Potential of in situ SSF laccase produced from Ganoderma lucidum RCK 2011 in biobleaching of paper pulp.

Production of laccase from Ganoderma lucidum RCK 2011 under solid-state fermentation (SSF) conditions was optimized using response surface methodology, resulting in an approximate eightfold increase compared to that in the unoptimized media. Further, the enzyme produced under SSF as whole fermented substrate (in situ SSF laccase) was found to be more stable than the in vitro enzyme (harvested by downstreaming processing of fermented wheat bran). Interestingly, the biobleaching potentials of both in situ and in vitro SSF laccases were comparable, saving 25% chlorine dioxide for achieving similar pulp brightness as obtained in the pulp treated chemically. The reduction in the demand of chlorine dioxide in the pulp bleaching sequence subsequently decreased the levels of adsorbable organic halogen (AOX) in the resulting effluents of the process by 20% compared to the effluents obtained from chemical bleaching sequence. Therefore, direct application of in situ SSF laccase in pulp biobleaching will be environmentally friendly as well as economical and viable for implementation in paper mills.

Bifunctional in vivo role of laccase exploited in multiple biotechnological applications.

Laccases are multicopper enzymes present in plants, fungi, bacteria, and insects, which catalyze oxidation reactions together with four electron reduction of oxygen to water. Plant, bacterial, and insect laccases have a polymerizing role in nature, implicated in biosynthesis of lignin, melanin formation, and cuticle hardening, respectively. On the other hand, fungal laccases carry out both polymerizing (melanin synthesis and fruit body formation) as well as depolymerizing roles (lignin degradation). This bifunctionality of fungal laccases can be attributed to the presence of multiple isoforms within the same as well as different genus and species. Interestingly, by manipulating culture conditions, these isoforms with their different induction patterns and unique biochemical characteristics can be expressed or over-expressed for a targeted biotechnological application. Consequently, laccases can be considered as one of the most important biocatalyst which can be exploited for divergent industrial applications viz. paper pulp bleaching, fiber modification, dye decolorization, bioremediation as well as organic synthesis. The present review spotlights the role of fungal laccases in various antagonistic applications, i.e., polymerizing and depolymerizing, and co-relating this dual role with potential industrial significance.

An efficient and economical method for extraction of DNA amenable to biotechnological manipulations, from diverse soils and sediments.

AIMS: An attempt was made to optimize a new protocol for isolation of pure metagenomic DNA from soil samples. METHODS AND RESULTS: Various chemicals (FeCl3 , MgCl2 , CaCl2 and activated charcoal) were tested for their efficacy in isolation of metagenomic DNA from different soil and compost samples. Among these trials, charcoal and MgCl2 when used in combination yielded highly pure DNA free from humic acids and other contaminants. The DNA extracted with the optimized protocol was readily digested, amplified and cloned. Moreover, compared with a well-established commercial DNA isolation kit (UltraClean™ Soil DNA Isolation Kit), our method for DNA isolation was found to be economical. This demonstrated that the method developed can be applied to a wide variety of soil samples and allows handling of multiple samples at a given time. CONCLUSIONS: The optimized protocol developed has successfully yielded pure metagenomic DNA amenable to biotechnological manipulations. SIGNIFICANCE AND IMPACT OF THE STUDY: A user-friendly and economical protocol for isolation of DNA from soil and compost samples has been developed.

Upgrading the antioxidant potential of cereals by their fungal fermentation under solid-state cultivation conditions.

UNLABELLED: Solid-state fermentation (SSF) at 30°C for 72 h with four generally recognized as safe (GRAS) filamentous fungi (Aspergillus oryzae NCIM 1212, Aspergillus awamori MTCC No. 548, Rhizopus oligosporus NCIM 1215 and Rhizopus oryzae RCK2012) showed high efficiency for the improvement of water-soluble total phenolic content (TPC) and antioxidant properties including ABTS(●+) [2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid)] and DPPH(●) (2,2'-diphenyl-1-picrylhydrazyl) scavenging capacities of four whole grain cereals, namely wheat, brown rice, maize and oat. A maximum 14-fold improvement in TPC (11·61 mg gallic acid equivalent g(-1) grain) was observed in A. oryzae fermented wheat, while extract of R. oryzae fermented wheat (ROFW) showed maximum of 6·6-fold and fivefold enhancement of DPPH(●) scavenging property (8·54 µmol Trolox equivalent g(-1) grain) and ABTS(●+) scavenging activity (19·5 µmol Trolox equivalent g(-1) grain), respectively. The study demonstrates that SSF is an efficient method for the improvement of antioxidant potentials of cereals and R. oryzae RCK2012 fermented wheat can be a powerful source of natural antioxidants. SIGNIFICANCE AND IMPACT OF THE STUDY: Antioxidant-rich food products are getting popularity day by day. In this study, potential of solid-state fermentation (SSF) has been studied for the improvement of antioxidant potential of different cereals by GRAS micro-organisms. The comparative evaluation of the antioxidant potential of various fungal fermented products derived from whole grain cereals, such as wheat, brown rice, oat and maize, has been carried out. Among these, Rhizopus oryzae RCK2012-fermented wheat was observed as a potent source of natural antioxidants. A diet containing fermented cereals would be useful for the prevention of free radical-mediated diseases.

