Screening of agro-industrial wastes to produce ligninolytic enzymes by Phanerochaete chrysosporium

Optimization and purification of laccase activity from Mammaliicoccus sciuri isolated from the soils of Similipal, Odisha, India: a kinetics study of crystal violet dye decolorization

Four laccase-producing bacteria were found in soil samples from the Similipal Biosphere Reserve in Odisha, according to the current study. The isolates (SLCB1 to SLCB4) were evaluated for their laccase-producing ability in LB broth supplemented with guaiacol. The ABTS assay was performed to assess the laccase activity. The bacterium Mammaliicoccus sciuri shows the highest laccase activity i.e., 0.5125 U/L at the optimized conditions of pH 5.5, temperature 32.5 °C, ABTS concentration of 0.75 μl with an incubation time of 9 d. Laccase activity of M. sciuri grown in Sawdust was significantly increased in comparison to that in other agro wastes. The partially purified laccase enzyme after ammonium sulfate precipitation and dialysis showed a molecular weight of ∼58.5 kDa as determined by SDS-PAGE. A decolorization efficiency of 66.67% was recorded for the dye crystal violet after 1 h treatment with dialyzed laccase enzyme compared with phenol red, brilliant blue, and methylene blue.

Improvement of the Nutraceutical Profile of Brewer's Spent Grain after Treatment with Trametes versicolor

Brewer's spent grain (BSG) is an important secondary raw material that provides a readily available natural source of nutraceuticals. It finds its largest application as animal feed and part of the human diet, while the future perspective predicts an application in the production of value-added products. In order to investigate a sustainable BSG treatment method, two BSG samples (BSG1 and BSG2) were evaluated as substrates for the production of hydrolytic (xylanase, β-glucosidase and cellulase) and lignolytic enzymes (laccase, manganese peroxidase and lignin peroxidase) by solid-state fermentation (SSF) with Trametes versicolor while improving BSG nutritional value. The biological treatment was successful for the production of all hydrolytic enzymes and laccase and manganese peroxidase, while it was unsuccessful for the production of lignin peroxidase. Because the two BSGs were chemically different, the Trametes versicolor enzymes were synthesized at different fermentation times and had different activities. Consequently, the chemical composition of the two BSG samples at the end of fermentation was also different. The biological treatment had a positive effect on the increase in protein content, ash content, polyphenolic compounds, and sugars in BSG1. In BSG2, there was a decrease in the content of reducing sugars. Cellulose, hemicellulose, and lignin were degraded in BSG1, whereas only cellulose was degraded in BSG2, and the content of hemicellulose and lignin increased. The fat content decreased in both samples. The safety-related correctness analysis showed that the biologically treated sample did not contain any harmful components and was therefore safe for use in nutritionally enriched animal feed.

Agro-industrial wastes revalorization as feedstock: production of lignin-modifying enzymes extracts by solid-state fermentation using white rot fungi

The purpose of the study was to evaluate the production of lignin-modifying enzyme extracts and delignified biomass from agro-industrial wastes using white rot fungi (Inonotus sp. Sp2, Stereum hirsutum Ru-104, Bjerkandera sp. BOS55, Pleurotus eryngii IJFM 169 and Phanerochaete chrysosporium BKM-F-1767). These were screened based on their adaptability and colonization ability on different substrates, as well as by the Laccase, Manganese peroxidase, and Lignin peroxidase enzymatic production. Native strains (Inonotus sp. Sp2 and S. hirsutum Ru-104) showed the highest growth kinetics under the solid-substrate fermentation conditions and the growth rate parameters of the kinetic logistic model for the different substrates were between 0.39-0.81 (1/d) and 0.42-0.83 (1/d), respectively; the determination coefficients were ≥0.99. Inonotus sp. Sp2 was subsequently cultured in static flasks to produce crude enzyme extracts, obtaining manganese peroxidase activity levels of 18.5 and 31.3 (U/g) when growing in corn cob husk and spent tea leaves, respectively. Besides, it was to establish that the best conditions for lignin-modifying enzymes production using corn cob husk are 70% of initial moisture and 2.12 mm of particle size; reaching after 30 incubation days a manganese peroxidase activity of 21 ± 6 (U/g) under these conditions; enzyme that showed a suitable thermostability.

