Exploring bioremediation strategies for heavy metals and POPs pollution: the role of microbes, plants, and nanotechnology

Heavy metal and Persistent Organic Pollutants (POPs) pollution stemming from industrialization, intensive agriculture, and other human activities pose significant environmental and health threats. These contaminants persist in the air, soil, and water, particularly in industrialized nations, adversely affecting human health and ecosystems. While physical and chemical methods exist for detoxifying contaminated soil, they often have drawbacks such as high cost and technical complexity. Bioremediation, utilizing plants and microbes, offers a promising solution. Certain microorganisms like Streptomyces, Aspergillus and plant species such as Hibiscus and Helianthus show high metal adsorption capacities, making them suitable for bioremediation. However, plants’ slow growth and limited remediation efficiency have been challenges. Recent advancements involve leveraging plant-associated microbes to enhance heavy metal removal. Additionally, nanotechnology, particularly nano-bioremediation, shows promise in efficiently removing contaminants from polluted environments by combining nanoparticles with bioremediation techniques. This review underscores bioremediation methods for heavy metals using plants and microbes, focusing on the role of Plant Growth Promoting Rhizobacteria (PGPR) in promoting phytoremediation. It also explores the implementation of nanotechnologies for eliminating metals from polluted soil, emphasizing the significance of soil microbiomes, nanoparticles, and contaminant interactions in developing effective nano-remediation strategies for optimizing agriculture in contaminated fields

Effect of maize root exudates on indole-3-acetic acid production by rice endophytic bacteria under influence of L-tryptophan [version 1; referees: 2 approved]

Background: It is assumed that plant growth regulators produced by beneficial bacterial species could also influence plant growth. IAA is a major plant growth regulator responsible for stimulation of plant growth. There are several microorganisms which are naturally responsible for L- tryptophan metabolism. Methods: In total, 56 indigenous morphologically distinct isolates from rice roots were selected and subsequently characterized with biochemical tests, 16S rRNA sequencing and plant growth promoting activities. Pseudomonas fluorescens RE1 (GenBank: MF102882.1) and RE17 (GenBank: MF103672.1) endophytes resulted in better PGP activity against the other 54 isolates. Both endophytes were tested to screen indole-3-acetic acid production ability in pure culture conditions with L-tryptophan at 0, 50, 100, 200 and 500µg/ml concentrations. Results: P. fluorescens RE1 was recorded efficient for indole production in comparison to P. fluorescens RE17 at various L-tryptophan concentrations. P. fluorescens RE1 was shown to produce between 0.8 µg/ml and 11.5µg/ml of indole at various tryptophan concentrations, while RE17 produced between 1.2µg/ml and 10.2µg/ml. At 200 and 500µg/ml tryptophan concentration, P. fluorescens RE17 produced 7.4pmol/ml and 9.3pmol/ml IAA, respectively.  Conclusions: Inoculation of maize seed with P. fluorescens RE1 and RE17 showed a significantly higher level of IAA production in comparison to non-inoculated seeds. Current study outcomes proved that plant growth regulators produced by Pseudomonas species could also play a critical role in plant growth promotion

Recent developments in Neem (Azadirachta indica – A. Juss) derived antimicrobial constituents for control of human and plant diseases – a review

Neem has immense biocontrol potential against a large number of pathogens causing various diseases in human beings and plants. The plant has maximum useful value in its leaves, bark, flowers and fruits than any other tree species. These values include antiallergic, antidermatic, antifeedent, antifungal and anti-inflammatory properties. Due to the vast activities of neem, it has become extremely valuable in making our ecosystem a green treasure. Neem leaves have been demonstrated to exhibit immuno-modulatory, anti-inflammatory, antiulcer, antimalarial properties. Neem tree plant parts contain a promising pest control substance which has found effective use against economically important agricultural pests. Neem plant products are easy to process by village level industries on the micro scale level and use by resource poor farmers in crop protection resulting thereby in income generation. This plant also has antioxidant properties and free radical scavenging potential in its different extracted solvents. The present review highlights the properties of neem against the pathogens of living organisms for environmental protection

Recent developments in Neem (Azadirachta indica – A. Juss) derived antimicrobial constituents for control of human and plant diseases – a review

Neem has immense biocontrol potential against a large number of pathogens causing various diseases in human beings and plants. The plant has maximum useful value in its leaves, bark, flowers and fruits than any other tree species. These values include antiallergic, antidermatic, antifeedent, antifungal and anti-inflammatory properties. Due to the vast activities of neem, it has become extremely valuable in making our ecosystem a green treasure. Neem leaves have been demonstrated to exhibit immuno-modulatory, anti-inflammatory, antiulcer, antimalarial properties. Neem tree plant parts contain a promising pest control substance which has found effective use against economically important agricultural pests. Neem plant products are easy to process by village level industries on the micro scale level and use by resource poor farmers in crop protection resulting thereby in income generation. This plant also has antioxidant properties and free radical scavenging potential in its different extracted solvents. The present review highlights the properties of neem against the pathogens of living organisms for environmental protection