Acid and salt tolerance behavior of Rhizobium isolates and their effect on microbial diversity in the rhizosphere of redgram (Cajanus cajan L.)

245-252Experiments were conducted in two phases, first under in vitro condition to study the stress tolerant ability and then in pot experiment to study the effect of Rhizobium isolates on rhizospheric microbial activity. The strain CHRS-7 could tolerate the pH 4.0, whereas RAN-1 and RAB-1 could not. The growth of all the strains was luxuriant in 1% NaCl solution and decreased with increase in the concentration of NaCl. All the strains could produce the phytohormone indole acetic acid (IAA) by metabolizing different carbon sources. The highest amount of IAA was produced by RAB-1 (81 µg/mL), CHRS-7 (78 µg/mL) and RAN-1 (72 µg/mL) by metabolizing mannitol, glucose , and sucrose, respectively. The higher bacteria and rhizobial population was enumerated in the treatment with inoculation of Rhizobium strains and added with 50% of soil test dose of nitrogen whereas higher fungi population was enumerated with the treatment receiving 150% of a soil test dose of nitrogen. The soil enzymes activity, microbial biomass carbon and nitrogen were also higher with a lower dose of external sources of N (50% of a soil test dose) and decreased with increase in nitrogen dose

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

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

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

327-333The 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

Acid and salt tolerance behavior of Rhizobium isolates and their effect on microbial diversity in the rhizosphere of redgram (Cajanus cajan L.)

Experiments were conducted in two phases, first under in vitro condition to study the stress tolerant ability and then in pot experiment to study the effect of Rhizobium isolates on rhizospheric microbial activity. The strain CHRS-7 could tolerate the pH 4.0, whereas RAN-1 and RAB-1 could not. The growth of all the strains was luxuriant in 1% NaCl solution and decreased with increase in the concentration of NaCl. All the strains could produce the phytohormone indole acetic acid (IAA) by metabolizing different carbon sources. The highest amount of IAA was produced by RAB-1 (81 µg/mL), CHRS-7 (78 µg/mL) and RAN-1 (72 µg/mL) by metabolizing mannitol, glucose , and sucrose, respectively. The higher bacteria and rhizobial population was enumerated in the treatment with inoculation of Rhizobium strains and added with 50% of soil test dose of nitrogen whereas higher fungi population was enumerated with the treatment receiving 150% of a soil test dose of nitrogen. The soil enzymes activity, microbial biomass carbon and nitrogen were also higher with a lower dose of external sources of N (50% of a soil test dose) and decreased with increase in nitrogen dose

Effect of different carbon, nitrogen and vitamine sources on exopolysaccharide production of Rhizobium species isolated from root nodule of redgram

Three bacterial strains CHRS-7, RAB-1 and RAN-1 were isolated from root nodules of redgram (Cajanus cajan) and identified as Rhizobium sp. based on 16S rDNA sequence homology and assigned accession number MH636329, MH636773 and MH541051, respectively by National Center for Biotechnology Information (NCBI). All the strains could produce copious amount of exopolysaccharides in yeast extract manitol broth medium. All the three strains had different stationary phases but the bacterial growth and exopolysaccharides production occurred simultaneously. The glucose (1.5 %), manitol (2.0%) and sucrose (1.5%) were the preferable carbon sources of CHRS-7, RAB-1 and RAN-1 respectively, for both growth and EPS production. Among the nitrogen sources glycine (0.1%), NaNO3 (0.1%) and KNO3 (0.1%) were the preferable N sources for CHRS-7, RAB-1 and RAN-1 respectively, whereas, CHRS-7, RAB-1 and RAN-1 preferred biotin 1.5%, 2.0% and 1%, respectively

Isolation and characterization of native Rhizobium from root nodules of raikia french bean growing area of Odisha

