Optimization of bagasse, nutrients and initial moisture ratios on the yield of penicillin in solid-state fermentation

An advanced solid-state fermentation (SSF) system (liquid medium absorbed o n an inert support) has been applied to antibiotic production. The main com ponents of this solid medium are: support (sugarcane bagasse), nutrients an d water. The first two are solids and have to be considered to calculate th e initial moisture content (IMC) of the medium. Earlier work indicated the importance of using high IMCs and concentrated media to obtain high penicil lin yields in SSF. Nevertheless, the present work shows that high values of IMC or nutrients content can stimulate or inhibit penicillin production, d epending on the strategy used to compensate this change (i.e. the proportio ns of the other two components). Conversely, increasing bagasse content alw ays showed an inhibitory effect on the production. Since penicillin product ion depends on the combinations of these components, a global approach was used. The effect of the proportions of the three components on penicillin p roduction was studied by means of a triangle of combinations and a 3D graph . It was possible to establish that high penicillin production is only obta ined in a zone of low support content (10-12.5%). Surprisingly, one product ion maximum was observed in a zone of low moisture and high nutrients conte nt (62 and 25.5% respectively); and another one in a zone of high moisture and a relatively low nutrients concentration (75.5 and 12.4% respectively).