Abhishek Chauhan

In vitro antibacterial activity of laboratory grown culture of Spirulina platensis

The hexane, ethyl acetate, dichloromethane, methanol extracts and spent media (extracellular substances) were tested in vitro for their antibacterial activity for which one Gram-positive bacterium (Staphylococcus aureus) and four Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Klebsiella pneumoniae) were used as test organisms. The methanol extract showed more potent activity than other organic extracts, spent medium of the culture exhibited little activity against E. coli only. No inhibitory effect was found against Klebsiella pneumoniae.The broth microdilution assay gave minimum inhibitory concentrations (MIC) values ranging from 1 to 512 μg/ml. The MIC of methanol extract against S. aureus and E. coli were 128 μg/ml and 256 μg/ml, respectively.

In vitro antibacterial evaluation of Anabaena sp. against several clinically significant microflora and HPTLC analysis of its active crude extracts.

The present study was conducted to evaluate the possible antibacterial activity of Anabaena extracts. Anabaena was isolated from a natural source and cultured in vitro. after suitable growth, cyanobacterial culture was harvested using different solvents. Extracts, thus prepared, were evaluated for their antibacterial potential by agar-well diffusion assay against bacterial species of clinical significance. MIC values were determined further to check the concentration ranges for significant inhibition. HPTLC analysis was done to separate the components of active crude extract in an attempt to identify the bio-active chemical entity. Methanol extract exhibited more potent activity than that of hexane and ethyl acetate extracts. No inhibitory effect was found against Pseudomonas aeruginosa, Salmonella typhi, and Klebsiella pneumoniae. Staphylococcus aureus required about 256 µg/ml of the crude methanol extract for effective inhibition. HPTLC evaluation at λ 254 nm was performed for the separation of a complex mixture of the methanol extract. The results provide evidence that Anabaena sp. extracts might indeed be potential sources of new antibacterial agents.

In-silico and in-vitro evaluation of human acetylcholinesterase inhibition by organophosphates

Organophosphates (OP) inhibit the acetylcholinesterase (AChE) activity and devastate the nervous system of pest however its mode of action is ubiquitous and acts similarly on human AChE (hAChE). Screening of OP was carried out by molecular docking with hAChE using Glide docking module of Schrodinger suite as the structural information of hAChE and OP together as co-crystal structure is rarely available. The docking was done at three different precision levels, high throughput virtual screening (HTVS), standard precision and extra precision. The ranking was done using over all binding energy i.e. dock score and molecular modelling generalized born surface area (MM-GBSA). Investigation reported Tryptophan (Trp86) residue involved in most interactions by forming a π-cation interaction apart from Ser203 on anionic subsite of hAChE. The top rank ligand was Phoxim ethyl phosphonate (PEP) interacting with Trp86, Gly121 and Ser203. However contact with Gly121 was lost during simulation and Asp74 appeared and sustained. Molecular dynamic simulation (GROMACS 4.5.5) of hAChE-PEP complex for 4 × 104 pico-second with SPC16 water system at 310 K temperature explained the evident role of Trp86 in stabilizing the ligand at P-site of the enzyme. Asp74 and Tyr124 were noticed in conveying H-bonds. Trp86 has shown consistent and better stability of bond based on distance between residues and ligand. The top ranked OP i.e. PEP was used to establish a dose response relationship between OP and hAChE. PEP inhibits half of the enzyme activity at concertation of 29.99 μM (calculated by sigmoid plot) at R2 = 0.996 and P < 0.0001.

Biological Control Agents for Sustainable Agriculture, Safe Water and Soil Health

Use of bio-agents must be encouraged in agriculture as the use of chemicals inversely impact population and natural resources. This chapter gives a wide variety of biological agents being used in India for various pests in different crops. Studies can further be stretched to use these bio-agents in turf and for ornamental pest control. Neem-based bio-insecticide is used at a concentration of 5% against Diamondback moth, Plutella xylostella in cabbage management. Farm yard manure (FYM) enriched with Trichoderma harzianum (4 g/kg) is used to control thrips, mites, and soil-borne diseases and Pseudomonas fluorescens is used (5 g/L) for inducing systemic resistance in hot peppers. Beauveria bassiana alone or in combination with BT have been used to control soil insects including potato beetles. The isolates of Trichoderma spp. have been characterized for biopriming, plant growth promotion characteristics, reduction of disease incidence, and corresponding yield increase in cabbage, cauliflower, mustard, and field pea at 5–10 g/kg seed. T. harzianum in the concentration of 2 × 108 cfu/g of soil and P. fluorescens 1 × 1012 cfu/g of soil was said to be the best towards management of root knot nematode (Meloidogyne incognita). Application of T. harzianum (250 g) + P. fluorescens (250 mL), and FYM (25 kg) + T. harzianum (250 g) + P. fluorescens (250 mL) against fusarium wilt, mites, and root knot nematode has been found promising in cucumber. The above bio-agents can also be successfully used for the control of turf and ornamental plants by conducting field trials.

Persistent Organic Pollutants in Biotic and Abiotic Components of Antarctic Pristine Environment

Over the past decades, research in Antarctica has built a new understanding of Antarctica, its past, present and future. Human activities and long-range pollutants are increasing on the Antarctic continent. Research on persistent organic pollutants (POPs) has been carried out internationally by several countries having their permanent research stations to explain the impact of an ever increasing range of POPs in Antarctic ecosystem. POPs have been detected in Antarctica despite its geographical isolation and almost complete absence of human settlements. The presence of POPs in different abiotic (atmosphere, water bodies, sediments, soil, sea ice) and biotic components (mosses, lichens, krill, penguins, skua, etc.) in Antarctica has been studied and documented around for decades and has either been banned or strictly regulated but is still found in the environment. This review focuses on recent research pertaining to sources and occurrence of POPs in Antarctic lake water, soil, sediment, lichen, mosses and other Antarctic marine community. This review also proposes to summarize the current state of research on POPs in Antarctica environment and draw the earliest conclusions on possible significance of POPs in Antarctica based on presently available information from related Antarctic environment.