Potential of agro-industrial produced laccase to remove ciprofloxacin

Ciprofloxacin (CIP), a widely used antibiotic, is frequently detected in the environment due to insufficient wastewater and water treatment. Hence, novel, green and cost-effective technologies are required to enhance the removal of these pollutants. The potency of crude enzymes, especially laccases, produced by white-rot fungi was tested to assess their effectiveness to degrade CIP from water. Crude laccase alone could not oxidize CIP. The addition of syringaldehyde, a redox mediator, resulted in a decrease in antibiotic concentration up to 68.09±0.12% in 24 h, which was the highest removal efficiency achieved with 0.15 mg/mL syringaldehyde and 2 mg/mL of crude laccase (0.1 U/ml). Crude laccase oxidation of CIP was inhibited after 6 h of treatment. To compare, a pure enzyme with the same activity as the crude one removed 86% of CIP in 24 h. No inhibitory effect during the treatment was observed. The estimation of antimicrobial efficiency revealed that after 6 h of treatment, the toxicity towards Escherichia coli decreased by 30%. The wastewater treatment by the crude laccase-mediated system was estimated to significantly reduce the cost of enzymatic treatment.

Strategies to Increase the Value of Pomaces with Fermentation

The generation of pomaces from juice and olive oil industries is a major environmental issue. This review aims to provide an overview of the strategies to increase the value of pomaces by fermentation/biotransformation and explore the different aspects reported in scientific studies. Fermentation is an interesting solution to improve the value of pomaces (especially from grape, apple, and olive) and produce high-added value compounds. In terms of animal production, a shift in the fermentation process during silage production seems to happen (favoring ethanol production rather than lactic acid), but it can be controlled with starter cultures. The subsequent use of silage with pomace in animal production slightly reduces growth performance but improves animal health status. One of the potential applications in the industrial context is the production of enzymes (current challenges involve purification and scaling up the process) and organic acids. Other emerging applications are the production of odor-active compounds to improve the aroma of foods as well as the release of bound polyphenols and the synthesis of bioactive compounds for functional food production.

Process performance improvement for the simultaneous production of ligninolytic enzymes in solid culture using agricultural wastes through the Taguchi method

Despite a large amount of published research on the production of ligninolytic enzymes, the latter are not yet being applied to combat environmental pollution. No cost-effective process has been developed to date. This study describes an improvement of the solid-state fermentation procedure for the production of ligninolytic enzymes via Phanerochaete chrysosporium ATX by applying the Taguchi method and using an agro-industrial waste as substrate. The production of lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase (Lac) were simultaneously increased within a packed-bed column. The factors and levels studied were humidity (A: 60, 70, 80%), inoculum concentration (B: 7.5, 10.0, 12.5 × 10⁵ spores/mL), packed density (C: 0.14, 0.16, 0.18 g/mL), and time (D: 6, 8, 10 days). The results showed that humidity was the factor with a higher effect upon LiP and Lac's production, while time was for MnP. Humidity exerted the greatest influence on the global desirability of the process. Improved conditions (A, 60%; B, 1.0 × 10⁶ spores/mL; C, 0.17 g/mL; D, 8 days) were further validated: the results revealed an overall desirability increase of 237% over the unoptimized process. Process performance was likewise maintained at a higher scale (1:10). The results contribute to establishing a cost-effective bioprocess to produce ligninolytic enzymes by reducing the cost associated with raw materials and purification steps.

Feasibility of the use of different types of enzymatically treated cellulosic fibres for polylactic acid (PLA) recycling

In the present study, the potential use of cellulosic microfibers (CMFs) extracted from hemp fiber (HF) and pulp and paper solid waste (mixed sludge (MS), deinked sludge (DS)) as a reinforcing agent in novel bio composite materials produced from recycled Polylactic acid (rPLA) was investigated. CMFs were extracted and treated using physicochemical method followed by enzymatic treatment with laccase and cellulase. The effects of CMFs concentrations (1.5, 3 and 6% w/w) and fiber size (75 μm-1.7 mm) on the mechanical properties (impact and tensile) and biodegradability of the biocomposite samples were investigated. A modified interfacial adhesion between rPLA matrix and the three fibers used, was clearly observed through mechanical tests due to alkali and enzymatic treatments. The use of different types of enzymatically treated cellulosic fibers for polylactic acid (PLA) recycling was assessed by Scaning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The combined physicochemical and enzymatic treatments led to a considerable size reduction of the cellulosic fibers (HF, MS and DS) resulting in the enhanced interfacial adhesion between rPLA matrix and fibers. The biocomposite obtained with rPLA with HF gave the most favorable values for Young's modulus (324.53 ± 3.10 MPa, p-value 0.03), impact strength (27.61 ± 2.94 kJ/m², p-value 0.01) and biodegradation rate (1.97%).

