Microbial species

The solubihty characteristics of sodium acyl isethionates allow them to be used in synthetic detergent (syndet) bars. Complex blends of an isethionate and various soaps, free fatty acids, and small amounts of other surfactants reportedly are essentially nonirritant skin cleansers (66). As a rule, the more detersive surfactants, for example alkyl sulfates, a-olefin sulfonates, and alkylaryl sulfonates, are used in limited amounts in skin cleansers. Most skin cleansers are compounded to leave an emollient residue on the skin after rinsing with water. Free fatty acids, alkyl betaines, and some compatible cationic or quaternary compounds have been found to be especially useful. A mildly acidic environment on the skin helps control the growth of resident microbial species. Detergent-based skin cleansers can be formulated with abrasives to remove scaly or hard-to-remove materials from the skin. 

Recently, there has developed a greater recognition of the complexity of the MIC process. MIC is rarely hnked to a unique mechanism or to a single species of microorganisms. At the present state of knowledge, it is widely accepted that the growth of different microbial species within adherent biofilms facihtates the development of structured consortia that may enhance the microbial effects on corrosion. 

The dilution rate D is equal to 1/t, where t = u/V, and is equal to the mean residence time of the tank. Equation 11-63 shows that controlling the dilution rate D (Le., the flowrate into the reactor) can control the specific cellular growth rate of a microbial species p. 

To conclude it must be stressed that recent work has directed attention to the interplay between different microbial species in most of the corrosion effects described. Microbial corrosion is therefore one special instance of the rapidly developing field of Microbial Ecology. ... 

Microbial kinetics can be quite complex. Multiple steady states are always possible, and oscillatory behavior is common, particularly when there are two or more microbial species in competition. The term chemostat can be quite misleading for a system that oscillates in the absence of a control system. 

Proces.s Exudate component Microbial species Reference... 

Such differences in the amount and type of rhizodeposition that occur on the root with time result in concomitant variations in microbial populations in the rhizosphere, both within the root (endorhizosphere), on the surface of the root (rhizoplane), and in the soil adjacent to the root (ectorhizosphere). The general microbial population changes and specific interaction of individual compounds from specific plants or groups of plants with individual microbial species are covered in detail elsewhere (Chap. 4). Consequently, this chapter is restricted to consideration of methodologies used to study carbon flow and microbial population dynamics in the rhizosphere, drawing on specific plant-microbe examples only when required. 

Teat canal Colonisation Microbial species, cellular reaction, milking... 

Husebye E, Hellstrom PM, Sundler F, Chen J, Midtvedt T Influence of microbial species on small intestinal myoelectric activity and transit in germ-free rats. Am J Physiol Gas-trointest Liver Physiol 2001 280 G368-G380. 

Minimal effects on intestinal flora were seen with rifaximin administration [9, 35]. In an early study, performed on healthy volunteers who received a short-term (5 days) rifaximin treatment, the observed changes in bowel flora returned to baseline levels within 1-2 weeks [9]. In a recent investigation fecal samples of patients with ulcerative colitis given three 10 day courses of the antibiotic were cultured and the different microbial species quantitated. Despite the high dose (i.e. 1800 mg daily) of rifaximin used there was only a minor change in bacterial counts which reverted back to pre-treatment values during the washout period [35]. It appears therefore that administration of this antibiotic does not disrupt intestinal microbial ecology. 

Fortunately, recent advances in molecular techniques have made it possible for scientists and engineers to monitor dye-degrading communities and their interaction with the other microorganisms during the degradation process (see review [150]). Before the advent of such techniques, the key microbial species in wastewater treatment plants were either unknown or sometimes inefficient bacteria were... 

The maximum rate of color removal is generally related to the optimum cell culture growth temperature for each microbial species, with an increase of decolorization proportional to the increase of temperature within the optimum temperature range [41, 42, 44, 75-78]. 

The links between microbial diversity and soil functioning are unknown because it is difficult to measure microbial diversity. In addition, we generally measure soil functions by determining the rates of microbial processes, without knowing the microbial species effectively involved in the measured process (Nannipieri et al. 2003). The central problem of the link between microbial diversity and soil function is to understand the relations between genetic diversity and community structure and between community structure and function. 

The relation between microbial diversity and soil functions is poorly understood because we cannot measure easily the microbial diversity, even if we can detect unculturable microorganisms by molecular techniques (Nannipieri et al. 2003). In addition, the present assays for measuring microbial functions determine the overall rate of entire metabolic processes, such as respiration, or specific enzyme activities, without identifying the active microbial species involved. The recent advances in RNA extraction from soil might permit us to determine active species in soil (Griffiths et al. 2000 Hurt et al. 2001). Further advances in understanding require us to determine the composition of microbial communities and microbial functions in microhabitats. 

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