ESTUDIO DEL PROCESO DE BIOMECANIZADO. PRESERVACIÓN DE LA CEPA ACIDITHIOBACILLUS FERROOXIDANS

Abstract

Green Machining has emerged as an alternative to the cost-intensive shaping tools. In previous studies, a biomachining process of oxygen-free copper at laboratory scale was design and successfully operated in continuous mode, using the mesophilic and acidophilic bacterium Acidithiobacillus ferrooxidans. In this study, the use of several preservation techniques was tested, in order to maintain backups and reserves of active cells for further use. Thus, freeze drying, freezing and desiccation were tested for the preservation of the ferrous ion-oxidizing bacterium A. ferrooxidans, evaluating cell viability after each preservation procedure. Regarding freeze drying, the influence of the primary drying duration (12 vs. 35 hours) and the addition of four different cryoprotectants on the process were studied. Freezing was carried out both in commercial cyovials and in Eppendorf tubes, and the influence of adding a cryoprotactant was tested. In addition, cell viability after short (4 days) and middle-term (28 days) storage was evaluated. Finally, desiccation was carried out at 30 ºC for 24 hours. It was concluded that freezing is the preservation technique that ensures higher Acidithiobacillus ferrooxidans viability after storage.