Degradation Of Cellulosic Materials Research Articles

Haloferax sulfurifontis GUMFAZ2 producing xylanase-free cellulase retrieved from Haliclona sp. inhabiting rocky shore of Anjuna, Goa-India.

Salt stable cellulases are implicated in detritic food webs of marine invertebrates for their role in the degradation of cellulosic material. A haloarchaeon, Haloferax sulfurifontis GUMFAZ2 producing cellulase was successfully isolated from marine Haliclona sp., a sponge inhabiting the rocky intertidal region of Anjuna, Goa. The culture produced extracellular xylanase-free cellulase with a maximum activity of 11.7 U/ml, using carboxymethylcellulose-Na (CMC-Na), as a sole source of carbon in 3.5 M NaCl containing medium, pH 7 at 40°C and produced cellobiose and glucose, detectable by thin-layer chromatography. Nondenaturing polyacrylamide gel electrophoresis of the crude enzyme, revealed a single protein band of 19.6 kDa which on zymographic analysis exhibited cellulase activity while corresponding sodium dodecyl sulfate polyacrylamidegelelectrophoresis revealed a molecular weight of 46 kDa. Unlike conventional cellulases, this enzyme is active in presence of 5 M NaCl and does not have accompanying xylanase activity, hence can be considered as xylanase-free cellulase. Such enzymes from haloarchaea offer great potential for biotechnological application because of their stability at high salinity and is therefore worth pursuing.

Screening of new secretory cellulases from different supernatants of white rot fungi from Misiones, Argentina

ABSTRACTCellulases hydrolyse the cellulose chain into single sugars efficiently. These sugars can be fermented in the bioethanol process, a source of renewable energy. Misiones rainforest is one of the most biodiverse systems on the planet subtropical ecoregions, which is the most probable site to find new fungal strains with potential for degrading cellulose through cellulases. The aim of this work was to find an efficient cellulolytic microorganism through the exploration of native white rot fungi from Misiones. From the qualitative screening 11 fungal strains were selected. The quantitative analysis revealed that the isolated LBM 033 was the best cellulases producer, reaching 57, 226 and 387 U/l of cellobiohydrolase, β-glucosidase and endoglucanase activity, respectively. The zymograms showed that the molecular mass of most of the endoglucanases ranged from 69 to 88 kDa and the molecular mass of most of the cellobiohydrolases was 45 kDa. The search of new cellulases of secretory organisms should lead to an efficient degradation of cellulosic materials, and thus facilitating potential applications in the production of bioenergy from lignocellulosic biomass.

Insight into a novel β-1,4-glucosidase from Streptomyces griseorubens JSD-1

Streptomyces griseorubens JSD-1 is novel isolate utilizing cellulose as a sole carbon source for growth, and cellulytic genes related to this process were expected to be crucial. To investigate the molecular mechanism of cellulose metabolism, bacterial genome sequencing was carried out. As a result, its draft genome map was obtained which has been deposited at GenBank. s-1,4-glucosidase (Glu) was acquired following with characterization of its cellular localization and expression profiles. Glu from S. griseorubens JSD-1 was suggested to be an intracellular enzyme which was different from those obtained from similar species through the combined analysis of multiple sequences alignment and putative 3D structure modeling. Expression of recombinant enzyme was optimized in heterogeneous hosts for the further determination of its optimum pH and temperature as well as the residual activity in the presence of metal ions and inhibitors. Novel Glu expected to have promising potential in the degradation of cellulosic materials.

Isolation of cellulolytic microcosms from bagasse compost in co-digested fibrous substrates

