Aerobic bacterial activity

Two studies compared the effect of rifaximin to that of neomycin and/or of rifampicin [72, 73] on the fecal flora in rats. In the first study [72] the antibiotic (1, 10, 30 and 100 mg/kg orally for 7 days) did inhibit both aerobic (especially coliforms and cocci) and anaerobic bacterial growth. Its activity was similar to that of neomycin and stronger than that of rifampicin. In the second investigation [73] the antibiotic effect on aerobic microorganisms was specifically investigated. Oral rifaximin treatment (50 mg/kg for 3 days) caused a marked reduction in the number of total aerobic bacteria and salmonellae, while neomycin led only to a decrease in salmonella counts, but did not cause statistically significant changes in the total aerobic bacterial population. 

Prior to the onset of sulfate reduction extensive organic matter degradation can occur by bacterially-mediated oxygen reduction (see Chapter 4). The influence of benthic bacterial activity under aerobic conditions on carbonate mineral dissolution has been nicely demonstrated by Moulin et al. (1985) for pore waters from sediments of the Gulf of Calvi, Corsica. Under aerobic conditions, the oxidation of organic matter may be written ... 

Acetic Fermentation.—Acetic acid in addition to its occurrence in nature in the form of esters is produced on the large scale by the acid fermentation (oxidation) of the alcohol obtained as the result of fermenting fruit juices which contain sugar, especially apple juice or cider, and wine. When the sugar present in cider is fermented, dueTo the action of the enzyme zymase, alcohol is produced (p. 95). This alcohol is then oxidized through the activity of an aerobic bacterial organism Bacterium aceti, which is present naturally in the fruit juice. The product is acetic acid. 

The carbon dioxide (CO ) had to be formed through destruction of the organic matter, a process taking place during bacterial activity which produce CO2 by assimilation of organic matter and in particular of petroleum. Under aerobic conditions the... 

In aerobic purification as currently under discussion, the changes in bacterial mass versus the initial supply of nutrient L (here represented by the BOD in the medium) can be illustrated as shown in Fig. 34b. Since bacterial activity varies with the age of the bacteria, the three loads often considered in sizing activated sludge can be approximately located on the diagram. These three loads are the high and medium loads and extended aeration (see 3,2,1) where very advanced age makes the sludge mineralize and reduces its production. 

The culture bottle technique employs successive dilutions of the field water in the cnlture media. The more dilute the sample bottle that shows bacterial activity, the more contaminated the field water sample. This technique is termed extinction dilution or serial dilntion. With suitable culture media bottles this method can be used for either aerobic bacteria or sulphate-reducing bacteria. 

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