Valorization of agro-industrial wastes by producing 2-phenylethanol via solid-state fermentation: Influence of substrate selection on the process

2-phenylethanol (2-PE) is a value-added compound widely used in industry due to its rose-like odor and antibacterial properties that can be bioproduced using wastes as raw materials. This study presents the valorization of nine agro-industrial wastes as potential substrates for 2-PE production using an isolated 2-PE producer Pichia kudriavzevii, and the solid-state fermentation (SSF) technology as an alternative approach. The assessed substrates comprised wastes of varied traits such that each of them provided different characteristics to the fermentation. Thus, by using a principal component analysis (PCA), it was possible to identify the most significant characteristics associated with the substrates affecting the 2-PE production. Results show that L-phenylalanine biotransformation was more efficient than de novo synthesis for producing 2-PE. Besides, from the evaluated set, the maximum 2-PE production was achieved with red apple pomace, reaching 1.7 and 25.2 mg_2PE per gram of used waste through de novo and L-phenylalanine biotransformation, respectively. In that scenario, volumetric productivity and precursor yield were 39.6 mg_2PE L^-1h^-1 and 0.69 g_2PE per gram of L-phenylalanine added_, respectively. From the PCA, it was identified that the reducing sugars content of the substrate, the air-filled porosity of the bed and the L-phenylalanine availability were the most critical parameters (associated with the substrates) influencing the microbial activity and 2-PE production. These results suggest that the desirable traits a solid media needs for promoting 2-PE production via SSF could be reached by using a combination of wastes in a synergistic approach.

Apple orchard waste recycling and valorization of valuable product-A review

Huge quantities of apple orchard waste (AOW) generated could be regarded as a promising alternative energy source for fuel and material production. Conventional and traditional processes for disposal of these wastes are neither economical nor environment friendly. Hence, sustainable technologies are required to be developed to solve this long-term existence and continuous growing problem. In light of these issues, this review pays attention towards sustainable and renewable systems, various value-added products from an economic and environmental perspective. Refined bio-product derived from AOW contributes to resource and energy demand comprising of biomethane, bioethanol, biofuels, bio-fertilizers, biochar, and biochemicals, such as organic acid, and enzymes. However, the market implementation of biological recovery requires reliable process technology integrated with an eco-friendly and economic production chain, classified management.

Effect of ascorbic acid, oxygen and storage duration on patulin in cloudy apple juice produced on a semi-industrial scale

Patulin (PAT), a mycotoxin mainly produced by Penicillium expansum, is of high concern with regard to human food safety. This study examined the stability of PAT in artificially contaminated cloudy apple juice (CAJ) produced on a semi-industrial scale using an innovative technology allowing degassing and pressing under low-oxygen conditions (VaculIQ 1000). The effects of adding ascorbic acid (AA), degassing during production and storing in the dark at 20 °C on the PAT concentration were studied, as well as possible degradation and reaction products formed. The highest PAT degradation (50%) was observed for flash-pasteurised juice with AA added, produced under low-oxygen conditions and degassed and stored for 14 days at 20 °C in the dark in aluminium laminate aseptic bags. Juices produced showed no significant differences in the quality parameters measured and did not show significant formation of reaction products. Further research needs to be focused on the fate of PAT in CAJ produced on an industrial level with and without addition of AA.

Laccase production by Trametes versicolor in solid-state fermentation using tea residues as substrate and its application in dye decolorization

An efficient valorization of tea residues into value-added product was developed by Trametes versicolor in solid-state fermentation (SSF). The laccase production of 25.7 U/g dry substrate was obtained by optimizing culture medium and condition, resulting in a 4.0-fold increase compared to that of 6.4 U/g dry substrate under unoptimized condition. During the 7-day cultivation under SSF, 44.7%, 12.2% and 9.8% degradation occurred for lignin, hemicellulose and cellulose in tea residues, respectively. Laccase production reached 31.2 U/g dry substrate by the scaling-up culture in shallow tray system. The dry fermented tea residues were directly used as crude enzyme in the decolorization of malachite green. It possessed a decolorization rate of more than 95% within 120 min and remained 81.3% of decolorization capacity after 6 cycles. The present study provided a useful strategy for low-cost laccase production by SSF and it exhibited great potential for the application in dye decolorization.

