Project description:A recombinant C. utilis strain expressing Candida shehatae xylose reductase K275R/N277D (NADH-preferring), C. shehatae xylitol dehydrogenase and Pichia stipitis xylulokinase produce ethanol from xylose. Here, we report the transcriptional-profiling in the engineered C. utilis strain grown on xylose using DNA microarray. Transcriptome analysis indicated that expression of genes encoding the tricarboxylic acid cycle, respiration enzymes and the ethanol consumption were increased significantly when cells were cultivated on xylose. Gene expression in Candida utilis cells grown on glucose or xylose was measured at 10.5 and 24 hours, respectively. Two or three independent experiments were performed at each time for each experiment.
Project description:Single cell proteins, such as Candida utilis, are known to have immunomodulating effects in the distal intestine (DI) of Atlantic salmon, whereas soybean meal (SBM) can cause soybean meal induce enteritis (SBMIE). Inflammatory or immunomodulatory stimuli at the local level in the intestine may alter the plasma protein profile of Atlantic salmon. These changes can be helpful tools in diagnosis for fish diseases and indicators for fish health. The present work aimed to identify local intestinal tissue responses and changes in plasma protein profiles of Atlantic salmon fed C. utilis yeast, SBM, or combined diets. Fish meal (FM) based diet was used as a control diet and the six experimental diets were: FM diet with 200 g/kg C. utilis (FM200CU) and five diets containing 200 g/kg SBM together with 0 (SBM group), 25, 50, 100 or 200 g/kg C. utilis (SBM25CU, SBM50CU, SBM100CU and SBM200CU groups, respectively). Intestine morphology of fish fed FM200CU where not affected whereas SBM group presented changes characteristic of SBMIE. Low inclusion of C. utilis in SBM diet showed a modulation of immune cell populations, but did not alleviate inflammatory symptom.
Project description:We previously reported that a recombinant Candida utilis strain expressing a Candida shehatae xylose reductase K275R/N277D, a C. shehatae xylitol dehydrogenase, and xylulokinase from Pichia stipitis produced ethanol from xylose. However, its productivity was low. In this study, metabolomic (CE-TOF MS) and transcriptomic (microarray) analyses were performed to characterize xylose metabolism by the engineered C. utilis and to identify key genetic changes contributing to efficient xylose utilization. Metabolomic analysis revealed that the xylose-fermenting strain accumulated more pentose phosphate pathway intermediates, more NADH, and more glycolytic intermediates upstream of glyceraldehyde 3-phosphate than wild-type. Transcriptomic analysis of the strain grown on xylose indicated a significant increase in expression of genes encoding tricarboxylic acid cycle enzymes, respiratory enzymes, and enzymes involved in ethanol oxidation. To decrease the NADH/NAD+ ratio and increase ethanol yield from the fermentation of xylose, ADH1 encoding NADH-dependent alcohol dehydrogenase was overexpressed. The resultant strain exhibited a 17% increase in ethanol production and a 22% decrease in xylitol accumulation relative to the control.