Microbe persistence

Hamilton SK, Bunn SE, Thoms MC et al (2005) Persistence of aquatic refugia between flow pulses in a dryland river system (Cooper Creek, Australia). Lirrmol Oceanogr 50 743-754 Bernal S, Butturini A, Sabater E (2002) Variability of DOC and nitrate responses to storms in a small Mediterranean forested catchment. Hydrol Earth Syst Sci 6 1031-1041 Romani AM, Vazquez E, Butturini A (2006) Microbial availability and size fractionation of dissolved organic carbon after drought in an intermittent stream biogeochemical link across the Stream-Riparian interface. Microb Ecol 52 501-512... 

The performance of a biotreatment system ultimately depends on optimization of the activity of microbes and the ability to control the process parameters of the treatment system [157]. In this respect, the ability to monitor gene copy numbers and gene expression is highly useful for real time optimization of the efficiency of a biotreatment system. Advanced molecular techniques as well as low cost methods (e.g., antibody detection of enzymes based on color reaction strips fluorescence i.e., GFP marked organisms with UV light detection) can also be applied to monitor the microbial community structure, persistence of the added bacteria, and their interactions with indigenous populations. 

Ellis et al. (2003) reduced Se(Vl) with anaerobic sediment slurries in order to approximate conditions in natural wetlands. Sediments and waters from the northern reach of the San Francisco estuary, the San Luis Drain, and a man-made wetland, all in California, were used. Reduction was apparently carried out by microbes, as autoclaved control experiments exhibited little reduction. Despite differences between the sediments and concentrations of Se(Vl) used in the various experiments, ese(vi)-se(iv) varied little, from 2.6%o to 3.1%o. The starting Se(Vl) concentrations of three experiments ranged from 230 nmol/L to 430 nmol/L that of a fourth experiment was much greater, at 100 pmol/L. Thus, it appears based on these few data that signihcant Se isotope fractionations persist to very low concentrations, though extrapolation to seawater concentrations (e.g., 1 nmol/L) would be risky. 

Most redox reactions in vitro reach equilibrium only extremely slowly with half times of the order of months or years, even though they may be highly favoured thermodynamically. This is illustrated by the persistence of N2 in oxic systems even though its oxidation to NOs is strongly favoured (Table 4.1). However, microbes in soil and water are capable of catalysing particular reactions from which they obtain energy for metabolism. The half times of such microbially catalysed reactions are of the order of hours or days. 

Weed seed longevity is attributed, at least in part, to inhibitors that protect the seed from decay by microbes. One of the reasons weeds pose such a serious problem is because their seeds can persist for decades. This problem might be attacked by either destroying the inhibitors or by developing strains of microbes that can destroy the seeds. 

The adaption of human pathogen strains to grow and persist on plants remains a relatively unexplored area. In many aspects, the adaption of human pathogens to plants would make sense given that the microbes need to survive in the environment between infecting hosts. 

In general, cresols will degrade in surface waters very rapidly. However, cresols may persist in groundwater due to a lack of microbes and/or anaerobic conditions. Cresols are largely released to groundwater via landfills and hazardous waste sites. Tables 5-2a through 5-2e include monitoring data for these sources. 

Rapidly kills microbes, action persisting for long periods because of slow release of Ag" ions from silver proteinate formed by interaction with tissue proteins. 

Tenser T, Gee DR. [2005). Modelling the evolution of secondary metabolic pathways. University of York, MPhil Project Report Abstract). Plants and microbes invest heavily in producing chemicals termed Natural Products. These chemicals are produced in secondary metabolic pathways. In this report, we develop a model for the evolution of secondary pathways, and investigate what factors are important in aUowing these pathways to arise and persist. The results imply that certain mutation rates are important in generating chemical diversity, and we give conditions on these for optimal fitness in a population. We also find that the rate of competitive evolution and the chances that new compounds have to be beneficial or harmful are important factors. 

POM in inshore waters, although it is readily degradable by marine microbes. Given the persistence of mucus, densities of benthic gastropods and their motility patterns, much of the gastropod-inhabited benthos is likely to be covered for most of the time with a layer of pedal mucus (Davies et ah, 1990). 

S. Baneijee et al, Environmental Degradation of 1,1-Dimethyl-Hydrazine , CEEDO-78-14 (Paper No 11), 113-28 (1978) CA 90, 115966 (1978) [The objective of the author s program was to find the rate of degradation of UDMH in natural lake water so as to predict its persistence in aquatic environments. The information derived from the study includes the rate of oxidation of UDMH with Cu++ concn, and the fact that the combination of the pH of the lake water plus dissolved oxygen causes the degradation of UDMH—HC1 in the absence of microbes to form an unidentified product with absorption... 

Lindane is relatively non-persistent, especially under anaerobic conditions, and although its more highly chlorinated residues may present the same problems as those of polychlorophenols, the less chlorinated residues should follow pathways similar to those established for the microbial degradation of the chlorinated phenoxyalkanoic acid herbicides. Recent evidence (46) indicates that certain microbes can dechlorinate DDT anaerobically, thereby making available intermediates which may undergo further aerobic attack, leading in principle to total degradation. The ultimate fate of the hexachloronorbornene nucleus of cyclodienes is still uncertain and this question continues to attract attention. 

With regular consumption of probiotics the composition of the gut microbes can be changed although they have to be consumed regularly if this change is to persist. The new bacteria might also make the... 

Exploration of the microbial world got off to a slow start some 350 years ago, when Leeuwenhoek and his contemporaries focused their microscopes on very small life forms. It was not until about 20 years ago, however, that exploration of the world of intra-terrestrial microbes gathered momentum. Until then, it was generally assumed that life could not persist deep underground, out of reach of the sun and a photosynthetic ecosystem base. In the mid 1980s, the drilling of deep holes for scientific research started. Holes up to thousands of metres deep were drilled in hard as well as sedimentary rock, and up came microbes in numbers equivalent to what could be found in many surface ecosystems (Pedersen, 1993). The deep subterranean biosphere had been discovered. 

Microbes (plant pathogens) and microbial products (phytotoxins) have been shown to have potential as weed control agents. Growth in the interest in these alternative weed control methods has been brought about by a need for less persistent, more selective, and more environmentally safe herbicides. Broad-spectrum and selective activity are concepts important to the development of a weed control agent. 

From our own analysis of potential risks, ve find it difficult to see how any public institution or private corporation would consider release of genetically modified microbes without incorporating some sort of containment system. First is the problem, perceived or actual, of liability. Secondly, they may find that their product persists too long, interfering with future sales and with introductions of improved strains. Finally, government approval may take an inordinate amount of time reviewing the risk factors of a non-contained system, as compared to one with a proven type of containment. 

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