Β-amylase Activity Research Articles

Malt protein inhibition of β-amylase alters starch molecular structure during barley mashing

The molecular structural changes in starch in barley malts during mashing (a major step in brewing beer) with and without protein removal were investigated using size exclusion chromatography. The aim was to uncover how proteins affects barley starch degradation in brewing. It was found that for malts containing lower β-amylase activity, protein removal significantly increased fermentable sugar content, whilst no significant change was observed for malts with higher β-amylase, with or without addition of a metalloprotease (Neutrase®). However, metalloprotease addition significantly reduced both the content and molecular sizes of remaining wort-soluble starches. This suggests that the effects of malt protein removal on starch degradation, particularly on fermentable sugar production, largely depend on malt enzyme activity, especially that of β-amylase. This provides useful information for brewers: for example, the fact that soluble starch molecular structure correlates significantly with fermentation efficiency gives a new criterion for selecting barley varieties for optimal brewing performance.

On the suitability of alternative cereals, pseudocereals and pulses in the production of alcohol-reduced beers by non-conventional yeasts

The growing interest in non-alcoholic and low alcohol beers (NABLAB) has fuelled research into innovative production methods. One means to produce NABLAB is through limited fermentation by non-Saccharomyces yeasts which have a naturally low fermentative capacity in cereal-based wort substrates. At the same time, adjunct brewing, the partial replacement of barley malt on the grain bill, enjoys growing popularity. In this study, 13 cereals, pseudocereals, and pulses were investigated for their suitability to produce a wort with limited amounts of fermentable sugars. Subsequently, the fermentation performance of two non-Saccharomyces yeast strains, namely Cyberlindnera subsufficiens C6.1 and Lachancea fermentati KBI 12.1, in the produced worts was investigated and compared to that of a brewers’ yeast strain. The worts were produced by harnessing endogenous amylolytic enzyme activity or the addition of an external amylase and analysed for their sugar composition and free amino acids (FAA) profile. All alternative substrates without endogenous β-amylase activity were found to be suitable for producing worts with a high proportion of unfermentable sugars. However, the extract yield was low for the pulses and most worts exhibited a low and/or unbalanced FAA profile. The ethanol production was limited and mostly dependent on the sugar spectrum of the worts and the sugar utilization characteristics of the applied yeast strains. The (partial) substitution of barley with alternative substrates when producing NABLAB by non-Saccharomyces yeast can be a means to alter the sugar and FAA profile of the wort, but must be considered in concert with the yeast strains’ characteristics.

곰팡이 균주별 무증자 쌀가루 개량누룩을 첨가한 막걸리의 품질특성

An easy and simple method of producing Nuruk using rice was developed. In addition, the quality characteristics of the prepared Nuruk were evaluated for Makgeolli production. A comparison of the enzyme activities between A. kawachii rice Koji (RK) and non-steamed rice flour Nuruk according to the fungal strain revealed the β-amylase activity of A. oryzae rice flour Nuruk (AON) to be the highest at 3697.85 SP/g. The α-amylase activity and protease activity were highest at 111.67 A.U and 33.23 tyrosine mg/min of P. candidum rice flour Nuruk (PCN), respectively. The ethanol contents of the four samples were similar at 16.1-16.4%. The sensory evaluation result showed that Makgeolli made with PCN had the highest preference score of 5.78 and showed a significant difference in overall preference. Moreover, Makgeolli made with PCN showed a higher preference than of Makgeolli made with RK. The titratable acidity and reducing sugar content of Makgeolli made with PCN were 0.48% and 4.14%, respectively, which were higher than those of Makgeolli made with RK. The ethanol content of Makgeolli made with PCN was 15.10%, which showed a 12.80% higher ethanol production yield than that of Makgeolli made with RK. Therefore the PCN produced in this study will be effective for Makgeolli production.

