Extracellular Cellulase Research Articles

Nghiên cứu thu nhận và tinh sạch enzyme ngoại bào cellulase từ chủng vi khuẩn ưa mặn Bacillus sp. X2

Extracellular cellulase was purified from culture supernatants of the halophilic bacterium X2, which was identified as a Bacillus species by analysis of 16S rRNA gene sequence and named as Bacillus sp X2. Under optimized conditions, including pH 7.0, 40°C and 30 g/L NaCl, incubation for 72 h in Luria-Bertani medium, the strain Bacillus sp. X2 exhibited a maximum production of cellulase. After purification by ion exchange chromatography with DEAE resin, the purified enzyme performed a specific activity of 0,11 U/mg, 7-fold higher than that of the supernatants, and showed 3 bands on SDS-PAGE with molecular weight of 25, 45, 85 kDa, respectively.

An isolated cellulolytic Escherichia coli from bovine rumen produces ethanol and hydrogen from corn straw

BackgroundLignocellulosic biomass is the most abundant resource on earth. Lignocellulose is mainly composed of cellulose, hemicelluloses, and lignin. The special construction of three kinds of constituents led to the prevention of effective degradation. The goal of this work was to investigate the great potentials of bovine rumen for novel cellulolytic bacterial isolation, which may be used for chemicals and biofuel production from lignocellulose.ResultsA cellulolytic strain, ZH-4, was isolated from Inner Mongolia bovine rumen. This strain was identified as Escherichia coli by morphological, physiological, and biochemical characteristics and 16S rDNA gene sequencing. The extracellular enzyme activity analysis showed that this strain produces extracellular cellulases with an exoglucanase activity of 9.13 IU, an endoglucanase activity of 5.31 IU, and a β-glucosidase activity of 7.27 IU at the pH 6.8. This strain was found to produce 0.36 g/L ethanol and 4.71 mL/g hydrogen from corn straw with cellulose degradation ratio of 14.30% and hemicellulose degradation ratio of 11.39%.ConclusionsIt is the first time that a cellulolytic E. coli was isolated and characterized form the bovine rumen. This provided a great opportunity for researchers to investigate the evolution mechanisms of the microorganisms in the rumen and provided great chance to produce biofuels and chemicals directly from engineered E. coli using consolidated bioprocess.

Genetic modification: a tool for enhancing cellulase secretion

Lignocellulosic (LC) biomass is abundantly available as a low-cost resource on the Earth. LC conversion into energy carriers is the most accepted alternative energy production policy because it is non-competitor to food or feed. LC ethanol has brought cellulases to the forefront which was otherwise lost in oblivion during last decades. LC biomass can be converted into value added products or into sugars by various routes, e.g., thermo-chemical, chemical, or biological methods. Biological route via enzymes is one of the most eco-friendly and feasible method. Both fungi and bacteria are known to degrade biomass. Fungi have been greatly exploited for cellulase production due to their inherent properties of secreting extracellular cellulase. These microorganisms are known as cellulase producers for many decades, however, to bring the enzymatic biomass conversion to an economically feasible status, extensive research efforts have been made in last decade to enhance cellulase titers. Mutations and genetic interventions along with bioprocess development have played a very important role for enhancing cellulase production. This review will present a critical overview of the on-going research towards improving cellulase production for biofuel industry via genetic modification, which will include mutation and genetic engineering employed to exert changes at genetic level in microorganisms.

Diversity Analysis and Bioresource Characterization of Halophilic Bacteria Isolated from a South African Saltpan.

