Mixed microbial population

Any bacterial species living in a mixed microbial population, such as that of the rhizosphere, may encounter not only the molecular signal produced by a cell of the. same species but also molecular signals produced by cells of different species. The situation is made more complex by the presence of plant molecular signals, and by the fact that the same AHL molecule can be used to regulate the... 

In conclusion, the behavior of the molecular signals can be markedly different in soil with respect to that observed in microcosm experiments involving only the ho.st plant and the infecting microorganism or a mixed microbial population, both without soil particles. Studies are needed to compare the diffusion of molecular signals in the presence of clay and/or humic barriers. 

Williams, P.A., Genetic interactions between mixed microbial populations, Philos. Trans. R. Soc. London, Ser. B, 297, 481-496, 1982. 

Steen, W.C., Karickhoff, S.W. (1981) Biosorption of hydrophobic organic pollutants by mixed microbial populations. Chemosphere 10, 27-32. 

The degradation of sulfur heterocycles in Prudhoe Bay crude oil by aerobic enrichment cultures of marine and soil microorganisms was studies by Fedorak and Westlake (22,22). Figure 4 shows typical results obtained when the aromatic fraction of the oil was analyzed by capillary GC with a sulfur-specific detector. The mixed microbial populations in these enrichments were able to degrade the n-alkanes, pristane, phytane and a number of polycyclic aromatics in this oil (21, 22). There were some similarities between the biodegradability of the sulfur heterocycles in Figure 4 and that of the aromatic hydrocarbons reported by Fedorak and Westlake (21,22). For example, although cultures without N and P addition were able to remove a number of the sulfur heterocycles from the oil, the addition... 

Nyman, J.A. (1999) Effect of crude oil and chemical additives on metabolic activity of mixed microbial populations in fresh marsh soils. Microb. Ecol. 37, 152-162. 

The first reaction is catalyzed by a mixed microbial population in which Bacillus azotoformans is the main denitrifying bacteria, and ethanol is the electron donor. Fe(II) is also regenerated from Fe(III) by means of reducing bacteria Dcfcrri-bacteres, using ethanol as the electron donor. These bacteria are found in the Veendam and Eerbeek sludges, as described in a previous section. 

The biodegradation of 2 mg of radiolabeled benzene in 100 g of soil with a mixed microbial population transformed only 47% of the added radioactivity to carbon dioxide after 10 weeks (Haider et al. 1981). 

Ramsay, J. A., Li, H., Brown, R. S. Ramsay, B. A. (2003). Naphthalene and anthracene mineralization linked to oxygen, nitrate, Fe(III) and sulphate reduction in a mixed microbial population. Biodegradation, 14, 321-9. 

Biodegradation approximately calculated rate constant k = 0.091 d in pond water plus sediment incubated under aerobic conditions based on time for 50% degradation (Johnson Lulves 1975 quoted, Klecka 1985) estimated biodegradation ty, 4-5 wk by naturally occurring, mixed microbial populations in river water (Saeger Tucker 1976) ... 

Surface water biodegradation 4 to 5 wk in river water by namrally occurring, mixed microbial populations (Saeger Tucker 1976) ... 

Amann R. 1., Binder B., Chisholm S. W., Olsen R., Devereux R., and Stahl D. A. (1990a) Combination of 16S rRNA-targeted oligonucleotide probes with flow cytometry for analyzing mixed microbial populations. Appl. Environ. Microbiol. 56, 1919-1925. 

Whether this reactor could be operated using a specially formulated culture of defined organisms or a mixed microbial population and how the reactor could be controlled are unanswered questions. Because of the low tolerance of some anaerobic microorganisms towards cations such as Na+, NH and K, we envisage the use of dolomitic fime or calcium hydroxide for control of the reactor pH. If the reactor is an auxostat based on product concentration, organisms that thrive at high concentrations of acetate salts should be selected automatically. 

Figure 9 Stone discs showing exfoliation after treatment with salts and mixed microbial populations...

Bacteria exposed to cyanide may exhibit decreased growth, altered cell morphology, decreased motihty, mutagenicity, and altered respiration. Mixed microbial populations capable of metabolizing cyanide and not previously exposed to cyanide were adversely affected at 0.3 mg HCN/kg however, these populations can become acclimatized to cyaiude and can then degrade wastes with... 

Mixed microbial populations capable of metabolizing cyanide and not previously... 

A pectinolytic bacterium isolated from a mixed microbial population by means of a chemostat enrichment procedure was identified as Erwinia carotoyora, It grew only on highly methylated pectin and produced a pectin lysase which released unsaturated monomer and dimer from 71% esterified citrus pectin. The pectin lyase was inducible only by pectins having a high methyl ester content. 

In some situations it may be appropriate to use single-species biocatalysts where the response profile is known to match the expected analyte composition of the sample or environment to be monitored. In other situations it may be desirable to have as broad a response as possible in order to allow the detection of both the expected and unexpected. In these latter cases, a number of different microbial species may be used either in multisensor arrays or as a mixed microbial population incorporated into the sensor. 

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