Injudicious application of nitrogenous fertilizers leads to soil quality deterioration which results into yield loss. The application of biofertilizer containing native efficient rhizobia enhances the nodular properties, N-fixation and soil quality. Therefore, fifty strains of Rhizobium were isolated from root nodule of Raikia french bean and among them only two isolates viz., RBHR-15 and RBHR-21 were confirmed as Rhizobium. The isolates were unable to grow under anaerobic conditions and failed to produce ketolactase enzyme, showed a negative response for gelatin liquefaction and Simmon’s citrate agar test, responded positively towards the indole test, MR-VP, TSI test and could produce NH4+ from peptone in the growth medium. The isolate RBHR-15, could reduce H2S and nitrate whereas, RBHR-21 could not. The growth of both isolates was luxuriant in the nutrient broth containing 1% NaCl and decreased with an increase in the concentration of NaCl and grew profusely in the pH range of 6-8. The generation time of RBHR-15 and RBHR-21 were 16.4and 10.6 h, respectively. The 16s rRNA of both isolates was sequenced and submitted to the National Center for Biotechnology Information (NCBI). The isolates RBHR-15, and RBHR-21 were assigned accession numbers MN480514 and MN480516

Exploring the Role of Mycorrhizal and Rhizobium Inoculation with Organic and Inorganic Fertilizers on the Nutrient Uptake and Growth of <i>Acacia mangium</i> Saplings in Acidic Soil

Strong and healthy saplings are a prerequisite to establish a successful forest. Therefore, an attempt has been made to develop the best package for nutrient supplementation to raise healthy Acacia mangium saplings, especially in acidic soil. The seeds were sown in pots, receiving different combinations of Arbuscularmycorrhizal (AM), Rhizobium inoculation with application of lime, and mustard oil cake (MOC). The highest spore count and infection percentage (3220 kg−1 soil and 69) were recorded in the AM + MOC + R treated pot, whereas the lowest (2553 kg−1 soil and 37) were recorded in the AM + L treated pot. Nitrogen concentration and uptake in the sapling were higher in the Rhizobium-inoculated treatments than the uninoculated ones. The sulfur concentration and uptake were higher in the MOC-supplemented treatment. Similarly, the P, K, Ca, and Mg concentrations and uptakes were higher in the limed treatments than the unlimed ones. The micronutrient concentration and uptake were higher in the unlimed treatments compared to the lime practice. The concentration of N in Rhizobium-treated pots, P and K in lime-treated pots, and S in MOC-treated pots were increased, whereas the soil pH decreased in all treatments except in the integrated package (AM + MOC + R + L) after 120 days. The Ca and Mg were reduced in all treatments, whereas micronutrients were reduced in all packages except the control. Under different nutrient management practices, plant height and stem girth continuously increased by 9.5 to 12 cm and 3 to 4 times, respectively. The production of robust saplings required integrated application of lime, MOC, AM, and Rhizobium in an acid soil that facilitated better root growth with availability of adequate nutrients for saplings

Exploring the Role of Mycorrhizal and Rhizobium Inoculation with Organic and Inorganic Fertilizers on the Nutrient Uptake and Growth of Acacia mangium Saplings in Acidic Soil

Strong and healthy saplings are a prerequisite to establish a successful forest. Therefore, an attempt has been made to develop the best package for nutrient supplementation to raise healthy Acacia mangium saplings, especially in acidic soil. The seeds were sown in pots, receiving different combinations of Arbuscularmycorrhizal (AM), Rhizobium inoculation with application of lime, and mustard oil cake (MOC). The highest spore count and infection percentage (3220 kg&minus;1 soil and 69) were recorded in the AM + MOC + R treated pot, whereas the lowest (2553 kg&minus;1 soil and 37) were recorded in the AM + L treated pot. Nitrogen concentration and uptake in the sapling were higher in the Rhizobium-inoculated treatments than the uninoculated ones. The sulfur concentration and uptake were higher in the MOC-supplemented treatment. Similarly, the P, K, Ca, and Mg concentrations and uptakes were higher in the limed treatments than the unlimed ones. The micronutrient concentration and uptake were higher in the unlimed treatments compared to the lime practice. The concentration of N in Rhizobium-treated pots, P and K in lime-treated pots, and S in MOC-treated pots were increased, whereas the soil pH decreased in all treatments except in the integrated package (AM + MOC + R + L) after 120 days. The Ca and Mg were reduced in all treatments, whereas micronutrients were reduced in all packages except the control. Under different nutrient management practices, plant height and stem girth continuously increased by 9.5 to 12 cm and 3 to 4 times, respectively. The production of robust saplings required integrated application of lime, MOC, AM, and Rhizobium in an acid soil that facilitated better root growth with availability of adequate nutrients for saplings