RESUMEN
A novel exopolysaccharide (EPS) was produced by a bacterium which was isolated from Psophocarpus tetragonolobus (L) D.C. and identified as 99% Rhizobium tropici SRA1 by 16S rDNA sequencing. The flocculating performances along with emulsifying activity began simultaneously with the growth and the production of EPS and reached its utmost at 28 h. EPS was purified via chilled ethanol precipitation followed by dialysis and lyophilization. The existence of hydroxyl, methoxyl, and carboxylic functional groups were confirmed by Fourier transform infrared (FT-IR) spectrum. EPS was found to be compose of 82.44% neutral sugar and 15.93% uronic acid. The average molecular weight of the exopolysaccharide was estimated as ~1.8×105. Gas-liquid chromatography indicated the presence of glucose and galactose at a molar ratio of 3:1 in EPS. In the pH range of 3-5 with EPS dosage of 15 mg/l at 30 °C, cation-independent flocculation greater than 90% was observed. Emulsification indices (E24) of EPS were observed as 86.66%, 83.33%, 76.66%, and 73.33% with olive oil, kerosene, toluene, and n-hexane respectively. Biosorption of Cu K [45.69 wt%], Cu L [05.67 wt%], Co K [15.58 wt%], and Co L [11.72 wt%] by EPS was confirmed by energy-dispersive X-ray spectroscopy (EDS). This report on the flocculating, emulsifying, and metal sorption properties of EPS produced by R. tropici SRA1 is unique in the literature
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Asunto(s)
Fabaceae/microbiología , Metales/metabolismo , Polisacáridos Bacterianos/metabolismo , Rhizobium tropici/aislamiento & purificación , Rhizobium tropici/clasificación , Rhizobium tropici/metabolismo , Cromatografía de Gases , Cromatografía Liquida , Análisis por Conglomerados , ADN Bacteriano , ADN Ribosómico , Análisis de Secuencia de ADN , Ácidos Urónicos/análisis , Espectroscopía Infrarroja por Transformada de Fourier , Azúcares/análisisRESUMEN
A novel exopolysaccharide (EPS) was produced by a bacterium which was isolated from Psophocarpus tetragonolobus (L) D.C. and identified as 99% Rhizobium tropici SRA1 by 16S rDNA sequencing. The flocculating performances along with emulsifying activity began simultaneously with the growth and the production of EPS and reached its utmost at 28 h. EPS was purified via chilled ethanol precipitation followed by dialysis and lyophilization. The existence of hydroxyl, methoxyl, and carboxylic functional groups were confirmed by Fourier transform infrared (FT-IR) spectrum. EPS was found to be compose of 82.44% neutral sugar and 15.93% uronic acid. The average molecular weight of the exopolysaccharide was estimated as ~ 1.8 × 105. Gas-liquid chromatography indicated the presence of glucose and galactose at a molar ratio of 3:1 in EPS. In the pH range of 3-5 with EPS dosage of 15 mg/l at 30 °C, cation-independent flocculation greater than 90% was observed. Emulsification indices (E24) of EPS were observed as 86.66%, 83.33%, 76.66%, and 73.33% with olive oil, kerosene, toluene, and n-hexane respectively. Biosorption of Cu K [45.69 wt%], Cu L [05.67 wt%], Co K [15.58 wt%], and Co L [11.72 wt%] by EPS was confirmed by energy-dispersive X-ray spectroscopy (EDS). This report on the flocculating, emulsifying, and metal sorption properties of EPS produced by R. tropici SRA1 is unique in the literature.
