Microbial Cellulases and Their Industrial Applications

Microbial cellulases have shown their potential application in various industries including pulp and paper, textile, laundry, biofuel production, food and feed industry, brewing, and agriculture. Due to the complexity of enzyme system and immense industrial potential, cellulases have been a potential candidate for research by both the academic and industrial research groups. Nowadays, significant attentions have been devoted to the current knowledge of cellulase production and the challenges in cellulase research especially in the direction of improving the process economics of various industries. Scientific and technological developments and the future prospects for application of cellulases in different industries are discussed in this paper

Laccase production by Coriolopsis caperata RCK2011: optimization under solid state fermentation by Taguchi DOE methodology

Laccase production by Coriolopsis caperata RCK2011 under solid state fermentation was optimized following Taguchi design of experiment. An orthogonal array layout of L(18) (2(1) × 3(7)) was constructed using Qualitek-4 software with eight most influensive factors on laccase production. At individual level pH contributed higher influence, whereas, corn steep liquor (CSL) accounted for more than 50% of the severity index with biotin and KH(2)PO(4) at the interactive level. The optimum conditions derived were; temperature 30°C, pH 5.0, wheat bran 5.0 g, inoculum size 0.5 ml (fungal cell mass = 0.015 g dry wt.), biotin 0.5% w/v, KH(2)PO(4) 0.013% w/v, CSL 0.1% v/v and 0.5 mM xylidine as an inducer. The validation experiments using optimized conditions confirmed an improvement in enzyme production by 58.01%. The laccase production to the level of 1623.55 Ugds(−1) indicates that the fungus C. caperata RCK2011 has the commercial potential for laccase

Kinetic study of batch and fed-batch enzymatic saccharification of pretreated substrate and subsequent fermentation to ethanol

<p>Abstract</p> <p>Background</p> <p>Enzymatic hydrolysis, the rate limiting step in the process development for biofuel, is always hampered by its low sugar concentration. High solid enzymatic saccharification could solve this problem but has several other drawbacks such as low rate of reaction. In the present study we have attempted to enhance the concentration of sugars in enzymatic hydrolysate of delignified <it>Prosopis juliflora</it>, using a fed-batch enzymatic hydrolysis approach.</p> <p>Results</p> <p>The enzymatic hydrolysis was carried out at elevated solid loading up to 20% (w/v) and a comparison kinetics of batch and fed-batch enzymatic hydrolysis was carried out using kinetic regimes. Under batch mode, the actual sugar concentration values at 20% initial substrate consistency were found deviated from the predicted values and the maximum sugar concentration obtained was 80.78 g/L. Fed-batch strategy was implemented to enhance the final sugar concentration to 127 g/L. The batch and fed-batch enzymatic hydrolysates were fermented with <it>Saccharomyces cerevisiae </it>and ethanol production of 34.78 g/L and 52.83 g/L, respectively, were achieved. Furthermore, model simulations showed that higher insoluble solids in the feed resulted in both smaller reactor volume and shorter residence time.</p> <p>Conclusion</p> <p>Fed-batch enzymatic hydrolysis is an efficient procedure for enhancing the sugar concentration in the hydrolysate. Restricting the process to suitable kinetic regimes could result in higher conversion rates.</p

Enhanced production and extraction of phenolic compounds from wheat by solid-state fermentation with Rhizopus oryzae RCK2012

