Solid-state culture of Azospirillum brasilense: a reliable technology for biofertilizer production from laboratory to pilot scale

摘要

A biofertilizer of Azospirillum brasilense was produced in solid-state culture (SSC) from laboratory to pilot scale. Similar operation conditions (continuous aeration and mild intermittent mixing) and two dimensionless numbers with similar L/D ratio and a similar working volume were applied to reach a scale-up factor of 75. An innovative bioreactor with rotating helical ribbons (15 kg wet matter) was used at pilot scale. A mathematical model was proposed and validated to evaluate the respirometry trends at laboratory and pilot scale exhibiting similar behavior. The cell viability was (1.3 +/- 0.4) x 10(9) and (1.3 +/- 0.3) x 10(9) colony-forming units per gram of initial dry mass at laboratory and pilot scale, at 36 and 43 h, respectively. A. brasilense maintains its viability twelve months of storage at 4 and 30 degrees C. This is the first report of A. brasilense being cultivated in SSC under controlled conditions. SSC processes involving unicellular microorganisms with tolerance to agitation are a promising technology to produce biofertilizers. Graphic abstract