Asunto(s)
Fabaceae/microbiología , Metales/metabolismo , Polisacáridos Bacterianos/metabolismo , Rhizobium tropici/aislamiento & purificación , Rhizobium tropici/metabolismo , Cromatografía de Gases , Cromatografía Liquida , Análisis por Conglomerados , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Emulsiones , Floculación , Filogenia , Polisacáridos Bacterianos/química , Polisacáridos Bacterianos/aislamiento & purificación , ARN Ribosómico 16S/genética , Rhizobium tropici/clasificación , Rhizobium tropici/genética , Análisis de Secuencia de ADN , Espectroscopía Infrarroja por Transformada de Fourier , Azúcares/análisis , Temperatura , Ácidos Urónicos/análisisRESUMEN
The pH of the culture medium directly influences the growth of microorganisms and the chemical processes that they perform. The aim of this study was to assess the influence of the initial pH of the culture medium on the production of 11 low-molecular-weight organic acids and on the solubilization of calcium phosphate by bacteria in growth medium (NBRIP). The following strains isolated from cowpea nodules were studied: UFLA03-08 (Rhizobium tropici), UFLA03-09 (Acinetobacter sp.), UFLA03-10 (Paenibacillus kribbensis), UFLA03-106 (Paenibacillus kribbensis) and UFLA03-116 (Paenibacillus sp.). The strains UFLA03-08, UFLA03-09, UFLA03-10 and UFLA03-106 solubilized Ca3(PO4)2 in liquid medium regardless of the initial pH, although without a significant difference between the treatments. The production of organic acids by these strains was assessed for all of the initial pH values investigated, and differences between the treatments were observed. Strains UFLA03-09 and UFLA03-10 produced the same acids at different initial pH values in the culture medium. There was no correlation between phosphorus solubilized from Ca3(PO4)2 in NBRIP liquid medium and the concentration of total organic acids at the different initial pH values. Therefore, the initial pH of the culture medium influences the production of organic acids by the strains UFLA03-08, UFLA03-09, UFLA03-10 and UFLA03-106 but it does not affect calcium phosphate solubilization.
Asunto(s)
Acinetobacter/metabolismo , Ácidos Carboxílicos/metabolismo , Medios de Cultivo/química , Paenibacillus/metabolismo , Fosfatos/metabolismo , Rhizobium tropici/metabolismo , Acinetobacter/crecimiento & desarrollo , Acinetobacter/aislamiento & purificación , Fabaceae/microbiología , Concentración de Iones de Hidrógeno , Paenibacillus/crecimiento & desarrollo , Paenibacillus/aislamiento & purificación , Rhizobium tropici/crecimiento & desarrollo , Rhizobium tropici/aislamiento & purificación , Nódulos de las Raíces de las Plantas/microbiologíaRESUMEN
The pH of the culture medium directly influences the growth of microorganisms and the chemical processes that they perform. The aim of this study was to assess the influence of the initial pH of the culture medium on the production of 11 low-molecular-weight organic acids and on the solubilization of calcium phosphate by bacteria in growth medium (NBRIP). The following strains isolated from cowpea nodules were studied: UFLA03-08 (Rhizobium tropici), UFLA03-09 (Acinetobacter sp.), UFLA03-10 (Paenibacillus kribbensis), UFLA03-106 (Paenibacillus kribbensis) and UFLA03-116 (Paenibacillus sp.). The strains UFLA03-08, UFLA03-09, UFLA03-10 and UFLA03-106 solubilized Ca3(PO4)2 in liquid medium regardless of the initial pH, although without a significant difference between the treatments. The production of organic acids by these strains was assessed for all of the initial pH values investigated, and differences between the treatments were observed. Strains UFLA03-09 and UFLA03-10 produced the same acids at different initial pH values in the culture medium. There was no correlation between phosphorus solubilized from Ca3(PO4)2 in NBRIP liquid medium and the concentration of total organic acids at the different initial pH values. Therefore, the initial pH of the culture medium influences the production of organic acids by the strains UFLA03-08, UFLA03-09, UFLA03-10 and UFLA03-106 but it does not affect calcium phosphate solubilization.
