Showing papers on "Amylase published in 2003"
TL;DR: The present results show no effect of essential oil constituents on growth performance in female broiler chickens, but it cannot be excluded that positive effects would have been observed under less hygienic environmental conditions or when using a less digestible diet.
Abstract: 1. The present experiment was conducted to describe the effects of thymol, cinnamaldehyde and a commercial preparation of essential oil components (CRINA® Poultry), in female broilers. Feed and water were provided for ad libitum consumption. 2. Feed intake, weight gain and feed:gain ratio were not different among the treatments. Water intake was significantly lowered by cinnamaldehyde. Relative liver weight (g/100 g of body weight) was highest in birds given thymol, but this was seen only at the age of 21 d and not at 40 d. Patterns of digestive enzymes in pancreatic tissue were similar for the 4 treatments. 3. Amylase activity in intestinal digesta was highest in chickens given CRINA® Poultry for 21 d, but the effect had disappeared after 40 d. Ileal digestibility coefficients for starch and protein were high and identical for all treatments. 4. Fatty acid composition of diet was reflected in that of adipose tissue. Plasma lipid concentrations were not changed by any dietary treatment. 5. Thus, the prese...
555 citations
TL;DR: In this paper, a thermostable α-amylase producing Bacillus sp. ANT-6 was isolated from soil samples and the enzyme showed optimum activity at pH 10.5 and 80.5.
335 citations
TL;DR: This review summarizes the current knowledge on the extent of in vitro hydrolysis of native legumes starches by α-amylases of different origin, the structural and morphological changes that occur in legume starches as a result of α- amylolysis, and the reactivity of amylases towards gelatinized, retrograded and modified legumes.
242 citations
TL;DR: In this paper, the effect of amylases on the texture of bread crumbs was studied during aging and after rebaking of stale bread, and three different starch-degrading enzymes were investigated.
Abstract: The present investigation aims at understanding the mechanism of bread firming during staling. Changes in the starch fraction due to the addition of amylases and their influence on the texture of bread crumb were studied during aging and after rebaking of stale bread. Pan bread was prepared by a conventional baking procedure. The influence of three different starch-degrading enzymes, a conventional α-amylase, a maltogenic α-amylase, and a β-amylase were investigated. The mechanical properties of bread were followed by uniaxial compression measurements. The microstructure was investigated by light microscopy, and starch transformations were assessed by differential scanning calorimetry (DSC) and wide-angle X-ray powder diffraction. Firming of bread crumb and crystallization of starch are not necessarily in agreement in systems with added amylases. Reorganization of both starch fractions, amylopectin and amylose, and the increase of starch network rigidity due to increase of polymer order are impor...
228 citations
TL;DR: In this article, the effects of polysaccharides in terms of displacing water and restricting gelatinisation with respect to the modified Flory-Huggins equation were investigated.
184 citations
TL;DR: In vitro influence of 14 individual spices on the activities of digestive enzymes of rat pancreas and small intestine was examined and it was inferred that this positive influence on the activity of enzymes may have a supplementary role in the overall digestive stimulant action of spices.
Abstract: In vitro influence of 14 individual spices (curcumin, capsaicin, piperine, garlic, onion, ginger, mint, coriander, cumin, ajowan, fennel, fenugreek, mustard, and asafoetida) on the activities of digestive enzymes of rat pancreas and small intestine was examined by including them in the reaction mixture at two different concentrations. A majority of spices enhanced the activity of pancreatic lipase and amylase when they are directly in contact with the enzyme. It is inferred that this positive influence on the activity of enzymes may have a supplementary role in the overall digestive stimulant action of spices, besides causing an enhancement of the titres of digestive enzymes in pancreatic tissue.
173 citations
TL;DR: The distribution, structuralfunctional aspects and factors for enhancing the stability of α-amylases, and engineering the enzymes for improved stability enhances their use industrially.
Abstract: Amylases are enzymes which hydrolyze the starch molecules into polymers composed of glucose units. α-Amylases are ubiquitous in distribution, with plants, bacteria and fungi being the predominant sources. Most of the microbial α-amylases belong to the family 13 glycosyl hydrolases, and they share several common properties. But different reaction specificities have been observed across the family members. Structurally α-amylases possess (β/α)8 or TIM barrel structures and are responsible for hydrolysis or formation of glycosidic bonds in the α-conformation. Stability of the α-amylases has been widely studied; pH and temperature have very important roles to play. Engineering the enzymes for improved stability enhances their use industrially. This review focuses on the distribution, structuralfunctional aspects and factors for enhancing the stability of α-amylases.