Antioxidant phenolic compounds (PCs) are gaining popularity day by day for their health promoting properties. Wheat is a very good source of natural antioxidant PCs. In the present study, extraction of PCs was improved by solid-state fermentation (SSF) of wheat by Rhizopus oryzae RCK2012 which helped to release the bound compounds from matrix. Different extraction conditions such as solvent composition (water, methanol, 70% methanol, ethanol, 70% ethanol, acetone and 70% acetone), extraction temperature (30–60 °C), extraction time (15–90 min) and solid-to-solvent ratio (1:2.5 to 1:20, w/v) have been optimized for the extraction of PCs from R. oryzae fermented wheat. Maximum PCs were extracted by water at 40 °C within 45 min with solid-to-solvent ratio of 1:15 (w/v). Compositional analysis of PCs was carried out by UPLC and TLC. Improved ABTS·−+ [2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] and DPPH (2,2-diphenyl-1-picrylhydrazyl), hydroxyl radical and hydrogen peroxide scavenging capacities, ferric reducing property and in vivo antioxidant capacity using Saccharomyces cerevisiae were observed in case of freeze-dried water extract of fermented wheat as compared to unfermented sample. Hence, SSF could be a promising technology to enhance the production and extraction of phenolic compounds for the design of different functional foods and for the specific use as nutraceuticals

Arbuscular mycorrhizae and phosphate solubilising bacteria of the rhizosphere of the mangrove ecosystem of Great Nicobar island, India

Mangroves form an important ecosystem of Great Nicobar, a continental island in the Bay of Bengal with luxuriant tropical rainforests. The rhizosphere of the mangrove plants of Great Nicobar was investigated for the presence of arbuscular mycorrhizal fungus (AMF) and phosphate solubilising bacteria (PSB). The soils of the Great Nicobar mangroves were silt–clays and were poor in phosphate content. Five species of AMF belonging to the genus Glomus were isolated. The %AMF colonization in the mangrove plants was between 0 and 17%, and the presence of AMF in the aerenchymatous cortex suggests that the mangrove plants may be aiding in AMF survival by providing oxygen. Two strains of phosphate solubilising Pseudomonas aeruginosa were found in the mangrove soils of Great Nicobar. Phosphate solubilisation by the two isolated strains was almost 70% under in vitro conditions. PSB may play a role in the mangrove ecosystems of Great Nicobar by mobilising insoluble phosphate. The plant roots could pick up the released phosphate directly or with the aid of AMF hyphae

Multiple Genes in a Single Host: Cost-Effective Production of Bacterial Laccase (cotA), Pectate Lyase (pel), and Endoxylanase (xyl) by Simultaneous Expression and Cloning in Single Vector in E. coli.

This study attempted to reduce the enzyme production cost for exploiting lignocellulosic materials by expression of multiple genes in a single host. Genes for bacterial laccase (CotA), pectate lyase (Pel) and endoxylanase (Xyl), which hold significance in lignocellulose degradation, were cloned in pETDuet-1 vector containing two independent cloning sites (MCS). CotA and xyl genes were cloned in MCS1 and MCS 2, respectively. Pel gene was cloned by inserting complete cassette (T7 promoter, ribosome binding site, pel gene, His tag and complete gene ORF) preceded by cotA open reading frame in the MCS1. IPTG induction of CPXpDuet-1 construct in E. coli BL21(DE3) resulted in expression of all three heterologous proteins of ~65 kDa (CotA), ~45 kDa (Pel) and ~25 kDa (Xyl), confirmed by SDS-PAGE and western blotting. Significant portions of the enzymes were also found in culture supernatant (~16, ~720 and ~370 IU/ml activities of CotA, Pel and Xyl, respectively). Culture media optimization resulted in 2, 3 and 7 fold increased secretion of recombinant CotA, Pel and Xyl, respectively. Bioreactor level optimization of the recombinant cocktail expression resulted in production of 19 g/L dry cell biomass at OD600nm 74 from 1 L induced culture after 15 h of cultivation, from which 9, 627 and 1090 IU/ml secretory enzyme activities of CotA, Xyl and Pel were obtained, respectively. The cocktail was also found to increase the saccharification of orange peel in comparison to the xylanase alone. Thus, simultaneous expression as well as extra cellular secretion of these enzymes as cocktail can reduce the enzyme production cost which increases their applicability specially for exploiting lignocellulosic materials for their conversion to value added products like alcohol and animal feed