The Experts below are selected from a list of 894 Experts worldwide ranked by ideXlab platform
S C Mukherjee - One of the best experts on this subject based on the ideXlab platform.
-
microbial levan in the diet of labeo rohita hamilton juveniles effect on non specific immunity and histopathological changes after challenge with aeromonas hydrophila
Journal of Fish Diseases, 2008Co-Authors: Subodh Gupta, A K Pal, N P Sahu, Rishikesh S Dalvi, Vikas Kumar, S C MukherjeeAbstract:A 60-day feeding trial was conducted to study the immuno-protective effect of microbial levan on Labeo rohita juveniles challenged with Aeromonas hydrophila. Six purified diets were prepared with different levels of microbial levan: control (no levan), T1 (Basal + 0.25%), T2 (Basal + 0.50%), T3 (Basal + 0.75%), T4 (Basal + 1%) and T5 (Basal + 1.25%), fed to six groups of fish in triplicate. Among the treatment groups the haemoglobin content and total leucocyte count were increased with a dietary supplementation of levan at 1% or more. An increasing trend for total erythrocyte count was observed with increasing level of dietary levan. Lower levan-supplemented groups showed a higher albumin/globulin ratio. As the levan supplementation was increased, there was a gradual increase in serum lysozyme activity and respiratory burst activity [nitroblue tetrazolium (NBT) assay] reduction values. The highest lysozyme activity and NBT were observed in the T5 group although this was similar to the T4 group (P > 0.05). No significant histo-architectural changes were associated with dietary levan levels. After challenge with A. hydrophila, moderately degenerated hepatocytes, oedema and leucocytic infiltration in parenchymatous tissues, and extensive haemorrhage and haemosiderosis in the kidney were observed in the control group. However, the T5 group supplemented with 1.25% levan showed infiltrating leucocytes in the liver while the kidney showed only moderate degeneration of renal tubules. The relative survival per cent of juveniles after challenge with A. hydrophila was the highest in the T5 group followed by T4. This suggests that microbial levan at 1.25% can be used as dietary immunostimulant for L. rohita juveniles.
-
dietary microbial levan enhances cellular non specific immunity and survival of common carp cyprinus carpio juveniles
Fish & Shellfish Immunology, 2007Co-Authors: Dina Rairakhwada, A K Pal, Narottam Prasad Sahu, Z P Bhathena, Ashish K Jha, S C MukherjeeAbstract:Abstract A preliminary study with a 75 days feeding trial was conducted to study the immunomodulatory effect of microbial levan on Cyprinus carpio juveniles. Five purified isonitrogenous and isocaloric diets with graded levels of levan, namely (T 1 ) 0.1% levan, (T 2 ) 0.2% levan, (T 3 ) 0.5% levan, (T 4 ) 1.0% levan, and a control group without levan were fed to five groups of fishes in triplicate. The total erythrocyte count and haemoglobin content was significantly ( p 3 group, though the total leucocyte counts, total protein and A/G ratio did not show any significant difference ( p > 0.05) when compared with the control group. The respiratory burst activity (NBT) of blood phagocytes and lysozyme activity was also highest in T 3 group. The relative survival percentage after challenge with Aeromonas hydrophila was highest (100%) in the T 3 group followed by 83.33% and 66.67% in the T 2 and T 4 groups, respectively. This suggests that microbial levan at 0.5% can be used as a dietary immunostimulant for C. carpio juveniles. This is the first report on microbial levan having an immunomodulatory effect on C. carpio .
Inglung Shih - One of the best experts on this subject based on the ideXlab platform.
-
factors affecting the production and molecular weight of levan of bacillus subtilis natto in batch and fed batch culture in fermenter
Journal of The Taiwan Institute of Chemical Engineers, 2013Co-Authors: Fangchen Wu, Shouzu Chou, Inglung ShihAbstract:Abstract The production of levan in batch and fed-batch culture of Bacillus subtilis (natto) Takahashi in fermenter was investigated. Efficient and high yield levan production (61 g/L at 24 h; 3.4 g/L/h) was obtained when the bacteria were cultured in medium containing sucrose (250 g/L) at pH 7.0, temperature 37 °C and agitation speed 175 rpm; in addition, pulsed feeding of sucrose enhanced the levan production significantly to 100 g/L (1.7 fold increase). This is the first systematic study of this strain in fermenter and the most efficient levan production reported to date. The yield and molecular weight of levan were strictly dependent on the reaction conditions. Sucrose concentration was the most effective factor controlling the molecular weight of the synthesized levan, this leads to tailor made levans of different molecular sizes for applications of different purposes.
