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International Journal of Current Microbiology and Applied Sciences (IJCMAS)
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National Academy of Agricultural Sciences (NAAS)
NAAS Score: *5.38 (2020)
[Effective from January 1, 2020]
For more details click here

ICV 2018: 95.39
Index Copernicus ICI Journals Master List 2018 - IJCMAS--ICV 2018: 95.39
For more details click here

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PRINT ISSN : 2319-7692
Online ISSN : 2319-7706
Issues : 12 per year
Publisher : Excellent Publishers
Email : editorijcmas@gmail.com / submit@ijcmas.com
Editor-in-chief: Dr.M.Prakash
Index Copernicus ICV 2018: 95.39
NAAS RATING 2020: 5.38

Int.J.Curr.Microbiol.App.Sci.2017.6(6): 2310-2320
DOI: https://doi.org/10.20546/ijcmas.2017.606.274


Selection of Hyper Exopolysaccharide Producing and Cyst Forming Azotobacter Isolates for Better Survival under Stress Conditions
S.L. Sivapriya and Pasupuleti Reddy Priya*
Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore 641003, Tamil Nadu, India
*Corresponding author
Abstract:

The present study was focused to select hyper exopolysaccharide producing and cyst forming Azotobacter isolates of rice from different locations of Tamil Nadu for better performance under the stress conditions prevailing in the rice ecosystem. The factors influencing cyst formation and exopolysaccharide (EPS) production in Azotobacter isolates and the performance of the isolates at different moisture regimes and fertilizer Nitrogen (N) levels in rice under pot culture conditions were also investigated. Based on morphological and biochemical characterization, 10 efficient Azotobacter isolates were selected for evaluating exopolysaccharide production in comparison with two standard strains. Based on exopolysaccharide production, three efficient Azotobacter isolates viz., AztRMD2 (1.755 g/50ml), AztPMK1 (1.56 g/50ml) and AztPMK2 (1.353 g/50ml) were selected for studying the cyst formation. The effect of limiting conditions of specific single micronutrient, combination of two micronutrients, reduced sucrose concentrations and addition of n- butanol as a carbon source on the induction of cyst formation was evaluated. The AztRMD2 showed maximum cyst formation of around 50 - 85 numbers in the growth medium without magnesium and also even when combinations of two micronutrients were eliminated from the growth medium, AztRMD2 formed 90 cysts ml-1. The salinity tolerance of AztRMD2 was evaluated by growing it in the growth medium containing different NaCl concentration. The results indicated that AztRMD2 can withstand upto 4% NaCl concentration whereas maximum polysaccharide production was noticed in the broth containing 0.02% of NaCl concentration. For artificial soil aggregation, AztRMD2 showed maximum pore space percentage (52.5%) and minimum bulk density (1.12g/cc). The aggregation stability (45stable aggregates) was also high in this isolate compared to Control. Hence based on these desirable characters such as exopolysaccharide production, cyst formation, salinity tolerance and soil aggregation, AztRMD2 was selected for studying its performance under different moisture regimes and fertilizer N levels as treatments in comparison with two standard strains in rice (var. ADT43) under pot culture conditions. Among three different moisture regimes, 50% field capacity with AztRMD2 showed the maximum plant height (90cm). With regard to fertilizer N levels used, AztRMD2 isolate with 75 % recommended dose of N showed higher plant height (80 cm). The results indicated that AztRMD2 performed better than the standard strains and other treatments in increasing the growth of rice under water limiting conditions and reduced fertilizer N application.


Keywords: Exopolysaccharide, Azotobacter, Survival and Stress Condition.
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How to cite this article:

Sivapriya, S.L. and Pasupuleti Reddy Priya. 2017. Selection of Hyper Exopolysaccharide Producing and Cyst Forming Azotobacter Isolates for Better Survival under Stress Conditions.Int.J.Curr.Microbiol.App.Sci. 6(6): 2310-2320. doi: https://doi.org/10.20546/ijcmas.2017.606.274