Nasib Singh

Toxicity, monitoring and biodegradation of the fungicide carbendazim

The increasing use of toxic pesticides is a major environmental concern. Carbendazim is a systemic fungicide having wide applications for controlling fungal diseases in agriculture, forestry and veterinary medicines. Carbendazim is a major pollutant detectable in food, soil and water. Carbendazim extensive and repeated use induces acute and delayed toxic effects on humans, invertebrates, aquatic life forms and soil microorganisms. Here, we review the pollution, non-target toxicity and microbial degradation of carbendazim for crop and veterinary purposes. We found that carbendazim causes embryotoxicity, apoptosis, teratogenicity, infertility, hepatocellular dysfunction, endocrine-disrupting effects, disruption of haematological functions, mitotic spindle abnormalities, mutagenic and aneugenic effect. We also found that carbendazim disrupted the microbial community structure in various ecosystems. The detection of carbendazim in soil and reservoir sites is performed by spectroscopic, chromatographic, voltammetric, nanoparticles, carbon electrodes and mass spectrometry. A review of the degradation of carbendazim shows that carbendazim undergoes partial to complete biodegradation in the soil and water by Azospirillum, Aeromonas, Alternaria, Bacillus, Brevibacillus, Nocardioides, Pseudomonas, Ralstonia, Rhodococcus, Sphingomonas, Streptomyces and Trichoderma.

Synergistic effects of Arbuscular mycorrhizal fungi and plant growth promoting rhizobacteria in bioremediation of iron contaminated soils.

ABSTRACT Three Arbuscular mycorrhizal fungi (AMF) from Glomus, Acaulospora and Scutellospora, and four plant growth promoting rhizobacteria (PGPR) isolates related to genera Streptomyces, Azotobacter, Pseudomonas and Paenibacillus were found to be effective in phytoremediation of Fe3+ contaminated soil where Pennisetum glaucum and Sorghum bicolor were growing as host plants. Co-inoculation of AMF and PGPR showed better results in comparison to either, AMF and PGPR under pot conditions. Both AMF and PGPR were able to produce siderophores. AMF and PGPR associated to P. glaucum and S. bicolor plants increased the extent of iron absorption. AMF and PGPR combination exhibited superior (p < 0.01) phytoremediation efficiency with P. glaucum compared to S. bicolor. These findings warrant further investigations of these synergistic interactions and large-scale in situ studies for bioremediation of iron-contaminated soils.

Small at Size, Big at Impact: Microorganisms for Sustainable Development

From being the first life originated on Earth ~3.8 billion years ago to the present time, microorganisms have enormously impacted the human, animal, and plant’s lives and global biogeochemical cycles in one way or another. These are widely distributed in almost all habitats and ecosystems on Earth, including the most hostile and extreme habitats which are otherwise uninhabitable to other organisms. Domain Bacteria and Archaea are composed entirely of prokaryotic microorganisms, whereas eukaryotic microbes, viz., fungi, algae, protozoa, slime molds, and water molds, belong to domain Eukarya. Archaea and bacteria represent the majority of life-forms on our planet. Recent estimate predicts 1011–1012 microbial species on Earth of which 99.9% microbial species are yet to be cultured in the laboratory. Ocean, soil, rhizosphere, human gut, animal body, etc. are some of the most densely populated microbial habitats. Microorganisms are excellent model organisms for the study of metabolism and genetics at cellular level. Considered as Earth’s greatest chemists, microorganisms have unparalleled metabolic capabilities, extraordinary adaptability, and remarkable survival strategies which undoubtedly make them the most successful living creatures. Most microbes are beneficial to humans, plants, and animals. These contribute significantly to ensure the quality of human life and in sustaining life on our planet. Microbes have established ecologically important symbiotic and nonsymbiotic associations with themselves, humans, plants, ruminants, vertebrates, and invertebrates. Incomparable importance of microorganisms led to the origin of concepts of microbiome, hologenome, and superorganism. Microorganisms offer numerous biotechnological compounds for human, animal and agriculture, and environment sustainability. These are the source of numerous bioproducts like antibiotics, biopharmaceuticals, single-cell proteins, organic acids, biofertilizers, biopesticides, enzymes, pigments, vitamins, biofuels, biocement, and many more. Harnessing microbial capabilities is undoubtedly the best possible sustainable solution to ever-increasing challenges of balanced diet, clean air, water, energy, medicine, and healthy environment.

Effect of rhizobacteria on arsenic uptake by macrophyte Eichhornia crassipes (Mart.) Solms

ABSTRACT Wastewater flowing in streams and nallahs across India carries several trace metals, including metalloid arsenic (As), which are considered serious environmental contaminants due to their toxicity, and recalcitrant nature. In this study, we determined the phytoremediation of As by Eichhornia crassipes (Mart.) Solms either alone or in association with plant growth-promoting rhizobacteria. Pseudomonas and Azotobacter inoculation to E. crassipes resulted in enhanced As removal compared to uninoculated control. Co-inoculation with a consortium of Pseudomonas, Azotobacter, Azospirillum, Actinomyces, and Bacillus resulted in a higher As (p < 0.05) phytoaccumulation efficiency. P. aeruginosa strain jogii was found particularly effective in augmenting As removal by E. crassipes. Our findings indicate that the synergistic association of E. crassipes and various rhizobacteria is an effective strategy to enhance removal of As and thus may be utilized as an efficient biological alternative for the removal of this metalloid from wastewaters.