Diversity of free-living nitrogen-fixing bacteria associated with Korean paddy fields

Islam, Md. Rashedul; Sultana, Tahera; Cho, Jang-Cheon; Joe, Manoharan Melvin; M., T.

doi:10.1007/s13213-012-0421-z

Cited by 23 publications

(14 citation statements)

References 34 publications

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“…N 2 -fixation ability was the first screening criteria of the isolates since this characteristic is vital and crucial to the plants as a potential alternative to reduce chemical Nfertilizer application. Bacterial strains with dual beneficial characteristics isolated from this study are slightly higher than isolation percentage of N 2 -fixing bacteria from Korean rice fields (Islam et al, 2012), 32 out of 165 (19.4%) and lower than isolation of diazotrophs from pepper vine (Zakry et al, 2010, 14 out of 45 (31.1%). Diazotrophs contain nitrogenase enzyme and thus capable of fixing atmospheric nitrogen into ammonium which are subsequently absorbed by plants via Biological N 2 Fixation (BNF) process (Boddey et al, 1995).…”

Section: Discussioncontrasting

confidence: 53%

Isolation and Characterization of Rhizobia and Plant Growth-Promoting Rhizobacteria and Their Effects on Growth of Rice Seedlings

Tan

Othman

Halimi

et al. 2014

American Journal of Agricultural and Biological Sciences

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Biofertilizer is a relatively safer, environmentally friendly and cost-effective approach as an alternative to reduce chemical fertilizer usage. The selection of bacterial strains with multiple beneficial characteristics are important to maximize the effectiveness on the host plant. Due to aforementioned interest, several Plant Growth-Promoting Rhizobacterial (PGPR) and rhizobial strains were isolated from rice and legume roots, respectively, at four locations in Malaysia namely Universiti Putra Malaysia (UPM), Serdang, Selangor; Besut, Terengganu; Tunjung, Kelantan and Sik, Kedah. Bacterial isolations were undertaken to select the best isolates which exhibit multiple beneficial effects to the rice plant and a total of 205 bacterial strains were isolated and categorized as follows; 94 rhizospheric and 107 endophytic bacteria from rice roots, one rhizobial strain from soybean and three from Mimosa pudica. These isolates were screened for their abilities to fix N 2 and solubilize phosphate; 52 were positive for both tests. The selected isolates were then tested for IAA production and other biochemical tests such as potassium solubilization, hydrolyzing enzymes (cellulase and pectinase) and iron siderophore productions. Four isolates, namely UPMB19 (rhizospheric PGPR from Tunjung, Kelantan), UPMB20 (endophytic PGPR from Besut, Terengganu), UPMR30 (rhizobia from soybean) and UPMR31 (rhizobia from Mimosa) were selected for subsequent plant inoculation tests with UPMB10, a PGPR isolated from oil palm root, as the reference strain. Based on 16S rDNA gene sequencing, these bacterial strains were identified under several genera: Lysinibacillus, Alcaligenes, Bradyrhizobium, Rhizobium and Bacillus, respectively. Results of plant inoculation test indicated that UPMB19 significantly enhanced the seedling height at the early growth stage (7 days after transplanting, DAT) which could be attributed to the higher N 2 fixation rate of this strain as compared to the other strains, except UPMB20. UPMB10 and UPMR31 also showed significant effects with increased seedling height and Total Dry Weight (TDW) at the later stage (14 DAT) possibly due to the higher bacterial population and IAA produced as observed in the residual nutrient solution without addition of fertilizer-N. This study has successfully demonstrated the effectiveness of locally isolated PGPR and rhizobial strains with multiple beneficial characteristics on early growth and vigor of rice seedlings under controlled condition. The result proved to be a vital information in the development of a liquid biofertilizer for rice; thus further studies will be done to evaluate the effectiveness of these isolates under glasshouse and field conditions on growth, tillering and yield of rice.

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Section: Discussioncontrasting

confidence: 53%

Isolation and Characterization of Rhizobia and Plant Growth-Promoting Rhizobacteria and Their Effects on Growth of Rice Seedlings

Tan

Othman

Halimi

et al. 2014

American Journal of Agricultural and Biological Sciences

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“…Screening for PGP ability of the strains All of the nitrogen-fixing bacterial strains were screened in terms of their PGP ability, and the results are presented in Table 1. ARA of the selected strains ranged from 1.8 to 102.6 nM of ethylene/h/mg of protein, and PCR amplification confirmed all strains to be positive for the nifH gene [21,32]. Even though all strains produced a significant amount of IAA, Lysinibacillus sp.…”

Section: Resultsmentioning

confidence: 97%

Nitrogen‐fixing bacteria with multiple plant growth‐promoting activities enhance growth of tomato and red pepper