170 citations
TL;DR: Production of extracellular amylase was demonstrated under stress conditions of high temperature and high salinity in aerobically cultivated culture of a newly isolated moderately halophilic bacterium of spore-forming Halobacillus sp.
167 citations
TL;DR: Among the various carbon sources tested, maltose was most effective for the formation of these enzymes, followed by soluble maize starch, glycogen and pullulan, which showed maximum activities at pH 6.5-7.0 and 85 and 80 degrees C, respectively.
158 citations
TL;DR: The results of this study indicate that extrusion improves the nutritional characteristics of both cereals, with corn containing diets, especially CR, exhibited lower trypsin activities than wheat containing diets in accordance with highertrypsin inhibitor levels measured for corn.
141 citations
TL;DR: Results of this study indicated that although enzyme addition to corn–SBM-based basal diets can significantly improve AMEn, the success of such improvement depended greatly on the raw ingredients available at the time.
Abstract: SUMMARY Corn and soybean meal (SBM) are high-quality feed ingredients for broiler diets. Antinutritive factors in SBM, such as protease inhibitors and lectins, are successfully inactivated by heat treatment. However, the nutritive value of these ingredients also depends on the amount of indigestible carbohydrates, in particular the amount of oligosaccharides and nonstarch polysaccharides (NSP). Despite the fact that such diets are low in indigestible carbohydrates, it has been suggested that the inclusion of exogenous feed enzymes to such diets could improve nutrient availability and, subsequently, improve energy digestibility. Four consecutive AME bioassays were conducted to investigate the effects of three singleactivity enzyme products, two multi-activity enzyme preparations, and a commercially available enzyme product added to a corn–SBM-based broiler diet. None of the evaluated enzyme combinations successfully improved the performance of 3- to 4wk-old broiler chickens. However, in experiments 1 and 2, when enzymes were included in a lowerenergy corn–SBM basal diet, the combination of pectinase, protease, and amylase significantly improved AMEn in comparison to the unsupplemented basal diet. Subsequent experiments with a higher energy and protein basal diet failed to show the same improvement when enzymes were added. Results of this study indicated that although enzyme addition to corn–SBM-based basal diets can significantly improve AMEn, the success of such improvement depended greatly on the raw ingredients available at the time.
TL;DR: It appears that with respect to the SBD, evolution in GH 13 shows a transition in the segment of the proteins C-terminal to the catalytic (beta/alpha)8-barrel(domain A).
Abstract: The alpha-amylase family (glycoside hydrolase family 13; GH 13) contains enzymes with approximately 30 specificities. Six types of enzyme from the family can possess a C-terminal starch-binding domain (SBD): alpha-amylase, maltotetraohydrolase, maltopentaohydrolase, maltogenic alpha-amylase, acarviose transferase, and cyclodextrin glucanotransferase (CGTase). Such enzymes are multidomain proteins and those that contain an SBD consist of four or five domains, the former enzymes being mainly hydrolases and the latter mainly transglycosidases. The individual domains are labelled A [the catalytic (beta/alpha)8-barrel], B, C, D and E (SBD), but D is lacking from the four-domain enzymes. Evolutionary trees were constructed for domains A, B, C and E and compared with the 'complete-sequence tree'. The trees for domains A and B and the complete-sequence tree were very similar and contain two main groups of enzymes, an amylase group and a CGTase group. The tree for domain C changed substantially, the separation between the amylase and CGTase groups being shortened, and a new border line being suggested to include the Klebsiella and Nostoc CGTases (both four-domain proteins) with the four-domain amylases. In the 'SBD tree' the border between hydrolases (mainly alpha-amylases) and transglycosidases (principally CGTases) was not readily defined, because maltogenic alpha-amylase, acarviose transferase, and the archaeal CGTase clustered together at a distance from the main CGTase cluster. Moreover the four-domain CGTases were rooted in the amylase group, reflecting sequence relationships for the SBD. It appears that with respect to the SBD, evolution in GH 13 shows a transition in the segment of the proteins C-terminal to the catalytic (beta/alpha)8-barrel(domain A).