Symbiotic cellulolytic microcosms represent a promising microbial agent for enhancing degradation of cellulosic materials in biotechnological processes. In this study, structurally stable lignocellulose-degrading microbial communities were constructed from cellulolytic seed culture from sugarcane bagasse compost using swine manure and Napier grass as co-digested carbon sources under static aerobic condition at 55 °C. The lignocellulolytic microbial consortium enriched in peptone and yeast extract-based medium (PLMC) showed higher cellulose-degrading activity compared to lignocellulolytic microbial consortium isolated in the water-based medium (WLMC). The composite microbes in both consortia were originated from the seed culture and the co-digested substrates according to denaturing gradient gel electrophoresis profile. PLMC exhibited higher CMCase, xylanase, FPase, and avicelase activities in the supernatant than those of WLMC and was capable of degrading 70 % of filter paper within 1 week. PLMC was capable of degrading substrate with higher efficiency than the control by 11.7, 9.2, 15.5, and 11.9 % of total solid, suspended solid, volatile solid, and volatile suspended solid, respectively. The work demonstrated the potential of cellulolytic microcosms enriched by this approach on enhancing conversion efficiency in biogas production from cellulosic wastes.

Fungal Degradation of Cellulosic Materials in Assam I Studies on Soil Aspergilliei

Nineteen species of Aspergillus were isolated from the soil of Assam, during a systematic investigation of soil mycoflora in 1972-74. The paper describes the presence of these species in different regions of Assam with special consideration to cellulose destroying capacity of these species, and the results indicate that these isolates play a very important role in degradation of cellulosic materials in stores under user conditions.

The effect of isosaccharinic acid and gluconic acid on the retention of Eu(III), Am(III) and Th(IV) by calcite

Calcite is an important component of many potential host rocks currently under consideration for the disposal of radioactive wastes. Even in the chemically disturbed zone formed around a cementitious repository, this mineral remains largely unaffected by the hyper-alkaline waters migrating out of the near field. Thus, due to its abundance and geochemical stability, calcite could play an important role in the retardation of radionuclides released from a repository for nuclear wastes. Actinides are an important class of elements present in almost all radioactive waste streams, and for this reason, investigations of their retention behaviour under representative chemical conditions are particularly relevant to assessing safe disposal in the long term. Organic ligands originating from the degradation of cellulosic materials in the repository or present as cement additives could possibly reduce the retardation of tri- and tetravalent actinides due to the formation of stable metal–ligand complexes in solution. In this study, isosaccharinic acid (ISA) and gluconic acid (GLU) have been taken as representatives of cellulose degradation products and concrete admixtures, respectively. Batch-type sorption experiments have been conducted to investigate the effect of ISA and GLU on the retardation of 152Eu, 241Am and 228Th by calcite. 152Eu and 241Am are representatives of the trivalent lanthanides and actinides, respectively, and 228Th is a representative of the tetravalent actinides. High ISA and GLU concentrations in solution were found to significantly affect the sorption of the radionuclides. R d values for Eu(III) and Am(III) decreased significantly at ISA concentrations above 10 −5 M and at GLU concentrations above 10 −7 M. The critical concentration limits were similar for Th(IV), that is 2 × 10 −5 M in the case of ISA and 10 −6 M in the case of GLU. The effects of ISA and GLU on the immobilisation of Eu(III), Am(III) and Th(IV) were interpreted in terms of complex formation in solution. In the case of Eu(III) and Am(III) in ACW, the metal–ligand complexes were found to have a 1:1 stoichiometry. Complexation constants of these aqueous ISA and GLU complexes with Eu(III) and Am(III) were determined and discussed in connection with the presently unclear situation concerning the stability constant of the Eu ( OH ) 3 0 species. In the case of Th(IV) in ACW, it was assumed that a Th(IV)–ISA–Ca complex and a Th(IV)–GLU–Ca complex are formed, both having a 1:2:1 stoichiometry. The complexation constants of these complexes were determined and compared with the literature data. Assuming maximum concentrations for ISA and GLU in the pore water of the disturbed zone of a cementitious repository based on representative near-field conditions ([ISA] aq = 3 × 10 −6 M, [GLU] aq = 10 −7 M), it is predicted that the formation of aqueous ISA and GLU complexes would not significantly affect Eu(III), Am(III) and Th(IV) sorption on calcite.

