Rujirek Noisangiam - Academia.edu (original) (raw)
Papers by Rujirek Noisangiam
Frontiers in Microbiology
Microbes and environments, Jan 31, 2017
With the aim of searching for potent diazotrophic bacteria that are free of public health concern... more With the aim of searching for potent diazotrophic bacteria that are free of public health concerns and optimize rice cultivation, the endophytic colonization and plant growth-promoting activities of some endophytic diazotrophic bacteria isolated from rice were evaluated. Among these bacteria, the emerging diazotrophic strains of the genus Novosphingobium effectively associated with rice plant interiors and consequently promoted the growth of rice, even with the lack of a nitrogen source. These results suggest that diazotrophic Novosphingobium is an alternative microbial resource for further development as a safe biological enhancer in the optimization of organic rice cultivation.
Molecular Plant-Microbe Interactions, 2016
Bradyrhizobium sp. strain DOA9 contains two copies of the nifDK genes, nifDKc, located on the chr... more Bradyrhizobium sp. strain DOA9 contains two copies of the nifDK genes, nifDKc, located on the chromosome, and nifDKp, located on a symbiotic megaplasmid. Unlike most rhizobia, this bacterium displays nitrogenase activity under both free-living and symbiotic conditions. Transcriptional analysis using gusA reporter strains showed that both nifDK operons were highly expressed under symbiosis, whereas nifDKc was the most abundantly expressed under free-living conditions. During free-living growth, the nifDKp mutation did not affect nitrogenase activity, whereas nitrogenase activity was drastically reduced with the nifDKc mutant. This led us to suppose that nifDKc is the main contributor of nitrogenase activity in the free-living state. In contrast, during symbiosis, no effect of the nifDKc mutation was observed and the nitrogen-fixation efficiency of plants inoculated with the nifDKp mutant was reduced. This suggests that nifDKp plays the main role in nitrogenase enzyme activity during ...
Http Dx Doi Org 10 1080 00380768 2013 804391, Aug 1, 2013
ABSTRACT Ethylene is synthesized at accelerated rate in response to stress conditions, and regard... more ABSTRACT Ethylene is synthesized at accelerated rate in response to stress conditions, and regarded as a stress hormone that inhibits overall plant growth. Apparently, the amount of ethylene can be reduced by using silver thiosulfate (STS) or bacteria containing 1-amino-cyclopropane-1-carboxylate (ACC) deaminase. In this study, we examined whether different concentrations of STS differently prevent legume growth under various environment stress conditions, and whether co-inoculation of mungbean (Vigna radiata (L.) R. Wilczek) by Bradyrhizobium and rhizobacteria containing ACC deaminase also alleviates legume stress. Mungbean is one of the most responsive plants among tested legume species, and different varieties of mungbean also respond differently to STS. Stress conditions and inappropriate concentrations of STS affect plant growth and symbiosis, while a suitable concentration of STS supports plant growth under stress conditions. Three isolates of bacteria containing ACC deaminase, Enterobacter sp. ACC1, Enterobacter sp. ACC2, and Chryseobacterium sp. ACC3, were selected according to their ACC deaminase activity and resistance abilities to high temperature, drought, and salt stress conditions. Interestingly, the gene encoding ACC deaminase, acdS, of selected ACC deaminase bacteria was highly induced when the cell culture was exposed to stress conditions. It coincided with co-inoculation of plants by Bradyrhizobium and rhizobacteria containing ACC deaminase. This co-inoculation obviously alleviated the stress of plants growing under stress conditions. These results revealed the role of bacteria containing ACC deaminase that can adjust its expression of ACC deaminase to different levels of stress conditions, which will be useful in agriculture under global warming.
