Characterization of Rhizobium sp (SAR-5) isolated from root nodule of Acacia mangium L.

Subudhi, Sachidananda ; Sethi, Debadatta ; Kumar Pattanayak, Sushanta

Abstract

The use of efficient strain of Rhizobium is of prime importance for optimum N2 harvest through legumes. The present investigation on microsymbiont associated with root nodulation of Acacia mangium L., an important forest species having wider adaptability. Certain biochemical and molecular techniques were used to characterize the microsymbiont. The 16S rRNA sequence was submitted to NCBI (National Center for Biotechnology Information) with an assigned accession number as MH 661260 (SAR-5). The dendrogram revealed that the strain MH 661260 (SAR-5) was Rhizobium alamii, exhibiting maximum similarity with Rhizobium mesosinicum strain: NR 043548. The maximum indole acetic acid (89.00 μg/mL) was produced by metabolizing glucose followed by fructose (70.4 μg/mL), mannitol (55.8 μg/mL), lactose (51.4 μg/mL), sucrose (46.2 μg/mL), starch (39.6 μg/mL), galactose (30.6 μg/mL) and maltose (26.4 μg/mL) and the least (16.5 μg/mL) was recorded in control. The plateau stage of growth was attained after 36 h of inoculation, but the exopolysaccharides (EPS) production was the highest (112 μg/mL) at 48 h after inoculation, thereafter reduced in yeast extract mineral medium. The most preferable carbon, nitrogen, and vitamin for EPS production were maltose, L-asparagine, and L-ascorbic acid, respectively and the least preferable were sucrose, KNO3, and riboflavin, respectively. The isolate (SAR-5) could survive in the pH range of 6 to 8 and the salinity level up to 3% NaCl in laboratory conditions.

Keyword(s)

The use of efficient strain of Rhizobium is of prime importance for optimum N2 harvest through legumes. The present investigation on microsymbiont associated with root nodulation of Acacia mangium L., an important forest species having wider adaptability. Certain biochemical and molecular techniques were used to characterize the microsymbiont. The 16S rRNA sequence was submitted to NCBI (National Center for Biotechnology Information) with an assigned accession number as MH 661260 (SAR-5). The dendrogram revealed that the strain MH 661260 (SAR-5) was Rhizobium alamii, exhibiting maximum similarity with Rhizobium mesosinicum strain: NR 043548. The maximum indole acetic acid (89.00 μg/mL) was produced by metabolizing glucose followed by fructose (70.4 μg/mL), mannitol (55.8 μg/mL), lactose (51.4 μg/mL), sucrose (46.2 μg/mL), starch (39.6 μg/mL), galactose (30.6 μg/mL) and maltose (26.4 μg/mL) and the least (16.5 μg/mL) was recorded in control. The plateau stage of growth was attained after 36 h of inoculation, but the exopolysaccharides (EPS) production was the highest (112 μg/mL) at 48 h after inoculation, thereafter reduced in yeast extract mineral medium. The most preferable carbon, nitrogen, and vitamin for EPS production were maltose, L-asparagine, and L-ascorbic acid, respectively and the least preferable were sucrose, KNO3, and riboflavin, respectively. The isolate (SAR-5) could survive in the pH range of 6 to 8 and the salinity level up to 3% NaCl in laboratory conditions.

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