TL;DR: The early and noticeable development of digestive enzyme activities was linked to a high survival after weaning, and variations observed in the activity profiles of the digestive enzymes were correlated either to developmental events or to changes in the nature of the diet.
Abstract: Activity of some of the main enzymes involved in protein digestion and absorption (acid and alkaline professes, leucine-aminopeptidase, acid and alkaline phosphatases) as well as those of amylase and lipase, was assessed during larval development of while sea bream Diplodus sargus. All enzyme activity was detected at the moment of mouth opening. The variations observed in the activity profiles of the digestive enzymes were correlated either to developmental events. such as the functional start of the stomach (22 days after hatching), or to changes in the nature of the diet. The early and noticeable development of digestive enzyme activities was linked to a high survival after weaning.
TL;DR: The lack of localization of enzyme production in the digestive tract of S. aurata is similar to many other species as reported in the literature, and the range of pHs recorded in the various regions of the gut were generally outside the cited optima for many digestive proteases in this species.
Abstract: Two investigations were carried out with 150 gilthead sea bream Sparus aurata to determine the relative activity of six digestive enzymes (pepsin, trypsin, chymotrypsin, carboxypeptidase A, carboxypeptidase B and amylase) and the pH variation in the lumen of different parts of the gut of fish fed one or two meals per day. Pepsin activity was found exclusively in the stomach, whereas activities of the other enzymes studied were found in all regions of the gut, including the stomach. The lack of localization of enzyme production in the digestive tract of S. aurata is similar to many other species as reported in the literature. The pH variations found in the different regions of the gut could be explained by general digestive physiology following the flow of digest along the digestive tract. The range of pHs recorded in the various regions of the gut were generally outside the cited optima for many digestive proteases in this species.
TL;DR: Both luteolin and oleanolic acid have an inhibitory effect on postprandial blood glucose increase in diabetic rats, and thus they may be a useful food supplement for the prevention of diabetes.
Abstract: Olive (Olea europaea L.) is recognized as a folk medicine for diabetes in Europe. The inhibitory action of an ethanol extract of olive leaves (OEE) on the activities of human amylases was examined in vitro. OEE inhibited the activities of α-amylases from human saliva and pancreas with IC50 values of 4.0 and 0.02 mg/ml, respectively. Two anti-α-amylase components were purified from a 50% ethanol soluble fraction of OEE using Sephadex LH-20 column chromatography. One was identified as luteolin-7-O-β glucoside and the other as luteolin-4′-O-β glucoside. The 50% ethanol insoluble fraction of OEE was dissolved in 98% ethanol and fractionated using Cosmosil C18-OPN column chromatography. The anti-α-amylase component purified by this chromatography was identified as oleanolic acid. Both luteolin and oleanolic acid have an inhibitory effect on postprandial blood glucose increase in diabetic rats. Olive leaves suppressed the elevation of blood glucose after oral administration of starch in borderline volunteers (fasting blood glucose: 110–140 mg/dl), and thus they may be a useful food supplement for the prevention of diabetes.
TL;DR: Marine amylase is necessary in saline conditions for successful saccharification of marine microalgae and was determined to have the highest concentration of intracellular carbohydrate.
Abstract: The saccharification of marine microalgae using amylase from marine bacteria in saline conditions was investigated. An amylase-producing bacterium, Pseudoalterimonas undina NKMB 0074 was isolated and identified. The green microalga NKG 120701 was determined to have the highest concentration of intracellular carbohydrate and was found from our algal culture stocks. P. undina NKMB 0074 was inoculated into suspensions containing NKG 120701 cells and increasingly reduced suspended sugars with incubation time. Terrestrial amylase and glucoamylase were inactive in saline suspension. Therefore, marine amylase is necessary in saline conditions for successful saccharification of marine microalgae.
TL;DR: In this paper, Bacillus sp. AS-1 and AS-2 were used to produce very high titers of α-amylase (198.950 U/g fermented dry matter) and glucoamylases (3426 U /g fermented fine matter), respectively, during solid state fermentation of wheat bran.
TL;DR: Results are the first step to understanding the importance of ALAB during pozol fermentation, and S. bovis strains were found to be predominant.