-
sequential production of two biopolymers levan and poly e lysine by microbial fermentation
Bioresource Technology, 2011Co-Authors: Inglung Shih, Tsaurchin Wang, Shouzoo Chou, Gender LeeAbstract:Sequential fermentation for the production of two invaluable biopolymers, levan and poly-e-lysine (e-PL), has been successfully developed. It involves fermentation of Bacillus subtilis (natto) Takahashi in sucrose medium to produce levan, separation of levan product from small remaining sugar molecules by ultrafiltration and fermentation of the remnant from levan production by Streptomyces albulus to produce e-PL. In the process, 50-60 g/L of levan was produced (100% recovery after precipitation by ethanol). The remnant from levan production with glucose adjusted to 30 g/L and with combined use of yeast extract (10 g/L), (NH(4))(2)SO(4) (2g/L) and basal salts was proven to be suitable for e-PL production. 4.37 g/L of e-PL accumulation (85% recovery after purification) was reached in 72 h using two-stage fermentation with control of pH. The process of using remnant (waste) from levan fermentation for the second biopolymer (e-PL) production is unprecedented and the products obtained are environmental-friendly.
-
levan production using bacillus subtilis natto cells immobilized on alginate
Carbohydrate Polymers, 2010Co-Authors: Inglung Shih, Lidar ChenAbstract:Abstract The immobilization of B. subtilis natto Takahashi on alginate matrix was attempted for repeated production of levan. Factors that influence the stability of the immobilized-cell beads and the levan production in the process of fermentation were also investigated. The levan production and the stability of immobilized beads were greatly affected by the sucrose concentration, medium pH, metal ions and agitation speed. When the immobilized cells were cultivated in the optimal conditions, high levan production (70.6 g/L) was obtained after 3 d of fermentation and no damaged beads were observed. In the repetitive cultivation, the supplement of organic nitrogen source and control of initial pH was critical for high levan production. Immobilized cells on alginate beads were reused in five successive reaction cycles (each cycle 72 h) without any loss of biocatalytic activity and 9 cycles with 72% residual activity.
-
selective production and characterization of levan by bacillus subtilis natto takahashi
Journal of Agricultural and Food Chemistry, 2005Co-Authors: Inglung Shih, Yunti Yu, Chwenjen Shieh, Chienyan HsiehAbstract:To meet the industrial need of an efficient microbial method for increased levan production, Bacillus subtilis (natto) Takahashi, a commercial natto starter for preparing fermented soybeans (natto), was used to produce levan. After cultivation for 21 h, 40−50 mg of levan mL-1 was produced in medium containing 20% (w/w) sucrose, which was ∼50% yield on available fructose. The product consisted of two fractions with different molecular masses (1794 and 11 kDa), which were easily separated by fractionation using an ethanol gradient. The products were well characterized by GPC, 13C NMR, and 1H NMR. The various sugars and concentrations, initial pH, fermentation temperature, and agitation speed affected the levan production by B. subtilis (natto) Takahashi. Takahashi strain is the most efficient levan-producing strain among all of the B. subtilis strains tested and, as previously reported, it produced the highest yield of levan in the least time (21 h) under the common cultivation condition. Keywords: Levan; B...
A K Pal - One of the best experts on this subject based on the ideXlab platform.
-
dietary microbial levan ameliorates stress and augments immunity in cyprinus carpio fry linnaeus 1758 exposed to sublethal toxicity of fipronil
Aquaculture Research, 2014Co-Authors: Sanjay K Gupta, A K Pal, Narottam Prasad Sahu, Neelam Saharan, Sagar C Mandal, Chandra Prakash, Mohammed Shahbaz Akhtar, A K PrustyAbstract:A 45-day feeding trial was conducted to study the stress ameliorating and immunomodulatory role of microbial levan in Cyprinus carpio fry exposed to sublethal dose (1/10th LC50) of fipronil [(±)-5-amino-1-(2,6-dichloro-α,α,α-trifluoro-p-tolyl)-4-trifluoromethylsulfinylpyrazole-3-carbonitrile]. Two hundred and twenty-five fry were randomly distributed in five treatments in triplicates. Four purified diets were prepared with graded levels of microbial levan. Five different treatment groups were levan control L0P0 (basalfeed + 0% levan without exposure to pesticide); pesticide control L0P1 (basalfeed + 0% levan with exposure to pesticide); L0.25P1 (basalfeed + 0.25% levan with exposure to pesticide); L0.50P1 (basalfeed + 0.50% levan with exposure to pesticide) and L0.75P1 (basalfeed + 0.75% levan with exposure to pesticide). Lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and fructose-1,6-diphosphatase (FDPase) activites were significantly (P < 0.05) increased, whereas alkaline phosphatase (ALP), adenosine triphosphatase (ATPase) and acetyl choline esterase (AchE) activities were significantly (P < 0.05) reduced in higher levan-fed groups. RBC, haemoglobin and WBC counts were significantly (P < 0.05) increased in the levan-fed groups. Similar trends were also observed for the total serum protein, globulin, NBT and lysozyme activities. Blood glucose and serum cortisol exhibited a third order polynomial relationship with increasing level of dietary levan. Overall result showed stress ameliorating, immunostimulating and protective role of microbial levan against fipronil-induced stress in C. carpio fry at 0.75% level of dietary levan supplementation.