Identification of Proteomic Components Associated with Resistance to Fusarium Head Blight in Rye

Rye was used here to dissect molecular mechanisms of resistance to Fusarium head blight (FHB) and to go deeper with our understanding of that process in cereals. F. culmorum-damaged kernels of two lines different in their potential of resistance to FHB were analyzed using two-dimensional gel electrophoresis and mass spectrometry to identify resistance markers. The proteome profiling was accompanied by measurements of α- and β-amylase activities and mycotoxin content. The proteomic studies indicated a total of 18 spots with clear differences in protein abundance between the more resistant and more susceptible rye lines after infection. Eight proteins were involved in carbohydrate metabolism of which six proteins showed a significantly higher abundance in the resistant line. The other proteins recognized here were involved in stress response and redox homeostasis. Three remaining proteins were associated with protease inhibition/resistance and lignin biosynthesis, revealing higher accumulation levels in the susceptible rye line. After inoculation, the activities of α- and β-amylases, higher in the susceptible line, were probably responsible for a higher level of starch decomposition after infection and a higher susceptibility to FHB. The presented results could be a good reference for further research to improve crop resistance to FHB.

Simultaneous enhancement of barley β-amylase thermostability and catalytic activity by R115 and T387 residue sites mutation

ObjectiveTo simultaneously increase the thermostability and catalytic activity of barley β-amylase. MethodsThe amino acid sequences of various barley β-amylases with different enzyme properties were aligned, two amino acid residues R115 and T387 were identified to be important for barley β-amylase properties. R115C and T387V were then generated using site-directed and saturation mutagenesis. ResultsR115C and T387V mutants increased the enzyme catalytic activity and thermostability, respectively. After combinational mutagenesis, the T50 value and t(1/2,60oC) value of R115C/T387V mutant reached 59.4 °C and 48.8 min, which were 3.6 °C higher and 29.5 min longer than those of wild-type. The kcat/Km value of mutant R115C/T387V were 59.82/s·mM, which were 54.7% higher than that of wild-type. The increased surface hydrophobicity and newly formed strong hydrogen bonds and salt bridges might be responsible for the enzyme thermostability improvement while the two additional hydrogen bonds formed in the active center may lead to the catalytic property enhancement. ConclusionsThe mutant R115C/T387V showed high catalytic activity and thermostability indicating great potential for application in industry.

Exogenous putrescine regulates leaf starch overaccumulation in cucumber under salt stress

To understand the mechanism by which exogenous putrescine (Put) alleviated starch overaccumulation in the leaves of cucumber subjected to salt stress, a greenhouse experiment was conducted. Our research findings focused on NaCl stress leading to an increase in the number of starch granules in the chloroplast and starch content in the leaves, resulting in the destruction of photosynthetic organs and reduced photosynthesis. However, exogenous Put reduced the number of starch granules and protected the photosynthetic organs, thereby enhancing photosynthesis. On the other hand, Put-treated seedlings reduced AGPase activity by downregulating AGPase and increased β-amylase activity by upregulating BAM1, resulting in relief from excess accumulation of leaf starch. The application of d-Arg under salt stress decreased the expression of ADC, inhibited Put synthesis, reduced the endogenous polyamine (PAs) content, and inhibited the growth of seedlings; exogenous Put partly alleviated the inhibitory effect of d-Arg and significantly increased the endogenous PAs content, indicating that the ADC pathway is important for Put synthesis in plants suffering from salt stress. Taken together, exogenous application of PAs could increase levels of endogenous PAs via important ADC pathways, mainly inducing AGPase and BAM1 expression, leading to changes in AGPase and β-amylase activities involved in starch metabolism to reduce excessive starch accumulation in leaves, relieve photosynthetic feedback repression and protect photosynthetic organs, thus enhancing cucumber seedling salt stress tolerance.

Comparisons of Modern United States and Canadian Malting Barley Cultivars with Those from Pre-Prohibition: V. Bmy1 Intron III Alleles and Grain β-Amylase Activity and Thermostability

