Suman Kumar Halder

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.

Microbial, saccharifying and antioxidant properties of an Indian rice based fermented beverage.

Haria, a popular rice based ethnic fermented beverage, is consumed as a staple food and refreshing drink by the vast number of Indian tribal people. In this study, the composition of microbial consortia and the occurrence of some important nutraceuticals during haria preparation were investigated. The quantities of moulds and yeasts were highest at 2nd day, and then declined, but, on the contrary, the quantity of Lactic Acid Bacteria and Bifidobacterium sp. increased concurrently during the course of fermentation. Accumulation of starch hydrolytic enzymes along with different types of malto-oligosaccharides like maltotetrose (26.18μg/gm), maltotriose (28.16μg/gm), and maltose (26.94μg/gm) were also noted. Furthermore, GC-MS analysis indicated the occurrence of pyranose derivatives in the fermented products. The fermented materials showed higher free radicals scavenging activity (82.54%, 4th day) against DPPH radicals. These studies clearly demonstrated that the microbial interaction during fermentation of rice makes it more nutritious, and most likely more beneficial for health.

Role of probiotic Lactobacillus fermentum KKL1 in the preparation of a rice based fermented beverage

A dominant lactic acid bacteria, Lactobacillus fermentum KKL1 was isolated from an Indian rice based fermented beverage and its fermentative behavior on rice was evaluated. The isolate grown well in rice and decreased the pH, with an increase of total titratable acidity on account of high yield in lactic acid and acetic acid. The production of α-amylase and glucoamylase by the strain reached plateau on 1st and 2nd day of fermentation respectively. The accumulation of malto-oligosaccharides of different degrees of polymerization was also found highest on 4th day. Besides, phytase activity along with accumulation of free minerals also unremittingly increased throughout the fermentation. The fermented materials showed free radical scavenging activity against DPPH radicals. In-vitro characteristics revealed the suitability of the isolate as probiotic organism. The above profiling revealed that probiotic L. fermentum KKL1 have the significant impact in preparation of rice beer and improves its functional characteristics.

Tannase Production by Penicillium purpurogenum PAF6 in Solid State Fermentation of Tannin-Rich Plant Residues Following OVAT and RSM

Tannase production by newly isolated Penicillium purpurogenum PAF6 was investigated by ‘one variable at a time’ (OVAT) approach followed by response surface methodology (RSM). Tannin-rich plant residues were used as supporting solid substrate and sole carbon source and, among them, tamarind seed was found to be the most favorable substrate than haritaki, pomegranate, tea leaf waste and arjun fruit. Physicochemical parameters were initially optimized using OVAT methodology and some important factors like incubation time, incubation temperature, substrate:moisture ratio as well as carbon, nitrogen and phosphate concentrations were verified with Box–Behken design of response surface methodology. Phosphate source, nitrogen source and temperature were found as the most favorable variables in the maximization of production. Tannase production was enhanced from 1.536 U/g to 5.784 U/g using tamarind seed OVAT optimization and further enhancement up to 6.15 U/g following RSM. An overall 3.76- and 4.0-fold increases in tannase production were achieved in OVAT and RSM, respectively.

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.

Rapid screening of tannase producing microbes by using natural tannin

Use of natural tannin in the screening of tannase producing microbes is really promising. The present work describes about the possibility and integrity of the newly formulated method over the previously reported methods. Tannin isolated from Terminalia belerica Roxb. (Bahera) was used to differentiate between tanninolytic and nontanninolytic microbes. The method is simple, sensitive and superior for the rapid screening and isolation of tannase-producing microbes.

Microbial Valorization of Chitinous Bioresources for Chitin Extraction and Production of Chito-Oligomers and N-Acetylglucosamine: Trends, Perspectives and Prospects

Chitin, the crystalline polymer of N-acetylglucosamine (GlcNAc) is the world’s second most abundant carbohydrate and principal structural component of cell wall of fungi, yeasts and algae, insect exoskeletons, shells of crustaceans and the microfilarial sheath of nematodes. GlcNAc is present in peptidoglycan, hyaluronic acid and keratin sulfate. In nature, chitin rich waste biomass get re-utilized by an array of microbes producing chitinases and proteases, but the presence of the microbes as well as activity of the enzymes depend on the abundance of the bioresource. Chitin polymer, chito-oligomers and GlcNAc have engrossed colossal attention due to their innumerable potential applications in food, biomedicine, pharmaceuticals, agriculture, cosmetics and environmental cleanup. Owing their immense and versatile appliances, extraction of chitin and production of chito-oligomers and GlcNAc in large scale is necessary to meet the market demand. In this context, chemical extraction/degradation of crustacean shell at elevated temperature is the traditional practice results in the formation of undesired byproducts, creates large quantities of toxic waste as well as associated with high cost, low yield and also deteriorates environmental health. In this perspective, microbial biotransformation and enzymatic treatment are alternative environment friendly ‘green technology’ for generation of chitin, chito-oligomers and GlcNAc in large scale in economical way by valorizing natural chitinous bioresources using potential organic acid, chitinase and protease producing microbes. Moreover, genetic manipulation and metabolic engineering was implemented in recent ages. Altogether, in the present assignment, cutting edge strategies of bioextraction of chitin and production of chito-oligomers and GlcNAc by microbial means as well as their multifaceted appliances in biological and biomedical sector are thoroughly discussed.

Multi-Response Optimization of Granaticinic Acid Production by Endophytic Streptomyces thermoviolaceus NT1, Using Response Surface Methodology

Streptomyces thermoviolaceus NT1, an endophytic isolate, was studied for optimization of granaticinic acid production. It is an antimicrobial metabolite active against even drug resistant bacteria. Different media, optimum glucose concentration, initial media pH, incubation temperature, incubation period, and inoculum size were among the selected parameters optimized in the one-variable-at-a-time (OVAT) approach, where glucose concentration, pH, and temperature were found to play a critical role in antibiotic production by this strain. Finally, the Box–Behnken experimental design (BBD) was employed with three key factors (selected after OVAT studies) for response surface methodological (RSM) analysis of this optimization study.RSM analysis revealed a multifactorial combination; glucose 0.38%, pH 7.02, and temperature 36.53 °C as the optimum conditions for maximum antimicrobial yield. Experimental verification of model analysis led to 3.30-fold (61.35 mg/L as compared to 18.64 mg/L produced in un-optimized condition) enhanced granaticinic acid production in ISP2 medium with 5% inoculum and a suitable incubation period of 10 days. So, the conjugated optimization study for maximum antibiotic production from Streptomyces thermoviolaceus NT1 was found to result in significantly higher yield, which might be exploited in industrial applications.