-
dietary microbial levan enhances tolerance of labeo rohita hamilton juveniles to thermal stress
Aquaculture, 2010Co-Authors: Sanjay Gupta, A K Pal, Narottam Prasad Sahu, Rishikesh S Dalvi, M S Akhtar, Asish K Jha, Kartik BaruahAbstract:Abstract A preliminary study was conducted to determine the ameliorating effect of dietary microbial levan against thermal stress in Labeo rohita juveniles. Six purified diets were prepared with different levels of microbial levan: basal (no levan), T1 (basal + 0.25%), T2 (basal + 0.50%), T3 (basal + 0.75%), T4 (basal + 1%) and T5 (basal + 1.25%), fed to six groups of fish in triplicate, reared at 26 °C. After feeding for 60 days, critical temperature maxima (CTMax), lethal temperature maxima (LTMax), and the level of heat shock protein (HSP) 70 in the liver and muscle tissues of fish under normal and after heat shock treatment at 35 °C was determined in each group. Results indicated significant increase in the temperature tolerance (CTMax and LTMax) of the group fed diets supplemented with 1.0 and 1.25% microbial levan compared to other experimental groups. In the sub-lethal thermal stress test, significantly higher level of HSP70 was observed in the liver of fish fed diet supplemented with 1.0 and 1.25% and in the muscle of fish fed diet supplemented with 1.25% microbial levan compared to that of other experimental groups. Overall results indicated that dietary microbial levan can confer protection against thermal stress in L. rohita juveniles.
-
microbial levan in the diet of labeo rohita hamilton juveniles effect on non specific immunity and histopathological changes after challenge with aeromonas hydrophila
Journal of Fish Diseases, 2008Co-Authors: Subodh Gupta, A K Pal, N P Sahu, Rishikesh S Dalvi, Vikas Kumar, S C MukherjeeAbstract:A 60-day feeding trial was conducted to study the immuno-protective effect of microbial levan on Labeo rohita juveniles challenged with Aeromonas hydrophila. Six purified diets were prepared with different levels of microbial levan: control (no levan), T1 (Basal + 0.25%), T2 (Basal + 0.50%), T3 (Basal + 0.75%), T4 (Basal + 1%) and T5 (Basal + 1.25%), fed to six groups of fish in triplicate. Among the treatment groups the haemoglobin content and total leucocyte count were increased with a dietary supplementation of levan at 1% or more. An increasing trend for total erythrocyte count was observed with increasing level of dietary levan. Lower levan-supplemented groups showed a higher albumin/globulin ratio. As the levan supplementation was increased, there was a gradual increase in serum lysozyme activity and respiratory burst activity [nitroblue tetrazolium (NBT) assay] reduction values. The highest lysozyme activity and NBT were observed in the T5 group although this was similar to the T4 group (P > 0.05). No significant histo-architectural changes were associated with dietary levan levels. After challenge with A. hydrophila, moderately degenerated hepatocytes, oedema and leucocytic infiltration in parenchymatous tissues, and extensive haemorrhage and haemosiderosis in the kidney were observed in the control group. However, the T5 group supplemented with 1.25% levan showed infiltrating leucocytes in the liver while the kidney showed only moderate degeneration of renal tubules. The relative survival per cent of juveniles after challenge with A. hydrophila was the highest in the T5 group followed by T4. This suggests that microbial levan at 1.25% can be used as dietary immunostimulant for L. rohita juveniles.