Though intensive research has been channeled towards the biotechnological applications of halophiles and other extremophilic microbes, these studies have not been, by any means, exhaustive. Saline environments still offer a vast diversity of microbes with potential to produce an array of natural products which can only be unlocked by concerted research efforts. In this study, a combination of culture and molecular approaches were employed to characterize halophilic bacteria from saltpan water samples and profile their potential biotechnological applications. Physicochemical analysis of the water samples showed that pH was alkaline (pH 8.8), with a salinity of 12.8%. 16S rRNA gene targeted amplicon analysis produced 10 bacterial phyla constituting of Bacteroidetes (30.57%), Proteobacteria (15.27%), Actinobacteria (9.05%), Planctomycetes (5.52%) and Cyanobacteria (3.18%). Eighteen strains were identified using sequencing analysis of the culturable bacterial strains. From these, the strains SP7 and SP9 were positive for cellulase production while the strains SP4, SP8 and SP22 were positive for lipase production. Quantitative enzyme assays showed moderate extracellular cellulase activity (1.95 U/mL) and lipase activity (3.71 U/mL) by the isolate SP9 and SP4 respectively. Further, of the six isolates, the isolate SP9 exhibited exploitable potential in the bioremediation of hydrocarbon pollution as demonstrated by its fairly high activity against benzanthracene (70% DCPIP reduction). Elucidation of the isolates secondary metabolites showed the production of the molecules 2,3-butanediol, hexahydro-3-(2-methylpropyl)pyrrole[1,2a]pyrazine-1,4-dione, aziridine, dimethylamine and ethyl acetate (GC-MS) and oxypurinol and 5-hydroxydecanoic acid (LC-MS), particularly by the isolate Salinivibrio sp. SP9. Overall, the study showed that the isolated halophiles can produce secondary metabolites with potential industrial and pharmaceutical application.

Screening and optimization of extracellular cellulase and pectinase enzymes produced from post-harvest fungi of apple (Pyrus malus L.) and tomato (Solanum lycopersicum L.)

Screening and optimization of extracellular cellulase and pectinase enzymes produced from post-harvest fungi of apple (Pyrus malus L.) and tomato (Solanum lycopersicum L.)

Endoglucanase and xylanase production by Bacillus sp. AR03 in co-culture

ABSTRACTThe behavior of three isolates retrieved from different cellulolytic consortia, Bacillus sp. AR03, Paenibacillus sp. AR247 and Achromobacter sp. AR476-2, were examined individually and as co-cultures in order to evaluate their ability to produce extracellular cellulases and xylanases. Utilizing a peptone-based medium supplemented with carboxymethyl cellulose (CMC), an increase estimation of 1.30 and 1.50 times was obtained by the co-culture containing the strains AR03 and AR247, with respect to enzyme titles registered by their individual cultivation. On the contrary, the extracellular enzymatic production decreased during the co-cultivation of strain AR03 with the non-cellulolytic Achromobacter sp. AR476-2. The synergistic behavior observed through the combined cultivation of the strains AR03 and AR247 might be a consequence of the consumption by Paenibacillus sp. AR247 of the products of the CMC hydrolysis (i.e., cellobiose and/or cello-oligosaccharides), which were mostly generated by the cellulase producer Bacillus sp. AR03. The effect observed could be driven by the requirement to fulfill the nutritional supply from both strains on the substrate evaluated. These results would contribute to a better description of the degradation of the cellulose fraction of the plant cell walls in nature, expected to an efficient utilization of renewable sources.

Disruption of comA homolog in Ralstonia solanacearum does not impair its twitching motility.

Ralstonia solanacearum is an important phyto-pathogenic bacterium. The bacterium exhibits type IV pili meditated twitching motility that has been implicated in the process of natural transformation in it. A comA gene homolog, alike in several other naturally competent bacteria, has been already reported in this bacterium. However, there are no report of direct link between comA and twitching motility during the natural transformation process in this pathogen. In order to figure out any connection between comA and twitching motility, we created an insertion mutation in comA gene homolog of R. solanacearum F1C1 strain. As anticipated, the insertion mutant (CBRS01 strain) was inefficient for natural transformation. CBRS01 strain was found to be proficient for twitching motility alike the wild-type F1C1. This is interesting since recent findings of Salzer et al. (2016;Environ Microbiol;18:65-74) showed deficiency of twitching motility due to comEC gene (comA homolog) mutation in another naturally competent Gram-negative bacterium Thermus thermophilus. Additionally, we also found CBRS01 strain to be proficient for extracellular cellulase activity and virulence on tomato seedlings. Our findings in this work indicate that an R. solanacearum strain inefficient in undergoing natural transformation can, however, be proficient in exhibiting twitching motility.

