Keshab Chandra Mondal

Studies on the extracellular tannase from newly isolated Bacillus licheniformis KBR 6

A tannase producing bacterial strain KBR 6 has been isolated from lateritic soil and identified as Bacillus licheniformis. It is capable of producing tannase in the medium containing only tannic acid. The rapid degradation of tannic acid and production of extracellular tannase was observed in three different media containing tannic acid (M1), tannic acid + basal salt (M2) and tannic acid + basal salt + glucose (M3). Maximum enzyme production and growth of the organism was obtained at 18–21 h and 30–36 h, respectively. The increased order of enzyme production in relation to different media is as per the following sequence, M3 > M2 > M1. The maximum growth and enzyme production was observed at pH 5.0. The pH and temperature optima of the enzyme activity were found to be at 5.75 and 60 °C respectively. Paper chromatographic analysis indicates that gallic acid is the enzymatic degradative product of tannic acid.

Production and characterization of extracellular and intracellular tannase from newly isolated Aspergillus aculeatus DBF 9

A comparative study on the simultaneous production of extra and intracellular tannase was made from newly isolated fungal strain Aspergillus aculeatus DBF 9. This strain produced five times more intracellular enzyme within 24 h in liquid culture than the extracellular form. Maximum tannase production occurred in the culture broth containing 1–2% (w/v) tannic acid and 0.05–0.1% (w/v) glucose. The pH and temperature optima of both the enzymes were found at 5.0 and 50–60 °C, respectively. Extra and intracellular tannase showed good stability at higher temperature, pH values and salt (NaCl) concentration. These properties make the enzyme suitable for pollution control and bioprocess industry.

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.

Enhanced production and partial characterization of an extracellular polysaccharide from newly isolated Azotobacter sp. SSB81.

A strain was selected by its highest extracellular polysaccharide (EPS) production ability compare to other isolates from the same rhizospheric soil. The selected strain was identified by 16S rDNA sequencing and designated as SSB81. Phylogenetic analysis of the gene sequence showed its close relatedness with Azotobacter vinelandii and Azotobacter salinestris. Maximum EPS (2.52 g l(-1)) was recovered when the basal medium was supplemented with glucose (2.0%), riboflavin (1 mg l(-1)) and casamino acid (0.2%). The EPS showed a stable viscosity level at acidic pH (3.0-6.5) and the pyrolysis temperature was found to be at 116.73 degrees C with an enthalpy (DeltaH) of 1330.72 J g(-1). MALDI TOF mass spectrometric result suggests that polymer contained Hex(5)Pent(3) as oligomeric building subunit. SEM studies revealed that the polymer had a porous structure with small pore size distribution indicating the compactness of the polymer. This novel EPS may find possible application as a polymer for environmental bioremediation and biotechnological processes.

Production of tannase by the immobilized cells of Bacillus licheniformis KBR6 in Ca-alginate beads

Aims:  The present study was aimed at finding the optimal conditions for immobilization of Bacillus licheniformis KBR6 cells in calcium‐alginate (Ca‐alginate) beads and determining the operational stability during the production of tannin‐acyl‐hydrolase (tannase) under semicontinous cultivation.

Production of cellulase-free xylanase by Trichoderma reesei SAF3

A xylanase producing fungi has been isolated from soil and identified as Trichoderma reesei SAF3. Maximum growth of the organism was found at 48 h under submerged condition in xylan containing enriched medium, whereas highest enzyme production (4.75U/mL) was recorded at 72 h. No detectable cellulase activity was noted during whole cultivation period. The partially purified enzyme hydrolyzed xylan into xylopentose and xylose. All these properties of xylanase highlighten its promising uses in industrial scale.

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.

Antimicrobial activity of the leaf extracts of Hyptis suaveolens (L.) poit

Steam distillation, petroleum ether, and ethanol extracts from Hyptis suaveolens leaves were evaluated for their antimicrobial activity in vitro . Steam distillation extract exhibited broad-spectrum antibacterial and antifungal activity against the tested organisms. It showed highest antifungal and antibacterial activity against Aspergillus niger and Micrococcus luteus, respectively. Activity indices of A. niger against miconazole (25 µg/ml) and M. luteus against chloramphenicol (10 µg/ml) were 0.89 and 0.67, respectively.

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.