Abdeshahian (2016) who found that increasing the time from 12 h to 48 h created a progressive increase in the production of lipid which indicated the positive influence of increasing the time on the metabolic activity of Cunninghamella bainieri 2A1 in the fermentation for lipid production. Table 2 summarized the butanol production, yield and productivities for butanol and total ABE at different times of DFT.…”
Section: Comparison Of Batch and Repeated Batch Fermentation For Butasupporting
confidence: 93%
“…The reduction was higher in 50% DFv compared to 25% DFv because of the increase in the volume of replacing medium which recorded as 1.12 at run 2 and 0.67 at the end of run 5. Dashti and Abdeshahian (2016) had stated that the highest level of the biomass concentration had been obtained during the first cycle of the repeated batch culture, which indicated that an increase in the number of repeated batch cycles had an adverse influence on biomass concentration and microbial cell growth.…”
Section: Fermentation In Repeated-batch Culturementioning
Butanol is the most promising alternative liquid biofuel that can substitute gasoline due to its properties which is more similar to gasoline than ethanol. In this study, butanol was produced by batch culture and repeated batch culture in acetone-butanol-ethanol fermentation (ABE) using a local strain of Clostridium acetobutylicum YM1. In batch culture using tryptone-yeast extract-acetate medium (TYA) containing 30 g/L glucose, the maximum butanol concentration was 3.78 g/L with a maximum butanol productivity of 0.08 g/L.h and the butanol yield was 0.15 g/g. Effect of some factors on the butanol production during repeated batch fermentation including drain and fill volume of medium and drain and fill time were investigated. The results of repeated batch fermentation showed that 50% (v/v) of drain and fill volume at 48 h maximized the production of butanol, productivity and yield. The highest butanol concentration was 5.12 g/L in the first cycle of repeated batch with a butanol productivity of 0.11 g/L.h and a butanol yield of 0.44 g/g. Repeated batch fermentation using free cells of Clostridium acetobutylicum YM1 eliminated the lag phase and then improved the productivity of butanol and total ABE. This study showed that repeated batch fermentation improved the efficiency of butanol production over batch culture fermentation by Clostridium acetobutylicum YM1.
“…Results in this study exhibited that increasing the time of drain and fill from 12 h to 48 h led to enhance butanol production, productivity and yield. This is in agreement with a study reported by Dashti and Abdeshahian (2016) who found that increasing the time from 12 h to 48 h created a progressive increase in the production of lipid which indicated the positive influence of increasing the time on the metabolic activity of Cunninghamella bainieri 2A1 in the fermentation for lipid production. Table 2 summarized the butanol production, yield and productivities for butanol and total ABE at different times of DFT.…”
Section: Comparison Of Batch and Repeated Batch Fermentation For Butasupporting
confidence: 93%
“…The reduction was higher in 50% DFv compared to 25% DFv because of the increase in the volume of replacing medium which recorded as 1.12 at run 2 and 0.67 at the end of run 5. Dashti and Abdeshahian (2016) had stated that the highest level of the biomass concentration had been obtained during the first cycle of the repeated batch culture, which indicated that an increase in the number of repeated batch cycles had an adverse influence on biomass concentration and microbial cell growth.…”
Section: Fermentation In Repeated-batch Culturementioning
Butanol is the most promising alternative liquid biofuel that can substitute gasoline due to its properties which is more similar to gasoline than ethanol. In this study, butanol was produced by batch culture and repeated batch culture in acetone-butanol-ethanol fermentation (ABE) using a local strain of Clostridium acetobutylicum YM1. In batch culture using tryptone-yeast extract-acetate medium (TYA) containing 30 g/L glucose, the maximum butanol concentration was 3.78 g/L with a maximum butanol productivity of 0.08 g/L.h and the butanol yield was 0.15 g/g. Effect of some factors on the butanol production during repeated batch fermentation including drain and fill volume of medium and drain and fill time were investigated. The results of repeated batch fermentation showed that 50% (v/v) of drain and fill volume at 48 h maximized the production of butanol, productivity and yield. The highest butanol concentration was 5.12 g/L in the first cycle of repeated batch with a butanol productivity of 0.11 g/L.h and a butanol yield of 0.44 g/g. Repeated batch fermentation using free cells of Clostridium acetobutylicum YM1 eliminated the lag phase and then improved the productivity of butanol and total ABE. This study showed that repeated batch fermentation improved the efficiency of butanol production over batch culture fermentation by Clostridium acetobutylicum YM1.
“…One way to overcome this would be in situ product removal by calcium salt precipitation as shown for U. maydis [48] and U. vetiveriae [44] or by reactive extraction methods [49]. Alternatively, a continuous or semi-continuous process with cell recycling can help to overcome product toxicity as well, by extending the productive time of the biomass [50]. Fig.…”
BackgroundUstilago cynodontis ranks among the relatively unknown itaconate production organisms. In comparison to the well-known and established organisms like Aspergillus terreus and Ustilago maydis, genetic engineering and first optimizations for itaconate production were only recently developed for U. cynodontis, enabling metabolic and morphological engineering of this acid-tolerant organism for efficient itaconate production. These engineered strains were so far mostly characterized in small scale shaken cultures.ResultsIn pH-controlled fed-batch experiments an optimum pH of 3.6 could be determined for itaconate production in the morphology-engineered U. cynodontis Δfuz7. With U. cynodontis ∆fuz7r
∆cyp3r
PetefmttA Pria1ria1, optimized for itaconate production through the deletion of an itaconate oxidase and overexpression of rate-limiting production steps, titers up to 82.9 ± 0.8 g L−1 were reached in a high-density pulsed fed-batch fermentation at this pH. The use of a constant glucose feed controlled by in-line glucose analysis increased the yield in the production phase to 0.61 gITA gGLC−1, which is 84% of the maximum theoretical pathway yield. Productivity could be improved to a maximum of 1.44 g L−1 h−1 and cell recycling was achieved by repeated-batch application.ConclusionsHere, we characterize engineered U. cynodontis strains in controlled bioreactors and optimize the fermentation process for itaconate production. The results obtained are discussed in a biotechnological context and show the great potential of U. cynodontis as an itaconate producing host.
“…This cultivation system allows for better dynamics and higher efficiency of the biosynthesis process by extending the effective production phase in comparison to traditional batch culture [7]. The RBC was already successfully used for lipid, ethanol and erythritol production [7–9].…”
BackgroundCitric acid is considered as the most economically feasible product of microbiological production, therefore studies on cheap and renewable raw materials for its production are highly desirable. In this study citric acid was synthesized by genetically engineered strains of Yarrowia lipolytica from widely available, renewable polysaccharide – inulin. Hydrolysis of inulin by the Y. lipolytica strains was established by expressing the inulinase gene (INU1 gene; GenBank: X57202.1) with its native secretion signal sequence was amplified from genomic DNA from Kluyveromyces marxianus CBS6432. To ensure the maximum citric acid titer, the optimal cultivation strategy–repeated-batch culture was applied.ResultsThe strain Y. lipolytica AWG7 INU 8 secreted more than 200 g dm− 3 of citric acid during repeated-batch culture on inulin, with a productivity of 0.51 g dm− 3 h− 1 and a yield of 0.85 g g− 1.ConclusionsThe citric acid titer obtained in the proposed process is the highest value reported in the literature for Yarrowia yeast. The obtained results suggest that citric acid production from inulin by engineered Y. lipolytica may be a very promising technology for industrial citric acid production.
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