My view of bioprocessing is influenced by a career-long interest in gut fermentation. My Masters research and my PhD were on the biochemistry and microbiology of silage fermentation. Silage of course is the fermentation of plant materials usually by naturally-occurring bacteria, although inoculants of lactic acid bacteria, such as
Lactobacillus plantarum
are increasingly being used to make silage these days. Depending on the environmental conditions imposed on the plant material (e.g. anaerobic conditions, moisture content, sugar content), the mixed culture fermentation could be shifted to produce predominantly lactic acid, rather than acetic and butyric acids which tended to dominate if the silage was badly made. Silage is but one example of a number of products made by natural mixed culture processes, where the quality of the product is determined by the conditions imposed on the process, and the nature of the original substrate. Other examples include wine, cider and beer fermentations, cheese manufacture, and a variety of fermented milks. There are a large number of traditional food and beverage fermentations continuing to be used particularly in tropical countries, where acidification by lactic acid production is an important form of preservation of the food or beverage, in the absence of refrigeration. These processes, many very ancient, are all forms of bioprocessing. They appear relatively uncontrolled and irreproducible, but this is not the case, as they have been optimised over time, and the critical control points acknowledged by trial and error...