Abstract: Pozol is an acid beverage obtained from the natural fermentation of nixtamal (heat- and alkali-treated maize) dough. The concentration of mono- and disaccharides from maize is reduced during nixtamalization, so that starch is the main carbohydrate available for lactic acid fermentation. In order to provide some basis to understand the role of amylolytic lactic acid bacteria (ALAB) in this fermented food, their diversity and physiological characteristics were determined. Forty amylolytic strains were characterized by phenotypic and molecular taxonomic methods. Four different biotypes were distinguished via ribotyping; Streptococcus bovis strains were found to be predominant. Streptococcus macedonicus, Lactococcus lactis, and Enterococcus sulfureus strains were also identified. S. bovis strain 25124 showed extremely low amylase yield relative to biomass (139 U g [cell dry weight]−1) and specific rate of amylase production (130.7 U g [cell dry weight]−1 h−1). In contrast, it showed a high specific growth rate (0.94 h−1) and an efficient energy conversion yield to bacterial cell biomass (0.31 g of biomass g of substrate−1). These would confer on the strain a competitive advantage and are the possible reasons for its dominance. Transient accumulation of maltooligosaccharides during fermentation could presumably serve as energy sources for nonamylolytic species in pozol fermentation. This would explain the observed diversity and the dominance of nonamylolytic lactic acid bacteria at the end of fermentation. These results are the first step to understanding the importance of ALAB during pozol fermentation.
TL;DR: It is found that spiny lobsters to feed predominantly on crabs, bivalves, ophiuroids and sponges and that the lobster is carnivorous.
Abstract: Digestive enzyme profiles of puerulus, post-puerulus, juvenile and adult stages of the spiny lobster Jasus edwardsii Hutton were determined in order to identify ontogenetic changes in digestive capabilities and assess capacity to use dietary components and to exploit diets to meet nutritional requirements. Juvenile and adult lobsters exhibited a diverse range of enzymes, suggesting they can exploit varied diets. Proteolytic activity of trypsin, chymotrypsin and carboxypeptidase A (1.86–3.70 U mg−1 digestive gland protein) was significantly higher than carbohydrase activity of amylase, α-glucosidase, cellulase and chitinase (0.0014–0.38 U mg−1 digestive gland protein), thus showing that dietary protein was more important than carbohydrate and that the lobster is carnivorous. These conclusions are consistent with other studies that found spiny lobsters to feed predominantly on crabs, bivalves, ophiuroids and sponges. Lipase activity (0.371 U mg−1 digestive gland protein) was also relatively high, thus showing the importance of dietary lipid. Total activities (units per digestive gland) of every enzyme assayed increased significantly with lobster carapace length. There were few significant ontogenetic trends in specific enzyme activity (U mg−1 digestive gland protein). Amylase and laminarinase specific activity was significantly higher in small lobsters than large lobsters (regression analyses, respectively, F
(1,23)=9.84, P=0.005; F
(1,11)=19.65, P=0.001), suggesting that carbohydrates including laminarin are more important in the diet of small juveniles. Trypsin, amylase and lipase activities were detected in all non-feeding puerulus stages, suggesting that feeding is not a cue for digestive enzyme production in J. edwardsii. Significant variations in total and specific activities of amylase (F
(1,3)=14.2, P=0.00; F
(1,3)=14.2, P=0.00) and trypsin (F
(1,3)=8.8, P=0.00; F
(1,3)=21.41, P=0.00) and a declining trend in lipase total activity between non-feeding puerulus stages suggests that they may be hydrolysing endogenous energy reserves to sustain their onshore swimming activity prior to settlement. Profiles suggest carbohydrate and lipid are utilised first, followed by protein. Consistently high levels of lipase in all puerulus stages (0.24–0.7 U digestive gland−1; P>0.05) confirm the importance of lipid as a major energy substrate.
TL;DR: The halophilic archaeon Haloferax mediterranei is able to grow in a minimal medium containing ammonium acetate as a carbon and nitrogen source, and α-amylase activity is excreted to the medium in low concentration.
Abstract: The halophilic archaeon Haloferax mediterranei is able to grow in a minimal medium containing ammonium acetate as a carbon and nitrogen source. When this medium is enriched with starch, α-amylase activity is excreted to the medium in low concentration. Here we report methods to concentrate and purify the enzyme. The relative molecular mass of the enzyme, determined by gel filtration, is 50±4 kDa, and on SDS-PAGE analysis a single band appeared at 58 kDa. These results indicated that the halophilic α-amylase is a monomeric enzyme. The enzyme showed a salt requirement for both stability and activity, being stable from 2 to 4 M NaCl, with maximal activity at 3 M NaCl. The enzyme displayed maximal activity at pHs from 7 to 8, and its optimal temperature was in a range from 50 °C to 60 °C. The results also implicated several prototropic groups in the catalytic reaction.
