Anaerobic growth, bacterial

Price-Carter M, J Tingey, TA Bobik, JR Roth (2001) The alternative electron acceptor tetrathionate supports Bjj-dependent anaerobic growth of Salmonella enterica serovar typhimurium on ethanolamine or 1,2-propandiol. J Bacterial 183 2463-2475. 

Facultative bacteria may provide an environment conducive to the growth of anaerobic bacteria. Although many bacteria isolated in mixed infections are nonpathogenic by themselves, their presence may be essential for the pathogenicity of the bacterial mixture. The role of facultative bacteria in mixed infections can include (1) promotion of an appropriate environment for anaerobic growth through oxygen consumption, (2) production of nutrients necessary for anaerobes, and (3) production of extracellular enzymes that promote tissue invasion by anaerobes. 

Ramirez-Arcos, S., Fernandez-Herrero, L.A., Marin, I., and Berenguer, J. (1998) Anaerobic growth, a property horizontally transferred by an Flfir-like mechanism among extreme thermophiles. /. Bacterial, 180, 3137-3143. 

Johnson MS, IB Zhulin, M-E R Gapuzan, BL Taylor (1997) Oxygen-dependent growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough. J Bacterial 179 5598-5601. 

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. 

Since anaerobic azo dye reduction is an oxidation-reduction reaction, a liable electron donor is essential to achieve effective color removal rates. It is known that most of the bond reductions occurred during active bacterial growth [48], Therefore, anaerobic azo dye reduction is extremely depended on the type of primary electron donor. It was reported that ethanol, glucose, H2/CO2, and formate are effective electron donors contrarily, acetate and other volatile fatty acids are normally known as poor electron donors [42, 49, 50]. So far, because of the substrate itself or the microorganisms involved, with some primary substrates better color removal rates have been obtained, but with others no effective decolorization have been observed [31]. Electron donor concentration is also important to achieve... 

Among the wide choice of reactor designs, the biofilm reactor is one of the best suited for azo-dye conversion as it meets two important process requisites. The first is related to the hindered growth feature of bacterial metabolism under anaerobic conditions. The second is related to the necessity to increase cell densities (see previous section) with respect to those commonly harvested in liquid broths [55, 56]. Except for bacteria that forms aggregates spontaneously, immobilization of cells on granular carriers and membrane reactor technology are the two common pathways to achieve high-density confined cell cultures in either discontinuous or flow reactors. 

The basic theoretical aspects of aerobic and anaerobic processes relevant for wastewater in sewer networks are focused on in Chapters 2 and 3. Figure 5.1 briefly illustrates an important difference between an aerobic and an anaerobic process exemplified with the transformations of protein in a wastewater sample originating from a sewer system. Under aerobic conditions, suspended protein components were significantly increased, and the soluble part was correspondingly reduced. This change is interpreted as the result of a growth process of the bacterial biomass. Under anaerobic conditions, no significant transformations of soluble and particulate protein took place. 

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