Islam

Sultana

Joe

et al. 2013

J. Basic Microbiol.

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As a suitable alternative to chemical fertilizers, the application of plant growth-promoting rhizobacteria has been increasing in recent years due to their potential to be used as biofertilizers. In the present work, 13 nitrogen-fixing bacterial strains belonging to 11 different genera were tested for their PGP attributes. All of the strains were positive for 1-aminocyclopropane-1-carboxylate deaminase (ACCD), indole-3-acetic acid (IAA), salicylic acid, and ammonia production while negative for cellulase, pectinase, and hydrocyanic acid production. The strains Pseudomonas sp. RFNB3 and Serratia sp. RFNB14 were the most effective in solubilizing both tri-calcium phosphate and zinc oxide. In addition, all strains except Pseudomonas sp. RFNB3 were able to oxidize sulfur, and six strains were positive for siderophore synthesis. Each strain tested in this study possesses at least four PGP properties in addition to nitrogen fixation. Nine strains were selected based on their multiple PGP potential, particularly ACCD and IAA production, and evaluated for their effects on early growth of tomato and red pepper under gnotobiotic conditions. Bacterial inoculation considerably influenced root and shoot length, seedling vigor, and dry biomass of the two crop plants. Three strains that demonstrated substantial effects on plant performance were further selected for greenhouse trials with red pepper, and among them Pseudomonas sp. RFNB3 resulted in significantly higher plant height (26%) and dry biomass (28%) compared to control. The highest rate of nitrogen fixation, as determined by acetylene reduction assay, occurred in Novosphingobium sp. RFNB21 inoculated red pepper root (49.6 nM of ethylene/h/g of dry root) and rhizosphere soil (41.3 nM of ethylene/h/g of dry soil). Inoculation with nitrogen-fixing bacteria significantly increased chlorophyll content, and the uptake of different macro- and micro-nutrient contents enhancing also in red pepper shoots, in comparison with uninoculated controls. The population estimation studies showed that nitrogen-fixing as well as total heterotrophic bacteria were also noticeably increased in soil and plant samples. The findings of this study suggest that certain nitrogen-fixing strains possessing multiple PGP traits could be applied in the development of biofertilizers.

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“…Sequences that showed >97% similarity with previously reported PGPR genera were grouped. Letter ‘a’ represents nitrogen fixing genera, ‘b’ represents IAA producing genera and ‘c’ represents phosphate solubilizing bacterial genera [ 18 ], [ 19 ], [ 20 ], [ 21 ], [ 42 ], [ 43 ], [ 44 ], [ 46 ], [ 47 ], [ 51 ], [ 52 ], [ 53 ], [ 54 ], [ 55 ], [ 56 ], [ 57 ], [ 58 ], [ 59 ],…”

Section: Resultsmentioning

confidence: 99%

“…Sequences related to nitrogen fixing genera like Azospirillum , Azoarcus , Azotobacter , Bacillus , Cyanobacterium , Enterobacter and Rhizobium were detected in rhizosheath soil. Nitrogen fixation by these genera has been widely described [ 46 ], [ 51 ], [ 52 ], [ 53 ], [ 54 ], [ 55 ], [ 56 ], [ 57 ],[ 58 ]. Similarly, sequences related to genera presenting phosphate solubilizing activity like Arthrobacter , Azospirillum , Bacillus , Enterobacter and Paenibacillus were detected.…”

Section: Discussionmentioning

confidence: 99%

Cultivation-Based and Molecular Assessment of Bacterial Diversity in the Rhizosheath of Wheat under Different Crop Rotations

et al. 2015

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A field study was conducted to compare the formationand bacterial communities of rhizosheaths of wheat grown under wheat-cotton and wheat-rice rotation and to study the effects of bacterial inoculation on plant growth. Inoculation of Azospirillum sp. WS-1 and Bacillus sp. T-34 to wheat plants increased root length, root and shoot dry weight and dry weight of rhizosheathsoil when compared to non-inoculated control plants, and under both crop rotations. Comparing both crop rotations, root length, root and shoot dry weight and dry weight of soil attached with roots were higher under wheat-cotton rotation. Organic acids (citric acid, malic acid, acetic acid and oxalic acid) were detected in rhizosheaths from both rotations, with malic acid being most abundant with 24.8±2 and 21.3±1.5 μg g-1 dry soil in wheat-cotton and wheat-rice rotation, respectively. Two sugars (sucrose, glucose) were detected in wheat rhizosheath under both rotations, with highest concentrations of sucrose (4.08±0.5 μg g-1and 7.36±1.0 μg g-1) and glucose (3.12±0.5 μg g-1 and 3.01± μg g-1) being detected in rhizosheaths of non-inoculated control plants under both rotations. Diversity of rhizosheath-associated bacteria was evaluated by cultivation, as well as by 454-pyrosequencing of PCR-tagged 16S rRNA gene amplicons. A total of 14 and 12 bacterial isolates predominantly belonging to the genera Arthrobacter, Azospirillum, Bacillus, Enterobacter and Pseudomonaswere obtained from the rhizosheath of wheat grown under wheat-cotton and wheat-rice rotation, respectively. Analysis of pyrosequencing data revealed Proteobacteria, Bacteriodetes and Verrucomicrobia as the most abundant phyla in wheat-rice rotation, whereas Actinobacteria, Firmicutes, Chloroflexi, Acidobacteria, Planctomycetes and Cyanobacteria were predominant in wheat-cotton rotation. From a total of 46,971 sequences, 10.9% showed ≥97% similarity with 16S rRNA genes of 32 genera previously shown to include isolates with plant growth promoting activity (nitrogen fixation, phosphate-solubilization, IAA production). Among these, the most predominant genera were Arthrobacter, Azoarcus, Azospirillum, Bacillus, Cyanobacterium, Paenibacillus, Pseudomonas and Rhizobium.

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Diversity of free-living nitrogen-fixing bacteria associated with Korean paddy fields

Cited by 23 publications

References 34 publications

Isolation and Characterization of Rhizobia and Plant Growth-Promoting Rhizobacteria and Their Effects on Growth of Rice Seedlings

Isolation and Characterization of Rhizobia and Plant Growth-Promoting Rhizobacteria and Their Effects on Growth of Rice Seedlings

Nitrogen‐fixing bacteria with multiple plant growth‐promoting activities enhance growth of tomato and red pepper

Cultivation-Based and Molecular Assessment of Bacterial Diversity in the Rhizosheath of Wheat under Different Crop Rotations

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