This study was conducted to determine the variation in Pre-Prohibition and modern barley malting genotype β-amylase activities and thermostabilities with differing Bmy1 intron III alleles. Sequencing of the endosperm specific β-amylase gene Bmy1 intron III of two- and six-row of Pre-Prohibition barley varieties revealed that both two- and six-row varieties had the Bmy1.a intron III allele. This is unusual in that previously there has been only one documented case of a two-row cultivar having the Bmy1.a intron III allele. In this study, all modern cultivars were found to have the expected Bmy1.b intron III allele and Bmy1.a intron III allele for two- and six-row cultivars, respectively. On a fresh weight or unit protein basis, the mean grain β-amylase activities of modern malting cultivars were significantly higher (P < 0.0001) than the mean for Pre-Prohibition malting varieties. This indicates that the many years of selection for diastatic power (DP) since the end of Prohibition in North America have increased the β-amylase activity significantly. Many studies have shown that DP strongly correlates with β-amylase activity. The β-amylase activities of modern cultivars with the highest β-amylase activity were significantly higher (P < 0.0001) than all Pre-Prohibition varieties. The β-amylase activities of Pre-Prohibition varieties with the lowest β-amylase activity were significantly lower (P < 0.0001) than all modern cultivars. Modern cultivars were significantly higher (P = 0.022) than for Pre-Prohibition varieties; although, the differences for most genotypes, be they Pre-Prohibition or modern, were not large. The two-row Pre-Prohibition varieties Hanna and Hannchen were the exceptions, being highly significantly lower (P < 0.0001) in thermostability than all other Pre-Prohibition and modern genotypes.

Production of recombinant beta-amylase of Bacillus aryabhattai

In this study, the effects of carbon source, nitrogen source, and metal ions on cell growth and Bacillus aryabhattai β-amylase production in recombinant Brevibacillus choshinensis were investigated. The optimal medium for β-amylase production, containing glucose (7.5 g·L−1), pig bone peptone (40.0 g·L−1), Mg2+ (0.05 mol·L−1), and trace metal elements, was determined through single-factor experiments in shake flasks. When cultured in the optimized medium, the β-amylase yield reached 925.4 U mL−1, which was 7.2-fold higher than that obtained in the initial medium. Besides, a modified feeding strategy was proposed and applied in a 3-L fermentor fed with glucose, which achieved a dry cell weight of 15.4 g L−1. Through this cultivation approached 30 °C with 0 g·L−1 initial glucose concentration, the maximum β-amylase activity reached 5371.8 U mL−1, which was 41.7-fold higher than that obtained with the initial medium in shake flask.

Effect of varying starch properties and mashing conditions on wort sugar profiles

The aim of this research was to investigate the relationship between starch composition in barley and its malted counterpart alongside malt enzyme activity and determine how these factors contribute to the fermentable sugar profile of wort. Two Australian malting barley varieties, Commander and Gairdner, were sourced from eight growing locations alongside a commercial sample of each. For barley and malt, total starch and gelatinisation temperature were taken, and for malt, α- and β-amylase activities were measured. Samples were mashed using two mashing profiles (infusion and Congress) and the subsequent wort sugar composition and other quality measures (colour, original gravity, soluble nitrogen) were tested. Variety had no significant (<0.05) effect on any barley, malt, enzyme or wort characteristics. However, growing location impacted gelatinisation temperature, colour, malt protein content and original gravity. The gelatinisation temperature in malt samples was higher, by ~0.8°C, than in the equivalent barley sample. Several malt samples, even with protein contents <12.0%, had gelatinisation temperature >65°C. The fermentable sugars measured in the malt prior to mashing showed a higher proportion of maltose than glucose or maltotriose. In addition, there were significant differences in the amount of sugar produced by each mashing method with the high temperature infusion producing a higher amount of sugar and proportionally more maltose. There is scope for further research on the effect of genetics and growing environment on gelatinisation temperature, mash performance and fermentable sugar development. Routinely measuring gelatinisation temperature and providing this information on malt specification sheets could help brewers optimise performance. © 2019 The Institute of Brewing & Distilling

Promotive Effect of Ascorbic Acid, Gallic Acid, Selenium and Nano-Selenium on Seed Germination, Seedling Growth and Some Hydrolytic Enzymes Activity of Cowpea (Vigna unguiculata) Seedling

