Clostridium growth rate

The stationary phase classically represents the stage at which the rate of cell division equals the rate of cell death, so the number of viable cells remains constant. This phase usually occurs when the cell concentration reaches a sufficient size that some property of the environment restricts growth rate, often a nutrient where phytoplankton are concerned. Physiological changes can occur, including adaptations that promote cell survival through periods of limited growth. Some bacteria (e.g. species of Bacillus and Clostridium) form endospores, which represent a dormant state that is resistant towards levels of desiccation, heat, chemical or radiation exposure that would prove lethal to the non-endospore forms. 

The inhibitory effect of each fermentation product on the cell growth rate and the kinetics of product formation was studied for the acetone-butanol fermentation with Clostridium acetobutylicum ATCC 824. Inhibition of cell growth was studied by challenging cultures with varying concentrations of each product. There was a threshold concentration which must be reached before growth inhibition occurred. This concentration was found to vary with each inhibitor. Above the threshold concentration, there was a linear decrease of the growth rate with an increase in product concentration. 

Clostridium thermoceUum demonstrated one of the fastest growth rates on crystalline cellulose by the use of a highly efficient cellulosome [54]. However, the construction of stable transgenic strains has been hmited by the lack of effective genetic tools. Tripathi etal. [55] developed positive and negative selectable markers to allow for the selection of strains that undergo allele replacement. The deletion of the Idh and pta genes, and a 2000-h adaptation, led to a 4.2-fold increase in the ethanol yield compared to wild-type cells. 

Salt is used in cheese manufacture to control the rate of lactic acid fermentation, to encourage lactic acid bacteria and to discourage the growth of undesirable bacteria. In processed cheese it contributes to the inhibition of Clostridium botulinum. 

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