Ecological Occurrences of Methylotrophs in Phyllosphere of crops

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dc.contributor.advisorGayan, Anjuma
dc.contributor.authorPhukan, Sanghamitra
dc.date.accessioned2020-06-12T06:27:47Z
dc.date.available2020-06-12T06:27:47Z
dc.date.issued2019-07
dc.description.abstractThe phyllosphere is an ecologically important habitat that hosts a large and diverse microbial community. Bacteria are among the most abundant inhabitants of the phyllospheric leaf surface, where the conditions are very harsh, due to heat, irradiation, rainfall, etc. The present investigation envisages the isolation, biochemical characterization and screening of phyllosphericmethlyotrophic bacteria associated with various crops for their plant growth promoting characteristics. Methylotrophs are a group of microorganisms that have the ability to utilize C1 compounds such as methanol or formaldehyde along with several multi carbon compounds, the most common genera being Methylobacterium, comprising mostly of pink pigmented facultative methylotroph (PPFM). In the present investigation leaf samples were collected from different crops comprising of five sites of Jorhat district, Assam. Leaf being the dominant aerial part, was considered for isolation purpose. Following the leaf imprinting and serial dilution technique, isolation of phyllopshericmethylotrophic bacteria were carried out. Eighteen isolates were screened for their plant growth promoting traits like Indole acetic acid (IAA), siderophore production, antibiotic resistance, ammonia production, etc. All the isolates produced IAA within a range of 0.69- 5.53 μg g⁻¹, with the highest in spinach (M16). The total nitrogen content of the isolates ranged between 1.4- 2.6 mg g⁻¹. Siderophore production was shown by the isolates M1 (chili) and M10 (cauliflower) and resistance to common antibiotics was also shown by few isolates, isolate M4,M15, M16 and M 17 from ivy gourd, cowpea, spinach and french bean crops respectively. Isolates M1, M10 and M12, retrieved from the phyllopshere of chilli and cauliflower crop possessed the ability to solubilize phosphorus, and isolate M7 from phyllosphere of tomato could solubilize zinc. After screening for plant growth promoting traits, twelve isolates were finally selected for a series of biochemical tests. All the isolates could hydrolyze casein, but none could hydrolyze starch. Catalase test was positive for all the isolates but all isolates did not possess cytochrome c oxidase enzyme. Few isolates M1, M4, M7, M10, M15, M16, M17 from chilli, ivy gourd, tomato, cauliflower, cowpea, spinach and frenchbean showed nitrate reduction. The isolate M13 showed positive urease activity. Citrate utilization was seen only in case of one isolate from phyllosphere of french bean (M17). Few isolates could show positive results for indole and VogesProskauer’s test but methyl red test was positive for one isolate from phyllosphere of chillicrop. Enumeration of methylotrophic bacterial population carried out for both phyllosphere samples and rhizospheric soil, resulted in a higher population in the phyllosphere. Soil samples of the study site were also analyzed for soil chemical (pH, available N, available P2O5,available K2O, organic carbon) and biological parameters (microbial biomass carbon, fluorescein diactetate, phosphomonoesterase). Correlation studies between the population of methylotroph in leaf and that of rhizospheric soil resulted in positive correlation (r=0.762*). Phyllospheric population of the methylotrophic bacteria and soil pH of the study sites also resulted in a positive correlation(r=0.934**). From the research initiative, it could be inferred that a wide array of methylotrophic bacteria occur in the phyllosphere of different crops, and possess plant growth promoting traits. These phyllosphericmethylotrophic bacteria could further be utilized for coinoculation with biofertilizers or used as bioinoculantsin crop improvement.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/5810147554
dc.language.isoenen_US
dc.publisherAAU, Jorhaten_US
dc.subSoil Scienceen_US
dc.themeEcological Occurrences of Methylotrophs in Phyllosphere of cropsen_US
dc.these.typeM.Scen_US
dc.titleEcological Occurrences of Methylotrophs in Phyllosphere of cropsen_US
dc.typeThesisen_US
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