Studying of nanoparticle structures is gaining momentum because of their great potential in improving several fields of science such as agriculture. The water soluble fraction of the extracellular polysaccharides (EPS)/matrix of the highly EPS producing cyanobacterium Nostoc commune have been used as a potent reducing and capping agent for green synthesis of silver nanoparticles. The size of these nanoparticles with the EPS coat was found to be in the range of 15–54 nm as analyzed using transmission electron micrographs. Interestingly, after washing the EPS coated silver nanoparticles by ethanol, the size of nanoparticles reduced to less than 15 nm due to the formation of silver oxide nanoparticles and removal of the EPS coat. Silver nanoparticles showed antibacterial properties against Escherichia coli. The minimum inhibitory concentration (MIC) was 0.012 mg/ml while the minimum bactericidal concentration (MBC) was 0.016 mg/ml. The slight difference between the MIC and MBC suggests that such silver nanoparticles act as a potent bactericidal agent against E. coli. Presoaking seeds of crop plants (Sorghum and broad bean) in five-fold MBC of silver nanoparticles (0.08 mg/ml) did not adversely affect the germination of Vicia faba L. and Sorghum bicolor plants. Concomitantly, such fivefold MBC concentration of silver nanoparticles was powerful sterilizing agent for seeds and grains against seed/grain-borne microorganisms. The results showed gradual depletion of the total colony forming units (CFU) in seeds and grains sterilized with silver nanoparticles than those sterilized with chlorine. These results suggest that the water soluble fraction of the extracellular polysaccharides (EPS)/matrix of Nostoc commune can be used as a potent reducing and capping agent for green synthesis of silver nanoparticles and that silver nanoparticles can be used as a potent surface sterilizi

Studying of nanoparticle structures is gaining momentum because of their great potential in improving several fields of science such as agriculture. The water soluble fraction of the extracellular polysaccharides (EPS)/matrix of the highly EPS producing cyanobacterium Nostoc commune have been used as a potent reducing and capping agent for green synthesis of silver nanoparticles. The size of these nanoparticles with the EPS coat was found to be in the range of 15–54 nm as analyzed using transmission electron micrographs. Interestingly, after washing the EPS coated silver nanoparticles by ethanol, the size of nanoparticles reduced to less than 15 nm due to the formation of silver oxide nanoparticles and removal of the EPS coat. Silver nanoparticles showed antibacterial properties against Escherichia coli. The minimum inhibitory concentration (MIC) was 0.012 mg/ml while the minimum bactericidal concentration (MBC) was 0.016 mg/ml. The slight difference between the MIC and MBC suggests that such silver nanoparticles act as a potent bactericidal agent against E. coli. Presoaking seeds of crop plants (Sorghum and broad bean) in five-fold MBC of silver nanoparticles (0.08 mg/ml) did not adversely affect the germination of Vicia faba L. and Sorghum bicolor plants. Concomitantly, such fivefold MBC concentration of silver nanoparticles was powerful sterilizing agent for seeds and grains against seed/grain-borne microorganisms. The results showed gradual depletion of the total colony forming units (CFU) in seeds and grains sterilized with silver nanoparticles than those sterilized with chlorine. These results suggest that the water soluble fraction of the extracellular polysaccharides (EPS)/matrix of Nostoc commune can be used as a potent reducing and capping agent for green synthesis of silver nanoparticles and that silver nanoparticles can be used as a potent surface sterilizi