Degradation of cellulosic materials under the alkaline conditions of a cementitious repository for low and intermediate level radioactive waste: Part I: Identification of degradation products

In order to assess the potential role of cellulose degradation products as metal-binding chelates in a repository for radioactive waste, different cellulosic materials (pure cellulose, cotton, tissues and recycling paper) were degraded under the chemical conditions of cement pore water (pH 13.3). The degradation products formed were characterised using different separation techniques (HPIEC, HPAEC, GC-MS, MS/MS) and by high resolution 1H-NMR spectroscopy. The main degradation products of pure cellulose are the diastereomeric α-isosaccharinic acid (α-ISA) and β-isosaccharinic acid (β-ISA), which accounted for ∼80% of total dissolved organic carbon formed. Minor components are short chain aliphatic acids such as formic acid, acetic acid, lactic acid and threonic acid comprising less than 10% of total dissolved organic carbon. The degradation of the other cellulosic materials resulted in lower amounts of α-ISA and β-ISA and in higher yields of small organic acids (acetic acid) and of unidentified compounds. The combination of the different MS and NMR techniques unequivocally shows the structural identity of β-ISA.

Degradation of Cellulosic Materials Under the Alkaline Conditions of a Cementitious Repository for Low- and Intermediate-Level Radioactive Waste. II. Degradation Kinetics

The degradation of cellulosic materials, differing mainly in the degree of polymerization and the number of reducing end groups, was studied under the alkaline conditions similar to those existing in a cementitious repository for low- and intermediate-level radioactive waste (pH 13.3, T = 25°C). The kinetics of alkaline degradation (peeling-off reaction) were studied and the data analyzed by the model of Haas et al. [13]. The observed kinetic parameters for the propagation reaction and overall stopping reaction were compared with literature data. Although measured under different experimental conditions, literature data and data from this study show a consistent picture. Differences in the extent of degradation observed for the different cellulosic materials could be satisfactorily explained by differences in reducing end group content and, consequently, by differences in the degrees of polymerization. Besides the number of reducing end groups, the degree of amorphousness also plays an important role. The main degradation products formed under the experimental conditions used are α- and β-(gluco)isosaccharinic acid. This is in agreement with many other studies on alkaline degradation of cellulose. The two isomers are formed in roughly equal amounts.

Characterization of engF, a gene for a non-cellulosomal Clostridium cellulovorans endoglucanase

A new Clostridium cellulovorans (strain ATCC 35296) endoglucanase gene engF has been isolated and sequenced. The gene contains 1671 bp and codes for a protein containing 557 amino acids and a mass of 60.1 kDa. A putative signal peptide of 29 amino acids is present and the mature protein has a mass of 57.1 kDa. EngF does not have amino acid sequence homology to previously isolated EngB and EngD, but does show sequence homology to family 5 glycosyl hydrolases from Bacillus, Erwinia carotovora, and C. acetobutylicum species. EngF is not a component of the cellulosome and does not contain a duplicated sequence (DS) at its C-terminal region. EngF is capable of binding to cellulose and hydrolyzing carboxymethylcellulose but not xylan. The cellulose binding domain (CBD) differs from types I, II and III CBDs and no obvious homology has been found to other CBD types. The maximum activity of EngF occurs at pH 5.5 and at 47°C. Its properties suggest that EngF plays an ancillary role in the degradation of cellulosic materials.

Degradation of cellulosic materials by Sporotrichum thermophile culture filtrate for sugar production

Sporotrichum thermophile Apinis, was the most active carboxymethyl-cellulose (CMC)-ase producer among seven thermophilic and four thermotolerant fungal species isolated from Egyptian soil and screened for their ability to produce extracellular cellulase in culture media containing CMC as a sole carbon source. The fungus also efficiently hydrolysed filter paper cellulose. Comparison of various untreated and alkali-treated cellulosic and lignocellulosic materials as substrates for cellulase production by S. thermophile revealed the most easily degraded substrate was sugarcane bagasse at 2% concentration. This substrate when alkali treated was the most susceptible to enzymic hydrolysis by culture filtrates of S. thermophile grown on untreated bagasse. Optimum hydrolysis was obtained after 18 h incubation with the filtrate at pH 3·5–4 and 45°C. Alkali treatment of bagasse reduced its lignin content significantly and the culture filtrate of S. thermophile grown on untreated bagasse was found to contain xylanase and polygalacturonase in addition to cellulase and cellobiase.