Nutritional and toxicological assessment of white-rot fermented animal feed.

The fungal fermented wheat straws as animal feeds have been evaluated for its toxicological and nutritional status in male rats (Holtzman strain). Digestibility of dry matter and other nutrients as well as fiber fractions were found significantly higher (P < 0.05) in straw fermented with either Ganoderma sp. rckk02 (T3) or Crinipellis sp. RCK-1 (T4) than unfermented straw (T1) or straw fermented with Pycnoporus cinnabarinus (T2). The aflatoxin B1, B2, G1 and G2 were either absent or present in permissive levels in T3 and T4 diets and exhibited normal stress enzyme activity in case of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) enzymes whereas, rats fed on T2 diet showed elevated levels of stress enzymes (ALT, AST and LDH activity), 100% high morbidity and 8.3% mortality. This study suggests that Ganoderma sp. rckk02 and Crinipellis sp. RCK-1 are efficient in improving the nutritive value of poor quality straw and do not posses any threat for their subsequent use as ruminant feed.

One-step purification and characterization of cellulase-free xylanase produced by alkalophilic Bacillus subtilis ash.

The present study describes the one-step purification and characterization of an extracellular cellulase-free xylanase from a newly isolated alkalophilic and moderately thermophilic strain of Bacillus subtilis ASH. Xylanase was purified to homogeneity by 10.5-fold with ~43% recovery using ion-exchange chromatography through CM-Sephadex C-50. The purified enzyme revealed a single band on SDS-PAGE gel with a molecular mass of 23 kDa. It showed an optimum pH at 7.0 and was stable over the pH range 6.0-9.0. The optimum temperature for enzyme activity was 55 °C. The purified xylanase did not lose any activity up to 45 ºC, however, it retained 80% and 51% of its activity after pre-incubation at 55 ºC and 60 ºC, respectively. The enzyme obeyed Michaelis-Menton kinetics towards birch wood xylan with apparent Km 3.33 mg/ml and Vmax 100 IU/ml. The enzyme was strongly inhibited by Hg(2+)and Cu(2+)while enhanced by Co(2+) and Mn(2+). The purified enzyme could be stored at 4 ºC for six weeks without any loss of catalytic activity. The faster and economical purification of the cellulase-free xylanase from B. subtilis ASH by one-step procedure together with its appreciable stability at high temperature and alkaline pH makes it potentially effective for industrial applications.

Organoiodine(III) mediated synthesis of 3,9-diaryl- and 3,9-difuryl-bis-1,2,4-triazolo[4,3-a][4,3-c]pyrimidines as antibacterial agents.

Nine 3,9-diaryl- and 3,9-difuryl-bis-1,2,4-triazolo[4,3-a][4,3-c]pyrimidines (3a-i) have been synthesized by the oxidation of bis-2,4-pyrimidinylhydrazones of various araldehydes and furfural with 2equiv of iodobenzene diacetate (IBD) in dichloromethane and tested in vitro for their antibacterial activity. Three compounds, namely 3,9-di-(4'-fluorophenyl)-bis-1,2,4-triazolo[4,3-a][4,3-c]pyrimidine (3f), 3,9-di-(4'-nitrophenyl)-bis-1,2,4-triazolo[4,3-a][4,3-c]pyrimidine (3g) and 3,9-di-(5'-nitro-2'-furyl)-bis-1,2,4-triazolo[4,3-a][4,3-c]pyrimidine (3i), were associated with substantially higher antibacterial activity than some commercial antibiotics against Gram-positive bacteria namely Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis; two Gram-negative bacteria namely Salmonella typhi and Escherichia coli at MIC (minimum inhibitory concentration) 10microg/ml.

Statistical optimization of alkaline xylanase production from Streptomyces violaceoruber under submerged fermentation using response surface methodology.

Response surface methodology employing central composite design (CCD) was used to optimize fermentation medium for the production of cellulase-free, alkaline xylanase from Streptomyces violaceoruber under submerged fermentation. The design was employed by selecting wheat bran, peptone, beef extract, incubation time and agitation as model factors. A second-order quadratic model and response surface method showed that the optimum conditions for xylanase production (wheat bran 3.5 % (w/v), peptone 0.8 % (w/v), beef extract 0.8 % (w/v), incubation time 36 h and agitation 250 rpm) results in 3.0-fold improvement in alkaline xylanase production (1500.0 IUml(-1)) as compared to initial level (500.0 IUml(-1)) after 36 h of fermentation, whereas its value predicted by the quadratic model was 1347 IUml(-1). Analysis of variance (ANOVA) showed a high coefficient of determination (R(2)) value of 0.9718, ensuring a satisfactory adjustment of the quadratic model with the experimental data.The economical and cellulase-free nature of xylanase would enhance its applicability in pulp and paper industry.

