ABSTRACTAparAgene in-frame deletion mutant ofAzorhizobium caulinodansORS571 (ORS571-ΔparA) was co... more ABSTRACTAparAgene in-frame deletion mutant ofAzorhizobium caulinodansORS571 (ORS571-ΔparA) was constructed to evaluate the roles of the chromosome-partitioning gene on various bacterial traits and on the development of stem-positioned nodules. The ΔparAmutant showed a pleiomorphic cell shape phenotype and was polyploid, with differences in nucleoid sizes due to dramatic defects in chromosome partitioning. Upon inoculation of the ΔparAmutant onto the stem ofSesbania rostrata, three types of immature nodule-like structures with impaired nitrogen-fixing activity were generated. Most showed signs of bacteroid early senescence. Moreover, the ΔparAcells within the nodule-like structures exhibited multiple developmental-stage phenotypes. Since thebacAgene has been considered an indicator for bacteroid formation, we applied the expression pattern ofbacAas a nodule maturity index in this study. Our data indicate that thebacAgene expression isparAdependent in symbiosis. The presence of thepar...
International journal of systematic and evolutionary microbiology, Jan 11, 2016
A polyphasic approach was used to characterize a novel bacterium, designated strain TPP412T, isol... more A polyphasic approach was used to characterize a novel bacterium, designated strain TPP412T, isolated from a paddy soil in Taiwan. Strain TPP412T was Gram-staining-negative, facultatively anaerobic, rod-shaped, motile with single polar flagellum and lacks bacteriochlorophyll. Growth was observed at 24-45 ºС (optimal 25 ºС), pH 5.0-10.0 (optimal pH 7.0) and salinity (0-0.75 %, w/v). Strain TPP412T showed highest 16S rRNA gene sequence similarity to the members of genera Rhodocyclus (94.1-94.5 %), Azospira (93.9-94.5 %) and Propionivibrio (93.4-94.4 %) and established a discrete taxonomic lineage during phylogenetic analysis. The major fatty acids found in strain TPP412T were C12:0, C12:0 3OH, iso-C15:0 3OH, C16:0, C16:1 ω7c/C16:1 ω6c and C18:1 ω7c/C18:1 ω6c. The major polar lipid profile consisted of phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and an unidentified lipid. The polyamine pattern showed predominance of putrescine and minor amount of sp...
Photosynthetic bacteria (PSB) possess versatile metabolic abilities and are widely applied in env... more Photosynthetic bacteria (PSB) possess versatile metabolic abilities and are widely applied in environmental bioremediation, bioenergy production and agriculture. In this review, we summarize examples of purple non-sulfur bacteria (PNSB) through biofertilization, biostimulation and biocontrol mechanisms to promote plant growth. They include improvement of nutrient acquisition, production of phytohormones, induction of immune system responses, interaction with resident microbial community. It has also been reported that PNSB can produce an endogenous 5-aminolevulinic acid (5-ALA) to alleviate abiotic stress in plants. Under biotic stress, these bacteria can trigger induced systemic resistance (ISR) of plants against pathogens. The nutrient elements in soil are significantly increased by PNSB inoculation, thus improving fertility. We share experiences of researching and developing an elite PNSB inoculant (Rhodopseudomonas palustris PS3), including strategies for screening and verifying...
Rhodopseudomonas palustris strain PS3, a phototrophic bacterium, was originally isolated from a p... more Rhodopseudomonas palustris strain PS3, a phototrophic bacterium, was originally isolated from a paddy field located in Taipei city, Taiwan, and showed positive effects on the growth of leafy vegetables. The aim of this study was to clarify the mechanism of the beneficial effects exerted by PS3 on plants. An ineffective R. palustris strain, YSC3, isolated from a paddy field located in Yilan County, was used as the negative control for comparative analyses. We cultivated non-heading Chinese cabbage (Brassica rapa var. chinensis) in 1/2 strength Hoagland hydroponic solution, in which nitrate is the main nitrogen source. We evaluated various plant physiological responses to inoculation with different bacterial inoculants. The N use efficiency (NUE) of PS3-inoculated plants was dramatically higher than that of YSC3-inoculated plants. The nitrate uptake efficiency (NUpE) was significantly elevated in plants treated with PS3; however, no excess nitrate accumulation was observed in leaves. ...
