Notes

The organism must be able to grow in a simple medium and should preferably not require growth factors (i.e. pre-formed vitamins, nucleotides, and acids) outside those which may be present in the industrial medium in which it is grown. It is obvious that extraneous additional growth factors may increase the cost of the fermentation and hence that of the finished product.ii. The organism should be able to grow vigorously and rapidly in the medium in use. A slow growing organism, regardless of its efficiency in terms of the production of the target material, could be a liability. In the first place, the slow rate of growth exposes it to a greater risk of contamination in comparison to other equally effective producers which are faster growers. Second, the rate of the turnover of the production of the desired material is lower in a slower growing organism, and hence capital and personnel are tied up for longer periods with consequently lower profits. iii. Not only should the organism grow rapidly, but it should also produce the desired materials, whether they be cells or metabolic products, in as short a time as possible for reasons given above.iv. Its end products should not include toxic and other undesirable materials, especially if these end products are for internal consumption.