## 4 Discussion
The result showed the possibility that the metabolic activity from fructose-6 phosphate to glycolaldehyde-3 phosphate was enhanced. The enhancement of the pentose phosphate pathway via ribose 5-phosphate was possibly reinforced to produce NADPH, which was consumed in the biosynthetic pathwaysof branched-chain amino acids such as glutamate and proline. So far, the cells are known to enhance the pentose phosphate pathway to produce NADPH [47], possibly indicating that culturing in wheat bran media promoted the synthesis of these amino acids using the pentose phosphate pathway. In particular, as shown in Figure 4a, in WG+HLMU medium towards in YG+HLMU medium, the transcription levels of _FBA1/LOT1_, _TDH1/GLD3_, _TDH2/GLD2_, and _TDH3/GLD1_ corresponding to the enzymes around glyceraldehyde in glycolysis were depressed; the transcription levels between glyceraldehyde-3 phosphate and glycerol were increased/maintained; the levels of all genes between glycerol and 3-phospho-d-glycerate were, conversely, enhanced. Those results indicated the possibility that glucose could flow to 3-phospho-d-glycerate via the pentose phosphate pathway and glycerol producing pathway rather than via fructose-6 phosphate. Regarding the production of tyrosine and phenylalanine, the transcription levels of _ARO3_, _ARO4_, and _ARO1_ should be considered to be controlling factors on the metabolic pathway. ARO3 and ARO4 are generally known to be feedback-inhibited by tyrosine and phenylalanine. Therefore, as [PERSON] suggested that the transcription levels of these genes were regulated by the presence of substrates [17; 48], the transcription levels of _ARO3_ and _ARO4_ could also be sensitively affected by the presence of tyrosine and phenylalanine in the medium. Additionally, the depressed transcription level of ARO1, an enzyme which controls the unique pathway between D-erythrose 4-phosphate and 5-O-3-phosphokinase via shikimate, could also be related to the decrease in activity for the production of tyrosine and phenylalanine. In the case of the use of wheat bran as an alternative to YNB, regarding the synthesis from 3-phospho-d-glycerate to serine, the depressed transcription levels of _SER1_ and _SER2_ and the enhanced levels of _ILV1_ and _CHA1_ could indicate the reinforcement of the synthesis via pyruvate (Figure 6b). Pyruvate serves as a starting point for synthesizing multiple amino acids, so that the cells might have prioritized the metabolic flow to pyruvate. Serine biosynthesized from pyruvate is an important intermediate metabolite. In WG+HLMU medium, with the regard to the synthesis from serine to threonine, the synthesis was mainly performed in the pathway via cystathionine and homoserine with the repression of the transcription levels of _TRP5_ and _SAM2_ in tryptophan synthesis. The fact that the transcription level of _TRP5_, which is a gene of an enzyme controlling the pathway from serine to tryptophan, was depressed could have the effect of decreasing runoff of intermediate metabolites on the pathway to cystathionine and homoserine. Similarly, SAM2, which does not receive negative feedback control depended on the methionine quantity unlike SAM1, controls methionine metabolism [49] so that the transcription level of this could also have the effect of decreasing runoff on the pathway. Homoserine is an important intermediate metabolite for producing threonine and methionine in the cell [50], meaning that BY4741 might be satisfied by taking the roundabout route. In addition, with regard to leucine biosynthesis from 2-oxoisovalerate, in WG+HLMU medium, the cells decreased the transcription activities of _LEU4_ and _LEU9_ as the unique genes in the pathway. As with the biosynthesis of methionine and tryptophan, the cells might control leucine synthesis.