Type VI secretion system (T6SS) is an effector delivery system used by gram-negative bacteria to ... more Type VI secretion system (T6SS) is an effector delivery system used by gram-negative bacteria to kill other bacteria or eukaryotic host to gain fitness. In Agrobacterium tumefaciens, T6SS has been shown to kill other bacteria such as Escherichia coli. Interestingly, the A. tumefaciens T6SS killing efficiency differs when using different E. coli strains as recipient cells. Thus, we hypothesize that a successful T6SS killing not only relies on attacker T6SS activity but also depends on recipient factors. A high-throughput interbacterial competition assay was employed to test the hypothesis by screening for mutants with reduced killing outcomes caused by A. tumefaciens strain C58. From the 3909 E. coli Keio mutants screened, 16 candidate mutants were filtered out. One strain, ΔclpP::Kan, showed ten times more resistant to T6SS-mediating killing but restored its susceptibility when complemented with clpP in trans. ClpP is a universal and highly conserved protease that exists in both pro...
In this study, the genetic diversity and identification of Bradyrhizobium symbionts of Crotalaria... more In this study, the genetic diversity and identification of Bradyrhizobium symbionts of Crotalaria zanzibarica, the most widely-distributed invasive legume in Taiwan, and other sympatric legume species growing along riverbanks of Taiwan were evaluated for the first time. In total, 59 and 54 Bradyrhizobium isolates were obtained from C. zanzibarica and its coexisting legume species, respectively. Based on the multilocus sequence analysis (MLSA) of concatenated four housekeeping genes (dnaK-glnII-recA-rpoB gene sequences, 1901bp), the 113 isolates displayed 53 unique haplotypes and grouped into 21 clades. Of these clades, 11 were found to be congruent to already defined Bradyrhizobium species, while the other 10 clades were found to not be congruent to any defined species. In particular, the C. zanzibarica isolates belong to 14 MLSA clades, six of which overlapped with the isolates of coexisting legumes. According to the nodA gene sequences (555bp) obtained from the 105 isolates, these...
World Journal of Microbiology and Biotechnology, 2016
Bacillus amyloliquefaciens strain WF02, isolated from soil collected at Wufeng Mountain, Taiwan, ... more Bacillus amyloliquefaciens strain WF02, isolated from soil collected at Wufeng Mountain, Taiwan, has siderophore-producing ability and in vitro antagonistic activity against bacterial wilt pathogen. To determine the impact of plant genotype on biocontrol effectiveness, we treated soil with this strain before infecting susceptible (L390) and moderately resistant (Micro-Tom) tomato cultivars with Ralstonia solanacearum strain Pss4. We also compared the efficacy of this strain with that of commercial Bacillus subtilis strain Y1336. Strain WF02 provided longer lasting protection against R. solanacearum than did strain Y1336 and controlled the development of wilt in both cultivars. To elucidate the genetic responses in these plants under WF02 treatment, we analyzed the temporal expression of defense-related genes in leaves. The salicylic acid pathway-related genes phenylalanine ammonia-lyase and pathogenesis-related protein 1a were up-regulated in both cultivars, whereas expression of the jasmonic acid pathway-related gene lipoxygenase was only elevated in the susceptible tomato cultivar (L390). These results suggest that WF02 can provide protection against bacterial wilt in tomato cultivars with different levels of disease resistance via direct and indirect modes of action.
Applied microbiology and biotechnology, Jan 6, 2016
Biofertilizers can help improve soil quality, promote crop growth, and sustain soil health. The p... more Biofertilizers can help improve soil quality, promote crop growth, and sustain soil health. The photosynthetic bacterium Rhodopseudomonas palustris strain PS3 (hereafter, PS3), which was isolated from Taiwanese paddy soil, can not only exert beneficial effects on plant growth but also enhance the efficiency of nutrient uptake from applied fertilizer. To produce this elite microbial isolate for practical use, product development and formulation are needed to permit the maintenance of the high quality of the inoculant during storage. The aim of this study was to select a suitable formulation that improves the survival and maintains the beneficial effects of the PS3 inoculant. Six additives (alginate, polyethylene glycol [PEG], polyvinylpyrrolidone-40 [PVP], glycerol, glucose, and horticultural oil) were used in liquid-based formulations, and their capacities for maintaining PS3 cell viability during storage in low, medium, and high temperature ranges were evaluated. Horticultural oil ...
