Bacteria carbon:nitrogen ratio

The PHB accumulation is directly proportional to the Carbon Nitrogen ratio (Macrae and Wilkinson, 1958). The hydroxyl acid monomer units depend on the carbon sonrce utilized. Bacteria such as Alcaligenes eutrophus utilize various C4 and C5 sources to produce polymers with monomer compositions of 3HB, 4HB, 3-hydroxyvalerate (HV), and 5HV (Anderson and Dawes, 1990). The C1-C9 alcohols and C2-C10 monocaiboxylic acid have also been tested as nutrient sources and proceed useful for PHB production and found that PHB could be obtained with the odd number of carbon sources. 

A buried corpse surrounded by plant material (e.g., straw, pine branches) can display a more rapid rate of decomposition than a cadaver buried without these materials (Mant 1950). Mant (1950) believed that these plant materials introduced additional bacteria into the burial environment while providing a layer of air between the cadaver and the soil. Also, an increase in the rate of cadaver decomposition following the addition of plant material is due to the widening of the carbon to nitrogen ratio, which promotes microbial activity. In fact, this is the premise behind the composting of dead animals (Elwell, Moller, and Keener 1998). 

Fig. 1 The effect of poly[(f )-3-hydroxybutyrate] (PHB) on survival capability of starved bacteria. Cells of Azospirillum brasilense Sp7 (filled triangles) and phaC mutant (filled circles) were grown on a medium with a high carbon to nitrogen ratio for 24 h and transferred to phosphate buffer, where they were incubated for 12 days. Bacterial density was determined using dilution plating (Reproduced from Kadouri et al. 2002, with kind permission from the American Society for Microbiology)...

Table 9.4. C N molar ratios (calculated and measured), total C and N content and stable carbon and nitrogen isotope data from bacteria, their growth medium (nutrient broth), and from collagen (infected and non-infected marten bone). The bacteria for inoculation were raised on nutrient broth (nb), with/without additives.

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