A CuSO4/Bicinchoninic acid/Reducing sugar based stable and non-ROS catalyst system for the CuAAC reaction in bioanalysis.

The limitations of commonly used sodium ascorbate-based catalyst system for copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction include excess production of reactive oxygen species and rapid catalyst deactivation. In this study instead of using a highly active reducing agent, such as, sodium ascorbate, we chose reducing sugar as a mild reducing agent to build up the catalyst system for CuAAC reaction. Interestingly, the bicinchoninic acid (BCA) assay system containing reducing sugar satisfies the essential elements of the catalyst system for CuAAC reaction. We found that CuSO4/BCA/Reducing sugar system can catalyze the CuAAC reaction but with low yield. Rational analyses of various parameters in CuSO4/BCA/Glucose catalyst system suggested storage at room temperature might enhance the catalytic activity, which was proven to be the case. Importantly, the system remains stable at room temperature and minimal H2O2 was detected. Notably, our study showed that the coordination between the slow reduction of Cu(I) by reducing sugar and the selective chelation of Cu(I) by BCA is key to developing this system. The CuSO4/BCA/Reducing sugar catalyst system was successfully applied to various CuAAC reaction based bioanalyses, and it is suitable for the CuAAC reaction based bioanalyses that are sensitive to ROS or request long reaction time.

Cryopreserved red blood cells maintain allosteric control of oxygen binding when utilizing trehalose as a cryoprotectant.

One of the most common life-saving medical procedures is a red blood cell (RBC) transfusion. Unfortunately, RBCs for transfusion have a limited shelf life after donation due to detrimental storage effects on their morphological and biochemical properties. Inspired by nature, a biomimetics approach was developed to preserve RBCs for long-term storage using compounds found in animals with a natural propensity to survive in a frozen or desiccated state for decades. Trehalose was employed as a cryoprotective agent and added to the extracellular freezing solution of porcine RBCs. Slow cooling (-1 °C min-1) resulted in almost complete hemolysis (1 ± 1 % RBC recovery), and rapid cooling rates had to be used to achieve satisfactory cryopreservation outcomes. After rapid cooling, the highest percentage of RBC recovery was obtained by plunging in liquid nitrogen and thawing at 55 °C, using a cryopreservation solution containing 300 mM trehalose. Under these conditions, 88 ± 8 % of processed RBCs were recovered and retained hemoglobin (14 ± 2 % hemolysis). Hemoglobin's oxygen-binding properties of cryopreserved RBCs were not significantly different to unfrozen controls and was allosterically regulated by 2,3-bisphosphoglycerate. These data indicate the feasibility of using trehalose instead of glycerol as a cryoprotective compound for RBCs. In contrast to glycerol, trehalose-preserved RBCs can potentially be transfused without time-consuming washing steps, which significantly facilitates the usage of cryopreserved transfusible units in trauma situations when time is of the essence.

Enzymatic synthesis of ß-d-fructofuranosyl α-d-glucopyranosyl-(1→2)-α-d-glucopyranoside using Escherichia coli glycoside phosphorylase YcjT.

YcjT is a kojibiose phosphorylase found in Escherichia coli. We found that sucrose was a good acceptor of YcjT in reverse phosphorolysis using ß-d-glucose 1-phosphate as a donor. The product was identified as ß-d-fructofuranosyl α-d-glucopyranosyl-(1→2)-α-d-glucopyranoside. This sugar was also synthesized from sucrose and maltose using YcjT and maltose phosphorylase and promoted the growth of the probiotic Bifidobacterium breve.

Efficient Secretory Production of Lytic Polysaccharide Monooxygenase BaLPMO10 and Its Application in Plant Biomass Conversion.