Journal of the science of food and agriculture, Jan 17, 2015
Plastic composite support (PCS) bioreactor was implemented to evaluate the effects on isoflavone ... more Plastic composite support (PCS) bioreactor was implemented to evaluate the effects on isoflavone deglycosylation in black soymilk fermented by Rhizopus oligosporus NTU 5. Evaluation for optimal PCS for mycelia immobilization was conducted, which led to the significant results that the most mycelium weight (0.237 g/PCS, p < 0.05) is held by S type PCS , therefore, it was selected for black soymilk fermentation. It was found that the PCS fermentation system without pH control exhibits better efficiency of isoflavone bioconversion (daidzin to daidzein and genistin to genistein) than the one with pH control at pH 6.5. As for the long run fermentation, those without pH control indeed accelerate the isoflavone bioconversion by continuously releasing β-glucosidase into soymilk. Deglycosylation can be completed in 8 to 24 h and sustained for at least 34 days as 26 batches. The non-pH-control fermentation system also exhibits highest total phenolic content (ranged from 0.147 to 0.340 mg G...
Journal of the Science of Food and Agriculture, 2014
Lactobacillus, which has great adhesion ability to intestinal mucosa and is able to hydrolyse pla... more Lactobacillus, which has great adhesion ability to intestinal mucosa and is able to hydrolyse plant cell walls, can be used more efficiently as a feed additive. To increase the adhesion ability and display a fungal xylanase on the cell surface of Lactobacillus casei, the Listeria monocytogenes cell-wall-anchoring protein gene, mub, was introduced into L. casei ATCC 393 cells and used as a fusion partner to display the rumen fungal xylanase XynCDBFV on the cell surface of the transformed strains. The transformed strain L. casei pNZ-mub, which harboured mub gene, displayed recombinant Mub on its cell surface and showed greater adhesion ability to Caco-2 cells than the parental strain. The transformed strain L. casei pNZ-mub/xyn, which harboured mub-xynCDBFV fusion gene, acquired the capacity to break down oat spelt xylan and exhibited greater competition ability against the adhesion of L. monocytogenes to Caco-2 cells, in comparison with the parental strain. Mub has a potential to be used as a fusion partner to display heterologous proteins on the cell surface of Lactobacillus. Moreover, this is the first report of the successful display of xylanase on the cell surface of Lactobacillus.
To guarantee the safety of chocolate ice cream production, the Hazard Analysis Critical Control P... more To guarantee the safety of chocolate ice cream production, the Hazard Analysis Critical Control Points (HACCP) system was applied to the production process. The biological, chemical, and physical hazards that may exist in every step of chocolate ice cream production were identified. In addition, the critical control points were selected and the critical limits, monitoring, corrective measures, records, and verifications were established. The critical control points, which include pasteurization and freezing, were identified. Implementing the HACCP system in food manufacturing can effectively ensure food safety and quality, expand the market, and improve the manufacturers&#39; management level.
Molecular plant-microbe interactions : MPMI, Aug 1, 2018
The bacterial type VI secretion system (T6SS) has been considered the armed force of bacteria bec... more The bacterial type VI secretion system (T6SS) has been considered the armed force of bacteria because it can deliver toxin effectors to prokaryotic or eukaryotic cells for survival and fitness. Although many legume symbiotic rhizobacteria encode T6SS in their genome, the biological function of T6SS in these bacteria is still unclear. To elucidate this issue, we used Azorhizobium caulinodans ORS571 and its symbiotic host Sesbania rostrata as our research model. By using T6SS gene deletion mutants, we found that T6SS provides A. caulinodans with better symbiotic competitiveness when coinfected with a T6SS-lacking strain, as demonstrated by two independent T6SS-deficient mutants. Meanwhile, the symbiotic effectiveness was not affected by T6SS because the nodule phenotype, nodule size, and nodule nitrogen-fixation ability did not differ between the T6SS mutants and the wild type when infected alone. Our data also suggest that under several lab culture conditions tested, A. caulinodans s...