The objective of this study is to explore the response of an activated Rhizobium tibeticum inoculum with a mixture of hesperetin (H) and apigenin (A) to improve the growth, nodulation, and nitrogen fixation of fenugreek (Trigonella foenum graecum L.) grown under nickel (Ni) stress. Three different sets of fenugreek seed treatments were conducted, in order to investigate the activated R. tibeticum pre-incubation effects on nodulation, nitrogen fixation and growth of fenugreek under Ni stress. Group (I): uninoculated seeds with R. tibeticum, group (II): inoculated seeds with uninduced R. tibeticum group (III): inoculated seeds with induced R. tibeticum. The present study revealed that Ni induced deleterious effects on rhizobial growth, nod gene expression, nodulation, phenylalanine ammonia-lyase (PAL) and glutamine synthetase activities, total flavonoids content and nitrogen fixation, while the inoculation with an activated R. tibeticum significantly improved these values compared with plants inoculated with uninduced R. tibeticum. PAL activity of roots plants inoculated with induced R. tibeticum and grown hydroponically at 75 and 100 mg L-1 Ni and was significantly increased compared with plants receiving uninduced R. tibeticum. The total number and fresh mass of nodules, nitrogenase activity of plants inoculated with induced cells grown in soil treated up to 200 mg kg-1 Ni were significantly increased compared with plants inoculated with uninduced cells. Plants inoculated with induced R. tibeticum dispalyed a significant increase in the dry mass compared with those treated with uninduced R.tibeticum. Activation of R. tibeticum inoculum with a mixture of hesperetin and apigenin has been proven to be practically important in enhancing nodule formation, nitrogen fixation and growth of fenugreek grown in Ni contaminated soils.

The objective of this study is to explore the response of an activated Rhizobium tibeticum inoculum with a mixture of hesperetin (H) and apigenin (A) to improve the growth, nodulation, and nitrogen fixation of fenugreek (Trigonella foenum graecum L.) grown under nickel (Ni) stress. Three different sets of fenugreek seed treatments were conducted, in order to investigate the activated R. tibeticum pre-incubation effects on nodulation, nitrogen fixation and growth of fenugreek under Ni stress. Group (I): uninoculated seeds with R. tibeticum, group (II): inoculated seeds with uninduced R. tibeticum group (III): inoculated seeds with induced R. tibeticum. The present study revealed that Ni induced deleterious effects on rhizobial growth, nod gene expression, nodulation, phenylalanine ammonia-lyase (PAL) and glutamine synthetase activities, total flavonoids content and nitrogen fixation, while the inoculation with an activated R. tibeticum significantly improved these values compared with plants inoculated with uninduced R. tibeticum. PAL activity of roots plants inoculated with induced R. tibeticum and grown hydroponically at 75 and 100 mg L-1 Ni and was significantly increased compared with plants receiving uninduced R. tibeticum. The total number and fresh mass of nodules, nitrogenase activity of plants inoculated with induced cells grown in soil treated up to 200 mg kg-1 Ni were significantly increased compared with plants inoculated with uninduced cells. Plants inoculated with induced R. tibeticum dispalyed a significant increase in the dry mass compared with those treated with uninduced R.tibeticum. Activation of R. tibeticum inoculum with a mixture of hesperetin and apigenin has been proven to be practically important in enhancing nodule formation, nitrogen fixation and growth of fenugreek grown in Ni contaminated soils.

The objective of this study is to explore the response of an activated Rhizobium tibeticum inoculum with a mixture of hesperetin (H) and apigenin (A) to improve the growth, nodulation, and nitrogen fixation of fenugreek (Trigonella foenum graecum L.) grown under nickel (Ni) stress. Three different sets of fenugreek seed treatments were conducted, in order to investigate the activated R. tibeticum pre-incubation effects on nodulation, nitrogen fixation and growth of fenugreek under Ni stress. Group (I): uninoculated seeds with R. tibeticum, group (II): inoculated seeds with uninduced R. tibeticum group (III): inoculated seeds with induced R. tibeticum. The present study revealed that Ni induced deleterious effects on rhizobial growth, nod gene expression, nodulation, phenylalanine ammonia-lyase (PAL) and glutamine synthetase activities, total flavonoids content and nitrogen fixation, while the inoculation with an activated R. tibeticum significantly improved these values compared with plants inoculated with uninduced R. tibeticum. PAL activity of roots plants inoculated with induced R. tibeticum and grown hydroponically at 75 and 100 mg L-1 Ni and was significantly increased compared with plants receiving uninduced R. tibeticum. The total number and fresh mass of nodules, nitrogenase activity of plants inoculated with induced cells grown in soil treated up to 200 mg kg-1 Ni were significantly increased compared with plants inoculated with uninduced cells. Plants inoculated with induced R. tibeticum dispalyed a significant increase in the dry mass compared with those treated with uninduced R.tibeticum. Activation of R. tibeticum inoculum with a mixture of hesperetin and apigenin has been proven to be practically important in enhancing nodule formation, nitrogen fixation and growth of fenugreek grown in Ni contaminated soils.