TL;DR: Changes in the enzyme activity after the shrimp reach 6 g in body weight are evidenced by a decrease in total protease and an increase in lipase and amylase activities, suggesting an adaptation of the enzymatic activity to diets with lower protein content as body weight increases.
Abstract: A study was conducted to evaluate variations of digestive enzyme activities in Litopenaeus vannamei (Boone) reared in commercial ponds under semi-intensive conditions. Shrimp were collected at each body weight increase of 2 g. As the shrimp grew (2^12 g), signi¢cant increases in the activities of lipase and chymotrypsin were observed. The total protease activity decreased from 6 g onwards. Trypsin activity showed a peak at 6 g and amylase activity increased two-fold after 2 g. Additionally, the stomach contents were analysed microscopically for shrimp between 2 and 10 g. Plant matter contributed above 30% of the total stomach content in 6-, 8- and 10-g shrimp. Detritus represented 58% and 62% of the total stomach content in 2- and 4-g shrimp, respectively, decreasing to 33^43% at greater shrimp weights. Arti¢cial feed showed a maximum contribution of 20% in 6-g shrimp. The present results show changes in the enzyme activity after the shrimp reach 6 g in body weight, evidenced by a decrease in total protease and an increase in lipase and amylase activities. The amylase/protease ratio was 2.6 in 2-g shrimp and increased steadily to 9.6 in 12-g shrimp. These ¢ndings suggest an adaptation of the enzymatic activity to diets with lower protein content as body weight increases, and may be related to the variation of the diierent items found in the stomach.
TL;DR: In this article, a maltooligosaccharide-forming amylase from B circulans GRS 313 was immobilized by entrapment in calcium alginate beads.
Abstract: A maltooligosaccharide-forming amylase from B circulans GRS 313 was immobilized by entrapment in calcium alginate beads. The immobilized activity was affected by the size of the bead and bead size of 2mm was found to be most effective for hydrolysis. Kinetics constants, Km and Vmax were estimated and were found to be affected by the bead size. The catalytic activity of the enzyme was studied in presence of various starchy residues and metal ions. HgCl2, CuSO4 and FeCl3 caused inhibition of the enzyme. The reaction conditions, pH and temperature, was optimized using response surface methodology. At the optimum pH and temperature of 4.9 and 57oC, the apparent activity was 25.6U/g of beads, resulting in almost 2-fold increase in activity. The immobilized enzyme showed a high operational stability by retaining almost 85% of the initial activity after seventh use.
TL;DR: It was shown that the co‐expression of these heterologous α‐amylase and glucoamylases genes enhance starch degradation additively in S. cerevisiae strains that could eventually be used in consolidated bioprocessing, and in the brewing, whisky, and biofuel industries.
Abstract: Lipomyces kononenkoae and Saccharomycopsis fibuligera possess highly efficient alpha-amylase and/or glucoamylase activities that enable both of these yeasts to utilize raw starch as a carbon source. Eight constructs containing the L. kononenkoae alpha-amylase genes (LKA1 and LKA2), and the S. fibuligera alpha-amylase (SFA1) and glucoamylase (SFG1) genes were prepared. The first set of constructs comprised four single gene cassettes each containing one of the individual amylase coding sequences (LKA1, LKA2, SFA1 or SFG1) under the control of the phosphoglycerate kinase gene (PGK1) promoter and terminator, while the second set comprised two single cassettes containing SFA1 and SFG1 linked to their respective native promoters and terminators. The third set of constructs consisted of two double-gene cassettes, one containing LKA1 plus LKA2 under the control of the PGK1 promoter and terminator, and the other SFA1 plus SFG1 controlled by their respective native promoters and terminators. These constructs were transformed into a laboratory strain Saccharomyces cerevisiae (Sigma1278b). Southern-blot analysis confirmed the stable integration of the different gene constructs into the S. cerevisiae genome and plate assays revealed amylolytic activity. The strain expressing LKA1 and LKA2 resulted in the highest levels of alpha-amylase activity in liquid media. This strain was also the most efficient at starch utilization in batch fermentations, utilizing 80% of the available starch and producing 0.61g/100 mL of ethanol after 6 days of fermentation. The strain expressing SFG1 under the control of the PGK1 expression cassette gave the highest levels of glucoamylase activity. It was shown that the co-expression of these heterologous alpha-amylase and glucoamylase genes enhance starch degradation additively in S. cerevisiae. This study has resulted in progress towards laying the foundation for the possible development of efficient starch-degrading S. cerevisiae strains that could eventually be used in consolidated bioprocessing, and in the brewing, whisky, and biofuel industries.