ABSTRACTAparAgene in-frame deletion mutant ofAzorhizobium caulinodansORS571 (ORS571-ΔparA) was co... more ABSTRACTAparAgene in-frame deletion mutant ofAzorhizobium caulinodansORS571 (ORS571-ΔparA) was constructed to evaluate the roles of the chromosome-partitioning gene on various bacterial traits and on the development of stem-positioned nodules. The ΔparAmutant showed a pleiomorphic cell shape phenotype and was polyploid, with differences in nucleoid sizes due to dramatic defects in chromosome partitioning. Upon inoculation of the ΔparAmutant onto the stem ofSesbania rostrata, three types of immature nodule-like structures with impaired nitrogen-fixing activity were generated. Most showed signs of bacteroid early senescence. Moreover, the ΔparAcells within the nodule-like structures exhibited multiple developmental-stage phenotypes. Since thebacAgene has been considered an indicator for bacteroid formation, we applied the expression pattern ofbacAas a nodule maturity index in this study. Our data indicate that thebacAgene expression isparAdependent in symbiosis. The presence of thepar...
International journal of systematic and evolutionary microbiology, Jan 11, 2016
A polyphasic approach was used to characterize a novel bacterium, designated strain TPP412T, isol... more A polyphasic approach was used to characterize a novel bacterium, designated strain TPP412T, isolated from a paddy soil in Taiwan. Strain TPP412T was Gram-staining-negative, facultatively anaerobic, rod-shaped, motile with single polar flagellum and lacks bacteriochlorophyll. Growth was observed at 24-45 ºС (optimal 25 ºС), pH 5.0-10.0 (optimal pH 7.0) and salinity (0-0.75 %, w/v). Strain TPP412T showed highest 16S rRNA gene sequence similarity to the members of genera Rhodocyclus (94.1-94.5 %), Azospira (93.9-94.5 %) and Propionivibrio (93.4-94.4 %) and established a discrete taxonomic lineage during phylogenetic analysis. The major fatty acids found in strain TPP412T were C12:0, C12:0 3OH, iso-C15:0 3OH, C16:0, C16:1 ω7c/C16:1 ω6c and C18:1 ω7c/C18:1 ω6c. The major polar lipid profile consisted of phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and an unidentified lipid. The polyamine pattern showed predominance of putrescine and minor amount of sp...
Photosynthetic bacteria (PSB) possess versatile metabolic abilities and are widely applied in env... more Photosynthetic bacteria (PSB) possess versatile metabolic abilities and are widely applied in environmental bioremediation, bioenergy production and agriculture. In this review, we summarize examples of purple non-sulfur bacteria (PNSB) through biofertilization, biostimulation and biocontrol mechanisms to promote plant growth. They include improvement of nutrient acquisition, production of phytohormones, induction of immune system responses, interaction with resident microbial community. It has also been reported that PNSB can produce an endogenous 5-aminolevulinic acid (5-ALA) to alleviate abiotic stress in plants. Under biotic stress, these bacteria can trigger induced systemic resistance (ISR) of plants against pathogens. The nutrient elements in soil are significantly increased by PNSB inoculation, thus improving fertility. We share experiences of researching and developing an elite PNSB inoculant (Rhodopseudomonas palustris PS3), including strategies for screening and verifying...
Rhodopseudomonas palustris strain PS3, a phototrophic bacterium, was originally isolated from a p... more Rhodopseudomonas palustris strain PS3, a phototrophic bacterium, was originally isolated from a paddy field located in Taipei city, Taiwan, and showed positive effects on the growth of leafy vegetables. The aim of this study was to clarify the mechanism of the beneficial effects exerted by PS3 on plants. An ineffective R. palustris strain, YSC3, isolated from a paddy field located in Yilan County, was used as the negative control for comparative analyses. We cultivated non-heading Chinese cabbage (Brassica rapa var. chinensis) in 1/2 strength Hoagland hydroponic solution, in which nitrate is the main nitrogen source. We evaluated various plant physiological responses to inoculation with different bacterial inoculants. The N use efficiency (NUE) of PS3-inoculated plants was dramatically higher than that of YSC3-inoculated plants. The nitrate uptake efficiency (NUpE) was significantly elevated in plants treated with PS3; however, no excess nitrate accumulation was observed in leaves. ...
