Anaerobic incubations

Bloomfield C., Pmden G. The effects of aerobic and anaerobic incubation on the extractabilities of heavy metals in digested sewage sludge. Envion Pollut 1975 8 214-232. 

Brannon and Patrick [129] reported on the transformation and fixation of arsenic V in anaerobic sediment, the long term release of natural and added arsenic, and sediment properties which affected the mobilization of arsenic V, arsenic III and organic arsenic. Arsenic in sediments was determined by extraction with various solvents according to conventional methods. Added arsenic was associated with iron and aluminium compounds. Addition of arsenic V prior to anaerobic incubation resulted in accumulation of arsenic III and organic arsenic in the interstitial water and the exchangeable phases of the anaerobic sediments. Mobilization of... 

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].

Figure 5.3 Calculated electron balance between CO2 produced and electron acceptors reduced during anaerobic incubation of 16 rice soils (a) after the initial reduction phase and (b) after 120 days (Yao et al., 1999). Reproduced with kind permission of Kluwer Academic Publishers...

Fig. 12.29 Reduction-time curves of various Fe oxides by Corynebacteria during anaerobic incubation (Fischer, 1987, with permission).

This eponymous method is widely used and as originally proposed or in modified form has served as a benchmark for other methods. In fact, it is often referred to simply as the in vitro digestibility. The first stage involves anaerobic incubation at 38°C in the dark with partially filtered rumen liquor which has been buffered with McDougall s artificial saliva solution, previously saturated with CO. ... 

These investigators found also59,115 that homogenates of rat liver were able to degrade both 2-PAM I and V If oxygen was present during the incubation anaerobic incubation left the concentrations of the oximes in mixtures with the homogenate the same as they had been before incubation. Dultz et al. 3 found that dog kidneys took up from the blood more than 5.4 times as much 2-PAM I as V and that V disappeared from the serum of nephrectomlzed rats at essentially the same rate as from that of normal rats. Excretion into the urine seems to be a much more Important route for removal of 2-FAM Balts than of V from the body. 

The rate of methylation of mercury in anaerobically incubated estuarine sediments proved to be inversely related to salinity (267) this is consistent with results reported in Section II,A. Methylmercuric ion forms in sediments upon addition of HgCl2, with a lag phase of 1 month (268). Biomethylation by lake water columns and by sediments coincided, apparently being related to overall microbial activity, and showed periodic fluctuations (269). Topping and Davies have demonstrated that mercury can be methylated in the water column of a sea loch (270). As has previously been noted, tin compounds can be methylated by sediments (121-124), and this is also true for lead (134-136, 271). The relative proportions of biotic and abiotic methylation processes for such systems still remain to be determined. 

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. 

Figure 5 The relationship between the temperature sensitivity (i.e., gio) of CH4 production and the ratio CO2 to CH4 produced in anaerobic incubations (van Hulzen et al., 1999) (reproduced by permission of Elsevier from Soil Bio/. Biochem. 1999,31,1919-1929).

The respiratory and photosynthetic electron-transfer pathways are proton pumps operating with the same polarity as does the A TP synthase when hydrolyzing A TP Since it is difficult to detect protons circulating in the steady-state, Mitchell and Moyle [19] studied the transient extrusion of protons when a small amount of oxygen is injected into an anaerobic incubation of mitochondria in the presence of substrate. Prior to this, Neumann and Jagendorf [20] had observed a light-dependent proton uptake into chloroplast thylakoid membranes. 

After anaerobic incubation of reaction mixture at 37°C for 24h, the alkane containing fraction was prepared by chloroform extraction. Chloroform extracts were separated on silica gel 60 thin layer chromatography (TLC) plate with hexane as a developing solvent. Radioactivity was measured by liquid scintillation counter (LS6500, Beckman). 

A petroleum-degrading strain HD-1 was able to grow autotrophically by using CQ2 as sole carbon source. Inside the cell there accumulated alkane/alkene besides fatty acids or poly-p-hydroxyalkanoic acid. Fatty acids and fatty aldehydes were shown to be reduced to alkane/alkene by anaerobic incubation with the HD-1 cell lysate. 

Typically, Fe(III) reduction is measured as the accumulation of HCl- or ascorbate-extractable Fe(II) or the disappearance of Fe(III) in anaerobically incubated sediments (Lovley and Phillips, 1986 Roden and Wetzel, 1996 Kostka et al., 2002c), but this approach cannot distinguish between biological and chemical Fe(III) reduction. One common method for separating the contributions of biological and abiotic reduction mechanisms involves suppressing H2S production [and... 

Figure 12. ESR spectra of nitro-anion free radicals from the microsomal reduction of nitro compounds, a. Radicals from the anaerobic incubation of 2 mM nitrobenzene with an NADPH-generating system and 1.5 mg/ml hepatic microsomes b, radicals from the anaerobic incubation of 1 mM nitrofurantoin with an NADPH-generating system and 1 mg/ml hepatic microsomes. From [88,169], with permission.

Fig. 5.5. Scanning electron micrograph, gold-shadowed, of the bacterial cells obtained from the 10 days culture when the mixture of mudstone and the medium for the sulfate-reducing bacteria was anaerobically incubated at 37°C. Bar 1 pm...

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