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.

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.

White-rot fungal conversion of wheat straw to energy rich cattle feed.

In order to improve the digestibility and nutrient availability in rumen, wheat straw was subjected to solid state fermentation (SSF) with white-rot fungi (i.e. Pleurotus ostreatus and Trametes versicolor) and the fermented biomass (called myco-straw) was evaluated for biochemical, enzymatic and nutritional parameters. The fungal treatment after 30 days led to significant decrease (P < 0.05) in cell wall constituents viz, acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose, lignin and cellulose to the extent of 35.00, 38.88, 45.00, 37.48 and 37.86%, respectively in P. ostreatus fermented straw, while 30.04, 33.85, 39.90, 31.29 and 34.00%, respectively in T. versicolor fermented straw. However, maximum efficiency of fermentation in terms of low carbohydrate consumption per unit of lignin degradation, favoring cattle feed production was observed for P. ostreatus on the 10th day (17.12%) as compared with T. versicolor on the 30th day (16.91%). The myco-straw was found to contain significantly high (P < 0.05) crude protein (CP; 4.77% T. versicolor, 5.08% P. ostreatus) as compared to control straw (3.37%). Metabolizable energy (ME, MJ/kg DM), percent organic matter digestibility (OMD) and short chain fatty acids (SCFAs; mmol) production also increased considerably from control straw (4.40, 29.91 and 0.292) to a maximum up to P. ostreatus fermented straw (4.92, 33.39 and 0.376 on 20th day) and T. versicolor fermented straw (4.66, 31.74 and 0.334 on 10th day), respectively. Moreover, the myco-straw had lower organic carbon and was rich in nitrogen with lower C/N ratio as compared to control wheat straw. Results suggest that the fungal fermentation of wheat straw effectively improved CP content, OM digestibility, SCFAs production, ME value and simultaneously lowered the C/N ratio, thus showing potential for bioconversion of lignin rich wheat straw into high energy cattle feed.

Reduced toxicity of malachite green decolorized by laccase produced from Ganoderma sp. rckk-02 under solid-state fermentation.

Statistical designs were applied for optimizing laccase production from a white-rot fungus, Ganoderma sp. rckk-02 under solid-state fermentation (SSF). Compared to unoptimized conditions [2,154 U/gds (Unit per gram of dry substrate)], the optimization process resulted in a 17.3-fold increase in laccase production (37,423 U/gds). The laccase produced was evaluated for its potential to decolorize a recalcitrant synthetic dye, malachite green. Laccase at dosage of 30 U/ml in presence of 1 mM of 1-hydroxybenzotriazole (HBT) almost completely decolorized 100 and 200 mg/l of malachite green in 16 and 20 h, respectively, at 30 °C, pH 5.5 and 150 rpm. While, higher dyes concentrations of 300, 400 and 500 mg/l were decolorized to 72, 62 and 55 % in 24, 28 and 32 h, respectively, under similar conditions. Furthermore, it was observed that the decolorized malachite green was less toxic towards the growth of five white-rot fungi tested viz. Crinipellis sp. RCK-1, Ganoderma sp. rckk-02, Coriolopsis Caperata RCK 2011, Phanerochaete chrysosporium K3 and Pycnoporous cinnabarinus PB. The present study demonstrates the potential of Ganoderma sp. rckk-02 to produce high titres of laccase under SSF, which can be exploited in conjunction with redox mediator for the decolorization of high concentrations of malachite green from water bodies.

Bioprocessing of wheat straw into nutritionally rich and digested cattle feed.

Wheat straw was fermented by Crinipellis sp. RCK-1, a lignin degrading fungus, under solid state fermentation conditions. The fungus degraded 18.38% lignin at the expense of 10.37% cellulose within 9 days. However, when wheat straw fermented for different duration was evaluated in vitro, the 5 day fungal fermented wheat straw called here "Biotech Feed" was found to possess 36.74% organic matter digestibility (OMD) and 5.38 (MJ/Kg Dry matter) metabolizable energy (ME). The Biotech Feed was also observed to be significantly enriched with essential amino acids and fungal protein by fungal fermentation, eventually increasing its nutritional value. The Biotech Feed upon in vitro analysis showed potential to replace 50% grain from concentrate mixture. Further, the calves fed on Biotech Feed based diets exhibited significantly higher (p<0.05) dry matter intake (DMI: 3.74 Kg/d), dry matter digestibility (DMD: 57.82%), total digestible nutrients (TDN: 54.76%) and comparatively gained 50 g more daily body weight.

Degradation and selective ligninolysis of wheat straw and banana stem for an efficient bioethanol production using fungal and chemical pretreatment.

Lignocelluloses from agricultural, industrial, and forest residues constitute a majority of the total biomass present in the world. Environmental concerns of disposal, costly pretreatment options prior to disposal, and increased need to save valuable resources have led to the development of value-added alternate technologies such as bioethanol production from lignocellulosic wastes. In the present study, biologically pretreated (with the fungus, Pleurotus ostreatus HP-1) and chemically pretreated (with mild acid or dilute alkali) wheat straw (WS) and banana stem (BS) were subsequently subjected to enzymatic saccharification (with mixture of 6.0 U/g of filter paper cellulase and 17 U/g of ß-glucosidase) and were evaluated for bioethanol production using Saccharomyces cerevisiae NCIM 3570. Biological and chemical pretreatments removed up to 4.0-49.2 % lignin from the WS and BS which was comparatively higher than that for cellulose (0.3-12.4 %) and for hemicellulose (0.7-21.8 %) removal with an average 5.6-49.5 % dry matter loss. Enzymatic hydrolysis yielded 64-306.6 mg/g (1.5-15 g/L) reducing sugars from which 0.15-0.54 g/g ethanol was produced from Saccharomyces cerevisiae NCIM 3570.

Middle-redox potential laccase from Ganoderma sp.: its application in improvement of feed for monogastric animals.

The variables influencing laccase production by white-rot fungus Ganoderma sp. rckk-02 were optimized employing response surface methodology. Malt extract (6.0% w/v), lignin (0.5% w/v) and pH (5.5) were found to be the most significant factors for enhanced laccase production by 7 fold (226.0 U/ml) as compared to unoptimized growth conditions (32.0 U/ml). The N-terminal sequence of laccase revealed its distinct amino acid profile (S- I- R- N- S- G), which suggested it as a novel enzyme. The Far-UV CD spectrum of the laccase showed single broad negative trough at around 213 nm, a typical signature of all ß proteins. The laccase was found to fall in the range of middle redox potential laccases. Purified laccase at dosage of 2.5 Ug(-1) body weight when supplemented with pelleted diet of rats, a significant improvement (p < 0.05) in nutrients digestibility without causing any elevation of blood stress enzymes was observed.

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.