Type VI secretion system (T6SS) is an effector delivery system used by gram-negative bacteria to ... more Type VI secretion system (T6SS) is an effector delivery system used by gram-negative bacteria to kill other bacteria or eukaryotic host to gain fitness. In Agrobacterium tumefaciens, T6SS has been shown to kill other bacteria such as Escherichia coli. Interestingly, the A. tumefaciens T6SS killing efficiency differs when using different E. coli strains as recipient cells. Thus, we hypothesize that a successful T6SS killing not only relies on attacker T6SS activity but also depends on recipient factors. A high-throughput interbacterial competition assay was employed to test the hypothesis by screening for mutants with reduced killing outcomes caused by A. tumefaciens strain C58. From the 3909 E. coli Keio mutants screened, 16 candidate mutants were filtered out. One strain, ΔclpP::Kan, showed ten times more resistant to T6SS-mediating killing but restored its susceptibility when complemented with clpP in trans. ClpP is a universal and highly conserved protease that exists in both pro...
In this study, the genetic diversity and identification of Bradyrhizobium symbionts of Crotalaria... more In this study, the genetic diversity and identification of Bradyrhizobium symbionts of Crotalaria zanzibarica, the most widely-distributed invasive legume in Taiwan, and other sympatric legume species growing along riverbanks of Taiwan were evaluated for the first time. In total, 59 and 54 Bradyrhizobium isolates were obtained from C. zanzibarica and its coexisting legume species, respectively. Based on the multilocus sequence analysis (MLSA) of concatenated four housekeeping genes (dnaK-glnII-recA-rpoB gene sequences, 1901bp), the 113 isolates displayed 53 unique haplotypes and grouped into 21 clades. Of these clades, 11 were found to be congruent to already defined Bradyrhizobium species, while the other 10 clades were found to not be congruent to any defined species. In particular, the C. zanzibarica isolates belong to 14 MLSA clades, six of which overlapped with the isolates of coexisting legumes. According to the nodA gene sequences (555bp) obtained from the 105 isolates, these...
World Journal of Microbiology and Biotechnology, 2016
Bacillus amyloliquefaciens strain WF02, isolated from soil collected at Wufeng Mountain, Taiwan, ... more Bacillus amyloliquefaciens strain WF02, isolated from soil collected at Wufeng Mountain, Taiwan, has siderophore-producing ability and in vitro antagonistic activity against bacterial wilt pathogen. To determine the impact of plant genotype on biocontrol effectiveness, we treated soil with this strain before infecting susceptible (L390) and moderately resistant (Micro-Tom) tomato cultivars with Ralstonia solanacearum strain Pss4. We also compared the efficacy of this strain with that of commercial Bacillus subtilis strain Y1336. Strain WF02 provided longer lasting protection against R. solanacearum than did strain Y1336 and controlled the development of wilt in both cultivars. To elucidate the genetic responses in these plants under WF02 treatment, we analyzed the temporal expression of defense-related genes in leaves. The salicylic acid pathway-related genes phenylalanine ammonia-lyase and pathogenesis-related protein 1a were up-regulated in both cultivars, whereas expression of the jasmonic acid pathway-related gene lipoxygenase was only elevated in the susceptible tomato cultivar (L390). These results suggest that WF02 can provide protection against bacterial wilt in tomato cultivars with different levels of disease resistance via direct and indirect modes of action.
Applied microbiology and biotechnology, Jan 6, 2016
Biofertilizers can help improve soil quality, promote crop growth, and sustain soil health. The p... more Biofertilizers can help improve soil quality, promote crop growth, and sustain soil health. The photosynthetic bacterium Rhodopseudomonas palustris strain PS3 (hereafter, PS3), which was isolated from Taiwanese paddy soil, can not only exert beneficial effects on plant growth but also enhance the efficiency of nutrient uptake from applied fertilizer. To produce this elite microbial isolate for practical use, product development and formulation are needed to permit the maintenance of the high quality of the inoculant during storage. The aim of this study was to select a suitable formulation that improves the survival and maintains the beneficial effects of the PS3 inoculant. Six additives (alginate, polyethylene glycol [PEG], polyvinylpyrrolidone-40 [PVP], glycerol, glucose, and horticultural oil) were used in liquid-based formulations, and their capacities for maintaining PS3 cell viability during storage in low, medium, and high temperature ranges were evaluated. Horticultural oil ...