The Different Roles of Penicillium oxalicum LaeA in the Production of Extracellular Cellulase and β-xylosidase.

Cellulolytic enzyme hydrolysis of lignocellulose biomass to release fermentable sugars is one of the key steps in biofuel refining. Gene expression of fungal cellulolytic enzymes is tightly controlled at the transcriptional level. Key transcription factors such as activator ClrB/CLR2 and XlnR/XYR1, as well as repressor CreA/CRE1 play crucial roles in this process. The putative protein methyltransferase LaeA/LAE1 has also been reported to regulate the gene expression of the cellulolytic enzyme. The formation and gene expression of the cellulolytic enzyme was compared among Penicillium oxalicum wild type (WT) and seven mutants, including ΔlaeA (deletion of laeA), OEclrB (clrB overexpression), OEclrBΔlaeA (clrB overexpression with deletion of laeA), OExlnR (xlnR overexpression), OExlnRΔlaeA (xlnR overexpression with deletion of laeA), ΔcreA (deletion of creA), and ΔcreAΔlaeA (double deletion of creA and laeA). Results revealed that LaeA extensively affected the expression of glycoside hydrolase genes. The expression of genes that encoded the top 10 glycoside hydrolases assayed in secretome was remarkably downregulated especially in later phases of prolonged batch cultures by the deletion of laeA. Cellulase synthesis of four mutants ΔlaeA, OEclrBΔlaeA, OExlnRΔlaeA, and ΔcreAΔlaeA was repressed remarkably compared with their parent strains WT, OEclrB, OExlnR, and ΔcreA, respectively. The overexpression of clrB or xlnR could not rescue the impairment of cellulolytic enzyme gene expression and cellulase synthesis when LaeA was absent, suggesting that LaeA was necessary for the expression of cellulolytic enzyme gene activated by ClrB or XlnR. In contrast to LaeA positive roles in regulating prominent cellulase and hemicellulase, the extracellular β-xylosidase formation was negatively regulated by LaeA. The extracellular β-xylosidase activities improved over 5-fold in the OExlnRΔlaeA mutant compared with that of WT, and the expression of prominent β-xylosidase gene xyl3A was activated remarkably. The cumulative effect of LaeA and transcription factor XlnR has potential applications in the production of more β-xylosidase.

An Active of Extracellular Cellulose Degrading Enzyme from Termite Bacterial Endosimbiont

Cellulase is an ezyme that specifically cleaves the 1,4-β-glycosidic bond of cellulose to produce thesmall fragments of simple carbohydrate. This work was aimed to characterize the extracellular cellulase fromPaenibacillus spp., which was previously isolated from macro termites, Odontotermes bhagwatii in our laboratory.Two Paenibacillus isolates were used in this experiment, namely Paenibacillus cellulositrophicus SBT1 andPaenibacillus, sp. SBT8. Analysis of the total proteins in the supernatants showed that P. cellulositrophicus SBT1and Paenibacillus sp. SBT8 roughly produced as much as 18.6 mg/l and 24.8 mg/l of extracellular cellulases,respectively. Enzymatic assay showed that SBT1 and SBT8 cellulase exhibited enzymatic acitivity of 0.17 U/mg and 0.12 U/mg, respectively. Temperature dependencies analysis indicated that both cellulases exhibitedmaximum activity at 35oC. At the temperature higher than 55oC, the enzymatic activities of both cellulases wereroughly 20% reduced compared to the maximum activity. SBT1 and SBT8 cellulases were both active at acidicpH. At basic pH (pH 8) the enzymatic activities of both cellulases were reduced roughly 30% compared to thatof acidic pH. Supplementing of Mg2+, Zn2+, and Ca2+ in range of 1-10 mM increased the enzymatic activity ofboth cellulases roughly 33 to 50%.