Systematic and Applied Microbiology, 2011
To study the invasion process and colonization of rice by nitrogen-fixing Sphingomonas sp. PS5, r... more To study the invasion process and colonization of rice by nitrogen-fixing Sphingomonas sp. PS5, rice seedlings cultured gnotobiotically in nitrogen-free medium were inoculated with the DsRed- or GUS-marked Sphingomonas sp. PS5. Observation using inverted fluorescence microscope showed that the bacterial cells initially colonized at root hairs and epidermal cells. The bacterial invasion occurs at the site of emerging lateral roots and at elongation and differentiation zones of root tip. Then, the bacterial cells spread further through the root cortex, xylem and pith, where the bacteria migrated to stems and leaves. The bacterial cells were found to locate in both inter- and intra-cellular spaces. Cellulase and nitrogenase activity of Sphingomonas sp. PS5 culture were examined by DNA method and acetylene reduction assay. The expression of cellulase and nitrogenase genes were detected by RT-PCR. In free-living state, the bacterium was found to have cellulase activity (0.72 U/mL), and t...
![Research paper thumbnail of Erratum to “Heavy metal tolerant Metalliresistens boonkerdii gen. nov., sp. nov., a new genus in the family Bradyrhizobiaceae isolated from soil in Thailand” [Syst. Appl. Microbiol. 33 (2010) 374–382]. Proposal of Rhodopseudomonas boonkerdii sp. nov., a new heavy metal tolerant bacterium isolated...](https://attachments.academia-assets.com/73667057/thumbnails/1.jpg)
](Systematic and Applied Microbiology, 2011
Erratum Erratum to "Heavy metal tolerant Metalliresistens boonkerdii gen. nov., sp. nov., a new g... more Erratum Erratum to "Heavy metal tolerant Metalliresistens boonkerdii gen. nov., sp. nov., a new genus in the family Bradyrhizobiaceae isolated from soil in Thailand" [Syst. Appl. Microbiol. 33 (2010) 374-382]. Proposal of Rhodopseudomonas boonkerdii sp. nov., a new heavy metal tolerant bacterium isolated from Thailand
PLOS ONE, 2015
Bradyrhizobium sp. DOA9 isolated from the legume Aeschynomene americana exhibited a broad host ra... more Bradyrhizobium sp. DOA9 isolated from the legume Aeschynomene americana exhibited a broad host range and divergent nodulation (nod) genes compared with other members of the Bradyrhizobiaceae. Genome analysis of DOA9 revealed that its genome comprised a single chromosome of 7.1 Mbp and a plasmid of 0.7 Mbp. The chromosome showed highest similarity with that of the nod gene-harboring soybean symbiont B. japonicum USDA110, whereas the plasmid showed highest similarity with pBBta01 of the nod gene-lacking photosynthetic strain BTAi1, which nodulates Aeschynomene species. Unlike in other bradyrhizobia, the plasmid of DOA9 encodes genes related to symbiotic functions including nodulation, nitrogen fixation, and type III/IV protein secretion systems. The plasmid has also a lower GC content (60.1%) than the chromosome (64.4%). These features suggest that the plasmid could be the origin of the symbiosis island that is found in the genome of other bradyrhizobia. The nod genes of DOA9 exhibited low similarity with those of other strains. The nif gene cluster of DOA9 showed greatest similarity to those of photosynthetic bradyrhizobia. The type III/IV protein secretion systems of DOA9 are similar to those of nod gene-harboring B. elkanii and photosynthetic BTAi1. The DOA9 genome exhibited intermediate characteristics between nod gene-harboring bradyrhizobia and nod gene-lacking photosynthetic bradyrhizobia, thus providing the evidence for the evolution of the Bradyrhizobiaceae during ecological adaptation. Bradyrhizobium sp. DOA9 isolated from the legume Aeschynomene americana exhibited a broad host range and divergent nodulation (nod) genes compared with other members of the Bradyrhizobiaceae. Genome analysis of DOA9 revealed that its genome comprised a single chromosome of 7.1 Mbp and a plasmid of 0.7 Mbp. The chromosome showed highest similarity with that of the nod gene-harboring soybean symbiont B. japonicum USDA110, whereas the plasmid showed highest similarity with pBBta01 of the nod gene-lacking photosynthetic strain BTAi1, which nodulates PLOS ONE |
Microbes and Environments, 2014
