Browsing by Author "Dolly Wattal Dhar"
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ThesisItem Open Access ADAPTIVE MECHANISMS IN CYANOBACTERIA FROM ACIDIC SOILS(DIVISION OF MICROBIOLOGY INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI, 2015) DNYANESHWAR NAMDEO BORASE; Dolly Wattal DharRepresentative acidic soil samples were collected from three sites namely Alipurduar, Ernakulam and Mokokchung districts of West Bengal, Kerala and Nagaland, India. Thirty cyanobacterial strains were isolated using BG-11 medium with pH ranging from 4 to 6. The low pH tolerance study indicated that Nostoc AD1, Nostoc AD2 and Anabaena AD3 from West Bengal showed a pH tolerance of 4, 4.5 and 5; Nostoc ER1, Anabaena ER2 and Nostoc ER3 from Kerala; and Nostoc MK1, Anabaena MK2 and Cylindrospermum MK3 from Nagaland depicted a pH tolerance of 4.5, 5 and 5.5. These nine cyanobacterial strains exhibited variation in terms of growth, pigment profile and other cellular constituents. Out of nine, four strains belonging to Nostoc having better low pH tolerance ability were used for further study under control (pH 7) and acidic pH (4, 4.5) grown conditions. Microscopic observations showed highly mucilaginous mats, formation of cell aggregates, reduced cell size and heterocysts frequency under acidic conditions in comparison to control. The growth rate was also reduced significantly under acidic conditions. There was an enhancement in chlorophyll, carotenoids, phycobilins and cellular constituents under acidic conditions compared to control; however, ammonia excretion was more in control grown cultures. The in vitro arginine deiminase (ADI) and anabolic ornithine carbamoyl transferase (OCT) activities were more under acidic as compared to control grown cultures. The activity of these was higher in stationary phase than log phase cultures; OCT activity was more than ADI under both the growth phases. The amplified argF gene sequences exhibited 88% similarity with reported argF sequence of Nostoc PCC 73102. The deduced protein sequences from argF gene sequences of two Nostoc strains showed 89% and 90% similarity with OCT protein sequence of Nostoc punctiformis. The argF expression was more under acidic than in the control grown conditions, with higher expression depicted by stationary phase grown cultures. The FAME profile of acid stress tolerant cyanobacterial strains showed higher percentage of SFA as compared to PUFA and MUFA. The protein profile exhibited differential expression of acid stress responsive and acid sensitive proteins at pH 4, 4.5, 5, 5.5 and 7 during log phase as well as stationary phase. These observations and results clearly indicated the usefulness of morphological and /or biochemical attributes in understanding the acid stress tolerance mechanisms in cyanobacteriaThesisItem Open Access Evaluation and optimization of cultural conditions for maximum lipid content in microalgal biomass(Division of Microbiology, 2011) BAGUL SAMADHAN YUVRAJ; Dolly Wattal DharDifferent aquatic sampling sites from Dalhousie and Chamba districts of Himachal Pradesh (Northern India) were identified for the collection of samples and isolation of microalgae from the chlorophyceae. Total ten micro-algal strains from five genera namely Chlamydomonas ; Chlorella; Chlorococcum ; Scenedesmus and Ulothrix were isolated and identified based upon microscopic observations and these were used for further studies. There was a gradual and continuous enhancement in the dry weight with incubation time in days. Mean dry weights varied from a lowest in Chlamydomonas to the highest in Scenedesmus. The chlorophyll content ranged from the highest in Scenedesmus to the lowest in Ulothrix. The strains differed significantly with respect to total soluble proteins and Chlorococcum showed the highest total soluble proteins and Ulothrix showed the lowest content. A lowest of total lipids (5.8% ) was recorded in Ulothrix and highest (18.7% ) was recorded in Chlorella. Three microalgal genera namely Chlamydomonas, Chlorococcum and Chlorella were selected for studies on the optimization of cultural conditions for enhanced lipid production. These were subjected to variable environmental and cultural conditions for a period of 28 days and the differential variables used were temperature , light intensity, pH, sodium chloride and 0.25 g N L-1 as NaNO3, NH4Cl and Urea. Highest lipids were exhibited by Chlorella in comparison to Chlamydomonas and Chlorococcum under different temperatures , light intensities, nitrogen