Relationship Between Extracellular Cellulase, Pectinase and Xylanase Activity of Isolated Aspergillus oryzae Strains Grown on Koji and the Umami-Tasting Amino Acid Content of Soy Sauce

ABSTRACTWe compared the koji-based extracellular carboxymethylcellulases (CM-cellulase), pectinases and xylanases of four Aspergillus oryzae isolates from soy sauce koji, A1, PRB-1 (A2), A3 and A4, with Aspergillus oryzae AS3.951 (A5) via enzyme assays and zymography and determined their correlation to the content of umami-tasting amino acids in high-salt diluted-solid state growth stage leading to soy sauce. In A2 koji, xylanase had the highest activity (28.75 U/g dry weight). Zymogram analysis revealed two different bands of CM-cellulase activity (termed Cel-1 and Cel-2) and one band of pectinase activity (Pec-1) in all koji samples. The intensity of these bands was comparable among all five strains. Interestingly, the same analysis revealed six different xylanase activity bands (termed Xyl-1 to Xyl-6) in all koji samples. After 60 days of cultivation, the free amino acid concentration was highest in soy sauce generated by A4 at 6709.41 mg/100 ml and contained 1690.82 mg/100 ml umami-tasting amino acids (including glutamic acid and aspartic acid), followed by soy sauce generated by A2. Pearson’s coefficient analysis indicated that Xyl-1 and Xyl-2 activities were positively associated with the umami-tasting amino acid content of soy sauce. In conclusion, these data suggested that the xylanases Xyl-1 and Xyl-2 in koji could be important contributors to the umami taste formation of soy sauce.

Biochemical Characterization of Extracellular Cellulase from Tuber maculatum Mycelium Produced Under Submerged Fermentation

Interaction of truffle mycelium with the host plant involves the excretion of extracellular enzymes. The ability of Tuber maculatum mycelium to produce an extracellular cellulase during submerged fermentation was demonstrated for the first time. T. maculatum mycelia were isolated and tested for extracellular cellulase production at variable pH on solid agar medium, and the highest activity was observed at pH7.0. Furthermore, T. maculatum was subjected to submerged fermentation in basal salt medium for cellulase production. Under optimized conditions using sodium carboxymethyl cellulose (0.5% w/v) as carbon source and an initial pH of 7.0, the enzyme production yielded 1.70U/mL of cellulase in the cell-free supernatant after 7days of incubation time. The optimum of the obtained cellulase's activity was at pH5.0 and a temperature of 50°C. The enzyme showed good thermostability at 50°C by retaining 99% of its maximal activity over an incubation time of 100min. The cellulase activity was inhibited by Fe2+ and slightly activated by Mn2+ and Cu2+ at 1mM concentration. The results indicated that truffle mycelium is utilizing cellulosic energy source in the root system, and the optimal conditions are those existing in the acidic Finnish soil.

Identification and characterization of putative xylose and cellobiose transporters in Aspergillus nidulans.