Bradyrhizobium sp. DOA9, a non-photosynthetic bacterial strain originally isolated from the root ... more Bradyrhizobium sp. DOA9, a non-photosynthetic bacterial strain originally isolated from the root nodules of the legume Aeschynomene americana, is a divergent nod-containing strain. It exhibits a broad host range, being able to colonize and efficiently nodulate the roots of most plants from the Dalbergioid, Millettioid, and Robinioid tribes (7 species of Papilionoideae). In all cases, nodulation was determinate. The morphology and size of DOA9 bacteroids isolated from the nodules of various species of Papilionoideae were indistinguishable from the free-living form. However, they were spherical in Arachis hypogaea nodules. GusA-tagged DOA9 also colonized rice roots as endophytes. Since broad-host-range legume symbionts often carry multiple replicons in their genome, we analyzed the replicons for symbiosis genes by electrophoresis. DOA9 carried two replicons, a chromosome (cDOA9) and single megaplasmid (pDOA9) larger than 352 kb. The genes for nodulation (nodA, B, C) and nitrogen fixation (nifH) were localized on the megaplasmid. Southern blot hybridization revealed two copies of nodA on the megaplasmid, single copies of nodB and C on the megaplasmid, and one copy each of nifH on the chromosome and megaplasmid. These results suggested that Bradyrhizobium sp. DOA9 may have the unusual combination of a broad host range, bacteroid differentiation, and symbiosis-mediating replicons.
Systematic and Applied Microbiology, 2010
Bacterial strains from inoculated soybean field soil in Thailand were directly isolated using Bra... more Bacterial strains from inoculated soybean field soil in Thailand were directly isolated using Bradyrhizobium japonicum selective medium (BJSM), on the basis of Zn 2+ and Co 2+ resistance of B. japonicum and B. elkanii. The isolates were classified into symbiotic and non-symbiotic groups by inoculation assays and Southern hybridization of nod and nif genes. In this study, a nearly full-length 16S rRNA gene sequence showed that the non-symbiotic isolates were more closely related to members of Rhodopseudomonas and to a number of uncultured bacterial clones than to members of Bradyrhizobium. Therefore, a polyphasic study was performed to determine the taxonomic positions of four representatives of the non-symbiotic isolates. Multilocus phylogenetic analysis of individual genes and a combination of the 16S rRNA and three housekeeping genes (atpD, recA and glnII) supported the placement of the non-symbiotic isolates in a different genus. The ability of heavy metal resistance in conjunction with phenotypic analyses, including cellular fatty acid content and biochemical characteristics, showed that the non-symbiotic isolates were differentiated from the other related genera in the family Bradyrhizobiaceae. Therefore, the nonsymbiotic isolates represented a novel genus and species, for which the name Metalliresistens boonkerdii gen. nov., sp. nov. is proposed. The type strain is NS23 (= NBRC 106595 T = BCC 40155 T).
Pedosphere, 2013
ABSTRACT Plant growth-promoting rhizobacteria (PGPR) have been widely recognized as an important ... more ABSTRACT Plant growth-promoting rhizobacteria (PGPR) have been widely recognized as an important agent, especially as a biofertilizer, in agricultural systems. The objectives of this study were to select effective PGPR for Chinese kale (Brassica oleracea var. alboglabra) cultivation and to investigate the effect of their inoculation on indigenous microbial community structure. The Bacillus sp. SUT1 and Pseudomonas sp. SUT19 were selected for determining the efficiency in promoting Chinese kale growth in both pot and field experiments. In the field experiment, PGPR amended with compost gave the highest yields among all treatments. The Chinese kale growth promotion may be directly affected by PGPR inoculation. The changes of microbial community structure in the rhizosphere of Chinese kale following PGPR inoculation were examined by denaturing gradient gel electrophoresis (DGGE) and principal coordinate analysis. The DGGE fingerprints of 16S rDNA amplified from total community DNA in the rhizosphere confirmed that our isolates were established in the rhizosphere throughout this study. The microbial community structures were slightly different among all the treatments, and the major changes depended on stages of plant growth. DNA sequencing of excised DGGE bands showed that the dominant species in microbial community structure in the rhizosphere were not mainly interfered by PGPR, but strongly influenced by plant development. The microbial diversity as revealed by diversity indices was not different between the PGPR-inoculated and uninoculated treatments. In addition, the rhizosphere soil had more influence on eubacterial diversity, whereas it did not affect archaebacterial and fungal diversities.