This study aimed to improve cowpea seed germination and seedling growth by using some antioxidant compounds naturally produced or up taken by plants. The effect of soaking cowpea (Vigna unguiculata) for 2 h in aerated solution of different antioxidants; ascorbic acid (AsA) and gallic acid (GA), each at 0.0, 50, 100, 150, 200, 250 and 300 ppm, sodium selenate (NaSeO4) and nanoselenium (SeNPs ≈ 33.4 nm) chemically prepared, each at 0.0, 6.25, 12.5, 25, 50 and 100 μM on seedling length and activities of some hydrolytic enzymes were tested. Seeds of treated and untreated cowpea were germinated at 25°C ± 0.5 under dark controlled conditions for 4 days. Results showed that AsA, GA, NaSeO4 and SeNPs at low concentrations significantly improved plumule and radicale lengths compared with their corresponding controls. Moreover, AsA and GA up to 150 ppm, NaSeO4 and SeNPs up to 25 μM significantly increased the activities of α-amylase, β-amylase and protease enzymes as well as the contents of total soluble sugars and total soluble proteins. The results indicate the successful use of ascorbic acid and gallic acid up to 150 ppm as well as sodium selenate and nanoselenium up to 25 μM in enhancing seedling growth and hydrolytic enzymatic activity in cowpea germinated seeds.Further promising results on the effect of these compounds on vegetative growth and yield can be concluded from the previous results on germination and seedling growth.

Reduction in arsenic toxicity and uptake in rice (Oryza sativa L.) by As-resistant purple nonsulfur bacteria.

This study aimed to investigate the potential of Rhodopseudomonas palustris C1 and Rubrivivax benzoatilyticus C31 to ameliorate As toxicity and to reduce As uptake in rice. Strain C1 was superior to strain C31 for siderophore production. The mixed culture (1: 1) was most effective in reducing the toxicity of As species [As(III) and/or As(V), each 30mg/l] by yielding maximal germination index that related to α- and β-amylase activities in two Thai rice cultivars (HomNil: HN and PathumThani 1: PT). Arsenic toxicity to the seed germination followed the order: mixed As species > As(III) > As(V); and the toxicity was reduced in inoculated sets, particularly with a mixed culture. The mixed culture significantly enhanced rice growth under As stress in both rice cultivars as indicated by an increase in the production of chlorophyll a and b, and also supporting the non-enzymatic (carotenoids, lipid oxidation, and nitric oxide) and enzymatic (superoxide dismutase, ascorbate peroxidase, catalase, and glutathione reductase) activities. These were concomitant with productions of 5-aminolevulinic acid, indole-3-acetic acid, exopolymeric substances, and siderophores which significantly reduced As accumulation in treated rice. It can be concluded that the mixed culture has great potential to ameliorate rice from As toxicity by preventing As species entry into rice for enhancing rice growth and also for reducing As accumulation to produce safe rice from rice grown in contaminated paddy fields.

Partial purification and characterisation of β-amylase isolated from malted pearl millet (&lt;i&gt;Pennisetum glaucum&lt;/i&gt;)

The industrial use of enzymes in the degradation of starch has become predominant over conventional methods of acid starch hydrolysis. As such, cheap sources of starch hydrolysing enzymes are being sought for. β-amylase, an exo-hydrolase which releases maltose by hydrolysing starch from the non-reducing end, is one of such important enzymes found to be common to the seeds of higher plants such as cereal grains. In this research, β-amylase was extracted from malted Pearl Millet grains and partially purified by ammonium sulphate precipitation (0-60%). The activity of β-amylase peaked at 72h of malting (7.40 imol/min/mL) with specific activity of 1.84 imol/min/mg. The enzyme extract at 72h was purified for characterization assays, giving a 1.33 purification fold and a yield of 9.28% after extensive dialysis against extraction buffer. Enzyme characterisation assays showed pearl millet β-amylase has optimal activity at pH 5.0 and 50 °C while a K m value of 10 mg/mL and V max value of 11.11 imol/min/mL were obtained when corn starch was used as substrate. The enzyme also showed significant activity over a wide temperature and pH range, indicating its potential as an industrial enzyme. The results from this study show that malted Pearl Millet is a cheap source of β-amylase with favourable kinetics and the desired characteristics of activity at low pH and elevated temperatures. Keywords: Partial Purification, Pearl Millet, β-amylase, Starch, Malting, Industrial Potential

Low Nitrogen Application Enhances Starch-Metabolizing Enzyme Activity and Improves Accumulation and Translocation of Non-structural Carbohydrates in Rice Stems.