Lytic polysaccharide monooxygenases (LPMOs) can oxidatively break the glycosidic bonds of crystalline cellulose, providing more actionable sites for cellulase to facilitate the conversion of cellulose to cello-oligosaccharides, cellobiose and glucose. In this work, a bioinformatics analysis of BaLPMO10 revealed that it is a hydrophobic, stable and secreted protein. By optimizing the fermentation conditions, the highest protein secretion level was found at a IPTG concentration of 0.5 mM and 20 h of fermentation at 37 °C, with a yield of 20 mg/L and purity > 95%. The effect of metal ions on the enzyme activity of BaLPMO10 was measured, and it was found that 10 mM Ca2+ and Na+ increased the enzyme activity by 47.8% and 98.0%, respectively. However, DTT, EDTA and five organic reagents inhibited the enzyme activity of BaLPMO10. Finally, BaLPMO10 was applied in biomass conversion. The degradation of corn stover pretreated with different steam explosions was performed. BaLPMO10 and cellulase had the best synergistic degradation effect on corn stover pretreated at 200 °C for 12 min, improving reducing sugars by 9.2% compared to cellulase alone. BaLPMO10 was found to be the most efficient for ethylenediamine-pretreated Caragana korshinskii by degrading three different biomasses, increasing the content of reducing sugars by 40.5% compared to cellulase alone following co-degradation with cellulase for 48 h. The results of scanning electron microscopy revealed that BaLPMO10 disrupted the structure of Caragana korshinskii, making its surface coarse and poriferous, which increased the accessibility of other enzymes and thus promoted the process of conversion. These findings provide guidance for improving the efficiency of enzymatic digestion of lignocellulosic biomass.

Optimization of alkali, acid and organic solvent pretreatment on rice husk and its techno economic analysis for efficient sugar production.

Excessive use of fossil fuels has accelerated climate change and global warming necessitates the need for renewable energy sources that have a lower environmental impact. In the recent decade, lignocellulosic biomass has become a prominent alternative to renewable energy resources for the production of bioenergy. The pretreatment procedure is considered a pivotal step for transforming biomass into value-added products such as sugars, biofuels, etc. Therefore, the present work aims to study the effect of different pretreatment approaches on rice husk with acids (H2SO4 and HCl), alkalis (NaOH and KOH), and organic solvents (ethanol and methanol) utilizing different concentrations like (2, 4 and 6% in case of acids), (2,4 and 6% for alkalis) and (50% and 70% for organic solvents) with different residence time (1, 3, 6, and 24 h). The most effective results obtained from the aforementioned steps were further adopted for enzymatic hydrolysis. Further, the changes in structural properties of biomass were assessed in relation to the pretreatment process employing scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared (FTIR) analyses. This paper also highlights the techno-economic analysis of alkali pretreatment. Additionally, the operational targets for the process were identified by using a modeling software-SuperPro Designer. Results obtained from the study showed a maximum yield of reducing sugar i.e., 1.906 ± 0.2 mg/ml (4% NaOH with 6 h of incubation). This study demonstrates that 4% NaOH pretreatment effectively disintegrates the biomass and yields high sugar recovery which can be used further for the production of biofuels and value-added products.

Influence of Novel EnZolv Pretreatment on the Release of Reducing Sugar and Proximate Content of Banana Fiber.

Lignocellulosic biomass (LCB) from agriculture residues has gained a lot of attention in recent years for its conversion to useful by-products. The one drawback that the conversion of biomass faces is its recalcitrant nature which can be overcome by effective pretreatment technology. One such process is the EnZolv, a novel pretreatment technique used for delignification of biomass and it was recognized as an eco-friendly approach. The main objective of our present study is to optimize the novel EnZolv process parameters for enhanced release of reducing sugar from banana fiber. Banana fiber pre-optimization for EnZolv pretreated at 100% moisture content, incubated at 40 °C temperature, with an enzyme load of 50 U·g-1 of biomass for an incubation time of 5 h at a shaking speed of 100 rpm yielded enhanced sugar release of 1.7 mg·mL-1. The effect of pretreatment on proximate composition results in a decrease in the volatile matter (53%) and moisture percentage (1.07%) and an increase in the other parameters such as ash content (12%) and fixed carbon content (34%) under the optimized condition. A significantly higher release of phenol content 1264 µg·mL-1 equivalent to gallic acid suggests that EnZolv pretreatment confirms the degradation of lignin content in the biomass. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01130-4.

Recent advance in technological innovations of sugar-reduced products.