BackgroundThe conversion of lignocellulosic biomass to biofuels (second-generation biofuel production) is an environmentally friendlier alternative to petroleum-based energy sources. Enzymatic deconstruction of lignocellulose, catalyzed by filamentous fungi such as Aspergillus nidulans, releases a mixture of mono- and polysaccharides, including hexose (glucose) and pentose (xylose) sugars, cellodextrins (cellobiose), and xylooligosaccharides (xylobiose). These sugars can subsequently be fermented by yeast cells to ethanol. One of the major drawbacks in this process lies in the inability of yeast, such as Saccharomyces cerevisiae, to successfully internalize sugars other than glucose. The aim of this study was, therefore, to screen the genome of A. nidulans, which encodes a multitude of sugar transporters, for transporters able to internalize non-glucose sugars and characterize them when introduced into S. cerevisiae.ResultsThis work identified two proteins in A. nidulans, CltA and CltB, with roles in cellobiose transport and cellulose signaling, respectively. CltA, when introduced into S. cerevisiae, conferred growth on low and high concentrations of cellobiose. Deletion of cltB resulted in reduced growth and extracellular cellulase activity in A. nidulans in the presence of cellobiose. CltB, when introduced into S. cerevisiae, was not able to confer growth on cellobiose, suggesting that this protein is a sensor rather than a transporter. However, we have shown that the introduction of additional functional copies of CltB increases the growth in the presence of low concentrations of cellobiose, strongly indicating CltB is able to transport cellobiose. Furthermore, a previously identified glucose transporter, HxtB, was also found to be a major xylose transporter in A. nidulans. In S. cerevisiae, HxtB conferred growth on xylose which was accompanied by ethanol production.ConclusionsThis work identified a cellobiose transporter, a xylose transporter, and a putative cellulose transceptor in A. nidulans. This is the first time that a sensor role for a protein in A. nidulans has been proposed. Both transporters are also able to transport glucose, highlighting the preference of A. nidulans for this carbon source. This work provides a basis for future studies which aim at characterizing and/or genetically engineering Aspergillus spp. transporters, which, in addition to glucose, can also internalize other carbon sources, to improve transport and fermentation of non-glucose sugars in S. cerevisiae.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0611-1) contains supplementary material, which is available to authorized users.

Production and Partial Characterization of Cellulase from Pseudomonas Isolates Obtained from Cow Dung and Municipal Solid Wastes

Cellulase producing bacteria were isolated from cow dung and municipal solid wastes using enrichment technique. Cellulase activity was determined on carboxymethyl cellulose (CMC) agar medium supplemented with 1% CMC. Production of clear zones by the bacterial isolates on CMC agar was considered as indicative of extracellular cellulase activity. The greater size of transparent zone diameter was found proportional to the higher amount of cellulase production. Two bacterial isolates producing significant clear zone were identified as Pseudomonas spp based on morphological, cultural and biochemical characteristics. Fermentation was carried out under shake flask conditions for production of cellulase from Pseudomonas isolates in a basal medium containing CMC, KH2PO4, K2HPO4, MgSO4, NH4SO4, CaCl2 and FeSO4 at pH 7.0. The assay of cellulase viz. endoglucanase and exoglucanase in terms of CMCase and FPase, respectively was done by measuring the release of the reducing sugar. Some parameters influencing the production of cellulase by these bacterial isolates were investigated. Optimum level of cellulase was produced after 48 h of fermentation at 37°C with 5% inoculums size under continuous agitation at 120 rpm in the growth medium of pH 7.0. Optimum temperature and pH for the activity of cellulase from these bacterial isolates was 40°C and 7.0, respectively. Cellulase from these isolates was found almost stable at 25-40°C and pH 6.0-8.0 for 1 h. Furthermore, the cellulase activity was stimulated by Ca2+ and K+ but inhibited by Hg2+ and Zn2+, whereas, Mg2+ showed very low effect. Results reported herein indicated that the Pseudomonas isolates can be used as producer of extracellular cellulase.Bangladesh J Microbiol, Volume 30, Number 1-2,June-Dec 2013, pp 11-16

Degradation properties of various macromolecules of cultivable psychrophilic bacteria from the deep-sea water of the South Pacific Gyre.

