Composition, biomass products

Cell growth and metabolic activities are similarly described as a simple chemical reaction. It is also necessary to establish a definite formula for dry cell matter. The elemental composition of certain strains of microorganism is defined by an empirical formula CHaO/3Ns. The general biochemical reaction for biomass production is based on consumption of organic substrate, as shown below. Substrate oxidation is simplified in the following biochemical oxidation ... 

Martin, B.J. Thorstenson, Y.R. (1988). Stable carbon isotope composition (6 C), water use efficiency and biomass productivity of Lycopersicon esculen-tum, Lycopersicon pennellii and the Fi hybrid. Plant Physiology 88, 218-23. 

The medium composition used in the fed-batch process was optimized, resulting in cell densities near 100 g l-1. By using an exponential feed rate resulting in a growth rate of 0.05 h-1, a maximum biomass concentration of 112 g 1 1 was attained, with a biomass productivity of 1.8 g 1 1 h. The poly(3HAMCL) productivity however was low, 0.34 g 1 1 h, caused by a steady decrease of the poly(3HAMCL) content during the last part of the fermentation [51]. When this optimized medium composition was used in the continuous culture system described above, a maximum biomass concentration of 18 g 1 1 was reached. The PHA content however remained low at approximately 10% [51]. It is still unclear what causes these low PHA contents. 

In the preceding discussions, we assumed labile DOC and DON to be produced at rates y/c and y/N, respectively, without discussing their sources and how the production rate and the composition of the produced material would be expected to vary with food web structure. The important differences among different models can be illustrated by some examples. One potential model is that DOC production is an overflow mechanism occurring in mineral-nutrient-limited phytoplankton not able to use the photo-synthetically produced organic carbon for biomass production due to lack... 

The microbial loop concept has been the prevailing paradigm for marine microbial food webs for two decades and has stimulated work on DOM sources and composition, rates of biomass production, transfer efficiencies, and respiratory losses (Benner, 1998 del Giorgio and Cole, 2000 Ducklow, 2000 Williams, 2000). The only major modification has arisen from new information on the abundance and ecology of viruses (Wilhelm and Suttle, 1999 Fuhrman, 1999, 2000). 

Stauffer, M.D., Chubey, B.B., and Dorrell, D.G., Growth, yield and compositional characteristics of Jerusalem artichoke as they relate to biomass production, in Fuels from Biomass and Wastes, Klass, D.L. and Emert, G.H., Eds., Ann Arbor Science, Ann Arbor, MI, 1981, pp. 79-97. 

In this chapter we discuss the distribution and the development of plant communities in floodplain areas, mainly of the big whitewater rivers, focusing on factors such as diversity, species composition, biomass and primary production. Based upon these factors, we also discuss the annual dynamics of bioelements stocks and their turnover through herbaceous and floodplain forest communities. Finally, we examine the implications of such nutrient dynamics and turnover for the aquatic biota. We do not address carbon and nutrient budgets, as these are thoroughly discussed in chapter 14. 

The fundamentals of photosynthesis are examined in this chapter, with emphasis on how they relate to biomass production and its limitations. The compositions of different biomass species and the chemical structures of the major components are also examined in the context of biomass as an energy resource and feedstock. 

The redox and carbon balances were used to determine the amount of carbon in the form of ethanol loss by stripping off to the gas phase. Lactic acid production at steady state conditions was less than 0.03 g/g thus, it was excluded from carbon and redox balance calculations. For biomass production, biomass yield of 0.045 g/g was assumed [15, 16] with biomass composition CH155N0.23O0.45 [17]. When growing the strain in batch culture, the carbon balance was almost closed (SD 2%), indicating that no other end products are formed than that included in redox and carbon balances. 

The laws relating optimum operating temperature to medium composition are not well known. This relation was theoretically Investigated for processes whose rates saturate in substrate concentration. The Michaells-Menten reaction mechanism was modified to describe microbial biomass production and metabolite excretion in both batch and continuous reactors. 

Similar affects on biomass production arc reported by Lin and Xing 2008 in the above mentioned study of ryegrass exposed to ZnO nanoparticles and the observed effects could not exclusively be ascribed to the dissolved Zn " ion concentration in the nutrient solution. Conversely, no effects occurred after uptake and distribution of Fc203 nanoparticles in pumpkin plants (Zhu et al. 2008). Hence, the chemical composition of the nanoparticle and/or the plant species plays an important role in this context. 

The situation changes significantly in the case of strains like C. necator, where autocatalytic growth of biomass is followed by a phase of linear PHA production. In this case, biomass production should occur in the first step in a CSTR which is coupled to a subsequent plug flow reactor (PFR). The combination CSTR-PFR not only ensures higher productivity, but also minimizes the loss of substrates and co-substrates. Furthermore, product quality can be enhanced by the fact that the PFR features a narrow residence time distribution, leading to higher uniformity of cell populations. This should also have positive impacts on the distribution of the PHA molecular masses and the composition of polyesters [128]. 

Photobioreactor engineering addresses optimization of the volumetric rate of biomass production, the surface rate of biomass production (with respect to the solar-energy collecting surface), and thermodynamic efficiency of the process as well as biomass composition (ie, the biomass quality). Hereafter, we mainly focus on construction of a predictive model for the volumetric rate (eg, expressed in kg, or moles of dry biomass per second and per m of the reaction volume). This is the main difficulty with assessing performance of a photobioreactor because most of the other parameters of interest can be deduced only from the value of < >, in a... 

Figure 6.51. Diagrammatic representation of a steady-state bioprocess in balance area (reactor) following the macroscopic principle by analyzing elemental composition of significant process variables (substrate, nitrogen source, biomass, product, O2, CO2, H2O). (Adapted from Roels, 1980a.)...

Catalytic Metal-/Bio-composites for Fine Chemicals Derived from Biomass Production... 

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