Sugar is crucial as an essential nutrient for humans as well as for providing texture, sweetness and so on to food. But with the rise in people's pursuit of health, it is becoming increasingly clear that excessive consumption of sugar can locate a load on the body. It has been that excessive sugar is associated with many diseases, such as dental caries, obesity, diabetes, and coronary heart disease. Therefore, researchers and industries are trying to reduce or substitute sugar in food without affecting the sensory evaluation. Substituting sugar with sweeteners is alternatively becoming the most traditional way to minimize its use. So far, the sweeteners such as stevia and xylitol have been are commercially applied. Several studies have shown that technological innovation can partially compensate for the loss in sweetness as a result of sugar reduction, such as cross-modal interactions that stimulate sweetness with aroma, nanofiltration that filters disaccharides and above, enzyme-catalyzed sugar hydrolysis, and microbial fermentation that turns sugar into sugar alcohol. This review summarizes these studies to enhance the safety and quality of sugar-reduced products, and will provide some theoretical frameworks for the food industry to reduce sugar in foods, meet consumers' needs, and promote human health.

Advancement of fermentable sugars from fresh elephant ear plant weed for efficient bioethanol production.

Bioethanol is considered one of the most promising next-generation automotive fuels, as it is carbon neutral and can be produced from renewable resources, like lignocellulosic materials. The present research investigation aimed to utilize the elephant ear plant, a hazardous plant (weed) also considered an invasive species, as a font of non-edible lignocellulosic biomass for bioethanol production. The freshly collected elephant ear plant (leaves and stalk) was chopped into small pieces (1-2 cm) and then homogenized to a paste using a mechanical grinder. The sample pretreatment was done by flying ash for three different time durations (T1 = 0 min, T2 = 15 min, and T3 = 30 min) with 3 replications. All treatment samples were measured for total sugar and reducing sugar content. The concentration of reducing sugar archived was T1 = 0.771 ± 0.1 mg/mL, T2 = 0.907 ± 0.032 mg/mL, and T3 = 0.895 ± 0.039 mg/mL, respectively. The results revealed that the chemical composition was different among treatments. The hydrolysis was performed using cellulase enzymes at 35 °C for the hydrolysis process. The hydrolysate was inoculated with 1% of S. cerevisiae and maintained at room temperature without oxygen for 120 h. Bioethanol concentration was measured by using an ebulliometer. The efficient ethanol percentage was 1.052 ± 0.03 mg/mL achieved after the fermentation. Therefore, the elephant ear plant invasive weed could be an efficient feedstock plant for future bioethanol production.

Immunoreactive Response of Plast-MIPs to Fasting and Their Functional Role in the Reduction of Hemolymph Reducing Sugars in the Brown-Winged Green Bug, Plautia stali.

Animals survive nutrient deficiency by controlling their physiology, such as sugar metabolism and energy-consuming developmental events. Although research on the insect neural mechanisms of the starvation-induced modulation has progressed, the mechanisms have not been fully understood due to their complexity. Myoinhibitory peptides are known to be neuropeptides involved in various physiological activities, development, and behavior. Here, we analyzed the responsiveness of Plautia stali myoinhibitory peptides (Plast-MIPs) to starvation and their physiological role in the brown-winged green bug, P. stali. First, we performed immunohistochemical analyses to investigate the response of Plast-MIP neurons in the cephalic ganglion to fasting under long day conditions. Fasting significantly enhanced the immunoreactivity to Plast-MIPs in the pars intercerebralis (PI), which is known to be a brain region related to various endocrine regulations. Next, to analyze the physiological role of Plast-MIPs, we performed RNA interference-mediated knockdown of Plast-Mip and injection of synthetic Plast-MIP in normally fed and fasted females. The knockdown of Plast-Mip did not have significant effects on the body weight or proportions of ovarian development in each feeding condition. On the other hand, the knockdown of Plast-Mip increased the gonadosomatic index of normally fed females whereas it did not have a significant effect on food intake. Notably, the knockdown of Plast-Mip diminished the fasting-induced reduction of hemolymph reducing sugar levels. Additionally, injection of synthetic Plast-MIP acutely decreased the hemolymph reducing sugar level. Our results suggested responsiveness of Plast-MIPs in the PI to fasting and their functional role in reduction of the hemolymph reducing sugar level.

