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Satoshi Tahara - One of the best experts on this subject based on the ideXlab platform.
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antagonistic Rhizoplane bacteria induce diverse morphological alterations in peronosporomycete hyphae during in vitro interaction
European Journal of Plant Pathology, 2005Co-Authors: Abhinandan Deora, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:A total of 150 bacteria were isolated from Rhizoplanes of the host and non-host plants of a phytopathogenic Peronosporomycete Aphanomyces cochlioides. Upon screening, 5% of the isolates were evaluated as antagonists as they inhibited radial growth of A. cochlioides AC-5 hyphae in a dual culture assay. In addition, those antagonistic bacteria also induced characteristic morphological alterations in the A. cochlioides AC-5 hyphae that grew towards bacterial colonies. Hyphal morphological alterations observed in AC-5 and other tested strains of Peronosporomycetes included excessive branching, curly growth, unusually longer and pointed tip formation and swelling; all of these were comparable to the alterations induced by known antimicrobial compounds. Among the antagonistic bacteria, Pseudomonas sp. strain EC-S101 induced a unique branching pattern (tree-like) in AC-5 hyphae by continuous apical bifurcation of successive hyphae, where increases in number of branches and hyphal area were linearly correlated with time up to 10 h. Our observations suggested that the pathogen might have lost its ability of normal branch production; however maintained the capability of self-branching. Soluble extracts from the culture fluids of Pseudomonas sp. strain EC-S101 and Stenotrophomonas maltophilia EC-S105 induced similar excessive branching and curly growth in A. cochlioides hyphae as the respective bacterium. These results revealed that bacterial metabolites appeared to be responsible for induction of morphological alterations. Interestingly, the antagonistic bacteria that induced hyphal morphological alterations, also efficiently suppressed in vivo damping-off disease caused by AC-5. We suggest that antagonistic Rhizoplane bacteria have the capability to induce diverse morphological alterations in Peronosporomycetes hyphae during in vitro interactions. Hyphal morphological alterations associated with growth inhibition and the induction of characteristic morphological changes indicate antagonistic activity against the Peronosporomycete.
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neutral Rhizoplane ph of local rice and some predominant tree species in south and central kalimantans a possible strategy of plant adaptation to acidic soil
Tropics, 2005Co-Authors: Yasuyuki Hashidoko, Toshihiro Hasegawa, Erry Purnomo, Motohiko Tada, Suwido H Limin, Mitsuru Osaki, Satoshi TaharaAbstract:To investigate the acid sulfate soil-adapting strategies of South Kalimantan local rice varieties, their Rhizoplane pH was preliminarily examined using a glass-made micro-electrode. Although raw acid-sulfate soils in paddocks in South Kalimantan were generally pH 3.5-4.5 and sometimes pH 2.5, pH values of the Rhizoplane of living roots directly measured by the microelectrode always converged to approximately 7.0 (variance 0.02-0.22, n=10). On the other hand, the pH of dead roots, which was measured after soil was thoroughly washed from the surface, was relatively low and often close to the soil pH itself. Similarly constant neutral Rhizoplane pH was also observed in the major Central Kalimantan tree species, Cratoxyllum arborescens (upland) and Combretocarpus rotundatus (swampy forests). Whilst, two other predominant grasses, Xyris complanata and Imperata cylindrica, inhabiting acidic soils in upland and lowland, had relatively low Rhizoplane pH (6.05 and 5.86, respectively), suggesting that these grasses have different strategies than the paddy rice varieties for adapting to acidic conditions. Rhizoplane bacteria are likely to be one of the factors for the maintenance of neutral Rhizoplane pH. In fact, some Sphingomonas sp. raised medium pH, originally set at pH 4.0, to 5.5. These findings suggested the importance of cationic charge in the Rhizoplane of local rice varieties for adapting to acid-sulfate soil, which is similar to strategy of some arboreal trees inhabiting acidic peat soil.