Applied and Environmental Microbiology, 2012
ABSTRACTThe diversity of bacteria nodulatingAeschynomene americanaL. in Thailand was determined f... more ABSTRACTThe diversity of bacteria nodulatingAeschynomene americanaL. in Thailand was determined from phenotypic characteristics and multilocus sequence analysis of the 16S rRNA gene and 3 housekeeping genes (dnaK,recA, andglnB). The isolated strains were nonphotosynthetic bacteria and were assigned to the genusBradyrhizobium, in whichB. yuanmingensewas the dominant species. Some of the other species, includingB. japonicum,B. liaoningense, andB. canariense, were minor species. These isolated strains were divided into 2 groups—nod-containing and divergentnod-containing strains—based on Southern blot hybridization and PCR amplification ofnodABCgenes. The divergentnodgenes could not be PCR amplified and failed to hybridizenodgene probes designed fromB. japonicumUSDA110, but hybridized to probes from other bradyrhizobial strains under low-stringency conditions. The grouping based on sequence similarity ofnodgenes was well correlated with the grouping based on that ofnifHgene, in which th...
Annals of Microbiology, 2014
ABSTRACT Population density of endophytic diazotrophic bacteria (EDB) was highest in the rice lan... more ABSTRACT Population density of endophytic diazotrophic bacteria (EDB) was highest in the rice landrace root tissues at nursery stage. Indole-3-acetic acid (IAA) production (0.85–16.66 μg mL−1) was found in 21 strains tested. More than 80 % (18 isolates) of the isolates solubilized phosphate, while only 28.57 % (six isolates) of selected strains produced siderophore. Seventy-one percent of tested isolates produced ammonia. The effects of EDB isolated from rice landraces on seed and on the growth of the commercial jasmine rice cultivar Khao Dawk Mali 105 were evaluated in greenhouse. Inoculation of all EDB on rice seeds significantly increased nitrogen content in roots (P = 0.05). The potentially useful isolates belonged to four different genera Burkholderia, Klebsiella, Novosphingobium and Sphingomonas. In vivo colonization of Burkholderia sp. SS5, Klebsiella sp. SS2, Novosphingobium sp. TR4 and Sphingomonas sp. PS5 was confirmed using the commercial rice cultivar Khao Dawk Mali 105 as a model host. The inoculated roots with ß-glucuronidase (GUS)-tagged bacteria exhibited a blue color, which was most intense at the tip of root hairs, root tips, germination point and leaf tips.
Microbes and environments / JSME, Jan 19, 2014
Bradyrhizobium sp. DOA9, a non-photosynthetic bacterial strain originally isolated from the root ... more Bradyrhizobium sp. DOA9, a non-photosynthetic bacterial strain originally isolated from the root nodules of the legume Aeschynomene americana, is a divergent nod-containing strain. It exhibits a broad host range, being able to colonize and efficiently nodulate the roots of most plants from the Dalbergioid, Millettioid, and Robinioid tribes (7 species of Papilionoideae). In all cases, nodulation was determinate. The morphology and size of DOA9 bacteroids isolated from the nodules of various species of Papilionoideae were indistinguishable from the free-living form. However, they were spherical in Arachis hypogaea nodules. GusA-tagged DOA9 also colonized rice roots as endophytes. Since broad-host-range legume symbionts often carry multiple replicons in their genome, we analyzed the replicons for symbiosis genes by electrophoresis. DOA9 carried two replicons, a chromosome (cDOA9) and single megaplasmid (pDOA9) larger than 352 kb. The genes for nodulation (nodA, B, C) and nitrogen fixat...