Production and characterization of Aspergillus niger GH29 family α-fucosidase and production of a novel non-reducing 1-fucosyllactose.

Fucosylated oligosaccharides are interesting molecules due to their bioactive properties. In particular, their application as active ingredient in milk powders is attractive for dairy industries. The objective of this study was to characterize the glycosyl hydrolase family 29 α-fucosidase produced by Aspergillus niger and test its ability to transfucosylate lactose with a view towards potential industrial applications such as the valorization of the lactose side stream produced by dairy industry. In order to reduce costs and toxicity the use of free fucose instead of environmentally questionable fucose derivatives was studied. In contrast to earlier studies, a recombinantly produced A. niger α-fucosidase was utilized. Using pNP-fucose as substrate, the optimal pH for hydrolytic activity was determined to be 3.8. The optimal temperature for a 30-min reaction was 60 °C, and considering temperature stability, the optimal temperature for a 24-h reaction was defined as 45 °C For the same hydrolysis reaction, the kinetic values were calculated to be 0.385 mM for the KM and 2.8 mmol/(mg*h) for the Vmax. Transfucosylation of lactose occurred at high substrate concentrations when reaction time was elongated to several days. The structure of the product trisaccharide was defined as 1-fucosyllactose, where fucose is α-linked to the anomeric carbon of the ß-glucose moiety of lactose. Furthermore, the enzyme was able to hydrolyze its own transfucosylation product and 2'-fucosyllactose but only poorly 3-fucosyllactose. As a conclusion, α-fucosidase from A. niger can transfucosylate lactose using free fucose as substrate producing a novel non-reducing 1-fucosyllactose.

Statistical optimization of a cellulase from Aspergillus glaucus CCHA for hydrolyzing corn and rice straw by RSM to enhance yield of reducing sugar.

OBJECTIVE: The unique GH5 cellulase, AgCMCase, from Aspergillus glaucus CCHA was identified and characterized as having high cellulose and straw hydrolysis activities that were thermostable, pH stable and salt-tolerant. Therefore, it is a potential straw-degradation enzyme that can release reducing sugars in industrial applications. To increase the efficiency of the AgCMCase' hydrolysis of straw to release simple sugars, response surface methodology (RSM) was introduced to optimize hydrolysis parameters such as pH, temperature, reaction time and enzyme dose. RESULTS: The enzyme showed only one major protein band from the fermentation broth by the Pichia pastoris GS115 expression. The crude enzyme (without purification) showed a satisfactory capability to hydrolyze CMC-Na after 4 days of production. Here, the crude AgCMCase also showed cellulose and straw hydrolysis capabilities as assessed by scanning electron microscopic and Fourier-transform infrared spectroscopic analyses. A high-performance liquid chromatographic analysis demonstrated that the degradation of corn and rice straw by crude AgCMCase mainly produced glucose and cellobiose. Temperature, reaction time and enzyme dose were the significant variables affecting corn and rice straw degradation. After the optimization of RSM, a model was proposed to predict 1.48% reducing sugar yield with the optimum temperature (51.45 °C) and reaction time (3.84 h) from the straw degradation. The reaction of crude AgCMCase and rice straw in the optimized condition resulted in reducing sugar production of 1.61% that agrees the prediction. CONCLUSION: Our findings suggest that the crude AgCMCase is suitable to be used in straw conversion.

[Correlation analysis of color change and Maillard reaction during processing of Gardeniae Fructus Praeparatus].

