Screening of Yeast in Various Vineyard Soil and Study on Its Flavor Compounds from Brewing Grape Wine

In order to screen out Saccharomyces cerevisiae suitable for table grape fermentation, and compare it with commercial Saccharomyces cerevisiae in terms of fermentation performance and aroma producing substances, differences of fermentation flavor caused by different strains were discussed. In this experiment, yeast was isolated and purified from vineyard soil, 26s rDNA identification and fermentation substrate tolerance analysis were carried out, and the causes of flavor differences of wine were analyzed from three aspects: GC-MS, PCA and sensory evaluation. The results showed that strain S1 had the highest floral aroma fraction, corresponding to its high production of ethyl octanoate and other substances, and it had the characteristics of high sugar tolerance. The fruit sensory score of S3 wine was the highest among the six wines. Through exploration and analysis, it was found that compared with commercial Saccharomyces cerevisiae, the screened strains had more advantages in fermenting table grapes. The flavor of each wine was directly related to the growth characteristics and tolerance of its strains.

Wobble Editing of Cre-box by Unspecific CRISPR/Cas9 Causes CCR Release and Phenotypic Changes in Bacillus pumilus

CRISPR-associated Cas9 endonuclease (CRISPR/Cas9) systems are widely used to introduce precise mutations, such as knocking in/out at targeted genomic sites. Herein, we successfully disrupted the transcription of multiple genes in Bacillus pumilus LG3145 using a series of unspecific guide RNAs (gRNAs) and UgRNA:Cas9 system-assisted cre-box editing. The bases used as gRNAs shared 30–70% similarity with a consensus sequence, a cis-acting element (cre-box) mediating carbon catabolite repression (CCR) of many genes in Bacillus. This triggers trans-crRNA:Cas9 complex wobble cleavage up/downstream of cre sites in the promoters of multiple genes (up to 7), as confirmed by Sanger sequencing and next-generation sequencing (NGS). LG3145 displayed an obvious CCR release phenotype, including numerous secondary metabolites released into the culture broth, ∼ 1.67 g/L white flocculent protein, pigment overflow causing orange-coloured broth (absorbance = 309 nm), polysaccharide capsules appearing outside cells, improved sugar tolerance, and a two-fold increase in cell density. We assessed the relationship between carbon catabolite pathways and phenotype changes caused by unspecific UgRNA-directed cre site wobble editing. We propose a novel strategy for editing consensus targets at operator sequences that mediates transcriptional regulation in bacteria.

Antihyperglycemic Activities of Uli Banana Leaves on Oral Sugar Tolerance

Banana has been widely cultivated. This study aimed to determine the antihyperglycemic activity of Uli banana leaves infusion. The antihyperglycemic activity was evaluated by oral glucose and sucrose tolerance test. A bolus of sugar was given after Uli banana leaves infusion and blood was sampled at 0, 15, 30, 60, 90 and 120 minutes for glucose analyses. The trapezoidal rule was used to determine the area under the curve (AUC) blood glucose. Infusion of Uli banana leaves 3.3 g/kg showed a significant decrease AUC (p<0.05) in the glucose tolerance test, while that of dose 0.8 g/kg reduced significantly (p<0.05) in the sucrose tolerance test. The results showed that Uli banana leaves infusion possesses antihyperglycemic effect in mice.

Disaccharidase deficiency

Disaccharidases are abundant enzymes expressed on the microvillous membrane of the small intestine: apart from free glucose and fructose, disaccharidases are required for the complete assimilation of nearly all carbohydrate present in food and drinks. The enzymes cleave disaccharides such as sucrose, maltose, and lactose, as well as dextrins derived from starch, into their component monosaccharides. Their activity is reduced in hereditary conditions or in generalized intestinal diseases. Disaccharidase deficiency causes dietary intolerance of carbohydrate induced by the fermentation of undigested sugars in the distal small intestine and colon. Abdominal symptoms are usually noticed within an hour of the ingestion of foods containing the offending sugars. By far the most common symptomatic disaccharidase deficiency is lactose intolerance. Lactase activity is high in healthy infants when milk is the principal food, but in most humans the activity declines after weaning and remains low (lactase nonpersistence), which greatly reduces the capacity to break down lactose. In contrast, those inheriting a Mendelian dominant trait that leads to sustained high intestinal lactase expression throughout life (lactase persistence) digest and tolerate large quantities. The distribution of lactase activity in adult populations is subject to great variation. Intestinal lactase phenotypes can be identified by assay of mucosal biopsy samples or appropriate sugar tolerance tests, as can other (much rarer) genetically determined disaccharidase variants. The most convenient diagnostic screen involves hydrogen breath testing after oral loading. Disaccharide intolerance is readily treated by institution of a strict exclusion diet; oral enzymatic supplementation may benefit patients with severe enzymatic deficiency. Innovative and early phase clinical trials suggest that modulation of the host intestinal microbiome with a pure short-chain galacto-oligosaccharide may be beneficial in symptom control and in favouring the outgrowth of lactose-fermenting flora.

