Bioremediation microbial requirements

There are several basic microbial requirements that must be in place if bioremediation is to be successful. 

The potential for microbial mobility under natural or perturbed conditions clearly has significant implications for in situ bioremediation. Implementation of in situ bioremediation may require inoculating a soil or aquifer with contaminant-degrading microbes, perhaps genetically modified bacteria. For source area cleanup, these microbes either must be introduced in proximity to the contaminants or be capable of migrating toward the contaminants. Understanding microbial mobility may be important in the proper design of in situ bioremediation schemes. 

Bioremediation systems in operation today rely on microorganisms indigenous to contaminated sites. The two main approaches, based on the actions of native microbial communities, are biostimulation and intrinsic bioremediation. In biostimulation, the activity of native microbes is encouraged, creating (in situ or ex situ) the optimum environmental conditions and supplying nutrients and other chemicals essential for their metabolism. The vast majority of bioremediation projects are based on this biostimulation approach. Intrinsic bioremediation is a remedial option that can be applied when there is strong evidence that biodegradation will occur naturally over time without any external stimulation i.e., a capable microbial community exists at the site, the required nutrients are available, and the environmental conditions are favorable. An additional prerequisite is that the naturally... 

Regardless of whether the microbes are native or artificially introduced into the soil, it is important to understand the mechanisms by which they degrade or detoxify hazardous pollutants through their metabolic activity. Understanding these mechanisms is essential for the proper design of bioremediation systems that provide the optimum conditions and the required nutritional supplements for the specific microbial process. 

Microbial activity, which is often stimulated during bioremediation projects, can alter the external pH. For instance, the anaerobic degradation of chlorinated compounds produces organic acids and HC1 and the pH may drop to acidic values if the soil has a low buffering capacity. In this case, control of the external pH will be required in order to maintain biodegradation activity at... 

Bioremediation also has its limitations. Some chemicals are not amenable to biodegradation, for instance, heavy metals, radionuclides, and some chlorinated compounds. In some cases, the microbial metabolism of the contaminants may produce toxic metabolites. Bioremediation is a scientifically intensive procedure that must be tailored to site-specific conditions, and usually requires treatability studies to be conducted on a small scale before the actual cleanup of a site.13 The treatability procedure is important, as it establishes the extent of degradation and evaluates the potential use of a selected microorganism for bioremediation. A precise estimate on vessel size or area involved, speed of reaction, and economics can therefore be determined at the laboratory stage. 

The primary metabolism of an organic compound uses a substrate as a source of carbon and energy. For the microorganism, this substrate serves as an electron donor, which results in the growth of the microbial cell. The application of co-metabolism for bioremediation of a xenobiotic is necessary because the compound cannot serve as a source of carbon and energy due to the nature of the molecular structure, which does not induce the required catabolic enzymes. Co-metabolism has been defined as the metabolism of a compound that does not serve as a source of carbon and energy or as an essential nutrient, and can be achieved only in the presence of a primary (enzyme-inducing) substrate. 

Future research related to biodegradation of azo dyes should focus on both basic and applied aspects of the subject. Since bioremediation is an important tool in detoxifying and eliminating environmental contaminants, a thorough understanding of microbial genetics, biochemistry, and physiology is required. Attempts should be... 

If there are significant amounts of both volatile and nonvolatile contaminants, remediation may be achieved by a combination of liquid and vapor extraction of the former, and bioremediation of the latter. This combination has been termed "bioslurping", where the act of pumping out the liquid contaminant phase draws in air at other wells to stimulate aerobic degradation (20). Such bioremediation requires that there be enough nutrients to allow microbial growth, and fertilizer nutrients are frequently added at the air injection wells. Bioslurping has had a number of well-documented successes. 

Bioremediation is also required for the cleanup of our environment. Bioremediation is mediated by the participation of several microbial communities. These microbial communities are required to break down several polyaromatic hydrocarbons (PAHs) and other toxic, mutagenic, and carcinogenic substances introduced into our environment by human activity. The removal of these substances from used water is critical before it is returned... 

Bacterial diversity is estimated to cover more than four million different taxa based on 16S RNA gene differences (Curtis, Sloan, Scannell, 2(X)2) and reflects adaptation to a wide variety of environments, including such diverse habitats as water, air, soil, the human body, food, etc. Each species is comprised of a multitude of individual strains with unique properties. Due to this large diversity, screening of the total microbial population for any desired phenotype or property is unrealistic, and so screening is normally limited to a collection of bacteria obtained fiom certain relevant habitats. Bioremediation applications could start with a collection of bacteria isolated from soil dairy tqtplications, a collection derived from environmoits were milk is present, and so on. In addition, the ability to isolate and identify individual bacterial strains with specific desirable properties requires not only microbiological expertise but also highly automated processes. 

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