Silicon(Si)is the second most abundant element in the Earth’s crust and has numerous roles in both soils and plants,although it is inaccessible to plants in its native state(insoluble silicate minerals).This inaccess...Silicon(Si)is the second most abundant element in the Earth’s crust and has numerous roles in both soils and plants,although it is inaccessible to plants in its native state(insoluble silicate minerals).This inaccessibility can lead to insufficiency,which induces anomalies in plant growth and development.Specifically,Si alleviates various biotic and abiotic stresses in plants by enhancing tolerance mechanisms at different stages of uptake/deposition as a monosilicic acid.Exclusive utilization of conventional Si fertilizers to boost agricultural productivity in an attempt to meet the world’s ever-increasing food demand may result in surface and groundwater pollution,waterway eutrophication,soil fertility depletion,and accumulation of hazardous elements such as arsenic in soil.By addressing the drawbacks of chemical fertilizers,this review emphasizes an environmentally friendly alternative,namely,Si-solubilizing microorganisms(SSMs),as bioinoculants to liberate soluble Si and thus making it available to plants.A deep understanding of recent advances in the functional diversity,colonization patterns,modes of action,role in biogeochemical cycling,and plant stress tolerance of SSMs and their implementation in Si-based agrowaste management through the fabrication of nanoparticles,could help to establish a reliable tool for economically and environmentally sustainable agriculture.From this perspective,in this review,we comprehensively summarize the latest methodologies for the isolation,screening,and characterization of SSMs and Si solubilization mechanisms,including ligands(divalent cations),acids(inorganic and organic),alkali(nucleophilic attack),extracellular polysaccharides,and factors affecting them,as well as Si-mediated regulation of gene expression involved in Si uptake,transportation,and mineralization.We have critically revised the role of SSMs according to the current literature.The contributions of SSMs to biofertilization are still being explored;hence,we also discuss trajectories for future research in relation to SSM-mediated increases in bioavailable Si.This will create new strategies to reduce the use of agrochemicals,improve plant health,and help us to globally gravitate towards more sustainable agricultural practices,based on the concept of a circular economy.展开更多
Samples of ground nut hull were converted to biosorbents using microwave assisted method [groundnut hull treated with hydrogen peroxide (HP-GH), groundnut hull treated with distilled water (W-GH) and raw groundnut hul...Samples of ground nut hull were converted to biosorbents using microwave assisted method [groundnut hull treated with hydrogen peroxide (HP-GH), groundnut hull treated with distilled water (W-GH) and raw groundnut hull (R-GH)]. The biosorbents were further characterized using physicochemical procedures (pH dependence, bulk density, surface area, ash content, and volatile matter, moisture content). The results show that HP-GH has pH = 8.9, W-GH pH = 8.4 and R-GH pH = 8.5 which is an indication that all the biosorbents have the appropriate pH values for the uptake of cationic species within aqueous systems. Surface area analysis revealed that HP-GH has the largest surface area (74.20 m<sup>2</sup>·g<sup>-1</sup>) while W-GH and R-GH have surface area values of 29.40 m<sup>2</sup>·g<sup>-1</sup> and 21.40 m<sup>2</sup>·g<sup>-1</sup> respectively. This suggests that modification of raw groundnut hull biomass with hydrogen peroxide possibly instigated delignification of the biomass which resulted in increased surface area for HP-GH. Results from Bulk density analysis also confirm the data obtained from surface area analysis. Accordingly, R-GH displayed the highest bulk density followed by W-GH with HP-GH showing the least bulk density. The variation in pH values among the biomass used in this study may be explained by the variation in their ash content as well because pH and ash content are positively correlated. Hence, HP-GH with a pH = 8.9 has high ash content (117.31%), W-GH with pH = 8.4 has 97.93% ash content and R-GH with pH = 8.5 has 94.26% ash content. Results from moisture content analysis show that HP-GH (99.95%), W-GH (99.97%) and R-GH (99.89%) may necessitate exposure of the biosorbents to moderate heat before use. The results obtained from this study suggest that modification of ground nut hull with either distilled water or Hydrogen peroxide by means of microwave irradiation improves physicochemical properties which may perhaps increase the adsorption capacity of the biomass.展开更多
In the present study,Paenibacillus lautus strain BHU3 isolated from landfill soil was evaluated for the presence of potential endoglucanases which are the first candidate of cellulase enzyme system to act on cellulose...In the present study,Paenibacillus lautus strain BHU3 isolated from landfill soil was evaluated for the presence of potential endoglucanases which are the first candidate of cellulase enzyme system to act on cellulose.In-silico analysis revealed high potential thermostable endoglucanases which can efficiently interact with cellulose.The most potent and thermostable endoglucanase(locus tag id.CPZ30_18280)belonged to glycosyl family-5 and had interaction energy of−12.981 kcal/mol for the best docked cluster containing three out of ten docking conformations,and Tm value of 73.3℃.MD simulation of 100 ns proved highly stable binding interactions of CPZ30_18280 endoglucanase with cellulose with root mean square deviation(RMSD)values ranging from 0.15 to 0.30 nm.Consistent interactions with characteristic active site residues(tyrosine,tryptophan and aspartate)of glycosyl family-5 endoglucanases were found.Further,to enhance the production of endoglucanases,the fermentation conditions were optimized employing approaches like one factor at a time(OFAT)and response surface methodology(RSM).Maximum activity of endoglucanase was determined at 60℃.The optimized condi-tions for enhanced production of endoglucanase(10.15 U/mL)were pH 6.63,yeast extract conc.3.44 g/L,wheat bran 3.59%,and inoculum size 2.65%.Hence,P.lautus strain BHU3 has enormous potential to synthesize highly efficient thermostable endoglucanases under optimized regime using agro-wastes.Thus,it could find immense industrial applications including large scale cellulose conversion to bioethanol.展开更多
