Aerobic incubations

The metabolism of C-labeled BTX has been examined in soil cultures, and a mass balance constructed after 4 weeks of aerobic incubation (Tsao et al. 1998). Mineralization of all substrates was ca. 70% but ca. 20% of the label in toluene and ca. 30% in o-xylene were found in humus. It was suggested that alkylated catechol metabolites were responsible for this association. 

The mechanism of the intracellular degradation of poly(HA) by bacteria, i.e., the mobilization of a previously accumulated polyester, is poorly understood (see also the chapter by Babel et al. in this book). Most of the research on intracellular poly(3HB) mobilization was done more than 30 years ago. Lemoigne observed in 1925 that 3-hydroxybutyrate was the main product of anaerobic breakdown of poly(3HB) in Bacillus M [12,137]. Macrae and Wilkinson [138, 139] noticed a reduction of the poly(3HB) content of Bacillus megaterium upon aerobic incubation of poly(3HB)-rich cells in phosphate buffer. The authors found that autolysis of poly(3HB)-rich cells occurred later and to a minor extent compared to poly(3HB)-poor cells and proposed that poly(3HB) might... 

There have been several reports of a pseudomonas sp in aerobic incubation with inorganic tin(II) and tin(IV) yielding Me2Sn2+ and probably Me4Sn42,43. 

Soil respiration (flush of C02) Field chamber Aerobic incubation for >1 week in lab Indicates soil microbial activity relatively simple equipment conducted in a nonstandard laboratory can be determined in field or in laboratory relatively time-consuming dependent upon organic inputs Parkin et al. (1996)... 

Fig. 3.101. HPLC analysis on metabolites resulting from decolourization of Remazol brilliant orange 3R under anaerobic-aerobic conditions (1) at the beginning of the anaerobic incubation (2) after anaerobic incubation for 24 h and (3) after aerobic incubation for 12 h. Reprinted with permission from N. Supaka et al. [158].

The lab half-life of carbofuran In six soils (each under 4 different levels of moisture and 2-3 different temperatures) was In the range of 5-261 days. After 28 days of aerobic Incubation In two of the six soils, parent carbofuran was the major extractable compound degradation products comprised <5% of the extractable material (65). However, under anaerobic (flooded soil) conditions, the degradation product carbofuran phenol was found to be the principal product and to persist (66). 

Figure 14.10. Principal component analysis of Py-FI mass spectra of (a) cold and (b) hot water extracts from the sequence of organic litter layers Oi-Oe-Oa in a beech stand (Fagus sylvat-ica) obtained before (-pre) and after (-post) aerobic incubation. The arrows indicate changes due to progressive decomposition top-down in the litter profile. Reprinted from Landgraf, D., Leinweber, P, and Makeschin, F. (2006). Cold and hot water extractable organic matter as indicators of litter decomposition in forest soils. Journal of Plant Nutrition and Soil Science 169,76-82, with permission of Wiley-VCH.

These rates are based on the disappearance of solvcnt-cxtractable parent compound under aerobic incubation conditions, unless stated otherwise. 

Both Components F and S were required for irreversible cleavage of the C-Co bond of adenosylcobalamin by oxygen upon aerobic incubation with the coenzyme in the absence of substrate. This suggests that activation of the C-Co bond of the coenzyme is dependent on both components. Sephadex G-25 filtration experiments showed that neither adenosylcobalamin nor cyanocobalamin was bound by the individual components, F or S. Both of them were necessary for the cobalamin binding (8). 

The decomposition of DOM in soil will lead to the re-immobilization of DOM-associated metals. Under aerobic incubation conditions, DOM decomposition could be observed clearly with an increase in incubation time. As a result, the amount of Cu in soil solution decreased drastically, especially for green manure DOM (Figure 10.9). This may be due to the breakdown of the soluble Cu-DOM complex through microbial degradation, leading to the re-adsorption of Cu onto the soil matrix. 

FIGURE 10.9 The correlation between Cu dissolution from Cu-contaminated sandy loam and remaining DOM derived from sludge (Slu) and green manure (GM) in the soil under aerobic incubation conditions. 

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. 

Under rigorous eopper-depleted eonditions, the dominant GOase species produced is Form I and this has been isolated and purified. Aerobic incubation of Form I with Cu leads to its eonversion to Form III, the visible spectrum showing this to be the aetivated form with the thioether bond formed. Incubation of Form I with Cu under anaerobic conditions gives a species with the same eireular diehroism speetrum as inaetive wild type indicating that copper has been ineorporated into the protein as Cu. ... 

Loss of the 4,4-Dimethyl Groups.—The formation of [ H5, " C5]-4-demethyl-cyclolaudenone (73) from [2- " C,3R,4R- H]mevalonate again shows that the first methyl group lost from C-4 is labelled by [2- " C]mevalonate. Three groups have examined this stage of biosynthesis in some detail. Aerobic incubation of a rat liver system, in the absence of NAD, gave a 4j8-methyl-4a-carboxylic acid intermediate (76). This type of intermediate was also encountered when the system was inhibited by cyclic AMP. When using... 

Cyclohydrolase activity in cell extract of M. kandleri is sensitive to air, but the purified enzyme is fairly air-stable [356]. Purified enzymes from M thermoautotrophicum and M. barkeri are air-stable [51,100,186]. However, the M barkeri enzyme requires nonionic detergents and ethylene glycol for stability [186]. On the other hand, cyclohydrolase activity in cell extracts of M thermoautotrophicum Marburg is stimulated 7-fold upon anaerobic incubation at 30°C in the presence of 2-mercaptoethanol or dithiothreitol, and 5-fold under the corresponding aerobic incubation [51] the mechanism of this stimulation is unknown. 

Sawai, Y., Yamaguchi, Y, Miyama, D., and Yoshitomi, H. 2001. Cycling treatment of anaerobic and aerobic incubation increases the content of y-aminobutyric acid in tea shoots. Amino Acids 20 331-34. 

Hexanal phenylhydrazone also serves as an inactivator of soybean lipoxygenase 1 (L-1) in a process which demonstrates kinetics more complex than those of standard mechanism-based inactivators (Galey et al., 1988). Aerobic incubation of hexanal phenylhydrazone with L-1 leads to enzyme inactivation and conversion of the compound to its corresponding a-azo hydroperoxide, which is also an inactivator. Four equivalents of the a-azo hydroperoxide are sufficient to inactivate the enzyme completely, whereas the amount of the parent phenylhydrazone required to fiilly inactivate the enzyme increases from 13 to a maximum of 70 as the ratio of hexanal phenylhydrazone to L-1 increases. Since the partition ratio is normally independent of inhibitor and enzyme concentrations, a more complex mechanism is apparent. The addition to reaction mixtures of glutathione peroxidase, which reduces the a-azo hydroperoxide metabolite to the corresponding alcohol, suppresses about 80% of the inactivation. The a-azo hydro-... 

Wang, W. J., P M. Chalk, D. Chen, and C. J. Smith. 2001. Nitrogen mineralisation, immobilisation and loss, and their role in determining differences in net nitrogen production during waterlogged and aerobic incubation of soils. Soil Biol. Biochem. 33 1305-1315. 

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