Frontiers in Microbiology
Microbes and environments, Jan 31, 2017
With the aim of searching for potent diazotrophic bacteria that are free of public health concern... more With the aim of searching for potent diazotrophic bacteria that are free of public health concerns and optimize rice cultivation, the endophytic colonization and plant growth-promoting activities of some endophytic diazotrophic bacteria isolated from rice were evaluated. Among these bacteria, the emerging diazotrophic strains of the genus Novosphingobium effectively associated with rice plant interiors and consequently promoted the growth of rice, even with the lack of a nitrogen source. These results suggest that diazotrophic Novosphingobium is an alternative microbial resource for further development as a safe biological enhancer in the optimization of organic rice cultivation.
Molecular Plant-Microbe Interactions, 2016
Bradyrhizobium sp. strain DOA9 contains two copies of the nifDK genes, nifDKc, located on the chr... more Bradyrhizobium sp. strain DOA9 contains two copies of the nifDK genes, nifDKc, located on the chromosome, and nifDKp, located on a symbiotic megaplasmid. Unlike most rhizobia, this bacterium displays nitrogenase activity under both free-living and symbiotic conditions. Transcriptional analysis using gusA reporter strains showed that both nifDK operons were highly expressed under symbiosis, whereas nifDKc was the most abundantly expressed under free-living conditions. During free-living growth, the nifDKp mutation did not affect nitrogenase activity, whereas nitrogenase activity was drastically reduced with the nifDKc mutant. This led us to suppose that nifDKc is the main contributor of nitrogenase activity in the free-living state. In contrast, during symbiosis, no effect of the nifDKc mutation was observed and the nitrogen-fixation efficiency of plants inoculated with the nifDKp mutant was reduced. This suggests that nifDKp plays the main role in nitrogenase enzyme activity during ...
Http Dx Doi Org 10 1080 00380768 2013 804391, Aug 1, 2013
ABSTRACT Ethylene is synthesized at accelerated rate in response to stress conditions, and regard... more ABSTRACT Ethylene is synthesized at accelerated rate in response to stress conditions, and regarded as a stress hormone that inhibits overall plant growth. Apparently, the amount of ethylene can be reduced by using silver thiosulfate (STS) or bacteria containing 1-amino-cyclopropane-1-carboxylate (ACC) deaminase. In this study, we examined whether different concentrations of STS differently prevent legume growth under various environment stress conditions, and whether co-inoculation of mungbean (Vigna radiata (L.) R. Wilczek) by Bradyrhizobium and rhizobacteria containing ACC deaminase also alleviates legume stress. Mungbean is one of the most responsive plants among tested legume species, and different varieties of mungbean also respond differently to STS. Stress conditions and inappropriate concentrations of STS affect plant growth and symbiosis, while a suitable concentration of STS supports plant growth under stress conditions. Three isolates of bacteria containing ACC deaminase, Enterobacter sp. ACC1, Enterobacter sp. ACC2, and Chryseobacterium sp. ACC3, were selected according to their ACC deaminase activity and resistance abilities to high temperature, drought, and salt stress conditions. Interestingly, the gene encoding ACC deaminase, acdS, of selected ACC deaminase bacteria was highly induced when the cell culture was exposed to stress conditions. It coincided with co-inoculation of plants by Bradyrhizobium and rhizobacteria containing ACC deaminase. This co-inoculation obviously alleviated the stress of plants growing under stress conditions. These results revealed the role of bacteria containing ACC deaminase that can adjust its expression of ACC deaminase to different levels of stress conditions, which will be useful in agriculture under global warming.