More than 4 billion inhabitants in Asia depend on rice for 35–60% of the calories consumed in their diets, but new rice cultivars frequently do not reach expected yields because of poor rice grain filling. Here, we quantified the activities of enzymes involved in starch metabolization in rice to investigate the mechanisms regulating the accumulation and translocation of stem non-structural carbohydrates (NSC) under different levels of nitrogen fertilizer application. A pot experiment was conducted using two rice cultivars, Liangyoupeijiu (LYPJ) and Shanyou63 (SY63), under high and low nitrogen applications. Compared with high nitrogen application (HN), low nitrogen application (LN) increased stem NSC concentration before the heading stage and NSC translocation during the grain filling stage; concomitantly, LN significantly shortened the active grain filling period and increased the grain filling rate in superior spikelets. Compared with the LYPJ cultivar, SY63 exhibited a higher grain weight, higher grain filling percentage, and higher stem NSC concentration before heading and greater NSC translocation after heading. During the period between panicle initiation and heading, the activities of adenosine diphosphate-glucose pyrophosphorylase (AGP), starch synthase (StS), and starch branching enzyme (SBE), all enzymes involved in starch synthesis, increased under the LN treatment and positively correlated with increases in stem NSC. During grain filling, the activities of enzymes involved in starch-to-sucrose conversion [α-amylase, β-amylase, and sucrose phosphate synthase (SPS)] increased under the LN treatment and positively correlated with stem NSC remobilization. Overall, the investigated enzymes exhibited higher activities in SY63 than in LYPJ. Our results suggest that low nitrogen increases the activities of AGP, StS, SBE, α-amylase, β-amylase, and SPS, leading to increased accumulation and remobilization of stem starch and NSC in SY63. We conclude that calculated reductions in nitrogen application and the choice of an appropriate cultivar may improve rice grain yields via enhanced stem NSC accumulation and translocation, thereby reducing the costs and increasing the sustainability of rice production.

Effect of jet milling on the physicochemical properties, pasting properties, and in vitro starch digestibility of germinated brown rice flour

Germinated brown rice (GBR) flours were prepared by hammer milling and jet milling. The effect of the milling on the physicochemical and pasting properties of the resultant flours were investigated. The jet milling of GBR resulted in flour with different particle sizes, which were air-classified into coarse and fine size fractions. As the particle size decreased, the amount of damaged starch increased. The WAI, WSI, and oil absorption of the jet-milled GBR flour was slightly lower than that of the hammer-milled flour. Increased α- and β-amylase activities were observed in the coarse fraction of the jet-milled GBR flour compared with the hammer-milled and jet-milled fine fractions. The RVA viscosity profiles of the fine fraction of the jet-milled GBR flour were significantly higher than those of the hammer-milled or the coarse fraction of the jet-milled GBR flour. Compared with the hammer-milled flour, jet milling increased in vitro starch hydrolysis.

Comparisons of Modern United States and Canadian Malting Barley Cultivars with Those from Pre-Prohibition: IV. Malting Quality Assessments Using Standard and Nonstandard Measures

This study was conducted to identify which traits or combination of traits associated with malting quality and mashing performance could best define the differences between and within a population of six pre-Prohibition malting barley varieties and a population of five modern elite malting barley cultivars. To accomplish this, standard and nonstandard metrics of malt quality and of performance during Congress mashing were analyzed by simple linear correlations and multivariate statistics. Analyses of the two populations combined revealed that activities of α-amylase at each time sampled during mashing were positively and significantly correlated with the concentrations of glucose at that same time, were not significantly correlated with maltose concentrations at any time, and were only significantly correlated with maltotriose concentrations for the first 30 min of mashing. Activities of β-amylase were not significantly correlated with concentrations of glucose, maltose, or maltotriose at any time during mashing. Analysis of α-glucosidase activities showed no consistent trends in correlations with either glucose or maltotriose and no significant correlation with maltose at any time. Analysis of limit dextrinase activities showed significant and positive correlations with glucose and maltotriose concentrations prior to the mash temperature reaching the starch conversion stage. Although no individual amylolytic enzyme activity was significantly correlated with maltose concentration, diastatic power was positively and significantly correlated with maltose at five of six times sampled during mashing. Diastatic power was not significantly correlated with glucose or maltotriose concentrations at any time. Malt extract values and osmolyte concentrations were positively and significantly correlated with mash glucose concentrations at all times sampled, with maltose concentrations at the first four times sampled, and with maltotriose for the first five times. Principal component analysis (PCA) of the traits analyzed in the two populations combined showed that the modern malting barleys were generally well separated from the pre-Prohibition barleys by three principal components that accounted for 75% of the variation among the 11 cultivars. The traits that collectively contributed the most to separation of the modern from the pre-Prohibition barleys were osmolyte concentrations, malt extract values and glucose concentration, which were higher in the modern cultivars, and α-glucosidase thermostability and concentrations of maltopentaose, maltohexaose and maltoheptaose, which were higher in the pre-Prohibition cultivars. PCA of the individual populations also separated Tradition from the other modern cultivars due to its lower levels of glucose, maltotriose, and α-amylase activity and by its higher levels of maltose and % plump. PCA of the pre-Prohibition population separated Hanna from the other pre-Prohibition cultivars primarily by its higher levels of maltopentaose through maltoheptaose and its low levels of osmolytes. Silver King was somewhat displaced from other pre-Prohibition cultivars due to its low levels of osmolytes and to its very high levels of α-glucosidase thermostability.

