本研究从南京板桥镇的灰潮土中,筛选出了一株高效固氮解磷菌,命名为JX14,其固氮酶活性达C2H438.9 nmol/(h·ml),对磷酸三钙的转化量达96.19 mg/L。通过形态观察、生理生化特征及16S r DNA基因序列分析,确定JX14为贪噬菌属(Variovora...本研究从南京板桥镇的灰潮土中,筛选出了一株高效固氮解磷菌,命名为JX14,其固氮酶活性达C2H438.9 nmol/(h·ml),对磷酸三钙的转化量达96.19 mg/L。通过形态观察、生理生化特征及16S r DNA基因序列分析,确定JX14为贪噬菌属(Variovorax sp.)。在温室条件下进行花生盆栽试验,结果表明,接种JX14菌株的处理,土壤NH4+-N、NO3–-N、矿质氮含量较不接菌处理分别提高了1.08、1.18、1.16倍,土壤有效磷含量提高了18.14%。花生根系总长、表面积、体积以及根尖数,较对照分别提高了1.61、1.28、1.37、1.12倍,花生根系变得更长更粗并且具有更多的分支,增强了根对土壤中营养元素的吸收,花生地上部鲜重、株高显著提高了44.78%、14.10%,花生全氮磷钾含量分别显著提高了35.14%、171.43%、133.33%。该结果为植物促生菌JX14在农业生产上的应用提供了理论依据和研究基础。展开更多
Plant growth-promoting bacteria(PGPB)play an important role in improving agricultural production under several abiotic stress factors.PGPB can be used to increase crop growth and development through hormonal balance a...Plant growth-promoting bacteria(PGPB)play an important role in improving agricultural production under several abiotic stress factors.PGPB can be used to increase crop growth and development through hormonal balance and increase nutrient uptake.The positive effect of PGPB may be due to its pivotal role in morphophysiological and biochemical characteristics like leaf number,leaf area,and stem length.Furthermore,relative water content,chlorophyll content,carotenoids,antioxidant enzymes,and plant hormones were improved with PGPB treatment.Crop yield and yield components were also increased with PGPB treatment in numerous crops.The anatomical structure of plant organs was increased such as lamina thickness,stem diameter,xylem vessel diameter,and number of xylem vessels as well as phloem thickness under treatment with PGPB.Additionally,PGPB can alleviate the negative effects of several abiotic stresses by regulating the antioxidant defense system to scavenge the reactive oxygen species resulting in an improvement of yield production in the stressed plants.Additionally,gene expressions were controlled by calcium ion modulation during secondary messengers that act upon calcium-dependent protein kinase and protein phosphatases.This includes many transcription factors such as MYB,AP2/ERF,bZIP,and NAC which regulate genes related to salinity stress signals.PGPB can demonstrate induction genes of signaling under abiotic stress conditions.This review gives an outline of the PGPB role in alleviating the harmful effects of abiotic factors such as salinity,drought,and heat associated with the improvement of the morpho-physiological and biochemical features especially,leaves and branches number,leaf area,antioxidant compounds,plant hormones,and relative water content.展开更多
Plant growth is hindered by high concentration of metals in soil by disturbing various physiological processes. However, some bacteria with plant growth promoting features have been recognized to alleviate stress in p...Plant growth is hindered by high concentration of metals in soil by disturbing various physiological processes. However, some bacteria with plant growth promoting features have been recognized to alleviate stress in plants even under elevated levels of metal concentration. The two bacterium NWM 71 and NWM 103, identified as Pseudomonas sp. and Bacillus sp. respectively were found to be resistant to the toxic effects of nickel （Ni2＋） and were identified with plant growth promoting features. Both the strains showed the production of indole acetic acid （IAA） and solubUisation of phosphate. Brassica juncea （mustard） was used as a test plant to identify the plant growth promoting activity of the selected strains of bacteria. The growth was positively influenced by the inoculation of both the strains. The tests for the measurement of chlorophyll contents and antioxidative activity were carried out to determine the level of stress in plants. High levels of Ni decreased the growth and chlorophyll content, however, significant increase in the antioxidant activity was recorded along the treatment. Inoculation of both the selected strains of bacteria increased the shoot and root biomass of mustard grown in both unspiked and spiked soil. This positive influence on growth can be attributed to the solubilisation of phosphate and production of IAA. Furthermore the observed high levels of antioxidant enzymes led to decrease in the toxic effects of Ni. This led to enhanced growth and chlorophyll content which in turn might have enhanced the photosynthetic capacity of the plants.展开更多