Bioprocessing strategies to increase the protein fraction of Rhizopus oryzae biomass using fish industry sidestreams

The sidestreams produced during fish processing end in a separation tank where the resulting fractions follow biogas production or wastewater treatment. These streams can alternatively be used for production of protein-rich fungal biomass for e.g. fish feed applications, a product in increasing demand. These streams and upper streams originated during fish processing were used in this study for production of biomass using the edible filamentous fungus Rhizopus oryzae. The COD of the streams varied between 11 and 54 kg/m3 and, after fungal conversion of organic matter into protein-rich biomass and separation, a reduction of 34-69% was achieved. The stream origin had an effect on the final production and composition of the fungal biomass: 480 kg of biomass containing 33% protein per ton of COD were produced after cultivation in the separation tank streams, while 220 kg of biomass containing 62% protein per ton of COD were produced in upper sidestreams with lower amounts of suspended solids. Changing the initial pH (6.1-6.5) to 5.0 had a negative influence on the amount of biomass produced while medium supplementation had no influence. Thus, fish processing sidestreams can be diverted from biogas production and wastewater treatment to the production of protein-rich biomass for feed applications.

Comprehensive studies on optimization of ligno-hemicellulolytic enzymes by indigenous white rot hymenomycetes under solid-state cultivation using agro-industrial wastes

The disposal of oil palm biomass is a huge challenge in Malaysian oil palm plantations. The aim of this study was to develop efficient solid-state cultivated (SSC) ligno-hemicellulolytic bio-degrader formulations of indigenous white-rot hymenomycetes (Trametes lactinea FBW and Pycnoporus sanguineus FBR) utilizing oil palm empty fruit bunches (EFB), rubber wood sawdust (SD) and vermiculite (V) either alone or in combination as substrates. Based on significant laccase (849.40 U mg^-1 protein), xylanase (42.26 U g^-1 protein) and amylase (157.49 U g^-1 protein) production, SD+V (T5) and V (T3) were the optimum substrates for SSC of T. lactinea FBW. Whereas, utilizing EFB (T1) substrate for SSC of P. sanguineus FBR enhanced the production of MnP (42.51 U mg^-1 protein), LiP (103.20 U mg^-1 protein) and CMCase (34.39 U g^-1 protein), enzymes. Apparently, this is the first study reporting on the protein profiles by T. lactinea FBW, producing two isoforms of un-purified laccase (~55 and 70 kDa) and MnP (~40 and 60 kDa) and a CMCase band (~60 kDa) during SSC on SD+V (T5) substrate. Interestingly, this is also the first report to document a single isoform of un-purified laccase (~50 kDa), MnP (~45 kDa), CMCase (~60 kDa) and xylanase (~55 kDa) by P. sanguineus FBR during SSC on empty fruit bunches substrate. The computed Principal Component Analysis (PCA) Biplot analysis elucidated the relationship between the solid substrate compositions, the hymenomycete strain, ligno-hemicellulolytic enzyme profiles, and cultivation time. Therefore, it is suggested to use PCA as a tool for multivariate analysis method for comprehensive selection and optimization of ligno-hemicellulolytic enzyme cocktails by the indigenous white rot hymenomycetes. These non-toxic (acute oral toxicity) formulations are safe to be used in field applications to efficiently degrade oil palm trunks and root mass that had been felled, chipped or pulverized under zero burning waste management program. This study could also serve as an alternative method for efficient utilization of agro-industrial waste as substrates for the development of cost-effective bio-degraders formulations for agro-waste management.

Biocomposite Fabrication from Enzymatically Treated Nanocellulosic Fibers and Recycled Polylactic Acid

Recycled polylactic acid (PLAr) was reinforced with treated nanocellulosic hemp fibers for biocomposite fabrication. Cellulosic fibers were extracted from hemp fibers chemically and treated enzymatically. Treated nanocellulosic fibers (NCF) were analyzed by Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Biocomposite fabrication was done with PLAr and three concentrations of treated NCF (0.1%, 0.25%, and 1% (v/v)) and then studied for thermal stability and mechanical properties. Increased thermal stability was observed with increasing NCF concentrations. The highest value for Young’s modulus was for PLAr + 0.25% (v/v) NCF (250.28 ± 5.47 MPa), which was significantly increased compared to PLAr (p = 0.022). There was a significant decrease in the tensile stress at break point for PLAr + 0.25% (v/v) NCF and PLAr + 1% (v/v) NCF as compared to control (p = 0.006 and 0.002, respectively). No significant difference was observed between treatments for tensile stress at yield.

