Microorganism adaptation

TABLE 3.1. Classification of the Nutritional Requirements of Microorganisms (adapted from Benefield and Randall, 1980). 

In oceanic sediments, macro- (> 1 mm) and microorganisms adapt to the existing environment. They play an important role in the mixing of surface sediment layers. Burrowing by organisms in marine sediments is so common that it is the preservation of depositional structures that requires explanation, not their destruction (Arrhenius, 1952, p. 86). 

Soils previously treated with certain herbicides often exhibit an increased ability to degrade these chemicals, seemingly as a result of a proliferation of microorganisms adapted to the herbicides in question. Such soils are said to have become "enriched". The enhanced degradation of herbicides in soil as a result of repeated applications has recently been reviewed (3). ... 

For all sources of seed (including the manufactured seed) the possibility exists that some wastes will cause poisoning of the microorganisms. Some wastes will have developed microorganisms adapted to the toxic conditions and hence give expected BOD results, but in other wastes the microorganisms will adapt over the period of the BOD test. Because of the lag time involved in adaptation, a lower BOD is obtained than might be expected. If the toxicity is sufficiently acute, a zero or close-to-zero result is obtained. 

In addition to enzymatic reactions, microbial growth phenomena involve the pronounced ability of living cells to adapt to environmental changes. A microorganism adapts its activities to changes in the environment by the following types of mechanisms (Fig. 4.9) ... 

In comparison with ozone and chlorine dioxide, the main advantage of chlorine species as disinfectants is their reservoir effect in a system over increased time. The main disadvantage is the formation of halogenated by-products. Because of this, and to avoid microorganism adaptation effects, continuous use of disinfection cells without periodic interruption is not recommended. 

The rhizosphere, the layer of soil in which plant roots are especially active, is a particularly important part of soil with respect to biodegradation of wastes. It is a zone of increased biomass and is strongly influenced by the plant root system and the microorganisms associated with plant roots. The rhizosphere may have more than ten times the microbial biomass per unit volume than nomhizospheric zones of soil. This population varies with soil characteristics, plant and root characteristics, moisture content, and exposure to oxygen. If this zone is exposed to pollutant compounds, microorganisms adapted to their biodegradation may also be present... 

Schematic view of synthesis of sugar-linked polystyrene and their attack by microorganisms (adapted from National Chemical Laboratory, Pune (India) websitewww.ncl-india.org). 

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