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20132
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Subject: Agricultural Microbiology × End date: 2013 × Start date: 2013 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Bioprospecting of pectinase enzymes from fungi
    (UAS Dharwad, 2013) Dushyantha D. K.; K. S. Jagadeesh
    The present study was conducted to isolate, and characterize fungi from diverse natural sources capable of producing pectinases. Based on the preliminary screening of 100 isolates, 48 isolates were found positive for pectinase production. Out of them, isolates RBF96 (3.25), RC27 (3.21) and DLP51 (3.21) possessed the highest potency index values compared to the reference strain Aspergillus niger MTCC1344 (2.99). Following the PCR based molecular methods, the isolates were identified as Aspergillus niger, Aspergillus oryzae and Penicillium citrinum respectively. Solid state fermentation (SSF) was carried out using various locally available agro-wastes as the carbon source. Citrus peel was identified as the most suitable substrate. The particle size of 2 mm, moisture level of 65 per cent, incubation temperature of 35oC, inoculum level of 1 x 107 spores g-1 and the incubation time of six days were found optimum. After purification the maximum specific activity of 83.06 U μg-1 protein was obtained for polygalacturonase (PG) by A. niger RBF96 with seven fold increase in purification. Similarly, about six folds and five folds increases in purification were obtained for pectin lyase (PL) and pectin esterase (PE) in P. citrinum DLP51 and A. oryzae RC27 respectively. The molecular weights of PG, PL and PE, as determined by SDSPAGE, were 45 kDa, 37 kDa and 31 kDa respectively. The purified PG showed maximum stability at pH 4.5, whereas, PL and PE showed at pH 6.5 and 5.0 respectively. The temperature of 50oC was found optimum. The orange pulp treated with (PG+PL+PE) at 100 U resulted in the highest juice yield (90.17%) and the highest clarity (96.28%). Similarly, in guava this treatment resulted in the highest juice yield (66.75%) and maximum clarity (37.57%). The organoleptic evaluation proved that pectinases could be used to improve the sensorial attributes of fruit juices.
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    ThesisItemOpen Access
    Studies on Ping Pigmented Facultative Methylotrophs of Major Chilli Growing Areas of North Karnataka
    (UAS Dharwad, 2013) Pesal Savitha; M. N. Sreenivasa
    Investigations were carried out to study the plant growth promotional ability and management of anthracnose by native pink pigmented facultative methylotrophs (PPFMs) of major chilli (Capsicum annuum L.) growing areas of North Karnataka. As many as 200 PPFM isolates were isolated and subjected to rapid screening for antibiosis against Colletotrichum capsici (C. capsici) and qualitative assay for production of Indole acetic acid (IAA). They were characterized based on morphological and biochemical characteristics. Selected isolates were further screened for beneficial characters. Highest IAA and GA production was recorded in PPFM6 (19.77 and 128.28 μg/ml of culture filtrate respectively) and highest zeatin production was recorded in PPFM170 (2.54 ıg/ml). Some of the isolates were positive for phosphate solubilization and antagonistic against Sclerotium rolfsii and Fusarium oxysporum. These antagonistic isolates produced catechol type of siderophores whereas production of HCN and volatile antibiotics was not displayed. Based on in vitro studies, six promising isolates were selected for pot culture experiments. The pathogen (C. capsici) was challenge inoculated and ISR activity was estimated. The defence molecules tested were significantly influenced by PPFM isolates. The peroxidase and PALase activity was increased from one DAI up to 7 DAI whereas chitinase, PPO and phenol contents increased up to 5 DAI, after which gradual decrease was noticed. Inoculation of PPFM isolates to chilli crop significantly improved plant height, dry matter and chlorophyll content. Significantly lesser disease incidence, more yield and more capsaicin content was observed with application of carbendazim followed by inoculation of PPFM6 + PPFM170 + PPFM35 and PPFM6 both under pot culture and field conditions. The results of the present study clearly indicated that PPFM6 is a very good plant growth promoter and have biocontrol efficiency against C. capsici.