C. Sreenivasulu

Bio: C. Sreenivasulu is an academic researcher. The author has contributed to research in topics: Bioremediation. The author has an hindex of 1, co-authored 1 publications receiving 22 citations.

Bioremediation of Contaminated Soils and Aquifers

Abstract: This chapter provides a review of the various in situ and ex situ bioremediation technologies and the situations to which they are applicable. As many as 2 billion people rely directly on aquifers for drinking water, and 40% of the world’s food is produced by irrigated agriculture that relies largely on groundwater. Two technologies - biopiles and windrow composting - currently dominate the ex situ bioremediation market for treatment of contaminated soils. Permeable reactive barriers (PRBs) have traditionally been designed as chemical and physical intervention techniques, with incidental biodegradation taking place, and it is only recently that deliberately turning PRBs into bioremediation technology has arisen. Even materials such as garden waste provide extra microbial communities, even though that is not the primary function in the bioremediation, which is normally to provide heat-generating materials during composting. A variety of genetically modified organism (GMO) that have been designed for bioremediation are still at the laboratory or early field test stage, but there is optimism that in the future, GMOs will be used for bioremediation, targeting most recalcitrant pollutants in inhospitable environments at relatively low cost. Delivery of bioaugmentation cultures in an immobilized form may offer more complete and/or more rapid degradation. The longer-term success of bioremediation may well depend upon developing in situ treatments that can greatly accelerate the rates of degradation of contaminants, especially in groundwater, in a predictable and cost-effective manner.

Characterization of Rhizobium strain isolated from the roots of Trigonella foenumgraecum (fenugreek)

Abstract: Trigonella foenumgraecum (fenugreek) is known for its dietary protein source, medicinal properties and symbiotic nitrogen fixation by Rhizobium present in its root nodules. The present study describes the characterization of a Rhizobium strain isolated from root nodules of fenugreek. The Rhizobium isolates were rod shaped, gram negative, acid and mucous producing. They were found to be temperature and pH sensitive, with optimum values of 29.4 and 7.0°C, respectively. The bacteria was sensitive to the antibiotics; chloramphenicol, kanamycin and streptomycin. It utilizes glucose, sucrose and starch as sole carbon source. The Rhizobium species isolated from fenugreek roots have the potential to produce industrially important enzymes; amylase and cellulase. Immobilizing the organism in agar and agarose does not affect its activity; indeed increased biomass yield and enzyme production was observed. The Rhizobium can be easily immobilized onto carriers like charcoal powder which can be applied as biofertilizer.

Bio- and Phytoremediation of Pesticide-Contaminated Environments: A Review

Abstract: Pesticide-contaminated fields can be found worldwide due to excessive use of insecticides, herbicides and fungicides. Many of the pesticides that were once used intensively are now forbidden and have been shown to have deleterious health effects. Plants, bacteria and fungi have been shown to possess pesticide-degrading capacities, which can be applied in the successful remediation of contaminated fields and water. This article will first provide an overview of the different types of pesticides, their application and their key characteristics, followed by an analysis of their behaviour in the environment. Pesticides that are introduced into the environment seldom stay where they were applied. A complex system of transport, transfer and transformation of pesticides throughout different environmental compartments often takes place. These processes all influence the possible remediation of the pesticide-contaminated media. We will then review several possible remediation strategies that are currently available. Bioremediation is the first technology that is reviewed. With bioremediation, the focus is on the remediation of pesticides by microorganisms in bulk soil, without the aid or presence of plants. Second, plant-associated remediation is discussed. When focussing on plant-associated remediation, a distinction has to be made between rhizoremediation in the rhizosphere and phytoremediation within the plant tissues. While rhizoremediation and phytoremediation processes are possible solely with the use of plants, many of these processes are optimized by associations between plants and microorganisms. Plants and bacteria or fungi often live in a symbiotic relationship that aids them in surviving contaminated environments, as well as with the degradation of the contaminants they encounter. In the last part of the review, we discuss the advantages and disadvantages of “natural” remediation strategies as compared to more classical industrial approaches.

Methyl parathion imprinted polymer nanoshell coated on the magnetic nanocore for selective recognition and fast adsorption and separation in soils.

Abstract: Core-shell magnetic methyl parathion (MP) imprinted polymers (Fe3O4@MPIPs) were fabricated by a layer-by-layer self-assembly process. In order to take full advantage of the synergistic effect of hydrogen-binding interactions and π-π accumulation between host and guest for molecular recognition, methacrylic acid and 4-vinyl pyridine were chosen as co-functional monomers and their optimal proportion were investigated. The core-shell and crystalline structure, morphology and magnetic properties of Fe3O4@MPIPs were characterized. The MP-imprinted nanoshell was almost uniform and about 100nm thick. Binding experiments demonstrated that Fe3O4@MPIPs possessed excellent binding properties, including high adsorption capacity and specific recognition, as well as fast adsorption kinetics and a fast phase separation rate. The equilibration adsorption capacity reached up to 9.1mg/g, which was 12 times higher than that of magnetic non-imprinted polymers, while adsorption reached equilibrium within 5min at a concentration of 0.2mmol/L. Furthermore, Fe3O4@MPIPs successfully provided selective separation and removal of MP in soils with a recovery and detection limit of 81.1-87.0% and 5.2ng/g, respectively.

Degradation of organophosphate insecticide by a novel Bacillus aryabhattai strain SanPS1, isolated from soil of agricultural field in Burdwan, West Bengal, India

Abstract: Organophosphate (OP) insecticides are widely used for controlling insect pests for better crop production in India. But indiscriminate use and lack of proper technical knowhow have resulted in contamination and pollution of large varieties of ecological niches. A novel bacterial strain designated as SanPS1, capable of utilizing chlorpyrifos and parathion, was isolated by enrichment culture from a soil sample of an agricultural field located at Narigram in Burdwan district of West Bengal, India. This novel Gram positive, endospore forming strain was identified as Bacillus aryabhattai based on 16S rDNA sequencing. The strain tolerated up to 500 μg mL−1 of chlorpyrifos and parathion and for both compounds optimal degradation was achieved at a concentration of 200 μg mL−1. The metabolites were identified by high performance liquid chromatography and gas chromatography-mass spectrometry analyses. We propose a degradation pathway of parathion for this strain through formation of 4-nitrophenol and 4-nitrocatechol intermediates. The strain could degrade approximately 56% of parathion in liquid mineral medium within 24 h at 37 °C.