Noncanonical interactions between serpin and β-amylase in barley grain improve β-amylase activity invitro.

Serpin protease inhibitors and β‐amylase starch hydrolases are very abundant seed proteins in the endosperm of grasses. β‐amylase is a crucial enzyme in the beer industry providing maltose for fermenting yeast. In animals and plants, inhibitory serpins form covalent linkages that inactivate their cognate proteases. Additionally, in animals, noninhibitory functions for serpins are observed such as metabolite carriers and chaperones. The function of serpins in seeds has yet to be unveiled. In developing endosperm, serpin Z4 and β‐amylase showed similar in vivo spatio‐temporal accumulation properties and colocalize in the cytosol of transformed tobacco leaves. A molecular interaction between recombinant proteins of serpin Z4 and β‐amylase was revealed by surface plasmon resonance and microscale thermophoresis yielding a dissociation constant of 10−7 M. Importantly, the addition of serpin Z4 significantly changes β‐amylase enzymatic properties by increasing its maximal catalytic velocity. The presence of serpin Z4 stabilizes β‐amylase activity during heat treatment without affecting its critical denaturing temperature. Oxidative stress, simulated by the addition of CuCl2, leads to the formation of high molecular weight polymers of β‐amylase similar to those detected in vivo. The polymers were cross‐linked through disulfide bonds, the formation of which was repressed when serpin Z4 was present. The results suggest an unprecedented function for a plant seed serpin as a β‐amylase‐specific chaperone‐like partner that could optimize β‐amylase activity upon germination. This report is the first to describe a noninhibitory function for a serpin in plants.

Process optimization of the extraction condition of β-amylase from brewer's malt and its application in the maltose syrup production.

β-Amylase is of important biotechnological aid in maltose syrup production. In this study, the extraction condition of β-amylase from brewer's malt and the optimal dosage of β-amylase in maltose syrup production were optimized using response surface methodology and uniform design method. The optimal extraction condition of β-amylase from brewer's malt was composed of 1:17 (g/v) material/liquid ratio, 44°C extraction temperature, pH 6.4 buffer pH, 2.3H extraction time, and 1.64gL-1 NaSO3 dosage with a predicted β-amylase activity of 1,290.99Ug-1 , which was close to the experimental β-amylase activity of 1,230.22Ug-1 . The optimal dosages of β-amylase used in maltose syrup production were 455.67Ug-1 starch and its application in maltose syrup production led to a 68.37% maltose content in maltose syrup, which was 11.2% and 28.9% higher than those using β-amylases from soybean and microbe (P<0.01). Thus, β-amylase from brewer's malt was beneficial for production of high maltose syrup.