The chromaticity space parameters of the samples during the processing of Gardeniae Fructus Praeparatus(Jiaozhizi in Chinese herbal name, JZZ) were measured by the visual analyzer to analyze the color variation rule during the processing of JZZ, and the content changes of total reducing sugar, total amino acid and 5-hydroxymethylfurfural(5-HMF) related to Maillard reaction were measured. Pearson correlation analysis and linear regression analysis of the data were carried out by SPSS 24.0 software. The experimental results showed that the objective coloration of the samples in the processing of JZZ was basically consistent with the traditional subjective color judgment; the contents of total reducing sugar and total amino acids showed a decreasing trend during the processing of JZZ, and the content of 5-HMF showed an increasing trend, which was in line with Maillard reaction law. Pearson correlation analysis results showed that there was a significant correlation between the chromaticity space parameters L~*(lightness value), a~*(red green value), b~*(yellow blue value), E~*ab(total color value) and the contents of total reducing sugar, total amino acid and 5-HMF(P<0.01), among which the values of L~*, a~*, b~*, E~*ab were positively correlated with the contents of total reducing sugar and total amino acid, and negatively correlated with the contents of 5-HMF. The results of linear regression analysis also showed that these two were highly correlated. In this study, by establishing the correspondence relationship between the color change of JZZ processing and Maillard reactants, wecan not only provide a basis for the objective digital expression of subjective color of JZZ, but also provide a reference for explaining the processing mechanism of JZZ from a new perspective.

Salivary α-Amylase Activity and Starch-Related Sweet Taste Perception in Humans.

Starch-related sweet taste perception plays an important role as a part of the dietary nutrient sensing mechanisms in the oral cavity. However, the release of sugars from starchy foods eliciting sweetness has been less studied in humans than in laboratory rodents. Thus, 28 respondents were recruited and evaluated for their starch-related sweet taste perception, salivary alpha-amylase (sAA) activity, oral release of reducing sugars, and salivary leptin. The results demonstrated that a 2-min oral mastication of starchy chewing gum produced an oral concentration of maltose above the sweet taste threshold and revealed that the total amount of maltose equivalent reducing sugars produced was positively correlated with the sAA activity. In addition, respondents who consistently identified the starch-related sweet taste in two sessions (test and retest) generated a higher maltose equivalent reducing sugar concentration compared to respondents who could not detect starch-related sweet taste at all (51.52 ± 2.85 and 29.96 ± 15.58 mM, respectively). In our study, salivary leptin levels were not correlated with starch-related sweet taste perception. The data contribute to the overall understanding of oral nutrient sensing and potentially to the control of food intake in humans. The results provide insight on how starchy foods without added glucose can elicit variable sweet taste perception in humans after mastication as a result of the maltose generated. The data contribute to the overall understanding of oral sensing of simple and complex carbohydrates in humans.

Evaluation of six white-rot fungal pretreatments on corn stover for the production of cellulolytic and ligninolytic enzymes, reducing sugars, and ethanol.

Fungal pretreatment on lignocellulosic biomass has the advantages of being eco-friendly, having low operating cost, and producing no inhibitor. In this study, six white-rot fungi (Trametes versicolor, Pleurotus ostreatus, Phanerochaete chrysosporium, Coriolopsis gallica, Pleurotus sajor-caju, Lentinula edodes) were applied to corn stover pretreatment. Biomass degradation, production of enzymes, reducing sugar via hydrolysis, and ethanol yield via yeast fermentation were quantified during 30 days cultivation, and samples were taken every 5 days. Among six fungi, the highest lignin degradation was 38.29% at 30 days for P. sajor-caju pretreatment, the highest sugar yield was 71.24%, and the highest ethanol yield was 0.124 g g-1 corn stover under P. sajor-caju pretreatment for 25 days. The highest activities of laccase and manganese peroxidase were 29.22 and 10.22 U g-1 dry biomass, respectively, under T. versicolor pretreatment at 25 days. The highest levels of enzyme, sugar, and ethanol production are comparable or higher than what has been reported in previous literature. P. sajor-caju is one of the most widely worldwide cultivated mushrooms. The findings in this study show the potential to incorporate P. sajor-caju mushroom cultivation into corn stover pretreatment to enhance the production of a suite of products such as enzymes, sugars, and ethanol.

Comparison of reducing sugar content, sensory traits, and fatty acids and volatile compound profiles of the longissimus thoracis among Korean cattle, Holsteins, and Angus steers.