source as well as sodium chloride concentration. The differential effect of environmental variables on total lipids could be recorded. Maximum lipids were recorded at a pH of 7.2 as compared to the pH of 6 and 6.6. The results clearly indicated that the optima for lipids varied in different microalgal cultures at different concentrations of sodium chloride. Fatty acid profile showed the presence of saturated as well as unsaturated fatty acids in three micro-algal strains tested in the present study. Results have clearly indicated that % of total FAME can be obtained from the lipid extract under normal growing conditions. FAME profile was found to be suitable for biodiesel and Chlorococcum and Chlorella can be considered as promising microalgae to be used as a source of lipids for biodiesel production.ThesisItem Open Access Genetic Relationships in Spirulina and Related Genera(DIVISION OF MICROBIOLOGY INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI, 2008) NIRBHAY KUMAR SINGH; Dolly Wattal DharThesisItem Open Access MORPHO-PHYSIOLOGICAL AND MOLECULAR CHARACTERIZATION OF CYANOBACTERIA FROM AQUATIC BODIES(iari, Division of Microbiology, 2009) DNYANESHWAR BORASE; Dolly Wattal DharWater samples were collected from Anasagar, Pushkar lake and Sambhar lake located around Ajmer district of Rajasthan, India. The pH of the water samples was alkaline and the Electrical Conductivity of Samhbar lake was highest and that of Anasagar was lowest. The exchangeable Na, organic carbon, available phosphorus and nitrogen of Sambhar lake was maximum. Most of the heavy metals could not be detected in Anasagar and Pushkar lake and Sambhar lake showed the presence of all the heavy metals analyzed. Out of the total twenty three cyanobacterial isolates, twelve were from Anasagar, eight were from Pushkar lake and only three were from the Sambhar lake. Microscopic examination indicated the presence of one colonial, nine heterocystous and the remaining non-heterocystous filamentous forms. When genera wise distribution was recorded, Nostoc, Phormidium and Plectonema were most abundant followed by Anabaena and Westiellopsis; and Microcystis and Oscillatoria were least abundant. There was a significant difference in chlorophyll, carotenoids and phycobilins amongst the cyanobacterial isolates. The phycocyanin, allophycocyanin and phycoerythrin differed significantly and phycocyanin/ phycoerythrin ratio was more than one in most of the cases. The nitrate reductase (NR) and glutamine synthetase (GS) activity differed significantly and the nitrogenase activity could be detected only in heterocystous strains.16S rRNA gene amplification depicted the presence of single amplified product of 1500bp. The digestion with restriction enzymes (Dpn II, Mse I and Hin f) exhibited differential restriction profile. Results on the basis of dendrogram developed indicated closeness of genera from the same order in most of the cases with few exceptions. Cyanobacterial strains Plectonema abornema, Phormidium molle, Phormidium foveolarum and Phormidium ceylanicum clustered together with 100% similarity.ThesisItem Open Access UNDERSTANDING THE INFLUENCE OF BENEFICIAL CYANOBACTERIA IN RICE CROP(CCUBGA, Division of Microbiology ICAR-Indian Agricultural Research Institute New Delhi, 2020) PREMSING SHIVSING MARAG; Dolly Wattal DharRice plants were collected along with their rhizospheric soil from New Delhi; Ludhiana, Punjab; Thrissur, Kerala; and Barapani, Meghalaya. These were utilized for the isolation and purification of cyanobacteria which were identified based upon microscopic observations. Rhizospheric soil subjected to Physico-chemical analysis depicted variability for pH, Electrical Conductivity, % organic carbon, available nitrogen, phosphorus and potassium. A total of 85 cyanobacterial strains (70 heterocystous, 15 non-heterocystous) were isolated from rhizospheric soil and plant parts of eight rice varieties. Out of these, 71 were from rhizospheric soil and others were from different plant parts. Out of 28 strains from rice varieties of New Delhi, 23 were from rhizospheric soil, whereas, others were from root, stem, and leaves. Amongst all, 24 were heterocystous and 4 were non heterocystous. From rice varieties of Ludhiana, 9 strains were from rhizospheric soil, 3 each were from root, stem and leaf. 16 strains were heterocystous and 2 were non-heterocystous. All the 23 strains from rice varieties of Thrissur, were from rhizospheric soil and 19 were heterocystous and 4 were non-heterocystous. Out of 16 