Systematic and Applied Microbiology, 2011
To study the invasion process and colonization of rice by nitrogen-fixing Sphingomonas sp. PS5, r... more To study the invasion process and colonization of rice by nitrogen-fixing Sphingomonas sp. PS5, rice seedlings cultured gnotobiotically in nitrogen-free medium were inoculated with the DsRed- or GUS-marked Sphingomonas sp. PS5. Observation using inverted fluorescence microscope showed that the bacterial cells initially colonized at root hairs and epidermal cells. The bacterial invasion occurs at the site of emerging lateral roots and at elongation and differentiation zones of root tip. Then, the bacterial cells spread further through the root cortex, xylem and pith, where the bacteria migrated to stems and leaves. The bacterial cells were found to locate in both inter- and intra-cellular spaces. Cellulase and nitrogenase activity of Sphingomonas sp. PS5 culture were examined by DNA method and acetylene reduction assay. The expression of cellulase and nitrogenase genes were detected by RT-PCR. In free-living state, the bacterium was found to have cellulase activity (0.72 U/mL), and t...
Systematic and Applied Microbiology, 2011
Erratum Erratum to "Heavy metal tolerant Metalliresistens boonkerdii gen. nov., sp. nov., a new g... more Erratum Erratum to "Heavy metal tolerant Metalliresistens boonkerdii gen. nov., sp. nov., a new genus in the family Bradyrhizobiaceae isolated from soil in Thailand" [Syst. Appl. Microbiol. 33 (2010) 374-382]. Proposal of Rhodopseudomonas boonkerdii sp. nov., a new heavy metal tolerant bacterium isolated from Thailand
PLOS ONE, 2015
Bradyrhizobium sp. DOA9 isolated from the legume Aeschynomene americana exhibited a broad host ra... more Bradyrhizobium sp. DOA9 isolated from the legume Aeschynomene americana exhibited a broad host range and divergent nodulation (nod) genes compared with other members of the Bradyrhizobiaceae. Genome analysis of DOA9 revealed that its genome comprised a single chromosome of 7.1 Mbp and a plasmid of 0.7 Mbp. The chromosome showed highest similarity with that of the nod gene-harboring soybean symbiont B. japonicum USDA110, whereas the plasmid showed highest similarity with pBBta01 of the nod gene-lacking photosynthetic strain BTAi1, which nodulates Aeschynomene species. Unlike in other bradyrhizobia, the plasmid of DOA9 encodes genes related to symbiotic functions including nodulation, nitrogen fixation, and type III/IV protein secretion systems. The plasmid has also a lower GC content (60.1%) than the chromosome (64.4%). These features suggest that the plasmid could be the origin of the symbiosis island that is found in the genome of other bradyrhizobia. The nod genes of DOA9 exhibited low similarity with those of other strains. The nif gene cluster of DOA9 showed greatest similarity to those of photosynthetic bradyrhizobia. The type III/IV protein secretion systems of DOA9 are similar to those of nod gene-harboring B. elkanii and photosynthetic BTAi1. The DOA9 genome exhibited intermediate characteristics between nod gene-harboring bradyrhizobia and nod gene-lacking photosynthetic bradyrhizobia, thus providing the evidence for the evolution of the Bradyrhizobiaceae during ecological adaptation. Bradyrhizobium sp. DOA9 isolated from the legume Aeschynomene americana exhibited a broad host range and divergent nodulation (nod) genes compared with other members of the Bradyrhizobiaceae. Genome analysis of DOA9 revealed that its genome comprised a single chromosome of 7.1 Mbp and a plasmid of 0.7 Mbp. The chromosome showed highest similarity with that of the nod gene-harboring soybean symbiont B. japonicum USDA110, whereas the plasmid showed highest similarity with pBBta01 of the nod gene-lacking photosynthetic strain BTAi1, which nodulates PLOS ONE |
Microbes and Environments, 2014