Decolorization of remazol brilliant blue R with laccase from Lentinus crinitus grown in agro-industrial by-products

Lentinus crinitus is a white-rot fungus that produces laccase, an enzyme used for dye decolorization. Enzyme production depends on cultivation conditions, mainly agro-industrial by-products. We aimed to produce laccase from Lentinus crinitus with agro-industrial by-products for dye decolorization. Culture medium had coffee husk (CH) or citric pulp pellet (CP) and different nitrogen sources (urea, yeast extract, ammonium sulfate and sodium nitrate) at concentrations of 0, 0.7, 1.4, 2.8, 5.6 and 11.2 g/L. Enzymatic extract was used in the decolorization of remazol brilliant blue R. CH medium promoted greater laccase production than CP in all evaluated conditions. Urea provided the greatest laccase production for CH (37280 U/L) as well as for CP (34107 U/L). In CH medium, laccase activity was suppressed when carbon-to-nitrogen ratio changed from 4.5 to 1.56, but the other nitrogen concentrations did not affect laccase activity. For CP medium, reduction in carbon-to-nitrogen ratio from 6 to 1.76 increased laccase activity in 17%. The peak of laccase activity in CH medium occurred on the 11th day (41246 U/L) and in CP medium on the 12th day (32660 U/L). The maximum decolorization within 24 h was observed with CP enzymatic extract (74%) and with CH extract (76%).

Supplement comprising of laccase and citric acid as an alternative for antibiotics: In vitro triggers of melanin production

An indiscriminate use of antibiotics in humans and animals has led to the widespread selection of antibiotic-resistance, thus constricting the use of antibiotics. A possible solution to counter this problem could be to develop alternatives that can boost the host immunity, thus reducing the quantity and frequency of antibiotic use. In this work, for the first time, citric acid and laccase were used as extracellular inducers of melanin production in yeast cells and human cell lines. It is proposed that the formulation of laccase and citric acid together could further promote melatonin-stimulated, melanocyte-derived melanin production. Melanization as a probe of immunity described in this study, is an easy and a rapid test compared to other immunity tests and it allows performing statistical analyses. The results showed the synergistic effect of citric acid and laccase on melanin production by yeast cells, with significant statistical differences compared to all other tested conditions (p: 0.0005-0.005). Laccase and citric acid together boosted melanin production after 8 days of incubation. An increase in melanin production by two human colon cells lines (Cacao-2/15 and HT-29) was observed on supplementation with both laccase and citric acid in the cell growth medium. Produced melanin showed antimicrobial properties similar to antibiotics. Therefore, a formulation with citric acid and laccase may prove to be an excellent alternative to reduce the antibiotic use in human and animal subjects.

Production of a halotolerant biofilm from green coffee beans immobilized on loofah fiber (Luffa cylindrica) and its effect on phenanthrene degradation in seawater

A biofilm developed from low quality green coffee beans was tested for its capacity to degrade the polynuclear aromatic hydrocarbon (PAH), phenanthrene (Phe), in seawater. Microorganisms were immobilized on two types of Luffa cylindrica (with three and four placental cavities), and the effects of moisture content (20, 30 and 40% of water holding capacity) and particle size (<0.42 mm, 0.42-0.86 mm and 0.86-2.0 mm) of green coffee beans on microbial activity were considered. Biofilm growth determined by respirometry showed a highest microbial activity at a moisture content of 40% and particle size of 0.42-0.86 mm. The loofah fiber with three placental cavities showed the highest adherence of microorganisms. The kinetics of microbial growth in both seawater and distilled water and the scanning electron microscopies indicated that the microorganisms associated with green coffee beans are halotolerant. In fact, I-GCB-SW-G biofilm degraded 67.56% of Phe (50 mg L^-1) in seawater, at a significantly higher rate than in distilled water (I-GCB-DW-W).

