Factors Affecting BNC Production

The effectiveness of microbial cellulose production depends mainly on the strain, the composition of the culture medium (the C source used being very significant), the fermentation temperature, oxygen supply, and the implementation of static or agitated systems. The cost of the media is an important factor for cost-effective BNC production, and therefore its composition and volume as well as the fermenter surface area should all be considered. 

Culture media for any fermentation process must include a balanced proportion of all the elements required by the microorganisms for their growth and for the obtention of the desired products. For submerged fermentations, they basically consist in water (the major component) solutions of macro and micronutrients, as well as other elements that may be needed by 

C source+ N source+ + minerals + specific nutrients — biomass + products +CO +H O 

Strong aeration that influences the BNC production of these strictly aerobic bacteria also brings significant changes in the supraorganization of cellulose chains, as amorphous cellulose II is formed instead of ribbon-like polymers as cellulose I [17]. 

Although in a general sense a large inoculum is another factor recommended, mainly for large-scale BNC processes [17], Zeng et al. reported that inoculum size (3% v/v to 9% v/v) did not affect the polymer production by A. xylinum according to statistical optimization studies performed in agitated fermentations. Also, Ruka et al. reported that cellulose production was not affected by the inoculum volume (0.25% v/v to 1.0% v/v) when G. xylinus was statically incubated in HS medium [15,27]. 

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