The cost of the enzymes for enzymatic hydrolysis of cellulosic biomass is clearly the critical parameter from an economic point of view. Most of the industrial enzymes are produced by organisms isolated from natural sources by a labor intensive, unpredictable classical screening, strain selection, medium optimization for over production, fermentation and recovery process development. Screening of naturally occurring

microorganisms still may be the best way to obtain new strains and/or enzymes for commercial applications (60). Fundamental tasks and strategies for commercial development of an enzyme from natural sources are shown in Figure 2. Recombinant DNA technology and protein engineering have also proven as effective means of production of industrial enzymes (61). The marketing of all enzymes is subject to a

Screening for microorganisms

I

Culture selection

1

Fermentation studies (preliminary)

I

Isolation, purification and final characterization

I

Evaluation

II

Toxicology

1

Regulatory agency

Improvement of fermentation and recovery process
development

I

Product formulation

II

Marketing

Figure 2. Strategies for commercial development of an enzyme

variety of Federal laws and regulations. The generally recognized as safe (GRAS) status of an industrial enzyme depends on the source of its origin. Federal laws, regulations and policies that have an impact on industrial enzymes have been reviewed by Fordham and Block (62).