Tanmay Paul

Production of cellulolytic enzymes by Aspergillus fumigatus ABK9 in wheat bran-rice straw mixed substrate and use of cocktail enzymes for deinking of waste office paper pulp.

Response surface methodology was employed to optimize mixed substrate solid state fermentation for the production of cellulases and xylanase by Aspergillus fumigatus ABK9. Among 11 different parameters, fermentation time (86-88 h), medium pH (6.1-6.2), substrate amount (10.0-10.5 g) and substrate ratio (wheat bran:rice straw) (1.1) had significantly influences on enzyme production. Under these conditions endoglucanase, β-glucosidase, FPase (filter paper degrading activity) and xylanase activities of 826.2, 255.16, 102.5 and 1130.4 U/g, respectively were obtained. The enzyme cocktail extracted (solid to water ratio of 1:10) from the ferments increased brightness of waste office paper pulp by 82.8% ISO, Ink(D) value by 82.1%, removed chromophores (2.53 OD; A(237)nm) and hydrophobic compounds (1.15 OD; A(465)nm) and also decreased the kappa number to 13.5 from 16.8.

Biosynthesis, structural architecture and biotechnological potential of bacterial tannase: A molecular advancement

Tannin-rich materials are abundantly generated as wastes from several agroindustrial activities. Therefore, tannase is an interesting hydrolase, for bioconversion of tannin-rich materials into value added products by catalyzing the hydrolysis of ester and depside bonds and unlocked a new prospect in different industrial sectors like food, beverages, pharmaceuticals, etc. Microorganisms, particularly bacteria are one of the major sources of tannase. In the last decade, cloning and heterologous expression of novel tannase genes and structural study has gained momentum. In this article, we have emphasized critically on bacterial tannase that have gained worldwide research interest for their diverse properties. The present paper delineate the developments that have taken place in understanding the role of tannase action, microbial sources, various cultivation aspects, downstream processing, salient biochemical properties, structure and active sites, immobilization, efforts in cloning and overexpression and with special emphasis on recent molecular and biotechnological achievements.

Appraisal of antioxidant, anti-hemolytic and DNA shielding potentialities of chitosaccharides produced innovatively from shrimp shell by sequential treatment with immobilized enzymes

Chitosaccharides (CS) of varied size were prepared from shrimp shell through sequential catalysis, using crude protease and chitinase enzymes immobilized on agar beads. In the optimized state, immobilization yield and activity yield for protease were 84% and 62%, and for chitinase were 75% and 57%, respectively. Immobilized protease and chitinase treatment improved CS yields (101 μg/ml) and retained 63% and 52% of activities after 10 reuses, respectively. Stronger radical-scavenging activity (RSA) of CS against ABTS, DPPH and hydroxyl radical was noted with EC50 values 19.1, 26.4 and 29.6 μg/ml, respectively. Peroxyl and superoxide RSAs of 96.8% and 88.6% were noticed at 70 μg/ml of CS. Singlet oxygen quenching, reducing power and ferrous ion-chelating activities of CS were also pronounced. CS reasonably reduced oxidative damage of DNA, protein and RBC by inhibiting H2O2 and AAPH radicals. Reversible CS-DNA condensation leads to DNA stabilization without changing its conformation and advocates its employment in gene therapy.

Thermodynamics and kinetic properties of halostable endoglucanase from Aspergillus fumigatus ABK9

An endoglucanase from Aspergillus fumigatus ABK9 was purified from the culture extract of solid‐state fermentation and its some characteristics were evaluated. The molecular weight of the purified enzyme (56.3 kDa) was determined by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, zymogram analysis and confirmed by MALDI‐TOF mass spectrometry. The enzyme was active optimally at 50 °C, pH 5.0 and stable over a broad range of pH (4.0–7.0) and NaCl concentration of 0–3.0 M. The pKa1 and pKa2 of the ionizable groups of the active sites were 2.94 and 6.53, respectively. The apparent Km, Vmax, and Kcat values for carboxymethyl cellulose were 6.7 mg ml−1, 775.4 µmol min−1, and 42.84 × 104 s−1, respectively. Thermostability of the enzyme was evidenced by the high activation energy (91.45 kJ mol−1), large enthalpy for activation of denaturation (88.77 kJ mol−1), longer half‐life (T1/2) (433 min at 50 °C), higher melting temperature (Tm) (73.5 °C), and Q10 (1.3) values. All the characteristics favors its suitability as halotolerant and thermostable enzyme during bioprocessing of lignocellulosic materials.

Therapeutic potential of Lactobacillus ingluviei ADK10, a newly established probiotic organism against acetaminophen induced uremic rats*

In the present study, Lactobacillus ingluviei ADK10 (Acc. No. JQ395039) from intestinal origin was tested for its probiotic characteristic as well as uremia ameliorating activity on acetaminophen induced uremic rats. The results revealed that L. ingluviei ADK10 was able to tolerate pH 3.0–9.0 and 0.5% bile salt along with good hydrophobicity (67%) and adherence index with Ht-29 cell line on 258/100 cells. It was susceptible to 20 antibiotics. The organism was able to degrade food ingredients, like starch and milk proteins. The strain showed significant growth inhibition of Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Shigella dysentery, Pseudomonas aeruginosa, and Klebsiella pneumoniae (average diameter of 10 mm). The therapeutic potentiality of this probiotic bacterium was tested against acetaminophen induced uremic rats. It was found that supplementation of L. ingluviei ADK10 for 14 days with food reduced severe increase of uremic profiles, such as blood urea (85%), creatinine (68%) and uric acid (41%) in comparison to the uremic rats. Moreover, during the feeding of rats with probiotic strain at a dose of 1×109 bacteria, reduction of enterobacteria in faeces was observed. Our studies indicated that L. ingluviei ADK10 could be used as a health-promoting probiotic along with antiuremic efficacy.