TL;DR: Three α-amylases were purified to apparent homogeneity from 72 h finger millet malt by three step purification via fractional acetone precipitation, DEAE-Sephacel ion exchange and Sephacryl S-200 gel permeation chromatographies with a recovery of 6.2.
TL;DR: An extracellular xylanase produced by a Mexican Aspergillus strain was purified and characterized and showed a higher affinity for 4-O-methyl-d-glucuronoxylan and displayed no activity toward other polysaccharides, including cellulose.
Abstract: An extracellular xylanase produced by a Mexican Aspergillus strain was purified and characterized Aspergillus sp FP-470 was able to grow and produce extracellular xylanases on birchwood xylan, oat spelt xylan, wheat straw, and corncob, with higher production observed on corncob The strain also produced enzymes with cellulase, amylase, and pectinase activities on this substrate A 22-kDa endoxylanase was purified 30-fold Optimum temperature and pH were 60 degrees C and 55, respectively, and isoelectric point was 90 The enzyme has good stability from pH 50 to 100, retaining >80% of its original activity within this range Half-lives of 150 min at 50 degrees C and 65 min at 60 degrees C were found K(m) and activation energy values were 38 mg/mL and 26 kJ/mol, respectively, using birchwood xylan as substrate The enzyme showed a higher affinity for 4-O-methyl-D-glucuronoxylan with a K(m) of 19 mg/mL The enzyme displayed no activity toward other polysaccharides, including cellulose Baking trials were conducted using the crude filtrate and purified enzyme Addition of both preparations improved bread volume However, addition of purified endoxylanase caused a 30% increase in volume over the crude extract
TL;DR: In this paper, the authors show that there is significant variation in the diastatic power of α-amylase and limit dextrinase in malts made from a wide range of Australian and international malting barley varieties.
Abstract: Diastatic power (DP), a measure of the level of activity of starch-hydrolyzing enzymes, is a term that refers to the combined activity levels of β-amylase, α-amylase, limit dextrinase, and α-glucosidase. The result of the action of these enzymes during brewing is to break down starch into component sugars that are readily fermented into alcohol by yeast. Although DP is a reasonable predictor of fermentability, it does not always accurately estimate the level of fermentable sugars generated during mashing or the subsequent fermentability of the resultant wort. Previously, it has been shown that allelic variation in β-amylase thermostability has a significant impact on wort fermentability. The thermostability of the DP enzymes is critical in determining fermentable sugar yield during mashing, where the mash temperature profile is a balance between the temperature required for starch gelatinization to enable efficient hydrolysis and the rate of thermal inactivation of the DP enzymes. This study demonstrates that there is significant variation in the thermostability of α-amylase and limit dextrinase in malts made from a wide range of Australian and international malting barley varieties. This variation in α-amylase and limit dextrinase thermostability combined with that of β-amylase provides an opportunity for barley breeders to produce divergent malting varieties that better fulfill brewers' fermentability requirements. The implications of the varying DP enzyme thermostability on the selection of malt by brewers to optimally suit different brewing styles and regimens are outlined.
TL;DR: Results confirm the character of the enzyme studied to be an α-amylase (1,4-α-glucan glucanohydrolase), which preferentially hydrolyzed starch, and to a lesser extent amylopectin, maltose, amylose and glycogen in that order.
