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2021 - 20233
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Author: Manmeet Kaur × Start date: 2020 × Type: Thesis ×
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    Characterization and industrial application of oxidative/hydrolytic enzymes of Pleurotus florida (Mont.) Sing. and Calocybe indica (Pur. & Chan.)
    (Punjab Agricultural University, 2023) Manmeet Kaur; Sharma, Shivani
    Pleurotus florida and Calocybe indica are the edible mushrooms that have been widely accepted due to their ability to grow on a variety of substrates and possess the potential to produce oxidative and hydrolytic enzymes. The present work involved the study and characterization of oxidative/hydrolytic enzymes of P. florida and C. indica for their potential applications in alcohol fermentation, dye decolorization, biobleaching and mushroom production. The oxidative and hydrolytic enzymes extracted from P. florida and C. indica were estimated at different mycelial growth stages for enzyme production. The intracellular and extracellular enzyme activity of P. florida and C. indica increased with time and maximum activity of lignocellulolytic enzymes was found to be on 14th day of incubation. In both mushrooms, ligninolytic enzyme activity increased during substrate colonisation but quickly decreased during fruiting body development. On the other hand, P. florida and C. indica showed relatively modest hydrolase activity during substrate colonisation. The activity of hydrolytic enzymes increased dramatically during primordial formation and peaked at the fruiting body stage. The purification of laccase, lignin peroxidase, manganese peroxidase and endoxylanase from the fruiting body of P. florida resulted in maximum purification fold of 21.49, 17.73, 16.81 and 12.78 with yield of 24.98%, 20.60%, 19.53% and 14.86%, respectively. However, the purification of laccase, lignin peroxidase, manganese peroxidase and endoxylanase from the fruiting body of C. indica resulted in maximum yield of 21.36%, 18.92%, 17.37% and 16.62% with purification fold of 25.6, 25.12, 20.88 and 19.97, respectively. The SDS-PAGE of the purified enzyme laccase and lignin peroxidase isolated from P. florida showed a single prominent band at 66 kDa and 55 kDa respectively. The SDS-PAGE of the purified enzyme laccase and lignin peroxidase isolated from C. indica showed a single prominent band at 64 kDa and 47 kDa, respectively. FTIR spectra of the purified enzymes indicated a secondary structure that reflected the amide I and amide II bands, respectively. The pretreatment of paddy straw and wheat straw with P. florida, C. indica and their ligninolytic enzyme resulted in decrease in lignin and hemicellulose content, respectively during the incubation period of 30 days. However, the decrease in cellulose content occurred during the pretreatment of substrates with fungus while relative increase in cellulose content during the treatment with ligninolytic enzymes was observed over the incubation period of 30 days. Under optimized conditions, saccharification of biologically pretreated paddy and wheat straw resulted in release of 0.415 and 0.389 g/gds reducing sugars, respectively. The fermentation of biologically pretreated and commercial cellulase saccharified paddy and wheat straw hydrolysate resulted in 0.129 and 0.119 g/g ethanol, respectively. The crude enzyme extract of P. florida and C. indica were able to degrade RBBR (25.74 %, 22.06%) and Amido Black (19.76%, 17.58%) dyes maximally after 96 hours of incubation at 30°C and pH 7.0. The paddy and wheat straw was treated with a ligninolytic crude enzyme, which stimulated faster mushroom growth and fructification. The present study thus revealed that expression of biosynthetic potential of P. florida and C. indica is highly dependent on the method of fungi cultivation. These ligninolytic enzymes showed a unique profile in terms of versatility, greenness, pollutant removal and efficiency in lignin degradation for the exploitation and valorization of agro-wastes.
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    Diapause induction and post-diapause development in Sesamia inferens Walker
    (Punjab Agricultural University, Ludhiana, 2021) Manmeet Kaur; Aggarwal, Naveen
    The investigations on diapause induction and post-diapause development in Pink stem borer, Sesamia inferens Walker larvae were conducted under laboratory conditions at varying temperature and photoperiodic combinations of 10±1 and 14±1oC (10:14 h LD), 25±1oC (12:12 h LD), 30±1 and 34±1oC (13:11 h LD). Diapause was observed at temperature and photoperiod combinations of 10±1 and 14±1oC (10:14 h LD) and no diapause induction was recorded at 25±1oC (12:12 h LD), 30±1 and 34±1oC (13:11 h LD). The larval period of S. inferens was longer (61.74 and 52.41 days) at 10±1 and 14±1oC. It was significantly shorter at 25±1oC (30.11 days), 30±1oC (24.87 days) and 34±1oC (23.89 days). The minimum larval survival (pupation) of 64.01 and 65.45 per cent was recorded at diapausing temperature. It was significantly more at 25±1oC (86.36 %), 30±1oC (81.32 %) and 34±1oC (71.86%), respectively. Pupal period was prolonged significantly to 12.64 : 14.12 and 10.52 : 12.04 days in males and females at diapasing temperatures, respectively. However, it was significantly