Rice bran contains dietary fiber that have a potency as prebiotic, and fermented by probiotic in colon to produce lactic acid and short chain fatty acid (SCFA). Synbiotic effect of fermented rice bran by Lactobacillus plantarum B2 and Lactobacillus casei in Wistar rats (Rattus norvegicus) were investigated. The aim of this research was to compare the synbiotic effect of fermented rice bran by probiotic lactic acid bacteria (L. plantarum B2 and L. casei) in Wistar rats (Rattus norvegicus). Research methods is using a two month old Wistar rats (Rattus norvegicus) consisted of four groups (F0, F1, F2, F3) with five rats of each group were adapted for ten days by giving standard diet (AIN-93). Experimental diets were: standard diet of AIN 93M (F0), standard diet with formulated rice bran media (F1), standard diet with fermented rice bran media by L. casei (F2) and standard diet with fermented rice bran media by L. plantarum B2 (F3). Total bacteria, LAB, Escherichia coli and Salmonella of rats fecal were measured for 20 days. The caecum LAB and SCFA production were measured at the 20th day after feeding. The results show that the newly isolated of L. plantarum B2 in conformity with rice bran (F3) showed higher characteristics in comparison to the commercial L. casei, with fecal bacteria at the 20th day experiment were 10,93 log CFU g-1, fecal LAB 7,76 log CFU g-1, total Escherichia coli 4,48 log CFU g-1, total Salmonella 4,22 log CFU g-1, the caecum LAB viability 8,83 log CFU g-1, SCFA total (acetic, propionic and butyric acids 11,05 and 11,49mg g-1, therefore the F3 formula has potential as symbiotic product

Candida tropicalis, a xylose-fermenting yeast, has the potential for converting cellulosic biomass to ethanol. Thermotolerant C. tropicalis X-17, which was isolated in Laos, was subjected to repetitive long-term cultivation with a gradual increase in temperature (RLCGT) in the presence of a high concentration of glucose, which exposed cells to various stresses in addition to the high concentration of glucose and high temperatures. The resultant adapted strain demonstrated increased tolerance to ethanol, furfural and hydroxymethylfurfural at high temperatures and displayed improvement in fermentation ability at high glucose concentrations and xylose-fermenting ability. Transcriptome analysis revealed the up-regulation of a gene for a glucose transporter of the major facilitator superfamily and genes for stress response and cell wall proteins. Additionally, hydropathy analysis revealed that three genes for putative membrane proteins with multiple membrane-spanning segments were also up-regulated. From these findings, it can be inferred that the up-regulation of genes, including the gene for a glucose transporter, is responsible for the phenotype of the adaptive strain. This study revealed part of the mechanisms of fermentability at high glucose concentrations in C. tropicalis and the results of this study suggest that RLCGT is an effective procedure for improving multistress tolerance.

Dandy Yusuf, Risa Kholifaturrohmah, Mochamad Nurcholis, R. Haryo Bimo Setiarto, Lutfi Anggadhania, and Sulistiani. Prev Nutr Food Sci 2023;28:453-62. https://doi.org/10.3746/pnf.2023.28.4.453

Kmmig1 as a disrupted mutant of MIG1 encoding a regulator for glucose repression in Kluyveromyces marxianus exhibits a histidine-auxotrophic phenotype. Genome-wide expression analysis revealed that only HIS4 in seven HIS genes for histidine biosynthesis was down-regulated in Kmmig1. Consistently, introduction of HIS4 into Kmmig1 suppressed the requirement of histidine. Considering the fact that His4 catalyzes four of ten steps in histidine biosynthesis, K. marxianus has evolved a novel and effective regulation mechanism via Mig1 for the control of histidine biosynthesis. Moreover, RNA-Seq analysis revealed that there were more than 1,000 differentially expressed genes in Kmmig1, suggesting that Mig1 is directly or indirectly involved in the regulation of their expression as a global regulator.