Abstract: An α-amylase produced by Scytalidium thermophilum was purified using DEAE-cellulose and CM-cellulose ion exchange chromatography and Sepharose 6B gel filtration. The purified protein migrated as a single band in 6% PAGE and 7% SDS-PAGE. The estimated molecular mass was 36 kDa (SDS-PAGE) and 49 kDa (Sepharose 6B). Optima of pH and temperature were 6.0 and 60°C, respectively. In the absence of substrate the purified α-amylase was stable for 1 h at 50°C and had a half-life of 12 min at 60°C, but was fully stable in the presence of starch. The enzyme was not activated by several metal ions tested, including Ca2+ (up to 10 mM), but HgCl2 and CuCl2 inhibited its activity. The α-amylase produced by S. thermophilum preferentially hydrolyzed starch, and to a lesser extent amylopectin, maltose, amylose and glycogen in that order. The products of starch hydrolysis (up to 6 h of reaction) analyzed by thin layer chromatography, showed oligosaccharides such as maltotrioses, maltotetraoses and maltopentaoses. Maltose and traces of glucose were formed only after 3 h of reaction. These results confirm the character of the enzyme studied to be an α-amylase (1,4-α-glucan glucanohydrolase).
TL;DR: Aims: Selection of suitable surfactants for enhancing and stabilizing α‐amylase of Geobacillus thermoleovorans.
Abstract: AIMS Selection of suitable surfactants for enhancing and stabilizing alpha-amylase of Geobacillus thermoleovorans. METHODS AND RESULTS Geobacillus thermoleovorans was cultivated in shake flasks containing 50 ml of starch-yeast extract-tryptone (SYT) medium with/without surfactants. Titres of the enzyme in media were monitored. The enzyme was also preserved at 4 degrees C with/without surfactants and enzyme activities were determined. Among polyethylene glycol (PEGs) of different molecular weights, PEG 8000 (0.5%, w/v) caused a slight increase in the enzyme titre, while Tween-20, Tween-40 and Tween-60 (0.03%, w/v) exerted a significant stimulatory effect on enzyme secretion. In the presence of SDS, Tween-80 and cholic acid (0.03%, w/v), the enzyme production was nearly twofold higher than that in the control. The anionic (SDS, cholic acid) and non-ionic (Tweens) detergents increased the cell membrane permeability, and thus, enhanced alpha-amylase secretion. Furthermore, anionic surfactants exhibited stabilizing effect on the enzyme during preservation at 4 degrees C. CONCLUSIONS PEG 8000 and the ionic detergents (SDS, cholic acid and Tween-80) were more effective in the solubilization of cell membrane components, and enhancing enzyme yields than the cationic detergents such as CTAB (N,Cetyl-N,N,N-trimethyl ammonium bromide). Further, these surfactants were found to stabilize the enzyme at 4 degrees C. SIGNIFICANCE AND IMPACT OF THE STUDY The secretion of Ca2+-independent hyperthermostable alpha-amylase was enhanced in the presence of certain anionic and non-ionic detergents in the medium. Furthermore, the surfactants stabilized the enzyme during preservation at 4 degrees C. The use of this enzyme in starch hydrolysis eliminates the addition of Ca2+ in starch liquefaction and its subsequent removal by ion exchange from sugar syrups.
TL;DR: Results showed that L. fermentum Ogi E1 was particularly acid tolerant, and well adapted to the acid conditions that develop during natural fermentation of cereal doughs, which may partly explain the dominance of L. fermentationum in various traditional African sourdoughs.
TL;DR: It appears that bacteria associated with marine sedentary organisms are the novel source of industrial enzymes for possible commercial applications and may play an important role in enzyme-catalysed organic matter cycling in marine environments.
Abstract: The abilities of bacteria isolated from eight marine sedentary organisms, six marine sponges (Spirastrella sp., Phyllospongia sp., Ircinia sp., Aaptos sp., Azorica sp. and Axinella sp.), one soft coral (Lobophytum sp.) and one alga (Sargassum sp.) to produce industrial enzymes (amylase, carboxymethylcellulase and protease) were examined. The mean total viable counts of the bacterial isolates ranged from 8.7 × 10 4 to 8.4 x 10 5 cfu/g wet weight of the organism. All eight organisms harboured amylase (0.05-0.5 IU/ml), carboxymethylcellulase (0.05-0.5 IU/ml) and protease (0.1-0.5 IU/ml) producing bacteria. Of 56 bacterial strains tested, as many as 60 to 83% of the strains produced at least one of the three enzymes, and 47% of strains were able to produce all three enzymes. High activities (> 0.5 IU/ml) of the three enzymes were recorded in bacterial strains belonging to the genera Alcaligenes and Bacillus. From the results of this study, it appears that bacteria associated with marine sedentary organisms are the novel source of industrial enzymes for possible commercial applications and may play an important role in enzyme-catalysed organic matter cycling in marine environments.