-
dietary microbial levan enhances cellular non specific immunity and survival of common carp cyprinus carpio juveniles
Fish & Shellfish Immunology, 2007Co-Authors: Dina Rairakhwada, A K Pal, Narottam Prasad Sahu, Z P Bhathena, Ashish K Jha, S C MukherjeeAbstract:Abstract A preliminary study with a 75 days feeding trial was conducted to study the immunomodulatory effect of microbial levan on Cyprinus carpio juveniles. Five purified isonitrogenous and isocaloric diets with graded levels of levan, namely (T 1 ) 0.1% levan, (T 2 ) 0.2% levan, (T 3 ) 0.5% levan, (T 4 ) 1.0% levan, and a control group without levan were fed to five groups of fishes in triplicate. The total erythrocyte count and haemoglobin content was significantly ( p 3 group, though the total leucocyte counts, total protein and A/G ratio did not show any significant difference ( p > 0.05) when compared with the control group. The respiratory burst activity (NBT) of blood phagocytes and lysozyme activity was also highest in T 3 group. The relative survival percentage after challenge with Aeromonas hydrophila was highest (100%) in the T 3 group followed by 83.33% and 66.67% in the T 2 and T 4 groups, respectively. This suggests that microbial levan at 0.5% can be used as a dietary immunostimulant for C. carpio juveniles. This is the first report on microbial levan having an immunomodulatory effect on C. carpio .
Narottam Prasad Sahu - One of the best experts on this subject based on the ideXlab platform.
-
dietary microbial levan ameliorates stress and augments immunity in cyprinus carpio fry linnaeus 1758 exposed to sublethal toxicity of fipronil
Aquaculture Research, 2014Co-Authors: Sanjay K Gupta, A K Pal, Narottam Prasad Sahu, Neelam Saharan, Sagar C Mandal, Chandra Prakash, Mohammed Shahbaz Akhtar, A K PrustyAbstract:A 45-day feeding trial was conducted to study the stress ameliorating and immunomodulatory role of microbial levan in Cyprinus carpio fry exposed to sublethal dose (1/10th LC50) of fipronil [(±)-5-amino-1-(2,6-dichloro-α,α,α-trifluoro-p-tolyl)-4-trifluoromethylsulfinylpyrazole-3-carbonitrile]. Two hundred and twenty-five fry were randomly distributed in five treatments in triplicates. Four purified diets were prepared with graded levels of microbial levan. Five different treatment groups were levan control L0P0 (basalfeed + 0% levan without exposure to pesticide); pesticide control L0P1 (basalfeed + 0% levan with exposure to pesticide); L0.25P1 (basalfeed + 0.25% levan with exposure to pesticide); L0.50P1 (basalfeed + 0.50% levan with exposure to pesticide) and L0.75P1 (basalfeed + 0.75% levan with exposure to pesticide). Lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and fructose-1,6-diphosphatase (FDPase) activites were significantly (P < 0.05) increased, whereas alkaline phosphatase (ALP), adenosine triphosphatase (ATPase) and acetyl choline esterase (AchE) activities were significantly (P < 0.05) reduced in higher levan-fed groups. RBC, haemoglobin and WBC counts were significantly (P < 0.05) increased in the levan-fed groups. Similar trends were also observed for the total serum protein, globulin, NBT and lysozyme activities. Blood glucose and serum cortisol exhibited a third order polynomial relationship with increasing level of dietary levan. Overall result showed stress ameliorating, immunostimulating and protective role of microbial levan against fipronil-induced stress in C. carpio fry at 0.75% level of dietary levan supplementation.
-
dietary microbial levan enhances tolerance of labeo rohita hamilton juveniles to thermal stress
Aquaculture, 2010Co-Authors: Sanjay Gupta, A K Pal, Narottam Prasad Sahu, Rishikesh S Dalvi, M S Akhtar, Asish K Jha, Kartik BaruahAbstract:Abstract A preliminary study was conducted to determine the ameliorating effect of dietary microbial levan against thermal stress in Labeo rohita juveniles. Six purified diets were prepared with different levels of microbial levan: basal (no levan), T1 (basal + 0.25%), T2 (basal + 0.50%), T3 (basal + 0.75%), T4 (basal + 1%) and T5 (basal + 1.25%), fed to six groups of fish in triplicate, reared at 26 °C. After feeding for 60 days, critical temperature maxima (CTMax), lethal temperature maxima (LTMax), and the level of heat shock protein (HSP) 70 in the liver and muscle tissues of fish under normal and after heat shock treatment at 35 °C was determined in each group. Results indicated significant increase in the temperature tolerance (CTMax and LTMax) of the group fed diets supplemented with 1.0 and 1.25% microbial levan compared to other experimental groups. In the sub-lethal thermal stress test, significantly higher level of HSP70 was observed in the liver of fish fed diet supplemented with 1.0 and 1.25% and in the muscle of fish fed diet supplemented with 1.25% microbial levan compared to that of other experimental groups. Overall results indicated that dietary microbial levan can confer protection against thermal stress in L. rohita juveniles.