OBJECTIVE: This study was performed to compare fat content, reducing sugar contents, sensory traits, and fatty acid (FA) and volatile compound profiles in longissimus thoracis (LT) among Korean cattle (KC), Holstein (HO), and Angus (AN) steers. METHODS: Twelve LT samples (about 500 g each) of KC with an average age of 31±0.42 months, an average carcass weight of 431±12.5 kg, and a quality grade (QG) of 1+ were obtained from the joint livestock products market. Twelve LT samples of HO cattle with an average age of 24±0.54 months, an average carcass weight of 402±7.81 kg, and a QG of 2 were also obtained from the same market. Twelve LT samples of AN steers with an average age of about 20 months and a QG of choice were purchased from a beef delivery company. After slaughter, samples were kept at 4°C for 42 days and prepared for immediate analysis or stored at appropriate conditions. The chemical composition, color, pH, shear force, collagen content, reducing sugars, sensory evaluation, FA composition, and volatile compound content for each LT sample were analyzed. RESULTS: The LT of KC had the highest (p<0.05) fat content, the highest reducing sugar content, and the highest scores in the sensory evaluation (flavor, tenderness, juiciness, and overall acceptance). All the sensory traits were positively correlated (p<0.001) with intramuscular fat and reducing sugar content. Several FAs and volatile compound profiles varied among the breeds. KC LT had the highest (p<0.05) concentrations of acetaldehyde, 3-methyl butanal, and 3-hydroxy-2-butanone, and these volatile compounds were positively correlated (p<0.05) with all the sensory traits. CONCLUSION: Variations in fat content and reducing sugar contents and FA and volatile compound profiles may contribute to differences in the sensory quality of LT among breeds.

[Development of LC-MS and LC-MS/MS Methods for Free Asparagine in Grains].

New analytical methods for the determination of free asparagine （Asn）, which is a precursor of acrylamide, in grains were developed using LC-MS and LC-MS/MS. Asn was extracted from a sample with 5％ （w/v） aqueous trichloroacetic acid solution, appropriately diluted with 0.1％ （v/v） formic acid solution, and then analyzed by LC-MS or LC-MS/MS. HPLC separation was performed by isocratic elution on a Penta Fluoro Phenyl （PFP） column using 0.1％ （v/v） formic acid and acetonitrile mixture as the mobile phase. The calibration curve was linear in the range of 0.005-0.1 µg/mL. The mean recoveries from potato starch, non-glutinous rice flour and whole wheat flour ranged from 95.4 to 100.9％, repeatability （RSD） ranged from 0.9 to 6.0％, and within-laboratory reproducibility （RSDwr） ranged from 2.8 to 7.1％. Limits of quantitation （LOQs） were 7 mg/kg for potato starch, and 5 mg/kg for non-glutinous rice flour. In addition, an inter-laboratory study was performed in 10 laboratories using 5 kinds of grains （non-glutinous brown rice flour, corn flour, strong flour, whole wheat flour, and whole rye flour）, which naturally contained free asparagine. The HORRATR values ranged from 0.4 to 1.0. These results are within the range of the procedural manual of the Codex Alimentarius Commission, confirming the effectiveness of the developed procedures.

Effects of blanching treatments on acrylamide, asparagine, reducing sugars and colour in potato chips.

This study aimed to determine the effect of combinations of blanching parameters, including blanching temperatures ranging from 65 to 85 °C and duration times ranging from 2 to 10 min, on reducing sugars, asparagine, acrylamide, and color levels of fried potato chips. Response surface methodology was used to develop response surface equations to estimate these effects. These latter were evaluated before and after a 3-month storage period of potato tubers at 10 °C. It was found that certain blanching parameters resulted in optimal maximum reductions of 64.2, 49.8, and 61.3% for reducing sugar, asparagine, and acrylamide, respectively. Analysis of variance (ANOVA) determined that blanching time had a more significant impact than blanching temperature. The blanching time that resulted in maximum reductions of asparagine, reducing sugars-and ultimately acrylamide-were in the range of 8.8-9.7 min at 68.7-75.0 °C. ANOVA also determined that after the 3-month storage period of potato tubers, variations in blanching time and temperature did not result in any significant differences in acrylamide formation in fried chips. Blanching consistently improved the appearance of the fried chip products, indicated by increases in L* value and decreases in a* values. The relationship between acrylamide formation and a* value was linear (R2 = 0.839), while the relationship between acrylamide formation and L* value was not (R2 = 0.375).