Journal of the science of food and agriculture, Jan 17, 2015
Plastic composite support (PCS) bioreactor was implemented to evaluate the effects on isoflavone ... more Plastic composite support (PCS) bioreactor was implemented to evaluate the effects on isoflavone deglycosylation in black soymilk fermented by Rhizopus oligosporus NTU 5. Evaluation for optimal PCS for mycelia immobilization was conducted, which led to the significant results that the most mycelium weight (0.237 g/PCS, p < 0.05) is held by S type PCS , therefore, it was selected for black soymilk fermentation. It was found that the PCS fermentation system without pH control exhibits better efficiency of isoflavone bioconversion (daidzin to daidzein and genistin to genistein) than the one with pH control at pH 6.5. As for the long run fermentation, those without pH control indeed accelerate the isoflavone bioconversion by continuously releasing β-glucosidase into soymilk. Deglycosylation can be completed in 8 to 24 h and sustained for at least 34 days as 26 batches. The non-pH-control fermentation system also exhibits highest total phenolic content (ranged from 0.147 to 0.340 mg G...
Journal of the Science of Food and Agriculture, 2014
Lactobacillus, which has great adhesion ability to intestinal mucosa and is able to hydrolyse pla... more Lactobacillus, which has great adhesion ability to intestinal mucosa and is able to hydrolyse plant cell walls, can be used more efficiently as a feed additive. To increase the adhesion ability and display a fungal xylanase on the cell surface of Lactobacillus casei, the Listeria monocytogenes cell-wall-anchoring protein gene, mub, was introduced into L. casei ATCC 393 cells and used as a fusion partner to display the rumen fungal xylanase XynCDBFV on the cell surface of the transformed strains. The transformed strain L. casei pNZ-mub, which harboured mub gene, displayed recombinant Mub on its cell surface and showed greater adhesion ability to Caco-2 cells than the parental strain. The transformed strain L. casei pNZ-mub/xyn, which harboured mub-xynCDBFV fusion gene, acquired the capacity to break down oat spelt xylan and exhibited greater competition ability against the adhesion of L. monocytogenes to Caco-2 cells, in comparison with the parental strain. Mub has a potential to be used as a fusion partner to display heterologous proteins on the cell surface of Lactobacillus. Moreover, this is the first report of the successful display of xylanase on the cell surface of Lactobacillus.
To guarantee the safety of chocolate ice cream production, the Hazard Analysis Critical Control P... more To guarantee the safety of chocolate ice cream production, the Hazard Analysis Critical Control Points (HACCP) system was applied to the production process. The biological, chemical, and physical hazards that may exist in every step of chocolate ice cream production were identified. In addition, the critical control points were selected and the critical limits, monitoring, corrective measures, records, and verifications were established. The critical control points, which include pasteurization and freezing, were identified. Implementing the HACCP system in food manufacturing can effectively ensure food safety and quality, expand the market, and improve the manufacturers&#39; management level.
Molecular plant-microbe interactions : MPMI, Aug 1, 2018
The bacterial type VI secretion system (T6SS) has been considered the armed force of bacteria bec... more The bacterial type VI secretion system (T6SS) has been considered the armed force of bacteria because it can deliver toxin effectors to prokaryotic or eukaryotic cells for survival and fitness. Although many legume symbiotic rhizobacteria encode T6SS in their genome, the biological function of T6SS in these bacteria is still unclear. To elucidate this issue, we used Azorhizobium caulinodans ORS571 and its symbiotic host Sesbania rostrata as our research model. By using T6SS gene deletion mutants, we found that T6SS provides A. caulinodans with better symbiotic competitiveness when coinfected with a T6SS-lacking strain, as demonstrated by two independent T6SS-deficient mutants. Meanwhile, the symbiotic effectiveness was not affected by T6SS because the nodule phenotype, nodule size, and nodule nitrogen-fixation ability did not differ between the T6SS mutants and the wild type when infected alone. Our data also suggest that under several lab culture conditions tested, A. caulinodans s...
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