Prickly palm cactus husk as a raw material for production of ligninolytic enzymes by Aspergillus niger

Prickly palm cactus husk was used as a solid-state fermentation support-substrate for production of the ligninolytic enzymes laccase, peroxide manganese, and lignin peroxidase by Aspergillus niger. Effects of water activity, temperature, and fermentation time on enzymatic production were evaluated using a central composite rotatable design. Response surface methodology revealed that maximum enzyme production was achieved at 73.38 h of fermentation, a water activity of 0.87 Aw, at 28.74°C for laccase, at 65.33 h, 0.89 Aw, and 28.96°C for lignin peroxidase, and at 70.44 h, 0.91 Aw, and 28.84°C for manganese peroxidase. Optimized enzyme production was 9,023.67 UI/L for laccase, 2,234.75 UI/L for lignin peroxidase, and 8,534.81 UI/L for manganese peroxidase. Thermostability and pH stability were observed for all enzymes. Enzymatic deactivation kinetic experiments indicated that enzymes remained active after freezing of crude extracts.

Enhanced Bio-Ethanol Production from Industrial Potato Waste by Statistical Medium Optimization

Industrial wastes are of great interest as a substrate in production of value-added products to reduce cost, while managing the waste economically and environmentally. Bio-ethanol production from industrial wastes has gained attention because of its abundance, availability, and rich carbon and nitrogen content. In this study, industrial potato waste was used as a carbon source and a medium was optimized for ethanol production by using statistical designs. The effect of various medium components on ethanol production was evaluated. Yeast extract, malt extract, and MgSO₄·7H₂O showed significantly positive effects, whereas KH₂PO₄ and CaCl₂·2H₂O had a significantly negative effect (p-value < 0.05). Using response surface methodology, a medium consisting of 40.4 g/L (dry basis) industrial waste potato, 50 g/L malt extract, and 4.84 g/L MgSO₄·7H₂O was found optimal and yielded 24.6 g/L ethanol at 30 °C, 150 rpm, and 48 h of fermentation. In conclusion, this study demonstrated that industrial potato waste can be used effectively to enhance bioethanol production.

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.

Statistical Optimization of Laccase Production and Delignification of Sugarcane Bagasse by Pleurotus ostreatus in Solid-State Fermentation

Laccases are oxidative enzymes related to the degradation of phenolic compounds, including lignin units, with concomitant reduction of oxygen to water. Delignification is a necessary pretreatment step in the process of converting plant biomass into fermentable sugars. The objective of this work was to optimize the production of laccases and to evaluate the delignification of sugarcane bagasse by Pleurotus ostreatus in solid-state fermentation. Among eight variables (pH, water activity, temperature, and concentrations of CuSO₄, (NH₄)₂SO₄, KH₂PO₄, asparagine, and yeast extract), copper sulfate and ammonium sulfate concentrations were demonstrated to significantly influence laccase production. The replacement of ammonium sulfate by yeast extract and the addition of ferulic acid as inducer provided increases of 5.7- and 2.0-fold, respectively, in laccase activity. Optimization of laccase production as a function of yeast extract, copper sulfate, and ferulic acid concentrations was performed by response surface methodology and optimal concentrations were 6.4 g/L, 172.6 μM, and 1.86 mM, respectively. Experimentally, the maximum laccase activity of 151.6 U/g was produced at the 5th day of solid-state fermentation. Lignin content in sugarcane bagasse was reduced from 31.89% to 26.36% after 5 days and to 20.79% after 15 days by the biological treatment of solid-state fermentation.

Tamarind kernel powder: a novel agro-residue for the production of cellobiose dehydrogenase under submerged fermentation by Termitomyces clypeatus

The study investigates the potential of substitution of the conventional carbohydrate nutrient (cellulose) in media with cheap agro-residues for cellobiose dehydrogenase production by Termitomyces clypeatus (CDHtc) under submerged conditions. Different agro-residues tested for enzyme production were characterized using FTIR and XRD analysis. As CDHtc production was highest with tamarind kernel powder (TKP), it was selected for process optimizations through shake-flask fermentations. The optimized parameters were then applied to batch cultures in a 5 L bioreactor that gave enzyme yield (57.4 U mL⁻¹) similar to that obtained under shake-flask fermentations (57.05 U mL⁻¹). The study also made an attempt to predict CDHtc production with respect to time of fermentation and mycelial growth. The specific growth rate and carrying capacity of the mycelia were also determined, and the values lie in the ranges of 0.024-0.027 h⁻¹ and 7.2-7.1 mg mL⁻¹, respectively.

