Gelatinisation of sago starch in the presence of sucrose and sodium chloride as assessed by differential scanning calorimetry

The inhibitory effect of sucrose and sodium chloride on sago starch gelatinisation was investigated by differential scanning calorimetry (DSC). The temperature of gelatinisation of starch in the presence of low levels of water and high levels of sucrose was found to increase in the presence of sucrose, whereas the gelatinisation enthalpy was unaffected. The gelatinisation temperature range was not as broad in the presence of sucrose as without sucrose. Furthermore, the shape of the gelatinisation endotherm was changed by the addition of sucrose. The double endotherm obtained in limited water:starch systems was changed into a single endotherm, similar to the endotherm obtained in excess water:starch systems at a higher temperature. DSC was also used to examine the effects of water and sodium chloride content on the phase transitions of sago starch. Samples were adjusted to starch:water ratios of 2:3 and 3:2 in sodium chloride concentrations of 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 M. The gelatinisation temperatures of sago starch increased and then decreased as the sodium chloride concentration increased. Sodium chloride created similar effects on the endotherms in excess water content and on the first endotherm with limited water content. In the presence of sucrose and sodium chloride, gelatinisation shifted to higher temperatures, and enthalpy associated with the endothermic process decreased. The extent of temperature shift and enthalpy change was dependent on the water to starch to solutes ratios.     

Enzymatic Improvement of the Cooking Quality of Aged Rice: A Main Mode of Protease Action

This study aims to improve the stickiness and brightness of cooked rice from aged rice grains by removing its albumins and globulins with proteases. In newly–harvested grains, the proteins were easily removed by extraction with water which contained minerals from rice. In aged grains, however, the proteins were already denatured and extracted with difficulty. Proteases hydrolyzed even the denatured proteins to make them extractable. As a result, starch granules on the surface of grains were liberated. Some proteases also hydrolyzed a starch granule-associated protein, and consequently, made the starch highly gelatinizable by heating. The protease treatment of aged grains was effective for two main reasons: liberation of starch granules and removal of the granule-associated protein. During cooking of rice the liberated starch without the associated proteins gelatinized to give rise to stickiness. The gelatinized starch is considered to form a more isotropic film on the surface of every cooked rice grain to give brightness as well.     

Glucose-forming amylase in human urine.

This paper describes the isolation and study of glucose-forming amylase existing in human urine as a normal component. After removing alpha-amylase [EC 3.2.1.1] by adsorption onto raw starch, urine was treated with DEAE-cellulose and Bio Gel P-150, and three fractionated proteins (F-1, F-2, and F-3), isolated in a homogeneous state by gel filtration, were shown to display glucose-formine amylase activity. They all hydrolyzed starch and glycogen, releasing glucose as the sole product, and also hydrolyzed maltose. However, their molecular weights, as estimated by gel filtration, isoelectric points, stabilities, and several enzymatic properties were different. The implications of the results are discussed.     

Development of a set of expression vectors in Hansenula polymorpha

Four expression vectors based on formate dehydrogenase promoter (FMDp) and methanol oxidase promoter (MOXp) from Hansenula polymorpha were developed to express heterologous genes in Hansenula polymorpha. A secretion signal sequence of the mating factor-alpha from Saccharomyces cerevisiae was inserted in the secretory expression plasmids for efficient secretion. A modified green fluorescent protein (mGFP5) was used as the marker of expression for the first time in H. polymorpha NCYC495 (leu 1.1) to determine the expression ability of these plasmids. The mGFP5 thus expressed retained its biochemical and physiological properties, such as accumulation inside cells and efficient secretion into the culture media. These results indicated that the four integrative vectors are useful expression systems which could be directly applied for production of heterologous proteins of interests in H. polymorpha.     

Adsorption of Hemoglobin and Casein onto Air Bubbles

Effects of pH, sodium chloride, temperature, and particle size were studied on the adsorption of proteins onto air bubbles. The results suggested that the froth flotation could be applied to the recovery of dissolved proteins with a comparable efficiency to the active sludge method. Such a strategy was proposed as to strip the dissolved hemoglobin under alkaline conditions or in the presence of sodium chloride, and to concentrate it under acidic conditions. Temperature was of little effect. Flotation of the precipitated proteins was much more efficient than that of the dissolved proteins. Particle size greatly affected the efficiency of flotation of the precipitated proteins.     