Asunto(s)
Acinetobacter/metabolismo , Ácidos Carboxílicos/metabolismo , Medios de Cultivo/química , Paenibacillus/metabolismo , Fosfatos/metabolismo , Rhizobium tropici/metabolismo , Acinetobacter/crecimiento & desarrollo , Acinetobacter/aislamiento & purificación , Fabaceae/microbiología , Concentración de Iones de Hidrógeno , Paenibacillus/crecimiento & desarrollo , Paenibacillus/aislamiento & purificación , Rhizobium tropici/crecimiento & desarrollo , Rhizobium tropici/aislamiento & purificación , Nódulos de las Raíces de las Plantas/microbiologíaRESUMEN
The purposes of this study were to isolate and evaluate the interaction between mineral-weathering bacteria and silicate minerals (feldspar and biotite). A mineral-weathering bacterium was isolated from weathered rocks and identified as Rhizobium tropici Q34 based on 16S rRNA gene sequence analysis. Si and K concentrations were increased by 1.3- to 4.0-fold and 1.1- to 1.7-fold in the live bacterium-inoculated cultures compared with the controls respectively. Significant increases in the productions of tartaric and succinic acids and extracellular polysaccharides by strain Q34 were observed in cultures with minerals. Furthermore, significantly more tartaric acid and polysaccharide productions by strain Q34 were obtained in the presence of feldspar, while better growth and more citric acid production of strain Q34 were observed in the presence of biotite. Mineral dissolution experiments showed that the organic acids and polysaccharides produced by strain Q34 were also capable of promoting the release of Si and K from the minerals. The results showed that the growth and metabolite production of strain Q34 were enhanced in the presence of the minerals and different mineral exerted distinct impacts on the growth and metabolite production. The bio-weathering process is probably a synergistic action of organic acids and extracellular polysaccharides produced by the bacterium.
Asunto(s)
Rhizobium tropici/clasificación , Rhizobium tropici/metabolismo , Silicatos/metabolismo , Ácidos Carboxílicos/metabolismo , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Datos de Secuencia Molecular , Polisacáridos Bacterianos/metabolismo , Potasio/metabolismo , ARN Ribosómico 16S/genética , Rhizobium tropici/genética , Rhizobium tropici/aislamiento & purificación , Análisis de Secuencia de ADNRESUMEN
The non-legume genus Parasponia has evolved the rhizobium symbiosis independent from legumes and has done so only recently. We aim to study the promiscuity of such newly evolved symbiotic engagement and determine the symbiotic effectiveness of infecting rhizobium species. It was found that Parasponia andersonii can be nodulated by a broad range of rhizobia belonging to four different genera, and therefore, we conclude that this non-legume is highly promiscuous for rhizobial engagement. A possible drawback of this high promiscuity is that low-efficient strains can infect nodules as well. The strains identified displayed a range in nitrogen-fixation effectiveness, including a very inefficient rhizobium species, Rhizobium tropici WUR1. Because this species is able to make effective nodules on two different legume species, it suggests that the ineffectiveness of P. andersonii nodules is the result of the incompatibility between both partners. In P. andersonii nodules, rhizobia of this strain become embedded in a dense matrix but remain vital. This suggests that sanctions or genetic control against underperforming microsymbionts may not be effective in Parasponia spp. Therefore, we argue that the Parasponia-rhizobium symbiosis is a delicate balance between mutual benefits and parasitic colonization.
Asunto(s)
Cannabaceae/microbiología , Especificidad del Huésped/fisiología , Nodulación de la Raíz de la Planta/fisiología , Rhizobium tropici/fisiología , Simbiosis/fisiología , Secuencia de Bases , Cannabaceae/ultraestructura , Muerte Celular , Fabaceae/microbiología , Fabaceae/ultraestructura , Genes Bacterianos/genética , Genoma Bacteriano/genética , Datos de Secuencia Molecular , Fijación del Nitrógeno , Filogenia , Proteobacteria/genética , Proteobacteria/aislamiento & purificación , Proteobacteria/fisiología , ARN Bacteriano/química , ARN Bacteriano/genética , ARN Ribosómico 16S/química , ARN Ribosómico 16S/genética , Rhizobium tropici/genética , Rhizobium tropici/aislamiento & purificación , Nódulos de las Raíces de las Plantas/ultraestructura , Análisis de Secuencia de ADN , Sinorhizobium/genética , Sinorhizobium/aislamiento & purificación , Sinorhizobium/fisiologíaRESUMEN
