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Assam Agricultural University, Jorhat

Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level. Genesis of AAU - The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati. Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.

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20171
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Subject: Soil Science × Author: Phukan, Amrita × End date: 2017 × Start date: 2013 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    SCREENING AND EVALUATION OF METHANOTROPHIC BACTERIA FROM RICE ECOSYSTEM
    (AAU, Jorhat, 2017-07) Phukan, Amrita; Baruah, Rajen
    Methane (CH4) is an important greenhouse gas with 25 times more global warming potential than carbon dioxide (CO2). Rainfed/wetland rice fields are one of the major anthropogenic sources of CH4 release to the atmosphere. Therefore, there is utmost need to mitigate the methane menace. Microorganisms especially Methanotrophs play vital role for biological sink of methame through oxidation to CO2. Considering the fact, the present study was undertaken to isolate and screen novel organisms with methane oxidising properties. A total of 28 Methanotrophic bacterial cultures were isolated from 20 different rice rhizosphere samples of Jorhat district. Altogether 11 out of 28 isolates were selected as methanotrophs on the basis of their growth in Nitrate Mineral Salt (NMS) with CH4 as their sole carbon source. The 11 Methanotrophic bacterial cultures were characterized on the basis of cell morphology, carbohydrate utilization and the degree of susceptibility towards the antibiotics to assess variation within the cultures. All the isolates were screened for their methane oxidizing property and other enzyme activities viz., soluble methane monooxygenase (sMMO), particulate methane monooxygenase (pMMO) and nitrate reductase. The results showed the variation among the cultures in enzyme activities, however all the selected cultures showed methane oxidizing property to the tune of 16053.153 ± 1.333 ppm CO2 to 1787.574 ± 0.938 ppm CO2. Nitrate reductase and sMMO activity was also determined quantitatively for all the isolates to screen the efficient cultures. Specific activity of sMMO by different cultures ranged from 685.489 ± 0.494 nmol h-1 mg of protein-1 to 55.712 ± 0.659 nmol h-1 mg of protein-1. The nitrogenase enzyme activity was determined to check the biofertilizer potential of the test cultures by acetylene reduction assay. The amount of acetylene reduced to ethylene by the test isolates ranged from 8.282 ± 0.240 µmole C2H4/ml/hr to 0.015 ± 0.003 µmole C2H4/ml/hr. The bacterial strains recorded varying soil enzyme activities under soil incubation study of 30 days indicating its role in maintaining soil health. Some of the enzyme activities studied were: MBC, Dehydrogenase, Phosphomonoesterase, FDA hydrolysis, arylsulfatase and urease. The test cultures showed variation in these properties. It was observed that methane oxidation and emission highly correlated with some of the enzyme activities. For instance, Dehydrogenase was found to be the most influencing parameter for methane oxidation ( r = 0.887, P =0.001) and emission ( r = -0.611, P =0.001). Similarly, there was a significant positive correlation between sMMO activity and methane oxidation ( r = 0.536, P =0.001) but a negative correlation with methane emission ( r = -0.539, P =0.001). Based on qualitative and quantitative evaluation, the Methanotrophic bacterial cultures were selected for pot culture evaluation taking rice as test crop. The rice seedlings were inoculated with Methanotrophic bacterial cultures and grown for 35 days. The methane flux were recorded at tillering stage using closed acrylic chamber method. Methane flux recorded for different strains along with uninoculated control ranged from 3639.504 ± 2.254 µg CH4/m2/day Soil to 313.202 ± 3.314 µg CH4/m2/day Soil and also plant growth promotion was observed in all inoculated treatments over uninoculated control which was evident from increase in plant height, root length, tiller number, fresh weight and dry weight. Among the test organisms, MB 16 and MB 28 significantly reduced the methane flux over other Methanotrophs. The results further showed that other Methanotrophic cultures also performed better in reducing methane emission when compared with uninoculated control. Inoculation of MB 16 and MB 28 significantly enhanced the plant growth parameters while other Methanotrophs was either at par or higher than uninoculated control in some of the parameters. 16S rRNA gene sequences of seven methanotrophic cultures revealed that they belonged to the group ɣ-proteobacteria and α-proteobacteria representing the genera Methylomonas, Methylomicrobium, Methylosinus, Chryseobacterium and Methylocystis. The resulted sequences of the organisms were deposited in NCBI, GeneBank with accession numbers. These strains possessed the particulate (pmoA) and soluble (mmoX) methane monooxygenase gene as functional marker for detection of methanotrophs.MB 16 identified as Methylosinus sp. (Type II Methanotroph) and MB 28 identified as Methylomicrobium buryaticum (Type I methanotroph) has been considered as efficient methane oxidizing bacteria having biofertilizer and bioremediation potential which could be exploited along with other potent novel Methanotrophs as future microbial inoculants.