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requirement of a relatively high threshold level of mg2 for cell growth of a Rhizoplane bacterium sphingomonas yanoikuyae ec s001
Applied and Environmental Microbiology, 2004Co-Authors: Henny Hoo, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:Mg(2+) is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg(2+)) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg(2+) levels in Sphingomonas yanoikuyae EC-S001 affected cell growth restoration in the host plant and what the threshold level is. S. yanoikuyae EC-S001, isolated from the Rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the Rhizoplane and phylloplane of the host seedlings. S. yanoikuyae EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg(2+) or more allowed S. yanoikuyae EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg(2+) requirements. For example, Burkholderia cepacia EC-K014, originally isolated from the Rhizoplane of a Melastoma sp., could grow even in Mg(2+)-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg(2+) for its growth. In contrast, S. yanoikuyae EC-S001, together with Bacillus subtilis IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg(2+) to Mg(2+)-free HSG medium. Our studies concluded that Mg(2+) is more than just the essential trace element needed for cell growth restoration in S. yanoikuyae EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg(2+) or another specific essential element for their growth.
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requirement of a relatively high threshold level of mg 2 for cell growth of a Rhizoplane bacterium sphingomonas yanoikuyae ec s001
Applied and Environmental Microbiology, 2004Co-Authors: Henny Hoo, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:Mg(2+) is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg(2+)) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg(2+) levels in Sphingomonas yanoikuyae EC-S001 affected cell growth restoration in the host plant and what the threshold level is. S. yanoikuyae EC-S001, isolated from the Rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the Rhizoplane and phylloplane of the host seedlings. S. yanoikuyae EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg(2+) or more allowed S. yanoikuyae EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg(2+) requirements. For example, Burkholderia cepacia EC-K014, originally isolated from the Rhizoplane of a Melastoma sp., could grow even in Mg(2+)-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg(2+) for its growth. In contrast, S. yanoikuyae EC-S001, together with Bacillus subtilis IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg(2+) to Mg(2+)-free HSG medium. Our studies concluded that Mg(2+) is more than just the essential trace element needed for cell growth restoration in S. yanoikuyae EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg(2+) or another specific essential element for their growth.
Henny Hoo - One of the best experts on this subject based on the ideXlab platform.
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requirement of a relatively high threshold level of mg2 for cell growth of a Rhizoplane bacterium sphingomonas yanoikuyae ec s001
Applied and Environmental Microbiology, 2004Co-Authors: Henny Hoo, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:Mg(2+) is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg(2+)) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg(2+) levels in Sphingomonas yanoikuyae EC-S001 affected cell growth restoration in the host plant and what the threshold level is. S. yanoikuyae EC-S001, isolated from the Rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the Rhizoplane and phylloplane of the host seedlings. S. yanoikuyae EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg(2+) or more allowed S. yanoikuyae EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg(2+) requirements. For example, Burkholderia cepacia EC-K014, originally isolated from the Rhizoplane of a Melastoma sp., could grow even in Mg(2+)-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg(2+) for its growth. In contrast, S. yanoikuyae EC-S001, together with Bacillus subtilis IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg(2+) to Mg(2+)-free HSG medium. Our studies concluded that Mg(2+) is more than just the essential trace element needed for cell growth restoration in S. yanoikuyae EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg(2+) or another specific essential element for their growth.
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requirement of a relatively high threshold level of mg 2 for cell growth of a Rhizoplane bacterium sphingomonas yanoikuyae ec s001
Applied and Environmental Microbiology, 2004Co-Authors: Henny Hoo, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:Mg(2+) is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg(2+)) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg(2+) levels in Sphingomonas yanoikuyae EC-S001 affected cell growth restoration in the host plant and what the threshold level is. S. yanoikuyae EC-S001, isolated from the Rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the Rhizoplane and phylloplane of the host seedlings. S. yanoikuyae EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg(2+) or more allowed S. yanoikuyae EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg(2+) requirements. For example, Burkholderia cepacia EC-K014, originally isolated from the Rhizoplane of a Melastoma sp., could grow even in Mg(2+)-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg(2+) for its growth. In contrast, S. yanoikuyae EC-S001, together with Bacillus subtilis IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg(2+) to Mg(2+)-free HSG medium. Our studies concluded that Mg(2+) is more than just the essential trace element needed for cell growth restoration in S. yanoikuyae EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg(2+) or another specific essential element for their growth.
Md Tofazzal Islam - One of the best experts on this subject based on the ideXlab platform.