Balloon flower (Platycodon grandiflorum) is widely cultivated vegetable and used as a remedy for asthma in East Asia. Experiments were conducted to isolate endophytic bacteria from 1-, 3-, and 6-year-old balloon flower roots and to analyze the enzymatic, antifungal, and anti-human pathogenic activities of the potential endophytic biocontrol agents obtained. Total 120 bacterial colonies were isolated from the interior of all balloon flower roots samples. Phylogenetic analysis based on 16S rRNA gene sequences showed that the population of 'low G + C gram-positive bacteria' (LGCGPB) gradually increased 60.0-80.0% from 1 to 6 years balloon flower sample. On the other hand, maximum hydrolytic enzyme activity showing endophytic bacteria was under LGCGPB, among the bacterial strains, Bacillus sp. (BF1-1 and BF3-8), Bacillus sp. (BF1-2 and BF3-5), and Bacillus sp. (BF1-3, BF3-6, and BF6-4) showed maximum enzyme activities. Besides, Bacillus licheniformis (BF3-5 and BF6-6) and Bacillus pumilus (BF6-1) showed maximum antifungal activity against Phytophthora capsici, Fusarium oxysporum, Rhizoctonia solani, and Pythium ultimum. Moreover, Bacillus licheniformis was found in 3 and 6 years balloon flower roots, but Bacillus pumilus was found only in 6 years sample. It is presumed that older balloon flower plants invite more potential antifungal endophytes for there protection from plant diseases. In addition, Bacillus sp. (BF1-2 and BF3-5) showed maximum anti-human pathogenic activity. So, plant age is presumed to influence diversity of balloon flower endophytic bacteria.
Asunto(s)
Antibacterianos/farmacología , Antifúngicos/farmacología , Bacterias , Raíces de Plantas/microbiología , Platycodon/microbiología , Antibacterianos/aislamiento & purificación , Antibiosis , Antifúngicos/aislamiento & purificación , Bacillus/clasificación , Bacillus/genética , Bacillus/aislamiento & purificación , Bacillus/metabolismo , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Bacterias/metabolismo , Biodiversidad , Brevibacillus/clasificación , Brevibacillus/genética , Brevibacillus/aislamiento & purificación , Brevibacillus/metabolismo , ADN Bacteriano/genética , Enterobacter/clasificación , Enterobacter/genética , Enterobacter/aislamiento & purificación , Enterobacter/metabolismo , Micrococcus luteus/clasificación , Micrococcus luteus/genética , Micrococcus luteus/aislamiento & purificación , Micrococcus luteus/metabolismo , Control Biológico de Vectores , Filogenia , Enfermedades de las Plantas/microbiología , Platycodon/crecimiento & desarrollo , ARN Ribosómico 16S/análisis , Rhizobium tropici/clasificación , Rhizobium tropici/genética , Rhizobium tropici/aislamiento & purificación , Rhizobium tropici/metabolismo , Análisis de Secuencia de ADN , Microbiología del Suelo , SimbiosisRESUMEN
Until recently, beans (Phaseolus vulgaris L.) grown in Minnesota were rarely inoculated. Because of this, we hypothesized that bean rhizobia collected in Minnesota would either share characteristics identifiable with Rhizobium etli of Mesoamerican or Andean origin, introduced into the region as seed-borne contaminants, or be indigenous rhizobia from prairie species, such as Dalea spp. The latter organisms have been shown to nodulate and fix N2 with Phaseolus vulgaris. Rhizobia recovered from the Staples, Verndale, and Park Rapids areas of Minnesota were grouped according to the results of BOXA1R-PCR fingerprint analysis into 5 groups, with only one of these having banding patterns similar to 2 of 4 R. etli reference strains. When representative isolates were subject to fatty acid - methyl ester analysis and 16S rRNA gene sequence analysis, the results obtained differed. 16S rRNA gene sequences of half the organisms tested were most similar to Rhizobium leguminosarum. Rhizobia from Dalea spp., an important legume in the prairie ecosystem, did not play a significant role as the microsymbiont of beans in this area. This appears to be due to the longer time needed for them to initiate infection in Phaseolus vulgaris. Strains of Rhizobium tropici IIB, including UMR1899, proved tolerant to streptomycin and captan, which are commonly applied as seed treatments for beans. Local rhizobia appeared to have very limited tolerance to these compounds.