The objective of this study is to explore the response of an activated Rhizobium tibeticum inoculum with a mixture of hesperetin (H) and apigenin (A) to improve the growth, nodulation, and nitrogen fixation of fenugreek (Trigonella foenum graecum L.) grown under nickel (Ni) stress. Three different sets of fenugreek seed treatments were conducted, in order to investigate the activated R. tibeticum pre-incubation effects on nodulation, nitrogen fixation and growth of fenugreek under Ni stress. Group (I): uninoculated seeds with R. tibeticum, group (II): inoculated seeds with uninduced R. tibeticum group (III): inoculated seeds with induced R. tibeticum. The present study revealed that Ni induced deleterious effects on rhizobial growth, nod gene expression, nodulation, phenylalanine ammonia-lyase (PAL) and glutamine synthetase activities, total flavonoids content and nitrogen fixation, while the inoculation with an activated R. tibeticum significantly improved these values compared with plants inoculated with uninduced R. tibeticum. PAL activity of roots plants inoculated with induced R. tibeticum and grown hydroponically at 75 and 100 mg L-1 Ni and was significantly increased compared with plants receiving uninduced R. tibeticum. The total number and fresh mass of nodules, nitrogenase activity of plants inoculated with induced cells grown in soil treated up to 200 mg kg-1 Ni were significantly increased compared with plants inoculated with uninduced cells. Plants inoculated with induced R. tibeticum dispalyed a significant increase in the dry mass compared with those treated with uninduced R.tibeticum. Activation of R. tibeticum inoculum with a mixture of hesperetin and apigenin has been proven to be practically important in enhancing nodule formation, nitrogen fixation and growth of fenugreek grown in Ni contaminated soils.

The nitrogen cycle of Earth is one of the most critical yet poorly understood biogeochemical cycles. Current estimates of global N2 fixation are approximately 240 Tg N y−1 with a marine contribution of 100–190 Tg N y−1. Of this, a single non-heterocystous genus, Trichodesmium sp. contributes approximately100 Tg N y−1 (Capone pers. comm.). Geochemical evidence suggests that, on a global scale, nitrogen fixation does not always keep pace with denitrification on time scales of centuries to millenia (Falkowski and Raven, 1997), yet it remains unclear what process (es) limits nitrogen fixation in the oceans. More importantly, given the potential for heterocystous cyanobacteria to outcompete organisms such as Trichodesmium, itis unclear why the apparent tempo of evolution of marine diazotrophic cyanobacteria is so slow. Diazotrophic cyanobacteria have effectively become the “gate keepers” of oceanic productivity, yet despite the rapid radiation of eukaryotic oxygenic photoautotrophs throughout the Phanaerozoic eon marine cyanobacteria seem like living fossils (Berman-Frank et al., 2003). Finally, some Questions needs answering, Are there N2-fixing picoplankton? What limits the growth of N2-fixing microorganisms in the open ocean? Is N2 fixation associated with zooplankton?