EFFECTS OF MALTING CONDITIONS TO QUALITY OF GERMINATED RED SORGHUM

Sorghum, one of the most popular cereals in the world, can be used directly or in malted and/or fermented form in the preparation of several traditional foods. The aim of this study was to investigate the effects of malting conditions to quality germination of red sorghum in order to select the malted sorghum for beverage production. Twenty malts types originated from red sorghum (Sorghum bicolor L. Moench) were produced under different experimental conditions: steeping (30 °C for 15 - 44 h with and without aeration), germination (30 °C, 98 % relative humidity, 45 - 72 h) and drying or lyophilisation. Dry matter loss, production of sugar, α and β-amylase activities were determined. The obtained results showed the distribution of dry matter loss during malting: steeping (2.2 - 4.0 %), germination (3.7 - 6.5 %), drying (1 %) and degerming (4.3 - 7.5 %). The starch was slightly hydrolysed (2.5 %) for producing soluble sugars: maltose (2.9 - 4.0 %) and glucose (1.7 - 3.6 %). Any organic acids production during the malting was detected. The obtained malted sorghum contained high α-amylase activity but a low level of β-amylase. The highest α- and β-amylase activities were 173.1 U.gms-1 and 3.4 U.gms-1, respectively. These results were obtained for steeping 44 h with aeration, germinated 45 h and lyophilised sorghum. The amylase activities were positively correlated with the water content of grain at the end of steeping.

Characterization of high-yielding rice cultivars with different grain-filling properties to clarify limiting factors for improving grain yield

Recently developed high-yielding rice varieties with extra-large sink capacity often have unstable grain filling. Therefore, understanding the factors that limit grain filling is essential for further improvement of rice grain yield. Because grain-filling is determined by the complex sink–source balance, grain-filling ability is very difficult to evaluate. In this study, we compared grain-filling-related traits of three high-yielding cultivars with high sink capacity. We found that the translocation of non-structural carbohydrates (NSC) from stem to panicle during early ripening and grain filling was significantly lower in Momiroman than in Hokuriku 193 and Teqing, whereas dry matter accumulation of the whole plant did not differ among the cultivars throughout ripening. The NSC-components, sucrose and starch were both remained higher in stems of Momiroman than other cultivars. ADP-glucose pyrophosphorylase (AGPase; EC 2.7.7.27) activity was not enhanced and α-Amylase (EC 3.2.1.1) and β-Amylase (EC 3.2.1.2) activities were not impeded in the stems. These data suggested lower sucrose translocation is responsible for lower NSC translocation in Momiroman, rather than too high starch synthesis and too low starch degradation activities. At early ripening, grain growth of the superior spikelets was slow in Momiroman even if carbon supply was increased by spikelet-thinning treatments. These results raise the possibility that low sink strength determines low grain filling in Momiroman, which delays grain growth and decreases sucking force of NSC from the stem.

Effects of fibrolytic enzymes and isobutyrate on ruminal fermentation, microbial enzyme activity and cellulolytic bacteria in pre- and post-weaning dairy calves

The objective of the present study was to evaluate the effects of fibrolytic enzymes (FE, containing 160 units of cellulase and 4000 units of xylanase) or isobutyrate (IB) supplementation on ruminal fermentation, microbial enzyme activity and cellulolytic bacteria in dairy calves. Forty-eight Holstein bull calves of 15 days of age and of 44.9 ± 0.28 kg of BW were randomly assigned to four groups in a 2 × 2 factorial arrangement. Two levels of FE (0 g (FE–) or 1.83 g per calf per day (FE+)) and IB (0 g (IB–) or 6 g per calf per day (IB+)) were added. Calves were weaned at 60-day-old and four calves were selected from each treatment at random and slaughtered at 45 and 90 days of age. There was no IB × FE interaction effect. Ruminal pH decreased with IB or FE supplementation for post-weaned calves, whereas concentrations of total volatile fatty acids and acetate increased with IB or FE supplementation for pre- and post-weaned calves. Acetate to propionate ratio increased with IB supplementation, but was unaffected by FE supplementation. Ammonia-N concentration decreased with IB or FE supplementation for pre- and post-weaned calves. For post-weaned calves, activities of CMCase increased with IB or FE supplementation, and activities of cellobiase, xylanase, pectinase, β-amylase and protease increased with IB supplementation. Populations of B. fibrisolvens and F. succinogenes for pre- and post-weaned calves and R. flavefaciens for post-weaned calves increased with IB or FE supplementation. It is suggested that ruminal fermentation and growth performance of calves was improved with IB and FE supplementation, and the combination of IB and FE has the potential to stimulate the growth of pre- and post-weaned dairy calves.