-
dietary microbial levan enhances cellular non specific immunity and survival of common carp cyprinus carpio juveniles
Fish & Shellfish Immunology, 2007Co-Authors: Dina Rairakhwada, A K Pal, Narottam Prasad Sahu, Z P Bhathena, Ashish K Jha, S C MukherjeeAbstract:Abstract A preliminary study with a 75 days feeding trial was conducted to study the immunomodulatory effect of microbial levan on Cyprinus carpio juveniles. Five purified isonitrogenous and isocaloric diets with graded levels of levan, namely (T 1 ) 0.1% levan, (T 2 ) 0.2% levan, (T 3 ) 0.5% levan, (T 4 ) 1.0% levan, and a control group without levan were fed to five groups of fishes in triplicate. The total erythrocyte count and haemoglobin content was significantly ( p 3 group, though the total leucocyte counts, total protein and A/G ratio did not show any significant difference ( p > 0.05) when compared with the control group. The respiratory burst activity (NBT) of blood phagocytes and lysozyme activity was also highest in T 3 group. The relative survival percentage after challenge with Aeromonas hydrophila was highest (100%) in the T 3 group followed by 83.33% and 66.67% in the T 2 and T 4 groups, respectively. This suggests that microbial levan at 0.5% can be used as a dietary immunostimulant for C. carpio juveniles. This is the first report on microbial levan having an immunomodulatory effect on C. carpio .
Clarita Olvera - One of the best experts on this subject based on the ideXlab platform.
-
Understanding the transfer reaction network behind the non-processive synthesis of low molecular weight levan catalyzed by Bacillus subtilis levansucrase.
Scientific reports, 2018Co-Authors: Enrique Raga-carbajal, Agustín López-munguía, Laura Alvarez, Clarita OlveraAbstract:Under specific reaction conditions, levansucrase from Bacillus subtilis (SacB) catalyzes the synthesis of a low molecular weight levan through the non-processive elongation of a great number of intermediates. To deepen understanding of the polymer elongation mechanism, we conducted a meticulous examination of the fructooligosaccharide profile evolution during the levan synthesis. As a result, the formation of primary and secondary intermediates series in different reaction stages was observed. The origin of the series was identified through comparison with product profiles obtained in acceptor reactions employing levanbiose, blastose, 1-kestose, 6-kestose, and neo-kestose, and supported with the isolation and NMR analyses of some relevant products, demonstrating that all of them are inherent products during levan formation from sucrose. These results allowed to establish the network of fructosyl transfer reactions involved in the non-processive levan synthesis. Overall, our results reveal how the relaxed acceptor specificity of SacB during the initial steps of the synthesis is responsible for the formation of several levan series, which constitute the final low molecular weight levan distribution.
-
size product modulation by enzyme concentration reveals two distinct levan elongation mechanisms in bacillus subtilis levansucrase
Glycobiology, 2016Co-Authors: Enrique Ragacarbajal, Ernesto Carrillonava, Miguel Costas, Jaime R Porrasdominguez, Agustin Lopezmunguia, Clarita OlveraAbstract:Two levan distributions are produced typically by Bacillus subtilis levansucrase (SacB): a high-molecular weight (HMW) levan with an average molecular weight of 2300 kDa, and a low-molecular weight (LMW) levan with 7.2 kDa. Previous results have demonstrated how reaction conditions modulate levan molecular weight distribution. Here we demonstrate that the SacB enzyme is able to perform two mechanisms: a processive mechanism for the synthesis of HMW levan and a non-processive mechanism for the synthesis of LMW levan. Furthermore, the effect of enzyme and substrate concentration on the elongation mechanism was studied. While a negligible effect of substrate concentration was observed, we found that SacB elongation mechanism is determined by enzyme concentration. A high concentration of enzyme is required to synthesize LMW levan, involving the sequential formation of a wide variety of intermediate size levan oligosaccharides with a degree of polymerization (DP) up to ∼70. In contrast, an HMW levan distribution is synthesized through a processive mechanism producing oligosaccharides with DP <20, in reactions occurring at low enzyme concentration. Additionally, reactions where levansucrase concentration was varied while the total enzyme activity was kept constant (using a combination of active SacB and an inactive SacB E342A/D86A) allowed us to demonstrate that enzyme concentration and not enzyme activity affects the final levan molecular weight distribution. The effect of enzyme concentration on the elongation mechanism is discussed in detail, finding that protein-product interactions are responsible for the mechanism shift.