This study was carried out to evaluate the efficacy of two bio-control agents, mycorrhizal fungi ... more This study was carried out to evaluate the efficacy of two bio-control agents, mycorrhizal fungi and the endoparasitic bacterium Pasteuria penetrans in managing development of root-knot nematode, Meloidogyne javanica on tomato. Use of both bio-agents P. penetrans and mycorrhizal fungi, either alone or combined, reduced significantly all related nematode parameters on tomato plants infected with M. javanica. The reduction in galls, egg masses, females/root system and eggs/egg mass as well as juveniles in soil was highly significant when both bio-agents inoculated together as reached 76; 68; 74; 47 and 73%, respectively. Consequently, nematode infected plants that were treated with both bio-agents showed improvement in vegetative plant growth characters as reflected by a significant increase in the fresh shoots and roots as well as dry shoot weights of tomato compared with untreated plants. Moreover the contents of Nitrogen, Phosphorus and Potassium in tomato plants treated with both ...
International journal of food, agriculture and environment, 2005
The community structure of nitrogen-fixing endophytic bacteria associated with roots of three var... more The community structure of nitrogen-fixing endophytic bacteria associated with roots of three varieties, Oryza sativa cv. Sprice and cv. Koshihikari and line NERICA 5 (an interspecific hybrid between O. sativa and O. glaberrima) was analyzed using culture-independent molecular techniques. A segment of nifH gene was amplified from crude rice root DNA, cloned to construct nifH library and sequenced. About 25 clone sequences from each rice root were recovered and their amino acid sequences were compared with those published in DNA Data Bank of Japan (DDBJ). Majority of nifH sequences (79%) of the clones recovered from cv. Sprice were similar to those of unknown and known nitrogen-fixing anaerobes forming cluster (cluster C) distantly related to other nitrogen-fixing bacteria. Moreover, no clone sequences belonging to β- and γ-subdivisions of Proteobacteria (cluster B) were recovered, revealing limited nifH diversity for cv. Sprice root associated community. Although the clone sequences...
Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild ... more Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild and traditionally cultivated rice varieties. Phylogenetic analyses based on 16S rDNA revealed a wide divergence among the isolates. However, the most frequently isolated groups were Methylobacterium sp. in the α-subdivision of Proteobacteria, and Curtobacterium sp. in the high G+ C Gram-positive group. Various phenotypic traits that are expected to be involved in the persistence and functions of the bacteria were analyzed: Most of the isolates from rice excreted pectinase, were motile, and showed an osmotic resistance to 0.6 M sucrose. These traits may be involved in endophytic characteristics in rice. About 50% of the isolates showed a cellulase activity. A few isolates fixed nitrogen, produced indole-3-acetic acid, and formed capsules. These activities were partially correlated with the phylogenetic group.
Bacterial communities of paddy and grassland soils were studied by a plate count method. The colo... more Bacterial communities of paddy and grassland soils were studied by a plate count method. The colony formation processes were simulated by a superposition of the first order reaction (FOR) model curves. Isolates from colonies formed along each FOR curve were collected as a colony forming curve (CFC) group. Sequencing 16SrDNA base sequences revealed that isolates had diverse phylogenetic positions and those of each CFC group showed a trend to make clusters. Bacteria in microaggregate clumps (ca. 0.1 mg) also showed CFC groups similar to those obtained with Ig of soil and were phylogenetically diverse. Based on the results we propose to catalogue all the bacteria of the community in the microaggregates.
Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 1997
Recent studies on the colony formation of soil bacteria opened the way to categorize soil bacteri... more Recent studies on the colony formation of soil bacteria opened the way to categorize soil bacteria into colony forming curve (CFC) groups of different growth rates. A bacterial culture collection comprising organisms from every CFC group is called an ecocollection. Outlines of ECs of paddy soil 1992 and grassland soil 1987 and 1992 were described. Phylogenetic studies by 16S rDNA
Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild ... more Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild and traditionally cultivated rice varieties. Phylogenetic analyses based on 16S rDNA revealed a wide divergence among the isolates. However, the most frequently isolated groups were Methylobacterium sp. in the α-subdivision of Proteobacteria, and Curtobacterium sp. in the high G+ C Gram-positive group. Various phenotypic traits that are expected to be involved in the persistence and functions of the bacteria were analyzed: Most of the isolates from rice excreted pectinase, were motile, and showed an osmotic resistance to 0.6 M sucrose. These traits may be involved in endophytic characteristics in rice. About 50% of the isolates showed a cellulase activity. A few isolates fixed nitrogen, produced indole-3-acetic acid, and formed capsules. These activities were partially correlated with the phylogenetic group.
Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified R... more Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified Rennie medium. Based on 16S ribosomal DNA (rDNA) sequences, the diazotrophic isolates were phylogenetically close to four genera: Herbaspirillum , Ideonella , Enterobacter , and Azospirillum . Phenotypic properties and signature sequences of 16S rDNA indicated that three isolates (B65, B501, and B512) belong to the Herbaspirillum genus. To examine whether Herbaspirillum sp. strain B501 isolated from wild rice, Oryza officinalis , endophytically colonizes rice plants, the gfp gene encoding green fluorescent protein (GFP) was introduced into the bacteria. Observations by fluorescence stereomicroscopy showed that the GFP-tagged bacteria colonized shoots and seeds of aseptically grown seedlings of the original wild rice after inoculation of the seeds. Conversely, for cultivated rice Oryza sativa , no GFP fluorescence was observed for shoots and only weak signals were observed for seeds. Obser...
Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified R... more Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified Rennie medium. Based on 16S ribosomal DNA (rDNA) sequences, the diazotrophic isolates were phylogenetically close to four genera: Herbaspirillum, Ideonella, Enterobacter, and Azospirillum. Phenotypic properties and signature sequences of 16S rDNA indicated that three isolates (B65, B501, and B512) belong to the Herbaspirillum genus. To examine whether Herbaspirillum sp. strain B501 isolated from wild rice, Oryza officinalis, endophytically colonizes rice plants, the gfp gene encoding green fluorescent protein (GFP) was introduced into the bacteria. Observations by fluorescence stereomicroscopy showed that the GFP-tagged bacteria colonized shoots and seeds of aseptically grown seedlings of the original wild rice after inoculation of the seeds. Conversely, for cultivated rice Oryza sativa, no GFP fluorescence was observed for shoots and only weak signals were observed for seeds. Observation...
This study was carried out to evaluate the efficacy of two bio-control agents, mycorrhizal fungi ... more This study was carried out to evaluate the efficacy of two bio-control agents, mycorrhizal fungi and the endoparasitic bacterium Pasteuria penetrans in managing development of root-knot nematode, Meloidogyne javanica on tomato. Use of both bio-agents P. penetrans and mycorrhizal fungi, either alone or combined, reduced significantly all related nematode parameters on tomato plants infected with M. javanica. The reduction in galls, egg masses, females/root system and eggs/egg mass as well as juveniles in soil was highly significant when both bio-agents inoculated together as reached 76; 68; 74; 47 and 73%, respectively. Consequently, nematode infected plants that were treated with both bio-agents showed improvement in vegetative plant growth characters as reflected by a significant increase in the fresh shoots and roots as well as dry shoot weights of tomato compared with untreated plants. Moreover the contents of Nitrogen, Phosphorus and Potassium in tomato plants treated with both ...
International journal of food, agriculture and environment, 2005
The community structure of nitrogen-fixing endophytic bacteria associated with roots of three var... more The community structure of nitrogen-fixing endophytic bacteria associated with roots of three varieties, Oryza sativa cv. Sprice and cv. Koshihikari and line NERICA 5 (an interspecific hybrid between O. sativa and O. glaberrima) was analyzed using culture-independent molecular techniques. A segment of nifH gene was amplified from crude rice root DNA, cloned to construct nifH library and sequenced. About 25 clone sequences from each rice root were recovered and their amino acid sequences were compared with those published in DNA Data Bank of Japan (DDBJ). Majority of nifH sequences (79%) of the clones recovered from cv. Sprice were similar to those of unknown and known nitrogen-fixing anaerobes forming cluster (cluster C) distantly related to other nitrogen-fixing bacteria. Moreover, no clone sequences belonging to β- and γ-subdivisions of Proteobacteria (cluster B) were recovered, revealing limited nifH diversity for cv. Sprice root associated community. Although the clone sequences...
Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild ... more Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild and traditionally cultivated rice varieties. Phylogenetic analyses based on 16S rDNA revealed a wide divergence among the isolates. However, the most frequently isolated groups were Methylobacterium sp. in the α-subdivision of Proteobacteria, and Curtobacterium sp. in the high G+ C Gram-positive group. Various phenotypic traits that are expected to be involved in the persistence and functions of the bacteria were analyzed: Most of the isolates from rice excreted pectinase, were motile, and showed an osmotic resistance to 0.6 M sucrose. These traits may be involved in endophytic characteristics in rice. About 50% of the isolates showed a cellulase activity. A few isolates fixed nitrogen, produced indole-3-acetic acid, and formed capsules. These activities were partially correlated with the phylogenetic group.
Bacterial communities of paddy and grassland soils were studied by a plate count method. The colo... more Bacterial communities of paddy and grassland soils were studied by a plate count method. The colony formation processes were simulated by a superposition of the first order reaction (FOR) model curves. Isolates from colonies formed along each FOR curve were collected as a colony forming curve (CFC) group. Sequencing 16SrDNA base sequences revealed that isolates had diverse phylogenetic positions and those of each CFC group showed a trend to make clusters. Bacteria in microaggregate clumps (ca. 0.1 mg) also showed CFC groups similar to those obtained with Ig of soil and were phylogenetically diverse. Based on the results we propose to catalogue all the bacteria of the community in the microaggregates.
Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 1997
Recent studies on the colony formation of soil bacteria opened the way to categorize soil bacteri... more Recent studies on the colony formation of soil bacteria opened the way to categorize soil bacteria into colony forming curve (CFC) groups of different growth rates. A bacterial culture collection comprising organisms from every CFC group is called an ecocollection. Outlines of ECs of paddy soil 1992 and grassland soil 1987 and 1992 were described. Phylogenetic studies by 16S rDNA
Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild ... more Endophytic bacteria were isolated from surface-sterilized stems, seeds, and leaf sheaths of wild and traditionally cultivated rice varieties. Phylogenetic analyses based on 16S rDNA revealed a wide divergence among the isolates. However, the most frequently isolated groups were Methylobacterium sp. in the α-subdivision of Proteobacteria, and Curtobacterium sp. in the high G+ C Gram-positive group. Various phenotypic traits that are expected to be involved in the persistence and functions of the bacteria were analyzed: Most of the isolates from rice excreted pectinase, were motile, and showed an osmotic resistance to 0.6 M sucrose. These traits may be involved in endophytic characteristics in rice. About 50% of the isolates showed a cellulase activity. A few isolates fixed nitrogen, produced indole-3-acetic acid, and formed capsules. These activities were partially correlated with the phylogenetic group.
Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified R... more Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified Rennie medium. Based on 16S ribosomal DNA (rDNA) sequences, the diazotrophic isolates were phylogenetically close to four genera: Herbaspirillum , Ideonella , Enterobacter , and Azospirillum . Phenotypic properties and signature sequences of 16S rDNA indicated that three isolates (B65, B501, and B512) belong to the Herbaspirillum genus. To examine whether Herbaspirillum sp. strain B501 isolated from wild rice, Oryza officinalis , endophytically colonizes rice plants, the gfp gene encoding green fluorescent protein (GFP) was introduced into the bacteria. Observations by fluorescence stereomicroscopy showed that the GFP-tagged bacteria colonized shoots and seeds of aseptically grown seedlings of the original wild rice after inoculation of the seeds. Conversely, for cultivated rice Oryza sativa , no GFP fluorescence was observed for shoots and only weak signals were observed for seeds. Obser...
Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified R... more Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified Rennie medium. Based on 16S ribosomal DNA (rDNA) sequences, the diazotrophic isolates were phylogenetically close to four genera: Herbaspirillum, Ideonella, Enterobacter, and Azospirillum. Phenotypic properties and signature sequences of 16S rDNA indicated that three isolates (B65, B501, and B512) belong to the Herbaspirillum genus. To examine whether Herbaspirillum sp. strain B501 isolated from wild rice, Oryza officinalis, endophytically colonizes rice plants, the gfp gene encoding green fluorescent protein (GFP) was introduced into the bacteria. Observations by fluorescence stereomicroscopy showed that the GFP-tagged bacteria colonized shoots and seeds of aseptically grown seedlings of the original wild rice after inoculation of the seeds. Conversely, for cultivated rice Oryza sativa, no GFP fluorescence was observed for shoots and only weak signals were observed for seeds. Observation...
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