Synthesis of carboxymethyl cellulose (CMC) and starch-based hybrids and their applications in flocculation and sizing

Starch and hydrolyzed starches along with carboxymethyl cellulose were independently subjected to cationization by reacting them with N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride (known commercially as Quat 188) in presence of alkaline catalyst. The cationization reaction was carried out under different conditions Optimal reaction conditions could be achieved at Quat 188 (2 mmol), NaOH (1 mmol) at temperature (70 °C) 60 min for CMC or 120 min for starch. The cationic products were characterized by FTIR spectroscopy, and nitrogen percentage. Application of the cationized products as well as their parent materials in textile sizing was also undertaken. Moreover, hybrids of starch-Quat 188 and CMC-Quat 188 were used as flocculants; flocculation was carried at pH 6 using different flocculant dose. Results obtained indicate that the cationic-based hybrids – under investigation display characteristics, which qualify them to function as an excellent sizing and flocculating agents.     

Effect of salinity stress on organic and mineral constituents in the leaves of pigeonpea (Cajanus cajan L. Var. C-11)

Summary Effects of sodium chloride and sodium sulphate on the content of some organic and inorganic constituents in the leaves of pigeonpea (Cajanus cajan L. Var. C-11) were studied. Increased water content under saline conditions made the leaves succulent. The concentration of reducing sugars appeared to be higher while that of total sugars and starch was lower. The plants also failed to accumulate proline at higher salinity levels. Phosphorus and potassium content were lowered while those of calcium, magnesium, sodium, chloride and sulphate were increase under both salinities. This indicates that there is no regulation on the uptake of latter elements under saline conditions.     

SDS聚丙烯酰胺凝胶电泳快速染色新方法的研究

通过几种金融盐溶液对SDS聚丙烯酰胺凝胶电泳染色的实验表明,0.25mol/L的CaCl2和MgCl2溶液能够对蛋白质进行有效的染色,经这2种溶液染色的蛋白质都能够从凝胶中洗脱回收。尤其是CaCl2法灵敏度更高,而且蛋白质条带形成之后也十分稳定,所以在运用制备电泳纯化蛋白质时这种新的染色方法较适用。     

Paraformaldehyde-Resistant Starch-Fermenting Bacteria in “Starch-Base” Drilling Mud

Starch-fermenting bacteria were found in each of 12 samples of nonfermenting starch-base drilling mud examined. Of the 12 samples, 3 contained very active starch-fermenting gram-positive spore-bearing bacilli closely resembling Bacillus subtilis. Similar active starch-fermenting bacteria were found in fermenting starch-base drilling mud and in corn starch and slough water used to prepare such mud. The active starch-fermenting microorganisms completely hydrolyzed 1% (w/v) corn starch within 24 hr at 37.5 C. The active starch-fermenting bacteria isolated from fermenting drilling mud were capable of surviving 12 hr of continuous exposure to 0.1% (w/w) paraformaldehyde or 1 hr of continuous exposure to 0.5% (w/w) paraformaldehyde, with no diminution in starch-fermenting ability. The same organisms fermented starch after 3 hr of continuous exposure to 0.5% (w/w) paraformaldehyde, but not after 4 hr of exposure. The phenomenon of rapid disappearance of paraformaldehyde from fermenting drilling mud was observed in the laboratory using a modified sodium sulfite test. Paraformaldehyde, initially present in a concentration of 0.192 lb per barrel of mud, completely disappeared in 9 hr at 22 to 23 C. A significant decrease in paraformaldehyde concentration was detected 0.5 hr after preparation of the mud. It is suggested that the presence of relatively high concentrations of ammonia and chloride in the mud may facilitate the disappearance of paraformaldehyde. The failure of 0.1% (w/w) paraformaldehyde to inhibit the strong starch-fermenting microorganisms isolated from fermenting drilling mud, and the rapid disappearance of paraformaldehyde from the mud, explains the fermentation of starch which occurred in this mud, despite the addition of paraformaldehyde.     

Cross-linking of wheat starch and hydroxypropylated wheat starch in alkaline slurry with sodium trimetaphosphate