Genome wide analysis in Drosophila reveals diet by gene interactions and uncovers diet-responsive genes

Genetic and environmental factors play a major role in metabolic health. However, they do not act in isolation, as a change in an environmental factor such as diet may exert different effects based on an individual’s genotype. Here, we sought to understand how such gene-diet interactions influenced nutrient storage and utilisation, a major determinant of metabolic disease. We subjected the Drosophila Genetic Reference Panel (DGRP), comprising 200 genetically divergent inbred fly strains, to diets varying in sugar, fat and protein. We assessed starvation resistance, a holistic phenotype of nutrient storage and utilisation that can be robustly measured. Diet influenced the starvation resistance of each strain, but this effect varied markedly between strains. This demonstrates that genetics plays a major role in the response to diet. Furthermore, heritability analysis revealed that the greatest variability arose from diets either high in sugar or high in protein. To uncover the genetic underpinnings of this variation, we mapped 1,239 diet-responsive SNPs in 534 genes, 325 of which have human orthologues. Using whole-body knockdown, we confirmed that 30 candidate genes were required for glucose tolerance, storage and utilization. In particular, we characterised CG4607, a GLUT6/GLUT8 homolog, as a key protein involved in sugar tolerance. Overall, this provides strong evidence that genetics is a major contributor to how individuals respond to diets of varying nutrient composition. It is likely that a similar principle may be applied to metabolic disease in higher organisms thus supporting the case for nutrigenomics as an important health strategy.

A simple method to monitor hepatic gluconeogenesis and triglyceride synthesis following oral sugar tolerance test in obese adolescents

Hepatic energy metabolism is a key element in many metabolic diseases. Hepatic anaplerosis provides carbons for gluconeogenesis (GNG) and triglyceride (TG) synthesis. We aimed to optimize a protocol that measures hepatic anaplerotic contribution for GNG, TG synthesis, and hepatic pentose phosphate pathway (PPP) activity using a single dose of oral [U−13C3]glycerol paired with an oral sugar tolerance test (OSTT) in a population with significant insulin resistance. The OSTT (75 g glucose + 25 g fructose) was administered to eight obese adolescents with polycystic ovarian syndrome (PCOS) followed by ingestion of [U-13C3]glycerol at t = 180 or t = 210 min. 13C-labeling patterns of serum glucose and TG-glycerol were determined by nuclear magnetic resonance. 13C enrichment in plasma TG-glycerol was detectable and stable from 240 to 390 min with the [U-13C3]glycerol drink at t = 180 min(3.65 ± 2.3 to 4.47 ± 1.4%; P > 0.4), but the enrichment was undetectable at 240 min with the glycerol drink at t = 210 min. The relative contribution from anaplerosis was determined at the end of the OSTT [18.5 ±3.4% ( t = 180 min) vs. 16.0 ± 3.5% ( t = 210 min); P = 0.27]. [U-13C3]glycerol was incorporated into GNG 390 min after the OSTT with an enrichment of 7.5–12.5%. Glucose derived from TCA cycle activity was 0.3–1%, and the PPP activity was 2.8–4.7%. In conclusion, it is possible to obtain relative measurements of hepatic anaplerotic contribution to both GNG and TG esterification following an OSTT in a highly insulin-resistant population using a minimally invasive technique. Tracer administration should be timed to allow enough de novo TG esterification and endogenous glucose release after the sugar drink.

Natural variation in sugar tolerance associates with changes in signaling and mitochondrial ribosome biogenesis

How dietary selection affects genome evolution to define the optimal range of nutrient intake is a poorly understood question with medical relevance. We have addressed this question by analyzing Drosophila simulans and sechellia, recently diverged species with differential diet choice. D. sechellia larvae, specialized to a nutrient scarce diet, did not survive on sugar-rich conditions, while the generalist species D. simulans was sugar tolerant. Sugar tolerance in D. simulans was a tradeoff for performance on low-energy diet and was associated with global reprogramming of metabolic gene expression. Hybridization and phenotype-based introgression revealed the genomic regions of D. simulans that were sufficient for sugar tolerance. These regions included genes that are involved in mitochondrial ribosome biogenesis and intracellular signaling, such as PPP1R15/Gadd34 and SERCA, which contributed to sugar tolerance. In conclusion, genomic variation affecting genes involved in global metabolic control defines the optimal range for dietary macronutrient composition.