Microorganisms as an alternative source of protein.

Demand for human food and animal feed proteins from nonconventional sources has increased, particularly in developing countries. Microbial protein is one such source. It is desirable because it is amenable to controlled intensive cultivation and is less dependent on variations in climate, weather, and soil. Microbial proteins must be evaluated for nutritive value, safety, and economic considerations before mass production is undertaken.

Improving the yield and quality of DNA isolated from white-rot fungi.

A new simple method used to eliminate polysaccharides that cause problems during DNA isolation was established for 6 different white-rot fungi using 1% hexadecyltrimethylammonium bromide (CTAB) as wash buffer and followed by centrifugation. Variation in the DNA yield and quality was ascertained using precipitating agents, detergents and cell-wall-hydrolyzing chitinase. Considerable amount of exopolysaccharides from fungal biomass was removed with the use of 1% CTAB wash buffer followed by centrifugation. The DNA varied in terms of yield and quality. For the DNA extraction use of 2% SDS in extraction buffer worked best for Pycnoporus cinnabarinus, Cyathus bulleri, Cyathus striatus and Cyathus stercoreus, while 2% CTAB worked best for Phanerochaete chrysosporium and Pleurotus ostreatus. Elimination of phenol and use of absolute ethanol for precipitating DNA resulted in good yield and quality of DNA. This DNA was amenable to restriction endonuclease digestion.

Solid state bioconversion of wheat straw into digestible and nutritive ruminant feed by Ganoderma sp. rckk02.

Solid state fermentation (SSF) of wheat straw with Ganoderma sp. rckk02 was carried out for 15 days for improving its digestibility and nutrients. Fungal growth caused a significant (P<0.05) decrease in acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose, lignin and cellulose content till 15th day. In vitro gas production (IVGP) test revealed that 10th day fermented feed possessed higher metabolizable energy (ME: 4.87 MJ/kg), in vitro organic matter digestibility (OMD: 334 g/kg) and short chain fatty acids (SCFAs: 1.82 mmol/g Dry Matter). The fermented feed was also evaluated in vivo in goats fed with either untreated wheat straw (T1) or fungal treated straw (T2). Dry matter intake (DMI), digestible crude protein (DCP), total digestible nutrients (TDN) and nitrogen (N) intake were found significantly (P<0.05) increased in T2 group. The study shows that fermentation of wheat straw with Ganoderma sp. rckk02 holds potential in improving its nutritive value.

An amperometric polyphenol biosensor based on laccase immobilized on epoxy resin membrane.

A polyphenol biosensor employing epoxy resin membrane bound Ganoderma sp. laccase has been developed. The biosensor showed optimum response within 30 s, when operated at 0.4 V in 0.1 M acetate buffer, pH 6.0 and 35 °C. Detection limit of the biosensor was 3.0 x 10-7 M. Analytical recovery of added guaiacol was 96.66%. Within batch and between batch coefficients of variation were <1.35% and <2.97% respectively. The biosensor was employed for amperometric determination of polyphenols in fruit juices and alcoholic beverages. The enzyme electrode was used 200 times over a period of 10 months, when stored at 4 °C.

Differential and synergistic effects of xylanase and laccase mediator system (LMS) in bleaching of soda and waste pulps.

AIMS: Investigation of waste pulps and soda pulp bleaching with xylanase (X) and laccase mediator system (LMS) alone and in conjunction (one after the other) (XLMS). METHODS AND RESULTS: Soda and different grades of waste pulp fibres [used for making three-layered duplex sheets - top layer (TL), protective layer (PL) and bottom layer (BL)] when pretreated with either xylanase (40.0 IU g(-1)) or LMS (up to 200.0 U g(-1)) alone and in combination (one after the other) (XLMS) exhibited an increase in release of reducing sugars [up to 881.0% soda pulp; up to 736.6% (TL), up to 215.7% (PL) and up to 198.0% (BL) waste pulp], reduction in kappa number [up to 17.6% soda pulp; up to 14.0% (TL), up to 25.3% (PL) and up to 10.9% (BL), waste pulp], improvement in brightness [up to 20.4% soda pulp; up to 23.6% (TL), up to 8.6% (PL) and up to 5.0% (BL), waste pulp] when compared with the respective controls. The usage of XLMS along with 15% reduced level of hypochlorite at CEHHXLMS/EHHXLMS bleaching stage reduced kappa number [5.5% soda pulp; 11.4% (TL), 7.9% (PL), waste pulp] and improved brightness [1.0% soda pulp; 0.9% (TL), 1.4% (PL) waste pulp] when compared with the controls. Scanning electron microscopic studies revealed development of cracks, flakes, pores and peeling off the fibres in the enzyme-treated pulp samples. These modifications of the fibre surface during enzymatic bleaching in turn indicated the removal of lignin and derived compounds from the fibre cell wall. CONCLUSIONS: The work describes synergistic action of xylanase with LMS for bleaching of waste and nonwood pulps for eco-friendly production of paper and thus reveals a new unexploited arena for enzyme-based pulp bleaching. SIGNIFICANCE AND IMPACT OF THE STUDY: The drastic improvement in pulp properties obtained after xylanase and LMS treatment would improve the competitiveness of enzyme-based, environmentally benign processes over chemicals both economically and environmentally.