Bradyrhizobium sp. DOA9, a non-photosynthetic bacterial strain originally isolated from the root ... more Bradyrhizobium sp. DOA9, a non-photosynthetic bacterial strain originally isolated from the root nodules of the legume Aeschynomene americana, is a divergent nod-containing strain. It exhibits a broad host range, being able to colonize and efficiently nodulate the roots of most plants from the Dalbergioid, Millettioid, and Robinioid tribes (7 species of Papilionoideae). In all cases, nodulation was determinate. The morphology and size of DOA9 bacteroids isolated from the nodules of various species of Papilionoideae were indistinguishable from the free-living form. However, they were spherical in Arachis hypogaea nodules. GusA-tagged DOA9 also colonized rice roots as endophytes. Since broad-host-range legume symbionts often carry multiple replicons in their genome, we analyzed the replicons for symbiosis genes by electrophoresis. DOA9 carried two replicons, a chromosome (cDOA9) and single megaplasmid (pDOA9) larger than 352 kb. The genes for nodulation (nodA, B, C) and nitrogen fixation (nifH) were localized on the megaplasmid. Southern blot hybridization revealed two copies of nodA on the megaplasmid, single copies of nodB and C on the megaplasmid, and one copy each of nifH on the chromosome and megaplasmid. These results suggested that Bradyrhizobium sp. DOA9 may have the unusual combination of a broad host range, bacteroid differentiation, and symbiosis-mediating replicons.
Systematic and Applied Microbiology, 2010
Bacterial strains from inoculated soybean field soil in Thailand were directly isolated using Bra... more Bacterial strains from inoculated soybean field soil in Thailand were directly isolated using Bradyrhizobium japonicum selective medium (BJSM), on the basis of Zn 2+ and Co 2+ resistance of B. japonicum and B. elkanii. The isolates were classified into symbiotic and non-symbiotic groups by inoculation assays and Southern hybridization of nod and nif genes. In this study, a nearly full-length 16S rRNA gene sequence showed that the non-symbiotic isolates were more closely related to members of Rhodopseudomonas and to a number of uncultured bacterial clones than to members of Bradyrhizobium. Therefore, a polyphasic study was performed to determine the taxonomic positions of four representatives of the non-symbiotic isolates. Multilocus phylogenetic analysis of individual genes and a combination of the 16S rRNA and three housekeeping genes (atpD, recA and glnII) supported the placement of the non-symbiotic isolates in a different genus. The ability of heavy metal resistance in conjunction with phenotypic analyses, including cellular fatty acid content and biochemical characteristics, showed that the non-symbiotic isolates were differentiated from the other related genera in the family Bradyrhizobiaceae. Therefore, the nonsymbiotic isolates represented a novel genus and species, for which the name Metalliresistens boonkerdii gen. nov., sp. nov. is proposed. The type strain is NS23 (= NBRC 106595 T = BCC 40155 T).
Pedosphere, 2013
ABSTRACT Plant growth-promoting rhizobacteria (PGPR) have been widely recognized as an important ... more ABSTRACT Plant growth-promoting rhizobacteria (PGPR) have been widely recognized as an important agent, especially as a biofertilizer, in agricultural systems. The objectives of this study were to select effective PGPR for Chinese kale (Brassica oleracea var. alboglabra) cultivation and to investigate the effect of their inoculation on indigenous microbial community structure. The Bacillus sp. SUT1 and Pseudomonas sp. SUT19 were selected for determining the efficiency in promoting Chinese kale growth in both pot and field experiments. In the field experiment, PGPR amended with compost gave the highest yields among all treatments. The Chinese kale growth promotion may be directly affected by PGPR inoculation. The changes of microbial community structure in the rhizosphere of Chinese kale following PGPR inoculation were examined by denaturing gradient gel electrophoresis (DGGE) and principal coordinate analysis. The DGGE fingerprints of 16S rDNA amplified from total community DNA in the rhizosphere confirmed that our isolates were established in the rhizosphere throughout this study. The microbial community structures were slightly different among all the treatments, and the major changes depended on stages of plant growth. DNA sequencing of excised DGGE bands showed that the dominant species in microbial community structure in the rhizosphere were not mainly interfered by PGPR, but strongly influenced by plant development. The microbial diversity as revealed by diversity indices was not different between the PGPR-inoculated and uninoculated treatments. In addition, the rhizosphere soil had more influence on eubacterial diversity, whereas it did not affect archaebacterial and fungal diversities.
