pH shift enhancement ofCandida utilis pyruvate decarboxylase production

Chen, Allen Kuan-Liang; Breuer, Michael; Hauer, Bernhard; Rogers, Peter L.; Rosche, Bettina

doi:10.1002/bit.20588

Cited by 9 publications

(13 citation statements)

References 26 publications

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“…However, our group found that the production of the biocatalyst pyruvate decarboxylase increased 2.7-fold when the pH control was switched off after 13 h cultivation, allowing Candida utilis to naturally acidify the fermentation broth from pH 6 to pH 2.9 (Chen et al, 2005). A similar result was obtained when the pH was abruptly lowered from pH 6 to pH 3 by the addition of sulfuric acid.…”

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confidence: 61%

Response of Saccharomyces cerevisiae to stress-free acidification

et al. 2009

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Genome-wide transcriptional analysis of a Saccharomyces cerevisiae batch culture revealed that more than 829 genes were regulated in response to an environmental shift from pH 6 to pH 3 by added sulfuric acid. This shift in pH was not detrimental to the rate of growth compared to a control culture that was maintained at pH 6 and the transcriptional changes most strikingly implicated not up- but down-regulation of stress responses. In addition, the transcriptional changes upon acid addition indicated remodeling of the cell wall and central carbon metabolism. The overall trend of changes was similar for the pH-shift experiment and the pH 6 control. However, the changes in the pH 6 control were much weaker and occurred 2.5 h later than in the pH-shift experiment. Thus, the reaction to the steep pH decrease was an immediate response within the normal repertoire of adaptation shown in later stages of fermentation at pH 6. Artificially preventing the yeast from acidifying the medium may be considered physiologically stressful under the tested conditions.

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confidence: 61%

Response of Saccharomyces cerevisiae to stress-free acidification

et al. 2009

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“…Subsequently, Cupdc1Á4-LDH2 was tested at 25 and 35 C, and the production at 35 C was found to be the highest among the three temperatures. Similarly, the yield of Cupdc1Á4-LDH2 at 35 C was the highest compared to that under the other conditions. Based on these data, we analyzed fermentation conducted by Cupdc1Á4-LDH2 at 35 C in YPD10 media over a 36-h time course (Fig.…”

Section: Fermentationmentioning

confidence: 77%

“…Cloning of PDC genes in C. utilis While enhancement of the production of pyruvate decarboxylase in C. utilis has been well studied in terms of culture conditions, e.g., oxygen supplied and medium pH, [35][36][37][38] the PDC genes of C. utilis (CuPDC) have not previously been identified. In the present study, we cloned a CuPDC gene.…”

Section: Resultsmentioning

confidence: 99%

“…Cupdc1Á4-LDH2 had the highest ability to produce L-lactic acid at 35 C, although it produced high concentrations of L-lactic acid over a range of temperatures, spanning 25 to 35 C. This feature is similar to a previous report that PDC in C. utilis was induced only at permissive growth temperatures, 5 to 35 C, and that the highest activity was detected at 35 C. 48) Accordingly, the high expression of CuPDC at 35 C might contribute to the large production of L-lactic acid at that temperature. This relatively high optimal temperature is also advantageous because lactic acid at high concentrations easily becomes solidified in the medium due to low solubility.…”

Section: Discussionmentioning

confidence: 99%

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Genetic Engineering ofCandida utilisYeast for Efficient Production ofL-Lactic Acid

Ikushima¹,

Fujii²,

Kobayashi³

et al. 2009

Bioscience, Biotechnology, and Biochemistry

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Polylactic acid is receiving increasing attention as a renewable alternative for conventional petroleum-based plastics. In the present study, we constructed a metabolically-engineered Candida utilis strain that produces L-lactic acid with the highest efficiency yet reported in yeasts. Initially, the gene encoding pyruvate decarboxylase (CuPDC1) was identified, followed by four CuPDC1 disruption events in order to obtain a null mutant that produced little ethanol (a by-product of L-lactic acid). Two copies of the L-lactate dehydrogenase (L-LDH) gene derived from Bos taurus under the control of the CuPDC1 promoter were then integrated into the genome of the CuPdc1-null deletant. The resulting strain produced 103.3 g/l of L-lactic acid from 108.7 g/l of glucose in 33 h, representing a 95.1% conversion. The maximum production rate of L-lactic acid was 4.9 g/l/h. The optical purity of the L-lactic acid was found to be more than 99.9% e.e.

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“…248. The cells were grown based on a developed protocol (Chen et al, 2005) and harvested after 44 h reaching a specific PDC activity of 380 U/g dry cell mass (DCM). Whole cells were used as detailed in Satianegara et al (2006).…”

Section: Microorganism and Pdc Productionmentioning

confidence: 99%

Comparative studies on enzyme preparations and role of cell components for (R)‐phenylacetylcarbinol production in a two‐phase biotransformation

Satianegara

Rogers²,

Rosche³

2006

Biotech & Bioengineering

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Whole cell pyruvate decarboxylase (PDC) from Candida utilis enhanced the enzymatic production of (R)-phenylacetylcarbinol (PAC) in an aqueous/octanol biotransformation compared to the partially purified PDC especially for a lower range of initial activities (0.3-2.5 U/mL). With an initial activity of 1.1 U/mL and at a 1:1 phase volume ratio, whole cell PDC achieved a maximum specific PAC production of 42 mg/U (2.8 g/L/h) in comparison to 13 mg/U (0.9 g/L/h) for partially purified PDC. The enhanced performance of whole cell PDC was associated with high stability towards the substrate benzaldehyde. The strong PDC inactivation by benzaldehyde was minimal even when whole cells were broken as long as cell debris was not removed from the broken cells. Biotransformations with various cellular components added to partially purified PDC revealed that membrane components especially 2 mg/mL phosphatidylcholine enhanced PAC concentrations. The role of surfactants was further confirmed from the results with synthetic surfactant sodium bis(2-ethyl-1-hexyl)sulfosuccinate (AOT). It was apparent that the membrane components in whole cells were sufficient for optimal PAC production and no further surfactant addition is required for optimal performance.

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pH shift enhancement ofCandida utilis pyruvate decarboxylase production

Cited by 9 publications

References 26 publications

Response of Saccharomyces cerevisiae to stress-free acidification

Response of Saccharomyces cerevisiae to stress-free acidification

Genetic Engineering ofCandida utilisYeast for Efficient Production ofL-Lactic Acid

Comparative studies on enzyme preparations and role of cell components for (R)‐phenylacetylcarbinol production in a two‐phase biotransformation

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