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2012 - 20182
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Subject: Microbiology × Author: Avneet Kaur × End date: 2018 × Start date: 2010 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Microbial production of tannase using agro waste
    (Punjab Agricultural University, Ludhiana, 2018) Avneet Kaur; Katyal, Priya
    Tannase (tannin acyl hydrolase, E.C.3.1.1.20) is an inducible enzyme that has wide applications in different food and feed industries including production of beverages, cosmetic chemicals and in clarification of beer and fruit juice. It has also been used for bioremediation of tannins from effluents of leather industries. Attempt was made for isolation of tannase producing microbes (bacteria/fungi) from tannery effluents using tannic acid supplemented media. On the basis of qualitative (zone of hydrolysis) assay, four fungal isolates – AV1, AV2, AV3 and AV4 were found to be more efficient than bacterial isolates for tannase production and the maximum zone was shown by AV3 isolate i.e. 2.3 cm. For the morphological characterization of fungal isolates, lactophenol cotton blue staining and Scanning Electron Microscopy were done. Isolate AV1, AV2, AV3 and AV4 were found to show morphological similarities to genera Penicillium, Fusarium, Aspergillus and Trichoderma, respectively. Quantitative tannase production by the selected four isolates (AV1, AV2, AV3 and AV4) for seven consecutive days revealed AV3 to be the maximum tannase producer (25.33 U/ml) on 5th day of incubation. Four different agrowastes i.e. spent tea powder, coconut coir, corn husk and fruit baggase were used as substrates for tannase production using selected isolate AV3 and the maximum tannase production (35.62 U/ml) was obtained using spent tea powder as substrate at pH 5.5 and temperature 40oC. Optimization of process parameters for maximum tannase activity with central composite design using response surface methodology reveals maximum tannin hydrolysis (93.33µMmin-1) at a temperature of 600C, pH 8.0 and 5% substrate concentration. On partial purification, by ammonium sulphate precipitation followed by dialysis using membrane-70, activity of the tannase increased to 153.33µMmin-1 and the yield of the enzyme was 83.33%. Partially purified enzyme was used for detannification of pomegranate juice and was found to reduce tannin content from 2.76 mg/ml to 1.03 mg/ml but with slight decolorization of juice.
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    ThesisItemOpen Access
    STUDIES ON BIODEGRADATION OF ENDOSULFAN BY BACTERIAL SPECIES FROM AGRICULTURAL SOILS.
    (Punjab Agricultural University, Ludhiana, 2012) Avneet Kaur
    For bioremediation of endosulfan, nine bacterial species isolated from sugarcane field soils and identified using 16S rDNA sequence homology. These could cause only partial endosulfan metabolization (maximum of 50.22%) coupled with appearance of toxic endosulfan sulphate as metabolite. Evaluation of earlier identified 15 bacterial species resulted in selection of Brevibacterium frigoritolerans, Bacillus alkalinitrilicus and Pseudomonas fulva causing 86.58, 81.30 and 71.58 % endosulfan reduction, respectively. These bacterial species could grow over a wide range of pH (4.0-11.0) and temperature (25-37°C), but optimally at pH of 6.0-6.5 and 37°C, though growth was more rapid in shake than stationary cultures. However, whereas, B. frigoritolerans was sensitive to high salt concentrations, P. fulva & B. alkalinitrilicus grew optimally at salt concentration of 3.0 and 4.0 %, respectively. Maximum endosulfan degradation by B. frigoritolerans and P. fulva was not affected by presence of additional carbon and/or nitrogen sources suggesting the endosulfan metabolization by these species to be inducible by endosulfan only. In case of B. alkalinitrilicus, improvement in endosulfan reduction by the presence of additional C and/or N sources (80.58 to 95.14%) established the constitutive nature of endosulfan degradation. Whereas B. alkalinitrilicus holds potential for bioremediation of endosulfan in nutrient enriched agricultural soils and sewage water, B. frigoritolerans and P. fulva could find equal exploitation for endosulfan degradation in nutrient deficit environments.