Applied and Environmental Microbiology, 2012
ABSTRACTThe diversity of bacteria nodulatingAeschynomene americanaL. in Thailand was determined f... more ABSTRACTThe diversity of bacteria nodulatingAeschynomene americanaL. in Thailand was determined from phenotypic characteristics and multilocus sequence analysis of the 16S rRNA gene and 3 housekeeping genes (dnaK,recA, andglnB). The isolated strains were nonphotosynthetic bacteria and were assigned to the genusBradyrhizobium, in whichB. yuanmingensewas the dominant species. Some of the other species, includingB. japonicum,B. liaoningense, andB. canariense, were minor species. These isolated strains were divided into 2 groups—nod-containing and divergentnod-containing strains—based on Southern blot hybridization and PCR amplification ofnodABCgenes. The divergentnodgenes could not be PCR amplified and failed to hybridizenodgene probes designed fromB. japonicumUSDA110, but hybridized to probes from other bradyrhizobial strains under low-stringency conditions. The grouping based on sequence similarity ofnodgenes was well correlated with the grouping based on that ofnifHgene, in which th...
Annals of Microbiology, 2014
ABSTRACT Population density of endophytic diazotrophic bacteria (EDB) was highest in the rice lan... more ABSTRACT Population density of endophytic diazotrophic bacteria (EDB) was highest in the rice landrace root tissues at nursery stage. Indole-3-acetic acid (IAA) production (0.85–16.66 μg mL−1) was found in 21 strains tested. More than 80 % (18 isolates) of the isolates solubilized phosphate, while only 28.57 % (six isolates) of selected strains produced siderophore. Seventy-one percent of tested isolates produced ammonia. The effects of EDB isolated from rice landraces on seed and on the growth of the commercial jasmine rice cultivar Khao Dawk Mali 105 were evaluated in greenhouse. Inoculation of all EDB on rice seeds significantly increased nitrogen content in roots (P = 0.05). The potentially useful isolates belonged to four different genera Burkholderia, Klebsiella, Novosphingobium and Sphingomonas. In vivo colonization of Burkholderia sp. SS5, Klebsiella sp. SS2, Novosphingobium sp. TR4 and Sphingomonas sp. PS5 was confirmed using the commercial rice cultivar Khao Dawk Mali 105 as a model host. The inoculated roots with ß-glucuronidase (GUS)-tagged bacteria exhibited a blue color, which was most intense at the tip of root hairs, root tips, germination point and leaf tips.
Microbes and environments / JSME, Jan 19, 2014
Bradyrhizobium sp. DOA9, a non-photosynthetic bacterial strain originally isolated from the root ... more Bradyrhizobium sp. DOA9, a non-photosynthetic bacterial strain originally isolated from the root nodules of the legume Aeschynomene americana, is a divergent nod-containing strain. It exhibits a broad host range, being able to colonize and efficiently nodulate the roots of most plants from the Dalbergioid, Millettioid, and Robinioid tribes (7 species of Papilionoideae). In all cases, nodulation was determinate. The morphology and size of DOA9 bacteroids isolated from the nodules of various species of Papilionoideae were indistinguishable from the free-living form. However, they were spherical in Arachis hypogaea nodules. GusA-tagged DOA9 also colonized rice roots as endophytes. Since broad-host-range legume symbionts often carry multiple replicons in their genome, we analyzed the replicons for symbiosis genes by electrophoresis. DOA9 carried two replicons, a chromosome (cDOA9) and single megaplasmid (pDOA9) larger than 352 kb. The genes for nodulation (nodA, B, C) and nitrogen fixat...