strains from rhizospheric soil from Barapani rice varieties, 11 were heterocystous and 5 were non-heterocystous. Isolated cyanobacterial strains belonged to ten genera with the sequence of percent abundance as Anabaena (51%) >Nostoc (21%) >Phormidium (12%) >Calothrix (5%) >Plectonema (4%) >Desmonostoc (2%) =Geitlerinema (2%) >Tolypothrix (1%) =Aulosira (1%) = Trichormus (1%). This indicated the dominance by Anabaena and Nostoc contributing to 72% distribution. Genera wise distribution showed that for New Delhi, Thrissur and Barapani rice varieties, Anabaena was most abundant, whereas, for Ludhiana rice varieties, Nostoc depicted the abundance. Diversity indices exhibited significant observations for Shannon’s diversity index (H), Margalf index, Menhinick index and Simpson’s index. First three showed maximum diversity indices from rice crops of Thrissur followed by New Delhi, Barapani and Ludhiana, whereas Simpson’s index of diversity was highest for Ludhiana followed by Barapani, New Delhi and Thrissur Attempts were further made to characterize the cyanobacterial strains in terms of cell dry weight, total soluble proteins, pigment profile and plant growth promoting (PGP) attributes. Results indicated that the cell dry weight and chlorophyll contents were higher in strains from Ludhiana varieties as compared to those from rice varieties of New Delhi, Thrissur and Barapani. In almost all, carotenoids were more than chlorophyll, and phycobilisomes were higher in strains from Ludhiana followed by New Delhi, Thrissur and Barapani varieties. Varied response was observed 314 amongst the strains for nitrogenase activity, extracellular ammonia and IAA production. Most efficient cyanobacterial strains selected in terms of chlorophyll, nitrogenase activity, extracellular ammonia and IAA production from four locations showed positive influence on % germination, radicle and plumule length. The interactive effect of N fertilizer and cyanobacterial inoculation was studied on photosynthetic efficiency and N assimilation in selected rice varieties at ICAR-IARI. The pot culture experiments were conducted under natural as well as controlled conditions of National Phytotron Facility. Observations were recorded for plant parameters (root and shoot length, fresh and dry weight, tiller and number of leaves), root architecture, photosynthetic rate, N assimilatory enzymes, percent N contents, and grain yield with its attributes. Studies were also conducted with respect to Image-based Plant Phenotyping at the Phenomics facility of the Institute. The cyanobacterial strains showed positive influence on root and shoot length and their dry weight, and root architecture as compared to 75% RDF dose of N. The enhanced total plant length was attributed to increase in shoot length and root length with cyanobacterial inoculation. A positive influence of cyanobacterial strains was also observed on pigment profile especially chlorophyll. The chlorophyll to carotenoid ratio indicated that chlorophyll contents, particularly chlorophyll a was much higher than chlorophyll b and carotenoids. However, statistically non-significant enhancement was recorded for tillers and leaf number. The results clearly depicted that the treatment with 75% N (un-inoculated) was not good in terms of various parameters studied, whereas, the treatments with cyanobacterial inoculation showed good influence on selected attributes. Nitrate reductase and glutamine synthetase activity in leaves increased with cyanobacterial inoculation in comparison to control.In inoculated plants, higher % nitrogen was recorded in shoot and grains with better root biomass over uninoculated control. In terms of grain yield and its attributes, % filled grain and test weight increased, however, no difference was found for panicle length and panicle number per plant. Phenomics study also revealed significant observations with positive influence of cyanobacterial strains over uninoculated control (75% N) on plant area, height, boundary point count, caliper length, convex hull area, and chlorophyll fluorescence of rice plants. Studies have aided in identification of region specific potential cyanobacterial strains with efficient plant growth promoting characteristics. Observations on pot culture experiments conducted under natural as well as controlled conditions showed that nitrogen fixing cyanobacterium can save about 20% to 25% of nitrogenous fertilizers, hence, can be utilized as an important component in integrated nutrient management of rice crop.