Cytosolic glyceraldehyde-3-phosphate dehydrogenases play crucial roles in controlling cold-induced sweetening and apical dominance of potato (Solanum tuberosum L.) tubers.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an important enzyme that functions in producing energy and supplying intermediates for cellular metabolism. Recent researches indicate that GAPDHs have multiple functions beside glycolysis. However, little information is available for functions of GAPDHs in potato. Here, we identified 4 putative cytosolic GAPDH genes in potato genome and demonstrated that the StGAPC1, StGAPC2, and StGAPC3, which are constitutively expressed in potato tissues and cold inducible in tubers, encode active cytosolic GAPDHs. Cosuppression of these 3 GAPC genes resulted in low tuber GAPDH activity, consequently the accumulation of reducing sugars in cold stored tubers by altering the tuber metabolite pool sizes favoring the sucrose pathway. Furthermore, GAPCs-silenced tubers exhibited a loss of apical dominance dependent on cell death of tuber apical bud meristem (TAB-meristem). It was also confirmed that StGAPC1, StGAPC2, and StGAPC3 interacted with the autophagy-related protein 3 (ATG3), implying that the occurrence of cell death in TAB-meristem could be induced by ATG3 associated events. Collectively, the present research evidences first that the GAPC genes play crucial roles in diverse physiological and developmental processes in potato tubers.

Amylases StAmy23, StBAM1 and StBAM9 regulate cold-induced sweetening of potato tubers in distinct ways.

Cold-induced sweetening (CIS) in potato is detrimental to the quality of processed products. Conversion of starch to reducing sugars (RS) by amylases is considered one of the main pathways in CIS but is not well studied. The amylase genes StAmy23, StBAM1, and StBAM9 were studied for their functions in potato CIS. StAmy23 is localized in the cytoplasm, whereas StBAM1 and StBAM9 are targeted to the plastid stroma and starch granules, respectively. Genetic transformation of these amylases in potatoes by RNA interference showed that ß-amylase activity could be decreased in cold-stored tubers by silencing of StBAM1 and collective silencing of StBAM1 and StBAM9. However, StBAM9 silencing did not decrease ß-amylase activity. Silencing StBAM1 and StBAM9 caused starch accumulation and lower RS, which was more evident in simultaneously silenced lines, suggesting functional redundancy. Soluble starch content increased in RNAi-StBAM1 lines but decreased in RNAi-StBAM9 lines, suggesting that StBAM1 may regulate CIS by hydrolysing soluble starch and StBAM9 by directly acting on starch granules. Moreover, StBAM9 interacted with StBAM1 on the starch granules. StAmy23 silencing resulted in higher phytoglycogen and lower RS accumulation in cold-stored tubers, implying that StAmy23 regulates CIS by degrading cytosolic phytoglycogen. Our findings suggest that StAmy23, StBAM1, and StBAM9 function in potato CIS with varying levels of impact.

The use of steam explosion to increase the nutrition available from rice straw.

In the present study, rice straw was pretreated using steam-explosion (ST) technique to improve the enzymatic hydrolysis of potential reducing sugars for feed utilization. The response surface methodology based on central composite design was used to optimize the effects of steam pressure, pressure retention time, and straw moisture content on the yield of reducing sugar. All the investigated variables had significant effects (P < 0.001) on the reducing sugar yield. The optimum yield of 30.86% was obtained under the following pretreatment conditions: steam pressure, 1.54 MPa; pressure retention time, 140.5 Sec; and straw moisture content, 41.6%. The yield after thermal treatment under the same conditions was approximately 16%. Infrared (IR) radiation analysis showed a decrease in the cellulose IR crystallization index. ST noticeably increases reducing sugars in rice straw, and this technique may also be applicable to other cellulose/lignin sources of biomass.