Microbial adaptation

Springael D, Top EM (2004) Horizontal gene transfer and microbial adaptation to xenobio-tics new types of mobile genetic elements and lessons from ecological studies. Trends Microbiol 12 53-58... 

Without appropriate cleanup measures, BTEX often persist in subsurface environments, endangering groundwater resources and public health. Bioremediation, in conjunction with free product recovery, is one of the most cost-effective approaches to clean up BTEX-contaminated sites [326]. However, while all BTEX compounds are biodegradable, there are several factors that can limit the success of BTEX bioremediation, such as pollutant concentration, active biomass concentration, temperature, pH, presence of other substrates or toxicants, availability of nutrients and electron acceptors, mass transfer limitations, and microbial adaptation. These factors have been recognized in various attempts to optimize clean-up operations. Yet, limited attention has been given to the exploitation of favorable substrate interactions to enhance in situ BTEX biodegradation. 

As with any other analytical method, MCA s capacity is enhanced if it is easy to remove interfering compounds. Microbial adaptation confers specificity in binding unwanted compounds so they can be swept out without losing the sample for analysis. Figures 5a and 5b show the data for phenol and vanillic acid stripping under convenient conditions, namely, with easily acquired amounts of stripper cells (5 x 1010 cells), and conditions where interfering compound concentrations are relatively large, i.e., up to 10 times the amount of sample for analysis. 

There is much evidence from observational and molecular research that indicates microbial adaptation for the mineralization of v-triaziiie herbicides has occurred since their first introduction into agriculture in the mid-1950s ... 

Aly and Faust (3) investigated the physical, chemical, and biological factors which influence the persistence of 2,4-D compounds in natural surface waters. They found that esters of 2,4-D in aerobically incubated lake waters were hydrolyzed biologically to the free acid and corresponding alcohol within 9 days and that 2,4-D was decomposed 81-85% within 24 hours by lake muds after microbial adaptation. 

Emergence of Foodborne Illness. New foodborne disease threats occur for a number of reasons. These include disaster conditions, an increase in international travel and trade, microbial adaptation, and changes in the food production system, as well as human demographics and behavior (such as complex emergencies). 

Microbial adaptation and change Human susceptibility to infection Climate and weather Changing ecosystems Human demographics and behavior Economic development and land use International travel and commerce Technology and industry Breakdown of public health measures Poverty and social inequality War and famine Lack of political will Intent to harm... 

Aamand J, Jorgensen C, Arvin E, et al. 1989. Microbial adaptation to degradation of hydrocarbons in polluted and unpolluted groundwater. Journal of Contaminant Hydrology 4 299-312. 

Wilson JT, McNabb JF, Cochran JW, et al. 1985. Influence of microbial adaptation on the fate of organic pollutants in groundwater. Environmental Toxicology and Chemistry 4(6) 721-726. 

During the 30 years following the discovery of microbial adaptation for pesticide degradation, there were intermittent reports of the same phenomenon affecting the persistence of other pesticides. However, due to the fact that virtually none of these reports concerned situations where reduced pesticide persistence affected pest control efficacy, microbial adaptation for pesticide degradation was largely relegated to the status of academic curiosity. In fact,... 

The degree to which carbamothioate herbicides cause microbial adaptation depends on specific herbicide structure (lj), 21 22). Vernolate and EPTC have similar structures and soil exposure to either herbicide fully affected the degradation of the other. 

The exact mechanisms for microbial adaptation to the pesticide molecule in soils that develop enhanced degradation capacity are not completely understood. These processes could be viewed from the ecological and population aspects, from their biochemical and enzymatic reactions, or from the genetic aspects, in which extrachromosomal elements may be involved as part of the process. 

The presence of more recalcitrant saturated ring structures (e.g., cycloate and molinate) or an increase in the number of halogens (e.g., 2,4,5-T and tefluthrin) could result in resistance to microbial adaptation. 

Another important variable that determines the microbial metabolism of soil-applied pesticides is the availability of the chemical to the microbial systems degrading it. The hydrolysis product and parent pesticide should be available to microbes so as to exert their toxicity or provide nutrient value. The lack of availability of some chemicals may result in resistance to microbial adaptation. 

Figure 1. Different patterns of biodegradation resulting from microbial adaptation. (A) Adaptation to p-nitrophenol in Lulu aquifer samples at 529 ng/mL, but not at 14 ng/mL (41). (B) Adaptation to the triazinone-ring of metribuzin, evidenced by an increasing mineralization rate over time in the surface soil, but not in the subsurface soils (351. (C) Adaptation to EPTC after long-term EPTC use (12). (Reproduced with permission from Ref. 12. 15, 43. Copyrights 1988, 1989, 1987 Weed Science Society of America, American Society of Agronomy, and American Society for Microbiology, respectively)...

The research efforts that have been stimulated by the phenomenon of enhanced degradation have resulted in the creation of a substantial knowledge base regarding microbial adaptation for pesticide degradation and associated pest control failures. The body of scientific literature on the subject has grown rapidly and Is now substantial. Recent reviews of enhanced degradation and microbial adaptation for pesticide degradation by Kaufman (2) (59 ref.),... 

There have also been major breakthroughs In the recognition of the differential susceptibility of pesticides to microbial adaptation based on chemical structure and availability of an accessible microbial catabolic pathway. Some classes of pesticides (e.g.,... 

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