Biofertilizer can be defined as preparation that contains?microbes capable of?nitrogen (N)-fixation and phosphate solubilization that promote plant?growth. These groups?of microbes, classified as Plant Growth-Promotin...Biofertilizer can be defined as preparation that contains?microbes capable of?nitrogen (N)-fixation and phosphate solubilization that promote plant?growth. These groups?of microbes, classified as Plant Growth-Promoting Bacteria (PGPB), colonize the rhizosphere and the soil. In this work, liquid biofertilizer was produced from whole orange, banana and grape, wheat and rice chaff,?Moringa oleifera?leaves, soil, and brown sugar (as carbon source) mixed with water and cultured in an anaerobic condition for two weeks. The sieved culture was stored in a tightly sealed PVC container at room temperature for biochemical analysis of microbial population. Nitrogen fixing bacteria (Azotobacter?sp.) and phosphorus solubilizing bacteria were isolated using Ashby’s Mannitol Azotobacter medium and Pisvikoya’s PSB medium respectively, while?Bacillus sp. was isolated using Bacillus agar. Field experiment was carried out to investigate the performance rates of the biofertilizer against those of the Nitrogen/Phosphorus/Potassium (NPK) chemical fertilizer and the control, on the growth of corn (Zea mays). The experimental design consisted of three treatments of the Biofertilizer, Chemical fertilizer (NPK) and Control, conducted in three replicates. Data collected were analyzed using?one-way ANOVA at?P?< 0.05. The results showed significant improvement in growth and yield of maize on which biofertilizer was applied as against those treated with NPK and the Control. The plants treated with the biofertilizer did not show signs of insects attack, which were easily observed on the blades of those treated with NPK and the control.展开更多
Emerging contaminants like metal nanoparticles get introduced into soil through different routes.Toxic effects of these contaminants on plant growth-promoting bacteria(PGPB),which influence plant productivity,can be d...Emerging contaminants like metal nanoparticles get introduced into soil through different routes.Toxic effects of these contaminants on plant growth-promoting bacteria(PGPB),which influence plant productivity,can be detrimental to soil health.Titanium dioxide is one of the most produced nanomaterials in the world and therefore potentially the most released nanoform in soil.The objective of this study was to evaluate the toxic effects of titanium dioxide nanoparticles(TiO2 NPs)on plant growth-promoting bacteria.Three types of PGPB,viz.,nitrogen fixers,phosphate solubilizers and biofilm formers were exposed to TiO2 NPs.Our results suggest that direct contact of the bacteria with these NPs is inhibitory as compared to when these bacteria are growing in laboratory nutrient media in the presence of NPs.The inhibitory effect did not follow a linear dose response but instead showed a pronounced step response.Soils with their varying characteristics may not afford the same protection to bacteria as laboratory nutrient media and thus TiO2 NPs may cause some sensitive PGPB to disappear from soil.The resultant shift in bacterial community composition may affect ecosystem functioning.展开更多
基金supported by the Deanship of Scientific Research,Vice Presidency for Graduate Studies and Scientific Research,King Faisal University,Saudi Arabia (Grant No.3783).
文摘Plant growth-promoting bacteria(PGPB)play an important role in improving agricultural production under several abiotic stress factors.PGPB can be used to increase crop growth and development through hormonal balance and increase nutrient uptake.The positive effect of PGPB may be due to its pivotal role in morphophysiological and biochemical characteristics like leaf number,leaf area,and stem length.Furthermore,relative water content,chlorophyll content,carotenoids,antioxidant enzymes,and plant hormones were improved with PGPB treatment.Crop yield and yield components were also increased with PGPB treatment in numerous crops.The anatomical structure of plant organs was increased such as lamina thickness,stem diameter,xylem vessel diameter,and number of xylem vessels as well as phloem thickness under treatment with PGPB.Additionally,PGPB can alleviate the negative effects of several abiotic stresses by regulating the antioxidant defense system to scavenge the reactive oxygen species resulting in an improvement of yield production in the stressed plants.Additionally,gene expressions were controlled by calcium ion modulation during secondary messengers that act upon calcium-dependent protein kinase and protein phosphatases.This includes many transcription factors such as MYB,AP2/ERF,bZIP,and NAC which regulate genes related to salinity stress signals.PGPB can demonstrate induction genes of signaling under abiotic stress conditions.This review gives an outline of the PGPB role in alleviating the harmful effects of abiotic factors such as salinity,drought,and heat associated with the improvement of the morpho-physiological and biochemical features especially,leaves and branches number,leaf area,antioxidant compounds,plant hormones,and relative water content.