Wheat starch was cross-linked at 40 °C and pH 11.0 by slurrying the starch (30% solids) in a solution of sodium trimetaphosphate (STMP), sodium hydroxide, and sodium sulfate. The extent of cross-linking was determined by an increase in alkaline fluidity or by a decrease in alkaline clarity. Response surface analysis showed that cross-linking increased with increasing levels of STMP (0.5-1.5%, based on starch, bos) and sodium sulfate (0–4.0%, bos) over a reaction period of 120–720 min. A regression equation with first and second order terms showed that STMP and sodium sulfate concentrations and the reaction time accounted for 99% of the variability in alkaline fluidity. Wheat starch (37% slurry) was hydroxypropylated by reaction with propylene oxide (8%, bos) for 24h at 45 °C in alkali (pH 11.5) containing 16.0% sodium sulfate (bos). The hydroxypropylated (4.5wt%) wheat starch (DS 0.12-0.13) was not isolated but was cross-linked with STMP (0.1-0.5%, bos) over a 10–40 min reaction period. A comparison of pasting curves at pH 3.5 showed that some of the cross-links produced by STMP were less stable than those produced by phosphoryl chloride, indicating a low level of pyrophosphate as well as monophosphate cross-links. The less stable cross-links were diminished by changing reaction conditions with STMP.     

Ultrafiltration recovery of entomotoxicity from supernatant of Bacillus thuringiensis fermented wastewater and wastewater sludge

The study investigates the recovery of active components (crystal proteins, spores and other factors of virulence) of Bacillus thuringiensis (Bt) based biopesticides from centrifuged supernatant, by ultrafiltration. The centrifuged fermented broths comprised, starch industry wastewater, non-hydrolyzed and hydrolyzed wastewater sludge and semi-synthetic soya medium (as control). The ultrafiltration membrane of 5 kDa gave highest recovery of the active components and increased the entomotoxicity in the retentates by 7.9%, 10.5%, 9.0%, 5.7%, for semi-synthetic soya medium, starch industry wastewater, non-hydrolyzed and hydrolyzed wastewater sludge, respectively. However, the retention of suspended solids on the membrane (measured via mass balance) varied with the type of fermented broths and was very high for hydrolyzed sludge (soya-15%; starch industry wastewater-12%; non-hydrolyzed sludge-7% and hydrolyzed sludge-68%). This reflected the deposit on the membrane. In the given context, scale-up of the ultrafiltration process will give better efficacy for non-hydrolyzed sludge and starch industry wastewater in comparison to soya and hydrolyzed sludge medium.     

Variations in protein glycosylation in Hansenula polymorpha depending on cell culture stage

A simple way to prevent protein hyperglycosylation in Hansenula polymorpha was found. When glucose oxidase from Aspergillus niger and carboxymethyl cellulase from Bacillus subtilis were expressed under the control of an inducible methanol oxidase (MOX) promoter using methanol as a carbon source, hyperglycosylated forms occurred. In contrast, MOX-repressing carbon sources (e.g., glucose, sorbitol, and glycerol) greatly reduced the extent of hyperglycosylation. Carbon source starvation of the cells also reduced the level of glycosylation, which was reversed to hyperglycosylation by the resumption of cell growth. It was concluded that the proteins expressed under actively growing conditions are produced as hyperglycosylated forms, whereas those under slow or nongrowing conditions are as short-glycosylated forms. The prevention of hyperglycosylation in the Hansenula polymorpha expression system constitutes an additional advantage over the traditional Saccharomyces cerevisiae system in recombinant production of glycosylated proteins.     

Starch Hydrolysis by Conidia of Aspergillus wentii

Soluble starch was hydrolyzed to glucose by conidia of Aspergillus wentii NRRL 2001. Peak yields of glucose were achieved in 3 days. A glucoamylase-like enzyme was assumed to be responsible since maltose was not detected during the conversion. Spore age, storage conditions, and temperature affected the level of glucose accumulated. Iodoacetate inhibited catabolism of the glucose formed and this inhibition increased product yield. Spores of other fungi also hydrolyzed starch but none accumulated glucose naturally as did A. wentii spores.     

Enzymatic methylation of carboxyl groups of chromaffin granule membrane proteins.

Carboxyl groups of membrane and soluble proteins from bovine adrenal medulla chromaffin granules were enzymatically methylated. The methylated peptides were resolved using gel electrophoresis under acidic conditions in the presence of N-cetylpyridinium chloride. There was a selective methylation of two groups of membrane peptides which did not correspond to any of the chromaffin granule soluble proteins. Dopamine beta-hydroxylase, an acidic protein accounting for up to 25% of the membrane proteins, was a poor substrate for protein carboxylmethylase. The methyl esters of membrane proteins were more labile than those of the chromaffin granule soluble proteins. At all pH values tested, membrane protein-methyl esters were hydrolyzed three times more rapidly than the soluble protein-methyl esters.     

Haloalkaliphilic maltotriose-forming alpha-amylase from the archaebacterium Natronococcus sp. strain Ah-36.