The deep-sea water of the South Pacific Gyre (SPG, 20°S-45°S) is a cold and ultra-oligotrophic environment that is the source of cold-adapted enzymes. However, the characteristic features of psychrophilic enzymes derived from culturable microbes in the SPG remained largely unknown. In this study, the degradation properties of 174 cultures from the deep water of the SPG were used to determine the diversity of cold-adapted enzymes. Thus, the abilities to degrade polysaccharides, proteins, lipids, and DNA at 4, 16, and 28°C were investigated. Most of the isolates showed one or more extracellular enzyme activities, including amylase, chitinase, cellulase, lipase, lecithinase, caseinase, gelatinase, and DNase at 4, 16, and 28°C. Moreover, nearly 85.6% of the isolates produced cold-adapted enzymes at 4°C. The psychrophilic enzyme-producing isolates distributed primarily in Alteromonas and Pseudoalteromonas genera of the Gammaproteobacteria. Pseudoalteromonas degraded 9 types of macromolecules but not cellulose, Alteromonas secreted 8 enzymes except for cellulase and chitinase. Interestingly, the enzymatic activities of Gammaproteobacteria isolates at 4°C were higher than those observed at 16 or 28°C. In addition, we cloned and expressed a gene encoding an α-amylase (Amy2235) from Luteimonas abyssi XH031(T), and examined the properties of the recombinant protein. These cold-active enzymes may have huge potential for academic research and industrial applications. In addition, the capacity of the isolates to degrade various types of organic matter may indicate their unique ecological roles in the elemental biogeochemical cycling of the deep biosphere.

The Endo-β-1,4-Glucanase of Bacillus amyloliquefaciens Is Required for Optimum Endophytic Colonization of Plants.

The eglS gene in Bacillus amyloliquefaciens encodes an endo-β-1,4-glucanase that belongs to glycosyl hydrolase family 5. In this study, a disruption mutant of gene eglS was constructed to examine its role in bacterial adaptation in plants. The mutant TB2k, eglS gene inactivated bacterial strain, was remarkably impaired in extracellular cellulase activity. When inoculated on Brassica campestris, the TB2k population was reduced by more than 60% compared with the wild-type strain in the root, stem, and leaf tissues. Overexpression of eglS in the wild-type strain increased the bacteria population in the plant tissues. Further studies revealed that the transcription level of eglS was correlated with bacterial population. These data demonstrate that endo-β-1,4-glucanase of B. amyloliquefaciens is required for its optimal endophytic colonization.

Use of Wheat Straw for Extracellular Cellulase Production from Aspergillus niger F8Isolated from Compost

An extracellular cellulase producing celluloytic Aspergillus niger F8 was isolated from compost sample expressing maximum cellulase activity of 6.75 IU/ml on basal salt medium, pH 4.5, temperature 30°C and inoculum size 10% with 1% substrate concentration on 7 days of incubation. 358.70% increase in enzyme activity was observed after optimisation of parameters under submerged fermentation. Further, enhancement in enzyme activity was done under solid-state fermentation using alkali+steam pretreated wheat straw. A. niger F8 exhibited enzyme activity of 71.22 U/g with pretreated (alkali+steam) biomass. It is a cost-effective enzyme production approach of utilising cheap and abundant lignocellulosic agricultural waste as carbon source.

Properties of <i>Bacillus</i> species Cellulase Produced Using Cellulose from Brewers Spent Grain (BSG) as Substrate

The properties of extracellular cellulase obtained from Bacillus species (FIIRO Strain B223) on supplying cellulose from Brewers Spent Grain (BSG) were studied. Generally, a crude cellulase activity between 11,757 Units to 13,930 Units was observed for both sources of carbon (BSG and crystalline cellulose). The optimum pH and temperature of 5.0, and 30°C - 40°C for both sources of carbon was observed. Heavy metals such as copper, zinc, and iron inhibited the activities of B223 cellulase while the cellulase activities on alkaline earth metal (manganese) were moderate. The co-factor behaviour of manganese ion was also established. Local production of cellulase in Nigeria using local raw materials such as Brewers Spent Grain reduces enzyme cost; cost of finished products and increases gross domestic products.