Fish processing wastes for microbial enzyme production: a review

Fishery processing industries generate large amounts of by-products. The disposal of these wastes represents an increasing environmental and health problem. To avoid wasting these by-products, various disposal methods have been applied including, ensilation, fermentation, hydrolysate and fish oil production. Interestingly, fish by-products provide an excellent nutrient source for microbial growth useful in enzyme production process, which is largely governed by the cost related to the growth media. Fish wastes (heads, viscera, chitinous material, wastewater, etc.) were prepared and tested as growth substrates for microbial enzymes production such as protease, lipase, chitinolytic and ligninolytic enzymes. This new approach described in this review can reduce environmental problems associated with waste disposal and, simultaneously, lower the cost of microbial enzyme production.

Bisphenol A degradation in water by ligninolytic enzymes

Many endocrine disruptor compounds, such as bisphenol A (BPA) are used today and released into the environment at low doses but they are barely degraded in wastewater treatment plants. One of the potential alternatives to effectively degrade endocrine disruptor compounds is based on the use of the oxidative action of extracellular fungal enzymes. The aim of this work is to study the ability of free and encapsulated enzymes (manganese peroxidase, lignin peroxidase and laccase) to degrade BPA. Higher degradation of BPA (90%) by ligninolytic enzymes encapsulated on polyacrylamide hydrogel and pectin after 8h was obtained. The degradation of BPA while using the free enzyme (26%) was lower than the value obtained with encapsulated enzymes. The presence of pectin in the formulation significantly (p>0.05) enhanced the activity of enzymes. Kinetics of BPA degradation showed an increase in Vm, while Km remained constant when enzymes were encapsulated. Hence, encapsulation protected the enzymes from non-competitive inhibition.

Screening and production of ligninolytic enzyme by a marine-derived fungal Pestalotiopsis sp. J63

Marine-derived fungi are prone to produce structurally unique secondary metabolites, a considerable number of which display the promising biological properties and/or industrial applications. Among those, ligninolytic enzymes have attracted great interest in recent years. In this work, about 20 strains were isolated from sea mud samples collected in the East China Sea and then screened for their capacity to produce lignin-degrading enzymes. The results showed that a strain, named J63, had a great potential to secrete a considerable amount of laccase. Using molecular method, it was identified as an endophytic fungus, Pestalotiopsis sp. which was rarely reported as ligninolytic enzyme producer in the literature. The production of laccase by Pestalotiopsis sp. J63 was investigated under submerged fermentation (SF) and solid state fermentation (SSF) with various lignocellulosic by-products as substrates. The SSF of rice straw powder accumulated the highest level of laccase activity (10,700 IU/g substrate), whereas the SF of untreated sugarcane bagasse provided the maximum amount of laccase activity (2,000 IU/ml). The value was far higher than those reported by other reports. In addition, it produced 0.11 U/ml cellulase when alkaline-pretreated sugarcane bagasse was used as growth substrate under SF. Meanwhile, the growth of fungi and laccase production under different salinity conditions were also studied. It appeared to be a moderately halo-tolerant organism.

Pomace waste management scenarios in Québec--impact on greenhouse gas emissions

Fruit processing industries generate tremendous amount of solid wastes which is almost 35-40% dry weight of the total produce used for the manufacturing of juices. These solid wastes, referred to as, "pomace" contain high moisture content (70-75%) and biodegradable organic load (high BOD and COD values) so that their management is an important issue. During the management of these pomace wastes by different strategies comprising incineration, landfill, composting, solid-state fermentation to produce high-value enzymes and animal feed, there is production of greenhouse gases (GHG) which must be taken into account. In this perspective, this study is unique that discusses the GHG emission analysis of agro-industrial waste management strategies, especially apple pomace waste management and repercussions of value-addition of these wastes in terms of their sustainability using life cycle assessment (LCA) model. The results of the analysis indicated that, among all the apple pomace management sub-models for a functional unit, solid-state fermentation to produce enzymes was the most effective method for reducing GHG emissions (906.81 tons CO(2) eq. per year), while apple pomace landfill resulted in higher GHG emissions (1841.00 tons CO(2) eq. per year). The assessment and inventory of GHG emissions during solid-state fermentation gave positive indications of environmental sustainability for the use of this strategy to manage apple pomace and other agricultural wastes, particularly in Quebec and also extended to other countries. The analysis and use of parameters in this study were drawn from various analytical approaches and data sources. There was absence of some data in the literature which led to consideration of some assumptions in order to calculate GHG emissions. Hence, supplementary experimental studies will be very important to calculate the GHG emissions coefficients during agro-industrial waste management.