Microbial environment

CDU in pure form is a white powder. It is made slowly available to the soil solution by nature of its limited solubihty in water. Once in the soil solution, nitrogen from CDU is made available to the plant through a combination of hydrolysis and microbial decomposition. As with any CRE which is dependent on microbial action, the mineralization of CDU is temperature dependent. Product particle size has a significant effect on CDU nitrogen release rate. Smaller particles mineralize more rapidly because of the larger surface contact with the soil solution and the microbial environment. The rate of nitrogen release is also affected by pH because CDU degrades more rapidly in acidic soils. 

E) Knapweed may have an indirect effect on other plants because it may modify the soil microbial environment to its advantage. However, studies on soil respiration indicated that there is no obvious enhancement or inhibition of soil microorganisms in the root zone of knapweed. 

On the other hand, fermented dairy products such as yoghurt have been hypothesized to reduce LDL-cholesterol due to their effects on encouraging a gut microbial environment to facilitate the production of short chain fatty acids and thus reduce the synthesis of cholesterol (Nestel, 2008). Fermented dairy has in fact been proposed as a nutraceuti-cal with cholesterol-lowering potential (Chen et al., 2008). 

Probiotic bacteria may counteract the inflammatory process by stabilizing the microbial environment of gut and permeability barrier of intestine, but the underlying mechanisms are still not completely discovered. It has in fact been demonstrated by Salminen et al. (1998) that probiotics participate in the exclusion of pathogens thereby preventing the generation of inflammatory mediators by intraluminal bacteria. 

Nienow, J.A., McKay, C.P. Friedmann, E.I. (1988) The cryptoendolithic microbial environment in the Ross Desert of Antarctica light in the photosynthetically active region. Microbial Ecology 16, 271-289. 

The availability of suitable nutrients in the particular microbial environment will determine whether or not a micro-organism will live and grow. In general microorganisms are versatile in their nutrient utilisation and many micro-organisms, particularly bacteria, have or can acquire, the ability to use many different nutrients. 

Methylstibines are subject to oxidation, quaternization, and complex formation, that could enhance or inhibit their environmental mobility. Environmentally significant concentrations of halocarbons (such as MeBr, MeCl, and Mel) are known to be produced naturally, and to accumulate in various environmental compartments. Early studies (mid-1970s), using NMR, indicated that trimethylstibine oxidizes rapidly to (Me)3SbO. However, detection of non-oxidized trimethylstibine produced from microbial environments that are not entirely anaerobic suggests... 

There is considerable debate concerning the antimicrobial effectiveness of alcohol used as a skin antiseptic. The antimicrobial efficacy of alcohol is highly dependent upon the concentration used, as well as the moisture level of the microbial environment treated. The short-chain, monovalent alcohols—ethanol and isopropanol—are probably the most effective for skin disinfection, because they are highly miscible with water, have low skin toxicity and allergenic potential, are fast-acting and are microbicidal, as opposed to microbiostatic. 

Consequentially to the marine environment due to an enigmatic transition from terrestrial to full aquatic habitat, the entire set of stress response proteins had to change and adapt. The innate TLR4 poised at the interface between host and an entirely new microbial environment has undergone a profound adaptive evolution ... 

During a soil burial biodegradation test for 27 months, samples specimen were withdrawn at time intervals and characterized by means of structural and thermal analysis. This method allows to watch any progress of oxidative degradation as a direct effect of the incubation in an active microbial environment. 

Coppola et al. (2001) first used DGGE to investigate a dairy microbial environment, specifically mozzarella cheese, and observed that the greatest diversity resulted... 

A more recent biodegradable polymer is polyhydroxybutyrate-valerate copolymer (PHBV) from ICI Americas Inc.. These copolymers are produced through biochanical means. In fact, these natural thermoplastics are derived from bacteria. They are fully degradable in many microbial environments. Other biodegradable polymers include Konjac, a water-soluble polysaccharide produced by FMC Chitin, another polysaccharide that is insoluble in water and Chitosan, which is soluble in water. 

Figure 10.15 Gel permeation chromatography (GPC) chromatograms of a synthetic oligomer mixture synthesised from 1,4-butanediol and terephthalic acid before and after incubation in different microbial active environments (synthetic mineral medinm at room temperature inoculated with a compost extract) soil at room temperature and compost at 60 °C. Grey area GPC profile of the oligomer mixture before incubation, dotted line GPC profile of the oligomer mixtnre after incubation in sterile water under conditions comparable with the degradation experiment (blank test), and solid line GPC profile of the oligomer mixtnre after incubation in the different microbial environments. RT room temperatnre.

Sutherland IW (2001) The biofilm matrix - an immobilized but dynamic microbial environment Trends Microbiol 9 222-227... 

Several mechanisms have been proposed to explain the antimicrobial properties of tannins. The antimicrobial effects of phenolic compounds are probably related to the inhibition of bacterial enzymes, alterations in cell wall permeability, an increase in the hydrogen ion activity of the microbial environment, a reduction in the surface and/or interfacial tension and perhaps chelation of essential minerals, particularly iron with a concomitant impairment of the microbial oxidative metabolic system (Chung et al. 1998). The antimicrobial activities of tannins are ascribed to the interactions of goats tannins with the extracellular enzymes secreted and... 

To be compostable the biomaterial requires a controlled microbial environment such as an industrial compost facility before they will degrade. This is because there are requirements of heat, moisture and aeration to activate and sustain the degradation process. To be considered compostable, a material must be able be put into an industrial composting process and breakdown by 90% within six months. Under the European Standard EN 13432 [2] they can be labelled or marked with a compostable symbol. 

An alternative is to use a biopolymer. In a similar film application for example, an option would be to use one that is starch-based and derived from corn (PCL, PVA or PLA). These biodegradable films, dependent on thickness, would meet the ASTM standard (American Standard for Testing Materials) and European [EN13432] for composting. However these materials require a controlled microbial environment such as an industrial compost facility before they will degrade. 

To he compostable a biomaterial requires a controlled microbial environment such as an industrial compost facility before they will degrade. 

An array of model systems of the gastrointestinal microbial environment of varying degrees of complexity have been developed and validated in recent years (Rumney and Rowland 1992 Molly et al. 1994). Such models, based around continuous flow culture, enable us to look at the human gut microflora under laboratory conditions and investigate such microflora-associated activities as fermentation of dietary constituents (e.g. dietary fibre, proteins and prebiotics). These models of the colonic microllora are invaluable in the development of efficacious or novel prebiotics. They may also be useful in conducting initial studies on the effect of antibiotics on the complex gut microllora and in DNA transfer studies between members of the gut microflora and genetically modified foods (Tuohy et al. 2002 Payne etal. 2003). 

I. W. Suntherland, The biofilm matrix—An immobilized but dynamic microbial environment. 

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