Strain improvement of thermotolerant Saccharomyces cerevisiae VS strain for better utilization of lignocellulosic substrates.

AIM: Pentose-utilizing yeast development by protoplast fusion and sequential mutations and ethanol fermentation using lignocellulosic substrate. METHODS AND RESULTS: Protoplasts of thermotolerant Saccharomyces cerevisiae and mesophilic, xylose-utilizing Candida shehatae were fused by electrofusion. The fusants were selected based on their growth at 42 degrees C and ability to utilize xylose. The selected best fusant was mutated sequentially and 3 mutant fusants obtained were tested for their stability. The mutant fusant CP11 was found to be stable and used for lignocellulosic fermentation. The Prosopis juliflora wood material was hydrolysed with 1% sulphuric acid initially for 18 h at room temperature and then for 20 min at 121 degrees C. The acid hydrolysate was separated and used for detoxification by ethyl acetate and overliming. The hard cellulosic fraction was hydrolysed with Aspergillus niger crude cellulase enzyme for 18 h at 50 degrees C. The substrate (15% w/v) yielded 84 g l(-1) sugars, representing 80% (w/w) hydrolysis of carbohydrate content present in the lignocellulosic material. The acid and enzyme hydrolysates were then equally mixed and used for fermentation with the developed fusant yeast (CP11). The fusant yeast gave an ethanol yield of 0.459 +/- 0.012 g g(-1), productivity of 0.67 +/- 0.015 g l(-1) h(-1) and fermentation efficiency of 90%. CONCLUSIONS: Protoplast fusion followed by sequential mutations method gave a stable and good performing fusant with maximum utilization of reducing sugars in the media. SIGNIFICANCE AND IMPACT OF THE STUDY: This new method could be applied to develop fusants for better biotechnological applications.

Isolation of three xylanase-producing strains of actinomycetes and their identification using molecular methods.

Eighty-eight actinomycetes were isolated from 20 samples collected from different locations in and around Delhi, India. Among these, 69 isolates were found positive for xylanase production. Of 69 isolates, 3 (SN32, SN77, and SN83) produced >125 IU/ml xylanase. Modern genetic tools were used for revealing the identities of these potent xylanase producers. The selected isolates were categorized under the genus Streptomyces based on their cultural and morphologic characteristics. Genetic diversity among these species of Streptomyces was established based on restriction length fragment polymorphism and random amplified polymorphic DNA analysis. The closest phylogenetic neighbours according to the 16S rRNA gene-sequence data for the three isolates SN32, SN77, and SN83 were Streptomyces cyaneus, S. tendae, and S. caelestis, respectively.

Use of xylan-rich cost effective agro-residues in the production of xylanase by Streptomyces cyaneus SN32.

AIM: The present study aimed at optimization of cultural and nutritional parameters for enhanced production of xylanase from Streptomyces cyaneus SN32. METHODS AND RESULTS: The xylanase production by S. cyaneus SN32 on most of the agro-residues tested in this study was more, as compared with the xylanase yield in the medium supplemented with commercial xylan. The presence of wheat bran as carbon source in the medium induced the highest production of xylanase followed by corn cob. Utilization of maize stalk, gram husk and black gram husk for microbial xylanase production has been reported first time in the present study. Among all the organic and inorganic sources of nitrogen tested in the study, peptone was found to be the best in stimulating xylanase production by S. cyaneus SN32. CONCLUSION: The production of xylanase from this thermoalkalophilic actinomycete has been enhanced 1.44-fold. To the best of our knowledge, the magnitude of enzyme yield i.e. 720 IU ml(-1) by S. cyaneus SN32 has not been reported for any other actinomycete so far. SIGNIFICANCE AND IMPACT OF STUDY: Present studies revealed that thermoalkalophilic S. cyaneus SN32, because of its simple nutritional requirements and its ability to exhibit considerably good enzyme yield, is a potent xylanase producer for its economical application in various industries.