Microbiology

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https://hdl.handle.net/20.500.14540/132

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Browsing Microbiology by TU Affiliated Institute "Central Campus of Technology, Hattisar, Dharan,"

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    Mass Production of Free-Living and Symbiotic Nitrogen-Fixing Biofertilizers and Comparative Efficacy Study of Different Carriers
    (Deparment of Microbiology, 2022) Karki, Sujan
    There is a high demand for food worldwide which has caused the increase in the use of chemical fertilizer to fulfill the global need for food. The use of chemical fertilizer has a negative impact on the environment which has exponentially raised the global interest in microbial fertilizer. This study focuses on the easy and costeffective use of carrier material that can be used in the production of microbial fertilizer. For these symbiotic bacteria (Rhizobium) and non-symbiotic bacteria (Azotobacter) were used as microorganisms and charcoal, rice husk, and farmyard manure as carrier material were used. Rhizobium species and Azotobacter species were isolated from pea plant root nodule and soil sample respectively. These isolated organisms were blended with carrier material and kept in two different temperatures i.e. at room temperature and refrigerator to know the survivability of microorganisms in normal conditions and preserved condition. A decline in moisture and pH on prolonged incubation was observed in both organisms. A high survivable rate of Rhizobium species is seen in rice husk and Azotobacter species is seen in farmyard manure stored in both temperatures. Whereas least survivability was seen in charcoal for both organisms stored in both temperature. Moisture and pH are normally responsible for more 50% of change in CFU in all carrier material except for rice husk blended with Rhizobium and farm yard manure blended with Azotobacter stored in room temperature. CFU in all the carrier material with respect to storage and carrier material have significant difference except for Azotobacter stored in room temperature. The rhizobia and Azotobacter strains population significantly decline over time regardless of the carrier material and storage temperature. A decline in population on prolonged incubation may be attributed to the depletion of nutrients, moisture, and cell death. Rice husk, however, demonstrated extraordinary potential, particularly in respect of shelf life. KEYWORDS: Rhizobium, Azotobacter, carrier, biofertilizer
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    Nitrogen Fixation Evaluation of Azotobacter Chroococcum Isolated from Soil of Forest
    (Deparment of Microbiology, 2022) Tolangi, Priskila
    With the continuous use of chemical fertilizers in Agriculture system may help to produce sufficient amount of food for growing population but these chemicals have an adverse effect both on the environment and living organisms. Biofertilizers are a promising alternative to hazardous chemical fertilizers and gaining importance for attaining sustainable agriculture. They play key role in maintaining soil health and plants. Microorganisms can interact with the crop plants and enhance their immunity, growth, and development. Nitrogen, Phosphorous, Potassium are the essential nutrients required for the growth of crops, but these nutrients are naturally present in insolubilized forms. Certain microorganisms make them soluble and can be easily assimilated by plants for their growth and development. In this study, Azotobacter chroococcum were isolated from forest surroundings of Panbari Dharan. 25 soil samples were collected in sterile bag and cultured in Ashby’s media by serial dilution and incubated at 30˚C for 5 days. Morphological, cultural, biochemical characterization was done and bacteria were identified. Isolated A. chroococcum was cultured in Ashby’s broth and inoculated on tomato seedlings by root dipping technique. It was found that tomato plants inoculated with A. chroococcum has significant growth in height, no. of leaves and root length than that of untreated tomato plants. The research result showed that this strain had positive effect on the increase of nitrogen content of soil. On the base of this study, it is concluded that Azotobacter chroococcum has positive effect in growth of plants. It could be good biofertilizer as an alternative to nitrogen fertilizer. Keywords: soil, free-living nitrogen fixers, nitrogen, PGPR effects, tomato plants