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antagonistic Rhizoplane bacteria induce diverse morphological alterations in peronosporomycete hyphae during in vitro interaction
European Journal of Plant Pathology, 2005Co-Authors: Abhinandan Deora, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:A total of 150 bacteria were isolated from Rhizoplanes of the host and non-host plants of a phytopathogenic Peronosporomycete Aphanomyces cochlioides. Upon screening, 5% of the isolates were evaluated as antagonists as they inhibited radial growth of A. cochlioides AC-5 hyphae in a dual culture assay. In addition, those antagonistic bacteria also induced characteristic morphological alterations in the A. cochlioides AC-5 hyphae that grew towards bacterial colonies. Hyphal morphological alterations observed in AC-5 and other tested strains of Peronosporomycetes included excessive branching, curly growth, unusually longer and pointed tip formation and swelling; all of these were comparable to the alterations induced by known antimicrobial compounds. Among the antagonistic bacteria, Pseudomonas sp. strain EC-S101 induced a unique branching pattern (tree-like) in AC-5 hyphae by continuous apical bifurcation of successive hyphae, where increases in number of branches and hyphal area were linearly correlated with time up to 10 h. Our observations suggested that the pathogen might have lost its ability of normal branch production; however maintained the capability of self-branching. Soluble extracts from the culture fluids of Pseudomonas sp. strain EC-S101 and Stenotrophomonas maltophilia EC-S105 induced similar excessive branching and curly growth in A. cochlioides hyphae as the respective bacterium. These results revealed that bacterial metabolites appeared to be responsible for induction of morphological alterations. Interestingly, the antagonistic bacteria that induced hyphal morphological alterations, also efficiently suppressed in vivo damping-off disease caused by AC-5. We suggest that antagonistic Rhizoplane bacteria have the capability to induce diverse morphological alterations in Peronosporomycetes hyphae during in vitro interactions. Hyphal morphological alterations associated with growth inhibition and the induction of characteristic morphological changes indicate antagonistic activity against the Peronosporomycete.
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requirement of a relatively high threshold level of mg2 for cell growth of a Rhizoplane bacterium sphingomonas yanoikuyae ec s001
Applied and Environmental Microbiology, 2004Co-Authors: Henny Hoo, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:Mg(2+) is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg(2+)) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg(2+) levels in Sphingomonas yanoikuyae EC-S001 affected cell growth restoration in the host plant and what the threshold level is. S. yanoikuyae EC-S001, isolated from the Rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the Rhizoplane and phylloplane of the host seedlings. S. yanoikuyae EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg(2+) or more allowed S. yanoikuyae EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg(2+) requirements. For example, Burkholderia cepacia EC-K014, originally isolated from the Rhizoplane of a Melastoma sp., could grow even in Mg(2+)-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg(2+) for its growth. In contrast, S. yanoikuyae EC-S001, together with Bacillus subtilis IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg(2+) to Mg(2+)-free HSG medium. Our studies concluded that Mg(2+) is more than just the essential trace element needed for cell growth restoration in S. yanoikuyae EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg(2+) or another specific essential element for their growth.
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requirement of a relatively high threshold level of mg 2 for cell growth of a Rhizoplane bacterium sphingomonas yanoikuyae ec s001
Applied and Environmental Microbiology, 2004Co-Authors: Henny Hoo, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:Mg(2+) is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg(2+)) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg(2+) levels in Sphingomonas yanoikuyae EC-S001 affected cell growth restoration in the host plant and what the threshold level is. S. yanoikuyae EC-S001, isolated from the Rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the Rhizoplane and phylloplane of the host seedlings. S. yanoikuyae EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg(2+) or more allowed S. yanoikuyae EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg(2+) requirements. For example, Burkholderia cepacia EC-K014, originally isolated from the Rhizoplane of a Melastoma sp., could grow even in Mg(2+)-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg(2+) for its growth. In contrast, S. yanoikuyae EC-S001, together with Bacillus subtilis IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg(2+) to Mg(2+)-free HSG medium. Our studies concluded that Mg(2+) is more than just the essential trace element needed for cell growth restoration in S. yanoikuyae EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg(2+) or another specific essential element for their growth.
Yasuyuki Hashidoko - One of the best experts on this subject based on the ideXlab platform.
