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In analyzing microbial cellulose utilization, it would be useful to independently measure the mass concentration of cells and cellulase enzymes. Such measurements would allow investigation of the allocation of cellular resources between synthesis of cells and cellulase, in vivo cell- and cellulase-specific cellulose hydrolysis rates, and bioenergetics. Methodological protocols are not established for independent determination of cell and cellulase concentrations for the common case in which a substantial fraction of cellulase is attached to the cell surface. Alternative analytical approaches by which to develop such protocols are examined from the perspective of error minimization. For cell concentration measurement, acceptable accuracy is expected when the concentrations of a cell-specific component (e.g., DNA) is determined or when total protein is determined in conjunction with a measurement specific to cellulase. For cellulase concentration measurement, acceptable accuracy is expected when a measurement specific to cellulase such as ELISA is used. Several analytical approaches are rejected based on large expected errors.

The effects of initial osmotic pressure (IOP) on the production of ginseng polysaeeharide and ginseng saponin were studied in suspension cultures of Panax notoginseng cells. At higher IOP, the specific saponin production and intraceUular carbohydrate storage were increased, while the plant cell volume, the consumption rates of major medium components and the specific cell growth rate were decreased. The specific production of polysaccharide was reduced with an increase of IOP from 4.45 to 5.18 atm, and levelled off at an even higher IOP.

The macroscopic mechanical properties of polyaniline (PANI) lie mainly on two factors, the structure of molecular aggregations of polymers and the mechanical properties of a single polymer chain. The former factor is well revealed; however, the latter is rarely studied. In this article, we have employed atomic force microscopy-based single-molecule force spectroscopy to investigate the mechanical properties of a kind of water-soluble PANI at a single-molecular level. We have carried out the study comparatively on single-chain-stretching experiments of oxidized, reduced, and doped PANI and obtained a full view of the single-chain elasticity of PANI in all these states. It is found that oxidized and reduced PANI chains are rigid, and the oxidized PANI is more rigid than the reduced PANI. Such a difference in single-chain elasticity can be rationalized by the molecular structures that are composed of benzenoid diamine and quinoid diimine in different proportions. The doped PANI has been found to be more flexible than the oxidized and reduced PANI, and the modified freely jointed chain parameters of doped PANI are similar with those of a common flexible-chain polymer. The results have explained the molecular-level origin of the outstanding flexibilities of materials made of doped PANI.

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