Journal of Environmental Biology

Harnessing the potential of native cyanobacteria for plant growth promoting substances and lipid content

N. Dutta¹*, K. Mahanta¹, A.Gayan², D.J. Nath¹ and B. Bhattacharyya³ 

¹Department of Soil Science, Assam Agricultural University, Jorhat-785 013, India

²Department of Soil Science, College of Sericulture, Assam Agricultural University, Jorhat-785 013, India

³Department of Entomology, Assam Agricultural University, Jorhat-785 013, India

*Corresponding Author Email : nilakhidutta18@gmail.com

Received: 13.06.2020                                                                   Revised: 15.11.2020                                                    Accepted: 15.12.2020

Abstract

Aim: Screening of prospective cyanobacterial strains from paddy fields of Assam to assess their potential for plant growth promoting traits and lipid content as possible feedstock for biofuel.

Methodology: The classical serial dilution technique was used for isolation of cyanobacteria employing BGIIo media. The morphological characterization, total dry biomass, packed cell volume, chlorophyll ‘a’, total nitrogen, extracellular ammonia secretion, indole acetic acids, total carbohydrates, total soluble protein and lipid content were determined following standard protocols.

Results: Out of 30 cyanobacterial isolates obtained initially, 5 prospective isolates viz. BGA₁, BGA₂, BGA₄, BGA₅ and BGA₆ were selected following screening for further studies. Out of 30, 4 were heterocystous (BGA₁, BGA₂, BGA₄ and BGA₆) and one was non-heterocystous (BGA₅). The isolates showed variation in type of filament, shape of vegetative cells, presence or absence of heterocyst and akinetes. Significantly higher biomass production (0.786 mg ml^-1) and chlorophyll ‘a’ content (7.87 µg ml^-1) was recorded in isolate BGA6 over other isolates. Isolate BGA₂ exhibited significantly highest amount of total nitrogen content and extracellular ammonia secretion in the tune of 3.52 % and 50.84 µg ml^-1 respectively. Substantial amount of IAA (1.56 µg ml^-1 -8.20 µg ml^-1), established their positive impact on plant growth. Isolate BGA2 produced significantly highest amount of IAA (8.20 μg ml^-1).      

Interpretation: The study established potential of isolate BGA₂ as a promising plant growth promoting bio-agent owing to its high total nitrogen content, extracellular ammonia secretion and significant production of IAA.       

Key words: Biofuel, Cyanobacteria, Heterocyst, Lipid content

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