A haloalkaliphilic archaebacterium, Natronococcus sp. strain Ah-36, produced extracellularly a maltotriose-forming amylase. The amylase was purified to homogeneity by ethanol precipitation, hydroxylapatite chromatography, hydrophobic chromatography, and gel filtration. The molecular weight of the enzyme was estimated to be 74,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amylase exhibited maximal activity at pH 8.7 and 55 degrees C in the presence of 2.5 M NaCl. The activity was irreversibly lost at low ionic strength. KCl, RbCl, and CsCl could partially substitute for NaCl at higher concentrations. The amylase was stable in the range of pH 6.0 to 8.6 and up to 50 degrees C in the presence of 2.5 M NaCl. Stabilization of the enzyme by soluble starch was observed in all cases. The enzyme activity was inhibited by the addition of 1 mM ZnCl2 or 1 mM N-bromosuccinimide. The amylase hydrolyzed soluble starch, amylose, amylopectin, and, more slowly, glycogen to produce maltotriose with small amounts of maltose and glucose of an alpha-configuration. Malto-oligosaccharides ranging from maltotetraose to maltoheptaose were also hydrolyzed; however, maltotriose and maltose were not hydrolyzed even with a prolonged reaction time. Transferase activity was detected by using maltotetraose or maltopentaose as a substrate. The amylase hydrolyzed gamma-cyclodextrin. alpha-Cyclodextrin and beta-cyclodextrin, however, were not hydrolyzed, although these compounds acted as competitive inhibitors to the amylase activity. Amino acid analysis showed that the amylase was characteristically enriched in glutamic acid or glutamine and in glycine.     

Studies on Amylolytic Enzymes Produced by Endornyces sp

Various saccharides were hydrolyzed with the purified amyloglucosidase of Endornyces sp. IFO 0111.

Glucose was the only reducing product in the digest of soluble starch. The amyloglucosidase could hydrolyze starch and amylose only incompletely though it had the ability to split α-d-(1→6) bonds and hydrolyzed amylopectin and glycogen to high extents.

It hydrolyzed maito-oligosaccharides by stepwise removal of glucose units from the nonreducing end of the molecules.     

STEP ENZYMATIC HYDROLYSIS OF SODIUM HYDROXIDE-PRETREATED CHINESE LIQUOR DISTILLERS' GRAINS FOR ETHANOL PRODUCTION

Distillers' grains are a co-product of ethanol production. In China, only a small portion of distillers' grains have been used to feed the livestock because the amount was so huge. Nowadays, it has been reported that the distillers' grains have the potential for fuel ethanol production because they are composed of lignocelluloses and residual starch. In order to effectively convert distillers' grains to fuel ethanol and other valuable production, sodium hydroxide pretreatment, step-by-step enzymatic hydrolysis, and simultaneous saccharification and fermentation (SSF) were investigated. The residual starch was first recycled from wet distillers' grains (WDG) with glucoamylase to obtain glucose-rich liquid. The total sugar concentration was 21.3 g/L, and 111.9% theoretical starch was hydrolyzed. Then the removed-starch dry distillers' grains (RDDG) were pretreated with NaOH under optimal conditions and the pretreated dry distillers' grains (PDDG) were used for xylanase hydrolysis. The xylose concentration was 19.4 g/L and 68.6% theoretical xylose was hydrolyzed. The cellulose-enriched dry distillers' grains (CDDG) obtained from xylanase hydrolysis were used in SSF for ethanol production. The ethanol concentration was 42.1 g/L and the ethanol productivity was 28.7 g/100 g CDDG. After the experiment, approximately 80.6% of the fermentable sugars in WDG was converted to ethanol.     

Mechanism of Cryoprecipitation

When plasma is frozen as done in the preparation of cryoprecipitates, all solutes, of which sodium chloride is a major component, concentrate in the inter-ice-crystalline spaces. This concentrated salt causes the precipitation of various proteins according to their solubilities. The theory was substantiated by “salting out” experiments of plasma proteins using sodium chloride of increasing concentration.     

樟树内生细菌EBS05发酵条件的研究

枯草芽胞杆菌EBS05是从樟树中分离的1株对多种植物病原真菌具有拮抗作用的内生细菌。以小麦纹枯病菌为靶标菌,通过单因素试验和正交设计试验对其发酵条件进行了优化。结果表明,内生细菌EBS05适宜的发酵培养基主要营养成分的组成和配比分别为可溶性淀粉3%、蛋白胨2%、NaCl 0.25%。最佳发酵条件为:初始pH5~9,最适温度34℃,装液量25 mL/250 mL三角瓶,接种量3%,发酵时间72 h。