less in non-diapausing populations exposed at 25±1, 30±1 and 34±1oC (5.85-8.09 days in males and 7.24-10.23 days in females), respectively. Overall, S. inferens had longer total development period of 81.2 : 82.68 and 69.75 : 71.23 days in males and females individuals at both diapausing temperatures. At 25±1, 30±1 and 34±1oC, it reduces significantly to 36.5044.04 days in males and 37.89-46.18 days in females individuals. The highest population loss of 62.48 and 60.15 per cent was recorded at 10±1 and 14±1oC (10:14 h LD). Whereas, at 25±1oC (12:12 h L:D), 30±1 and 34±1oC (13:11 h LD) loss of only 6.3, 26.13 and 42.01 per cent was recorded. Morphometric parameters of diapausing larvae revealed that it completely lacks cuticular pigmentation and had reduction in the body size (9.98-12.03 mm) and head capsule width (0.62-0.67 mm). The non-diapause larvae had 12.88-26.95 mm body size and 0.71-1.91 mm head capsule width. The pupal (male: 9.59-10.58 mm length and 1.65-1.92 mm breadth; female: 11.42-12.52 mm length and 2.36-2.69 mm breadth) and adult sizes (male: 10.10-11.04 mm length and 2.04-2.48 mm breadth; female: 13-14.41 mm length and 3.25-3.76 mm breadth) of diapause populations were smaller and adults emerged from these populations were darker in colour than nondiapausing (male: 11.66-12.57 mm length and 3.23-3.52 mm breadth; female: 14.95-15.55 mm length and 4.42-4.63 mm breadth of adults and for pupa male: 10.86-12.24 mm length and 2.64-3.21 mm breadth and female: 12.76-14.66 mm length and 3.28-4.02 mm breadth) populations. About 14.6 per cent (10±1oC) diapausing larvae exhibited additional 2 instars followed by 9.3 per cent of larvae (14±1oC). The diapause in S. inferens significantly reduces the percentage pupation (64.01-65.45) and weights of pupae (62.98-65.41 mg of male and 128.69-133.7 mg of female), ultimately lowering the weight (34.98-37.83 mg of male and 50.4-52.70 mg of female) and reproductive performance of adults. The results clearly indicate that a reduction in oviposition period, fecundity and egg viability in a diapausing population of S. inferens ultimately leads to a reduction in population growth parameters. Larvae of S. inferens undergo for some biochemical adaptations for its survival during the diapausing conditions. More amount of proteins (27.5659.81 mg/g b.wt.) and glycogen (23.82-30.26 mg/g b.wt.) were estimated at temperature exposure of 2530oC. Lipids (10.53-12.02 mg/g b.wt.), trehalose (19.95-22.89 mg/g b.wt.) and total soluble sugars (24.9129.76 mg/g b.wt.) were significantly high in diapausing conditions. In present studies, facultative diapause was observed at 10±1 and 14±1oC alongwith shortday exposure of (10:14 h LD), indicated that population might be surviving during December-January under North-Indian winter and even the lower surviving population is sufficient for its carryover.
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    ThesisItemOpen Access
    Evaluation of synthesized ferrite nanocomposites with N-doped graphene and carbon microspheres for the removal of heavy metals and organic pollutants
    (Punjab Agricultural University, Ludhiana, 2021) Manmeet Kaur; Manpreet Kaur
    Magnetic ferrites and their nanocomposites with nitrogen doped graphene oxide (N-GO) and hollow mesoporous silica have received immense interest as adsorbents and photocatalysts for water decontamination. This work reports facile strategy for the synthesis and evaluation of N-GO, MFe2O4 NPs (M= Mg, Ca), MFe2O4-NGO (M= Mg, Ca) and hollow mesoporousnanocomposites for the removal of Pb(II), Ni(II), As(III), CR dye and PNP from contaminated water.NCs of NGO with MFe2O4 NPs were prepared using ultra sonication method. For dual core shell nanocomposite, hollow mesoporous SiO2 core was synthesized using polyethylene glycol (PEG) and cetyltrimethyl ammonium bromide (CTAB) as cotemplates. Synthesized SiO2 was used as template over which MgFe2O4 NPs were loaded using sodium dodecyl sulphate (SDS) as a surfactant to synthesize MgFe2O4@SiO2 core-shell nanocomposite. This nanocomposite was further loaded with N-GO in order to design NGO@MgFe2O4@SiO2 dual core nanocomposite by ultra sonication method. Structural, magnetic and surface properties of the nanocomposites were analyzed using various physicochemical techniques. The effectiveness of NPs and nanocomposites for the removal of Pb(II), Ni(II) and As(III) and photodegradation of CR and PNP was studied.MgFe2O4@SiO2 displayed maximum heavy metal removal whereas, NGO@MgFe2O4@SiO2 dual corenanocomposite exhibited maximum photocatalytic degradation for organic pollutants. The mechanism of adsorption and photocatalysis from spiked water was investigated by batch experiment studies.The adsorption data was best fitted into Langmuir adsorption isotherm and followed pseudo-second-order kinetic model.The degradation mechanism for CR and PNP was proposed on the basis of mass spectrometric analysis of products formed during photodegradation. Also, the comparative photocatalytic activity of spiked distilled water and contaminated water revealed reduction in photocatalysis of 17% and 22% in the contaminated water. The synthesis of NCs of MgFe2O4 NPs with doped carbon material and core-shell synthesis using SiO2 core provide new synthetic strategy for further modification of pristine ferrite NPs for future applications.