Soil microbes

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  • This book is for anyone interested in the consequences of disturbance. What happens after the lava cools, or when the muddy floodwaters recede or an old road is abandoned? Primary succession is the process of ecosystem development on barren surfaces where severe disturbances have removed most vestiges of biological activity. It includes the development of complex systems from simple biotic and abiotic (non-biological) components. Primary succession starts when plants, animals and microbes colonize new surfaces. The process is influenced by local conditions, context and site history.

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  • This is an insider's account of 50 years of genetic studies of the soil-inhabiting microbes that produce most of the antibiotics used to treat infections, as well as anti-cancer, anti-parasitic and immunosuppressant drugs. The book begins by describing how these microbes - the actinomycetes - were discovered in the latter part of the nineteenth century, but remained a 'Cinderella' group until, in the 1940s, they shot to prominence with the discovery of streptomycin, the first effective treatment for tuberculosis and only the second antibiotic after penicillin to become a medical marvel.

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  • One ot the most representative (sub)tropical soil microbe,Chro-mobacterium violaceum, produces many important substances and has great potential for biotechnology and medicine. On the other hand, it can also act as an opportunistic human pathogen. The bacterium produces the lectin CV-IIL, that can help the adhesion bacterium to saccharide moieties at host cells¢ surface.

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  • Though alternative methods of controlling insects, rodents, insect pests, pathogens, microbes and weeds have been developed, pesticides could not be replaced. The prosperous role of pesticides in the management of insect pests and diseases is indisputable. However, its nature of non selective toxicity towards other organisms and deposition in the environment warrants the legislation of usage. Pesticide use raises a number of environmental concerns.

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  • Sorption is a process by which chemicals or organisms become attached to soils and/or the geologic rock material (aquifer solids) and removed from the water. Often the sorption process is reversible and solutes desorb and hence dissolved-solute plumes are retarded, rather than solutes being permanently retained by the solids. Cation exchange is the interchange between cations in solution and cations on the surfaces of clay particles or organic colloids. Filtration is a process that affects particulate contaminants (e.g.

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  • An additional benefit of hydrogen peroxide and Fenton's Reagent is the temporary increase of oxygen levels in and around the treatment area. The increased oxygen levels at the fringes of the treatment area can enhance naturally occurring aerobic biodegradation processes that reduce contaminant mass. While there may be concerns about oxidizing hydrocarbon-degrading bacteria in the chemical oxidation treatment area, many studies have shown that soil cannot be readily sterilized by Fenton's Reagent and that microbial populations rapidly rebound following chemical oxidation treatment.

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  • In modifying soil pH, the addition of amendments, fertilizers, tillage practices, soil organic matter levels, and drainage should all be considered. A common amendment used to acidify alkaline soils is sulfur (S) (Slaton et al., 2001). Elemental sulfur (S0 ) is oxidized by microbes to produce sulfate (SO4 2- ) and H+, causing a lower pH. Ferrous sulfate (FeSO4 ) and aluminum sulfate (Al 2 (SO4 )3 ) can also be used to lower pH, not due to SO4 , but because of the addition of acidic cations (Fe2+, Al 3+) (see Q & A #1).

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  • Healthy soil is the foundation of organic farming. Regular additions of organic matter in the form of cover crops, compost, or manure create a soil that is biologically active, with good structure and capacity to hold nutrients and water (note that any raw manure applications must occur at least 120 days before harvest). Decomposing plant materials will activate a diverse pool of microbes, including those that break down organic matter into plant-available nutrients, as well as others that compete with plant pathogens in the soil and on the root surface.

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