The nitrogen cycle of Earth is one of the most critical yet poorly understood biogeochemical cycles. Current estimates of global N2 fixation are approximately 240 Tg N y−1 with a marine contribution of 100–190 Tg N y−1. Of this, a single non-heterocystous genus, Trichodesmium sp. contributes approximately100 Tg N y−1 (Capone pers. comm.). Geochemical evidence suggests that, on a global scale, nitrogen fixation does not always keep pace with denitrification on time scales of centuries to millenia (Falkowski and Raven, 1997), yet it remains unclear what process (es) limits nitrogen fixation in the oceans. More importantly, given the potential for heterocystous cyanobacteria to outcompete organisms such as Trichodesmium, itis unclear why the apparent tempo of evolution of marine diazotrophic cyanobacteria is so slow. Diazotrophic cyanobacteria have effectively become the “gate keepers” of oceanic productivity, yet despite the rapid radiation of eukaryotic oxygenic photoautotrophs throughout the Phanaerozoic eon marine cyanobacteria seem like living fossils (Berman-Frank et al., 2003). Finally, some Questions needs answering, Are there N2-fixing picoplankton? What limits the growth of N2-fixing microorganisms in the open ocean? Is N2 fixation associated with zooplankton?

Impact of harsh environmental conditions play an essential role in the control of legume-rhizobia interactions. They can arrest the growth, multiplication and survival of rhizobia in soil rhizosphere. The harsh environmental conditions may also have depressive effect on the steps involved in legume-Rhizobium symbiosis such as molecular signaling, infection process, nodule development and function, resulting in low nitrogen fixation and crop yield. Selection of hosts and their nitrogen-fixing endosymbionts that are tolerant to a broad range of environmental stresses is important for agriculture system. Understanding the key molecular factors and steps in rhizobia-legume interaction is of crucial importance for the development of Rhizobium strains and legume cultivars with high N2-fixation potential. Prevelence and aboundance of rhizobia species vary in their tolerance to major environment factors; consequently, the selection of resistant strains is an important option. Better N2 fixation can be achieved by selecting tolerance or resistance rhizobia from soil subjected to environmental stress. The selection and characterization of harsh conditions-tolerant strains with efficient symbiotic performance may be a strategy to improve Rhizobium-legume symbiosis and crop yield in adverse environments. Environmental stress severely affected on various metabolic activities of legumes including, nod gene expression, photosynthesis, synthesis of proteins, enzymes and carbohydrates. Therefore, understanding the environmental stress– rhizobia–legume interactions is urgently required for growing legumes under harsh environmental stress. Research into these areas is currently underway in several research groups throughout the world and it is anticipated that this research will provide beneficial outcomes resulting in improved sustainability and productivity in agricultural systems

Impact of harsh environmental conditions play an essential role in the control of legume-rhizobia interactions. They can arrest the growth, multiplication and survival of rhizobia in soil rhizosphere. The harsh environmental conditions may also have depressive effect on the steps involved in legume-Rhizobium symbiosis such as molecular signaling, infection process, nodule development and function, resulting in low nitrogen fixation and crop yield. Selection of hosts and their nitrogen-fixing endosymbionts that are tolerant to a broad range of environmental stresses is important for agriculture system. Understanding the key molecular factors and steps in rhizobia-legume interaction is of crucial importance for the development of Rhizobium strains and legume cultivars with high N2-fixation potential. Prevelence and aboundance of rhizobia species vary in their tolerance to major environment factors; consequently, the selection of resistant strains is an important option. Better N2 fixation can be achieved by selecting tolerance or resistance rhizobia from soil subjected to environmental stress. The selection and characterization of harsh conditions-tolerant strains with efficient symbiotic performance may be a strategy to improve Rhizobium-legume symbiosis and crop yield in adverse environments. Environmental stress severely affected on various metabolic activities of legumes including, nod gene expression, photosynthesis, synthesis of proteins, enzymes and carbohydrates. Therefore, understanding the environmental stress– rhizobia–legume interactions is urgently required for growing legumes under harsh environmental stress. Research into these areas is currently underway in several research groups throughout the world and it is anticipated that this research will provide beneficial outcomes resulting in improved sustainability and productivity in agricultural systems