文摘Plant growth is hindered by high concentration of metals in soil by disturbing various physiological processes. However, some bacteria with plant growth promoting features have been recognized to alleviate stress in plants even under elevated levels of metal concentration. The two bacterium NWM 71 and NWM 103, identified as Pseudomonas sp. and Bacillus sp. respectively were found to be resistant to the toxic effects of nickel （Ni2＋） and were identified with plant growth promoting features. Both the strains showed the production of indole acetic acid （IAA） and solubUisation of phosphate. Brassica juncea （mustard） was used as a test plant to identify the plant growth promoting activity of the selected strains of bacteria. The growth was positively influenced by the inoculation of both the strains. The tests for the measurement of chlorophyll contents and antioxidative activity were carried out to determine the level of stress in plants. High levels of Ni decreased the growth and chlorophyll content, however, significant increase in the antioxidant activity was recorded along the treatment. Inoculation of both the selected strains of bacteria increased the shoot and root biomass of mustard grown in both unspiked and spiked soil. This positive influence on growth can be attributed to the solubilisation of phosphate and production of IAA. Furthermore the observed high levels of antioxidant enzymes led to decrease in the toxic effects of Ni. This led to enhanced growth and chlorophyll content which in turn might have enhanced the photosynthetic capacity of the plants.
文摘Biofertilizer can be defined as preparation that contains?microbes capable of?nitrogen (N)-fixation and phosphate solubilization that promote plant?growth. These groups?of microbes, classified as Plant Growth-Promoting Bacteria (PGPB), colonize the rhizosphere and the soil. In this work, liquid biofertilizer was produced from whole orange, banana and grape, wheat and rice chaff,?Moringa oleifera?leaves, soil, and brown sugar (as carbon source) mixed with water and cultured in an anaerobic condition for two weeks. The sieved culture was stored in a tightly sealed PVC container at room temperature for biochemical analysis of microbial population. Nitrogen fixing bacteria (Azotobacter?sp.) and phosphorus solubilizing bacteria were isolated using Ashby’s Mannitol Azotobacter medium and Pisvikoya’s PSB medium respectively, while?Bacillus sp. was isolated using Bacillus agar. Field experiment was carried out to investigate the performance rates of the biofertilizer against those of the Nitrogen/Phosphorus/Potassium (NPK) chemical fertilizer and the control, on the growth of corn (Zea mays). The experimental design consisted of three treatments of the Biofertilizer, Chemical fertilizer (NPK) and Control, conducted in three replicates. Data collected were analyzed using?one-way ANOVA at?P?< 0.05. The results showed significant improvement in growth and yield of maize on which biofertilizer was applied as against those treated with NPK and the Control. The plants treated with the biofertilizer did not show signs of insects attack, which were easily observed on the blades of those treated with NPK and the control.
基金the University Grants Commission(UGC)of the Government of India(Minor research grant:47-584/13(WRO)).
文摘Emerging contaminants like metal nanoparticles get introduced into soil through different routes.Toxic effects of these contaminants on plant growth-promoting bacteria(PGPB),which influence plant productivity,can be detrimental to soil health.Titanium dioxide is one of the most produced nanomaterials in the world and therefore potentially the most released nanoform in soil.The objective of this study was to evaluate the toxic effects of titanium dioxide nanoparticles(TiO2 NPs)on plant growth-promoting bacteria.Three types of PGPB,viz.,nitrogen fixers,phosphate solubilizers and biofilm formers were exposed to TiO2 NPs.Our results suggest that direct contact of the bacteria with these NPs is inhibitory as compared to when these bacteria are growing in laboratory nutrient media in the presence of NPs.The inhibitory effect did not follow a linear dose response but instead showed a pronounced step response.Soils with their varying characteristics may not afford the same protection to bacteria as laboratory nutrient media and thus TiO2 NPs may cause some sensitive PGPB to disappear from soil.The resultant shift in bacterial community composition may affect ecosystem functioning.