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antagonistic Rhizoplane bacteria induce diverse morphological alterations in peronosporomycete hyphae during in vitro interaction
European Journal of Plant Pathology, 2005Co-Authors: Abhinandan Deora, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:A total of 150 bacteria were isolated from Rhizoplanes of the host and non-host plants of a phytopathogenic Peronosporomycete Aphanomyces cochlioides. Upon screening, 5% of the isolates were evaluated as antagonists as they inhibited radial growth of A. cochlioides AC-5 hyphae in a dual culture assay. In addition, those antagonistic bacteria also induced characteristic morphological alterations in the A. cochlioides AC-5 hyphae that grew towards bacterial colonies. Hyphal morphological alterations observed in AC-5 and other tested strains of Peronosporomycetes included excessive branching, curly growth, unusually longer and pointed tip formation and swelling; all of these were comparable to the alterations induced by known antimicrobial compounds. Among the antagonistic bacteria, Pseudomonas sp. strain EC-S101 induced a unique branching pattern (tree-like) in AC-5 hyphae by continuous apical bifurcation of successive hyphae, where increases in number of branches and hyphal area were linearly correlated with time up to 10 h. Our observations suggested that the pathogen might have lost its ability of normal branch production; however maintained the capability of self-branching. Soluble extracts from the culture fluids of Pseudomonas sp. strain EC-S101 and Stenotrophomonas maltophilia EC-S105 induced similar excessive branching and curly growth in A. cochlioides hyphae as the respective bacterium. These results revealed that bacterial metabolites appeared to be responsible for induction of morphological alterations. Interestingly, the antagonistic bacteria that induced hyphal morphological alterations, also efficiently suppressed in vivo damping-off disease caused by AC-5. We suggest that antagonistic Rhizoplane bacteria have the capability to induce diverse morphological alterations in Peronosporomycetes hyphae during in vitro interactions. Hyphal morphological alterations associated with growth inhibition and the induction of characteristic morphological changes indicate antagonistic activity against the Peronosporomycete.
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neutral Rhizoplane ph of local rice and some predominant tree species in south and central kalimantans a possible strategy of plant adaptation to acidic soil
Tropics, 2005Co-Authors: Yasuyuki Hashidoko, Toshihiro Hasegawa, Erry Purnomo, Motohiko Tada, Suwido H Limin, Mitsuru Osaki, Satoshi TaharaAbstract:To investigate the acid sulfate soil-adapting strategies of South Kalimantan local rice varieties, their Rhizoplane pH was preliminarily examined using a glass-made micro-electrode. Although raw acid-sulfate soils in paddocks in South Kalimantan were generally pH 3.5-4.5 and sometimes pH 2.5, pH values of the Rhizoplane of living roots directly measured by the microelectrode always converged to approximately 7.0 (variance 0.02-0.22, n=10). On the other hand, the pH of dead roots, which was measured after soil was thoroughly washed from the surface, was relatively low and often close to the soil pH itself. Similarly constant neutral Rhizoplane pH was also observed in the major Central Kalimantan tree species, Cratoxyllum arborescens (upland) and Combretocarpus rotundatus (swampy forests). Whilst, two other predominant grasses, Xyris complanata and Imperata cylindrica, inhabiting acidic soils in upland and lowland, had relatively low Rhizoplane pH (6.05 and 5.86, respectively), suggesting that these grasses have different strategies than the paddy rice varieties for adapting to acidic conditions. Rhizoplane bacteria are likely to be one of the factors for the maintenance of neutral Rhizoplane pH. In fact, some Sphingomonas sp. raised medium pH, originally set at pH 4.0, to 5.5. These findings suggested the importance of cationic charge in the Rhizoplane of local rice varieties for adapting to acid-sulfate soil, which is similar to strategy of some arboreal trees inhabiting acidic peat soil.
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requirement of a relatively high threshold level of mg2 for cell growth of a Rhizoplane bacterium sphingomonas yanoikuyae ec s001
Applied and Environmental Microbiology, 2004Co-Authors: Henny Hoo, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:Mg(2+) is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg(2+)) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg(2+) levels in Sphingomonas yanoikuyae EC-S001 affected cell growth restoration in the host plant and what the threshold level is. S. yanoikuyae EC-S001, isolated from the Rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the Rhizoplane and phylloplane of the host seedlings. S. yanoikuyae EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg(2+) or more allowed S. yanoikuyae EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg(2+) requirements. For example, Burkholderia cepacia EC-K014, originally isolated from the Rhizoplane of a Melastoma sp., could grow even in Mg(2+)-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg(2+) for its growth. In contrast, S. yanoikuyae EC-S001, together with Bacillus subtilis IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg(2+) to Mg(2+)-free HSG medium. Our studies concluded that Mg(2+) is more than just the essential trace element needed for cell growth restoration in S. yanoikuyae EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg(2+) or another specific essential element for their growth.