文摘Silicon(Si)is the second most abundant element in the Earth’s crust and has numerous roles in both soils and plants,although it is inaccessible to plants in its native state(insoluble silicate minerals).This inaccessibility can lead to insufficiency,which induces anomalies in plant growth and development.Specifically,Si alleviates various biotic and abiotic stresses in plants by enhancing tolerance mechanisms at different stages of uptake/deposition as a monosilicic acid.Exclusive utilization of conventional Si fertilizers to boost agricultural productivity in an attempt to meet the world’s ever-increasing food demand may result in surface and groundwater pollution,waterway eutrophication,soil fertility depletion,and accumulation of hazardous elements such as arsenic in soil.By addressing the drawbacks of chemical fertilizers,this review emphasizes an environmentally friendly alternative,namely,Si-solubilizing microorganisms(SSMs),as bioinoculants to liberate soluble Si and thus making it available to plants.A deep understanding of recent advances in the functional diversity,colonization patterns,modes of action,role in biogeochemical cycling,and plant stress tolerance of SSMs and their implementation in Si-based agrowaste management through the fabrication of nanoparticles,could help to establish a reliable tool for economically and environmentally sustainable agriculture.From this perspective,in this review,we comprehensively summarize the latest methodologies for the isolation,screening,and characterization of SSMs and Si solubilization mechanisms,including ligands(divalent cations),acids(inorganic and organic),alkali(nucleophilic attack),extracellular polysaccharides,and factors affecting them,as well as Si-mediated regulation of gene expression involved in Si uptake,transportation,and mineralization.We have critically revised the role of SSMs according to the current literature.The contributions of SSMs to biofertilization are still being explored;hence,we also discuss trajectories for future research in relation to SSM-mediated increases in bioavailable Si.This will create new strategies to reduce the use of agrochemicals,improve plant health,and help us to globally gravitate towards more sustainable agricultural practices,based on the concept of a circular economy.
文摘Samples of ground nut hull were converted to biosorbents using microwave assisted method [groundnut hull treated with hydrogen peroxide (HP-GH), groundnut hull treated with distilled water (W-GH) and raw groundnut hull (R-GH)]. The biosorbents were further characterized using physicochemical procedures (pH dependence, bulk density, surface area, ash content, and volatile matter, moisture content). The results show that HP-GH has pH = 8.9, W-GH pH = 8.4 and R-GH pH = 8.5 which is an indication that all the biosorbents have the appropriate pH values for the uptake of cationic species within aqueous systems. Surface area analysis revealed that HP-GH has the largest surface area (74.20 m<sup>2</sup>·g<sup>-1</sup>) while W-GH and R-GH have surface area values of 29.40 m<sup>2</sup>·g<sup>-1</sup> and 21.40 m<sup>2</sup>·g<sup>-1</sup> respectively. This suggests that modification of raw groundnut hull biomass with hydrogen peroxide possibly instigated delignification of the biomass which resulted in increased surface area for HP-GH. Results from Bulk density analysis also confirm the data obtained from surface area analysis. Accordingly, R-GH displayed the highest bulk density followed by W-GH with HP-GH showing the least bulk density. The variation in pH values among the biomass used in this study may be explained by the variation in their ash content as well because pH and ash content are positively correlated. Hence, HP-GH with a pH = 8.9 has high ash content (117.31%), W-GH with pH = 8.4 has 97.93% ash content and R-GH with pH = 8.5 has 94.26% ash content. Results from moisture content analysis show that HP-GH (99.95%), W-GH (99.97%) and R-GH (99.89%) may necessitate exposure of the biosorbents to moderate heat before use. The results obtained from this study suggest that modification of ground nut hull with either distilled water or Hydrogen peroxide by means of microwave irradiation improves physicochemical properties which may perhaps increase the adsorption capacity of the biomass.
基金This research work was financially assisted by University Grants Commission,Government of India,New Delhi,in the form of Junior and Senior Research Fellowship to Suman(Grant No.09/013(0617)/2016-EMR-I).
文摘In the present study,Paenibacillus lautus strain BHU3 isolated from landfill soil was evaluated for the presence of potential endoglucanases which are the first candidate of cellulase enzyme system to act on cellulose.In-silico analysis revealed high potential thermostable endoglucanases which can efficiently interact with cellulose.The most potent and thermostable endoglucanase(locus tag id.CPZ30_18280)belonged to glycosyl family-5 and had interaction energy of−12.981 kcal/mol for the best docked cluster containing three out of ten docking conformations,and Tm value of 73.3℃.MD simulation of 100 ns proved highly stable binding interactions of CPZ30_18280 endoglucanase with cellulose with root mean square deviation(RMSD)values ranging from 0.15 to 0.30 nm.Consistent interactions with characteristic active site residues(tyrosine,tryptophan and aspartate)of glycosyl family-5 endoglucanases were found.Further,to enhance the production of endoglucanases,the fermentation conditions were optimized employing approaches like one factor at a time(OFAT)and response surface methodology(RSM).Maximum activity of endoglucanase was determined at 60℃.The optimized condi-tions for enhanced production of endoglucanase(10.15 U/mL)were pH 6.63,yeast extract conc.3.44 g/L,wheat bran 3.59%,and inoculum size 2.65%.Hence,P.lautus strain BHU3 has enormous potential to synthesize highly efficient thermostable endoglucanases under optimized regime using agro-wastes.Thus,it could find immense industrial applications including large scale cellulose conversion to bioethanol.