Isolation, Screening and Characterization of Cellulase Producing Bacterial Isolates from Municipal Solid Wastes and Rice Straw Wastes

Cellulolytic bacteria were isolated and screened from municipal solid wastes and rice straw wastes using Carboxy Methyl Cellulose (CMC) agar medium as a selective medium. Production of clear zones by the bacterial isolates on CMC agar medium supplemented with 1% CMC was considered as indicative of extracellular cellulase activity. The size of transparent zone diameter was considered as proportional to the level of cellulase production. These bacterial isolates were identified as Bacillus sp., Pseudomonas sp. and Serratia sp. based on morphological, cultural and biochemical characteristics. A basal medium containing CMC, KH2PO4, K2HPO4, MgSO4, (NH4)2SO4, CaCl2 and FeSO4 at pH 7.0 was used for cellulase production. The assay of cellulase in term of CMCase was performed by measuring the release of reducing sugar. Different physicochemical parameters were optimized for cellulase production at shake flask fermentation. Time course study revealed that maximum level of cellulase was produced by Bacillus and Serratia isolates after 24 h of cultivation and by Pseudomonas isolates after 42 h of cultivation. Optimum level of cellulase was produced by Pseudomonas and Bacillus isolates at 37°C, and that by Serratia isolate was at 35°C. Optimum pH for cellulase production by these bacterial isolates was 7.0. Optimum temperature and pH for the activity of cellulase from these isolates were 40°C and 7.0, respectively. The cellulase from these isolates was found almost stable up to 55°C and at pH 7.0 for 1 h. The crude cellulase could liberate reducing sugar from filter paper through hydrolysis. Results showed that bacterial isolates produced significant level of cellulase with cellulose degrading capability.

Purification and Characterisation of Extracellular Cellulase Main Components from Aspergillus terreus

The filamentous fungus Aspergillus terreus was cultivated in a 2-L stirred tank bioreactor, and the resulting culture filtrate was used for protein purification. From the cultivation broth, seven crude extracts of glucanase and one of β-glucosidase were purified. A total of eight components were identified, including endoglucanases (Endo I, II, III, and IV), cellobiohydrolases (CBH I, II, and III), and β-glucosidase. The eight major components in the fermentation broth of A. terreus, which most likely constitute the essential enzymes for cellulose hydrolysis, were further purified by a series of column chromatography steps. Interestingly, the β-glucosidase from A. terreus displayed an extremely high activity on p-nitrophenyl-β-D-glucopyranoside (pNPG), which suggests that it is a good candidate enzyme for the conversion of cellobiose to glucose. The temperature and pH ranges for optimal activity of the purified enzyme were 46 to 62 °C and 5.0 to 6.0, respectively.

Bioprocessing of Crop Residues using Fibrolytic Enzymes and Flavobacterium bolustinum for Enriching Animal Feed

Flavobacterium bolustinum and its extracellular cellulase were tested for animal feed pretreatment. The fibrolytic enzymes, cellulase and pectinase were applied to various crop residues such as wheat straw, rice straw, corn seeds and sorghum for enriching animal feed. Different parameters like temperature, incubation time and enzyme dose had been optimized for maximum reducing sugar and protein release. The highest amount of reducing sugar obtained was 29.83 mg g -1 dry substrate and soluble protein was 27.34 mg g -1 dry substrate on single cellulase enzyme treatment at 50°C for 6 h. An increase in amount of released reducing sugar (39.5 mg g -1 dry substrate) and protein (33.88 mg g -1 dry substrate) was observed when enzyme cocktail (cellulose and pectinase) was used. Solid state fermentation using F. bolustinum had also been performed for all crop residues. It released higher amount of reducing sugar (41.36 mg g -1 ) and protein (47.21 mg g -1 ) as compared to enzymatic treatment. Different substrates resulted in appreciable weight loss by enzymatic treatment (15-35%) as well as fermentation using F. bolustinum (40%). Liquefaction of lignocellulosic rich crop residues, for better utilization of feed has never been reported earlier.