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requirement of a relatively high threshold level of mg 2 for cell growth of a Rhizoplane bacterium sphingomonas yanoikuyae ec s001
Applied and Environmental Microbiology, 2004Co-Authors: Henny Hoo, Yasuyuki Hashidoko, Md Tofazzal Islam, Satoshi TaharaAbstract:Mg(2+) is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg(2+)) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg(2+) levels in Sphingomonas yanoikuyae EC-S001 affected cell growth restoration in the host plant and what the threshold level is. S. yanoikuyae EC-S001, isolated from the Rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the Rhizoplane and phylloplane of the host seedlings. S. yanoikuyae EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg(2+) or more allowed S. yanoikuyae EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg(2+) requirements. For example, Burkholderia cepacia EC-K014, originally isolated from the Rhizoplane of a Melastoma sp., could grow even in Mg(2+)-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg(2+) for its growth. In contrast, S. yanoikuyae EC-S001, together with Bacillus subtilis IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg(2+) to Mg(2+)-free HSG medium. Our studies concluded that Mg(2+) is more than just the essential trace element needed for cell growth restoration in S. yanoikuyae EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg(2+) or another specific essential element for their growth.
Andrew K Lilley - One of the best experts on this subject based on the ideXlab platform.
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diversity of mercury resistance plasmids obtained by exogenous isolation from the bacteria of sugar beet in three successive years
FEMS Microbiology Ecology, 1996Co-Authors: Andrew K Lilley, Mark J Bailey, Martin J Day, John C FryAbstract:Self-transmissible plasmids conferring mercury resistance were exogenously isolated from the bacterial populations of sugar beet roots (Rhizoplane) and leaves (phyllosphere) into a Pseudomonas putida recipient. Fifty Rhizoplane plasmids and 29 phyllosphere plasmids (60–383 kb) were purified. Numerical analysis of plasmid DNA restriction enzyme digest patterns identified five distinct groups. Three of these plasmid groups were isolated from sugar beet crops grown at the same site over three consecutive years, demonstrating their established presence. Each group of plasmids comprised individual isolates with structural additions or deletions. The frequency of exogenous isolation correlated with factors likely to influence plant growth, bacterial activity and the physiological state of donors prior to sampling. All plasmids investigated conferred narrow spectrum mercury resistance with a reductase detoxification mechanism. None of the plasmids conferred resistance to a range of antibiotics, other heavy metals, or to UV, and following transfer to recipient bacteria the range of carbon source utilisation was not altered. This is the first report of the persistence of Pseudomonas spp. plasmid structural types isolated over several years from a terrestrial habitat.
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research articlediversity of mercury resistance plasmids obtained by exogenous isolation from the bacteria of sugar beet in three successive years
FEMS Microbiology Ecology, 1996Co-Authors: Andrew K Lilley, Mark J Bailey, Martin J Day, John C FryAbstract:Self-transmissible plasmids conferring mercury resistance were exogenously isolated from the bacterial populations of sugar beet roots (Rhizoplane) and leaves (phyllosphere) into a Pseudomonas putida recipient. Fifty Rhizoplane plasmids and 29 phyllosphere plasmids (60–383 kb) were purified. Numerical analysis of plasmid DNA restriction enzyme digest patterns identified five distinct groups. Three of these plasmid groups were isolated from sugar beet crops grown at the same site over three consecutive years, demonstrating their established presence. Each group of plasmids comprised individual isolates with structural additions or deletions. The frequency of exogenous isolation correlated with factors likely to influence plant growth, bacterial activity and the physiological state of donors prior to sampling. All plasmids investigated conferred narrow spectrum mercury resistance with a reductase detoxification mechanism. None of the plasmids conferred resistance to a range of antibiotics, other heavy metals, or to UV, and following transfer to recipient bacteria the range of carbon source utilisation was not altered. This is the first report of the persistence of Pseudomonas spp. plasmid structural types isolated over several years from a terrestrial habitat.